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DIGITAL PRESSURE CONTROLLER

1. 2 5 TABLE 3 1 GENERAL SPECIFICATIONS GENERAL 3 TABLE 6 15 ELECTRONICS SELF TEST 6 2 TABLE A 1 PERFORMANCE 6 xii INTRODUCTION SECTION 1 0 GENERAL INFORMATION 1 1 INTRODUCTION This manual contains operation and routine and preventive maintenance instructions for the Model 7252 Digital Pressure Controller DPC manufactured by Ruska Instrument Corporation Houston Texas This section of the manual provides general information about the DPC and presents its features and options 1 2 GENERAL INFORMATION The Ruska Model 7252 DPC uses force balanced fused quartz Bourdon tube technology to provide the precise measurement of pressure During normal operation the DPC performs in either Measure mode or Control mode In Control mode the DPC simultaneously measures and controls pressure Control mode is commonly used in the calibration and testing of pressure gauges transducers pressure switches and production pressure instruments In Measure mode the DPC measures pressure Typically Measure mode applications are found in research laboratories wind tunnel testing power plant testing and bubbler tank volume accountancy systems It is also used to monitor barometric pressures vacuum systems and differential pressure devices The 7252 has two full scale pressure ranges and two pressure controllers integrated i
2. Get error message cprintf buffer return retval y write 7000 write a command to the 7250 xy NS void write 7000 char s ibwrt device 5 strlen s as Xy request 7000 write a query command and read the response void request 7000 char s ibwrt device 5 strlen s ibrd device buffer sizeof buffer 5 6 3 SAMPLE PROGRAM 3 7250 SERIAL RS 232 CONTROLS PRESSURE 20 000 FS Sample Program 3 7250 Serial RS 232 y Controls pressure to 20 000 5 E REMOTE OPERATION 5 16 define TRU define FAL include lt stdio h gt include lt stdlib h gt include lt conio h gt include lt dos h gt include lt time h gt 1 E 0 ca pH define TIMEOUT CLK TCK 5 5 second timeout define XON 0 11 define XOFF 0x13 define CLEAR 0x03 define DLE 0x10 define QUEUE SIZE 1024 char buffer QUEUE SIZE buffer for input output strin do in in in in VO ch in in VO in uble pressure Pressure read from unit status Status register from unit address portbase intnum atile int transmit enabled TRUI r inqueue QUEUE SIZE inq in inq out d interrupt old vector check errors void void serial initialize void void write
3. PU DE 5 3 5 4 3 ANSI IEEE 488 2 1987 COMMAND SUMMARY 5 4 5 4 4 SCPI COMMAND SUMMARY ser or da en tre ias 5 4 5 4 5 55 5 556 Lb es 5 8 5456 SCPIESTATUS REGISTERS 5 9 SERIAL 5 11 SAMPLE 65 5 11 5 6 1 SAMPLE PROGRAM 1 7252 GPIB IEEE 488 CONTROLS PRESSURE 20 000 ES 2e bere CERO 5 11 5 6 2 SAMPLE PROGRAM 2 7252 GPIB IEEE 488 ZERO SEQUENCE 5 13 5 6 3 SAMPLE PROGRAM 3 7252 SERIAL RS 232 CONTROLS PRESSURE 20 000 FS 5 17 5 6 4 SAMPLE PROGRAM 4 QBASIC EXAMPLE FOR 7252 5 21 SECTION 6 0 MAINTENANCE INTRODUCTION eicere due 6 1 OBSERVING THE SOFTWARE VERSION 6 1 PREVENTIVE 6 1 6 3 INITIATING THE DPC S SELF TEST Veo ed eoe tre er rtr quen 6 1 6 3 2 REMOVING THE DPC S COVER 6 2 6 3 3 MOISTURE FILTER roo tints eie d e Ey eoe Nun 6 2 PARTICLE FILTERS t ri da Etico PEE 6 2 6 3 5 VACUUM PUMP S pru S v etl eque 6 2 6 3 6 PROCESSOR BATTERY da iit eec nde eta Pede 6 3 CALIBRATION erit
4. To access the Calibration screen from the Main Menu select MODE MENU CALIBRATE Select the atmospheric sensor by pressing the Sensor F6 key until the words Vacuum Sensor A or B is displayed above the calibration coefficients To begin the calibration process press CALIBRATE If the calibration access code is enabled enter it at the prompt The first Calibration screen will appear You will use the calibration standard to apply the two vacuum points on the vacuum sensor The Actual value will be highlighted This is your first pressure point in the calibration procedure This calibration requires the generation of two pressures within the range of 50 to 350 mtorr absolute The selected pressures should be spaced as far apart as possible within the allowable range Generate the first pressure Enter the actual value of the applied pressure generated by the standard and press ENTER Generate the second pressure Enter the actual value of the applied pressure generated by the standard and press ENTER The Vacuum sensor is now linearly compensated Once the calibration procedure is complete the user should verify several pressure readings against the pressure standard If there are variances beyond the stated precision then an error was probably made in generating one of the calibration pressures and the calibration procedure should be repeated If the instrument is fitted with two vacuum sensor calibr
5. Step 7 Step 8 From the Main Menu use the numeric keypad to enter the starting pressure The pressure is entered in the units set in the previous exercise As the pressure is entered each digit will be displayed in the numeric scratchpad the highlighted box in the lower section of the display If a mistake is made press the CLEAR key found in the numeric keypad and the numeric scratchpad will be cleared Setpoint Step Jog Step CHANNEL A MAIN MENU When the entry is correct press the ENTER key The scratchpad will be cleared and the value will appear as the new set point Now that the starting pressure is entered enter Control mode Press Control the F2 key The CONTROL label will be highlight and the message Press Enter to Confirm will appear below the scratch pad Notice that the upper left corner still shows MEASURE The DPC stays in Measure mode until the change is confirmed Press ENTER to confirm the mode change The upper left corner will change to CONTROL and the pressure will start moving towards the set point After the pressure is stabilized assure that the word Step is highlighted in the Step Jog the F5 key The Step Jog the F5 key toggles between Step and Jog to switch between these modes press the function key 5 F5 In addition to using the key pad to enter a pressure set point you can also use the step function Using the rotary knob rotate the knob clock wise to inc
6. Verify that the DPC has been at stable environmental temperature and that the oven temperature MODE MENU DISPLAY has been stable for at least three hours 4 Verify that the DPC is in Measure mode Section 4 0 If desired change the DPC s units of measure Section 4 0 to match those of the calibration standard Set the gas head to 0 Select MODE MENU SETUP USER To access the calibration screen select MODE MENU CALIBRATION Primary Co 110 00 psi 272 Calibrate COL 288 HOZ 280 507 0 0000176 12870 K10 328 K11 0 0000200 K12 344 Last Zero 0000 00 00 00 00 00 Last Calibrate 0000 00 00 00 00 00 Sensor 8 When you first enter the Calibration menu the top left hand side of the display will indicate which sensor is being the viewed The sensors coefficients are then shown below the sensor label On the 7252 there are two primary sensors The first sensor that is shown is the primary measuring sensor A This is indicated by the word A Primary displayed in the top of the display To cycle through the various sensors that exist in the system you would press the Sensor F6 function key Assure that you are in the screen that is labeled A Primary or B Primary depending on which channel is being calibrated 9 To begin the calibration process press the Calibrate F2 button If the calibration access code is enabled enter it at the prompt The first calibration screen will
7. device ibdev 4 NO SAD 15 0 REOS LF ERR if ibsta amp cprintf return ERA Tu if zero ibonl device return 0 Pressure read from unit Status register from unit First GPIB Board GPIB Address of 7250 No secondary addressing 1 Second Timeout No automatic EOI for transmit Terminate read on Line Feed GPIB Driver not installed n int zero void int cstat pstat tstat rstat Glirser lt 4 cprintf Zeroing 1 1 23 6 gotoxy gotoxy cprintf cprintf perform zero adjust of 7250 Pressure Reading Sensor Temperature gotoxy 1 7 cprintf Referenc Enter Zero Mode CAL ZERO INIT write 7000 CAL ZERO INIT n REMOTE OPERATION Pressure 5 14 f Wait for calibration values to be within limits CAL ZERO INIT rc SSeS 2122 if kbhit getch break request 7000 CAL ZERO INIT n sscanf buffer d d d d amp cstat amp pstat amp tstat amp rstat if check errors return 0 gotoxy 20 5 if pstat 0 cprintf Stable Ty else if pstat 0 cprintf Out of Range ys else if pstat 0 cprintf Unstable 2d seconds pstat gotoxy 20 6 if tstat 0 cprintf
8. 4 7 LOCAL OPERATION 4 3 1 SETTING THE PRESSURE SET POINT The pressure set point is the destination of the pressure control algorithm It should be set before entering Control mode The pressure set point is set to zero at power up or whenever a pressure error occurs 1 The pressure set point can be set from the dual display menu or the Main Menu of the single channel mode On the dual channel display mode use the rotary knob to select which channels set point is being edited 2 Use the numeric keypad to enter the new pressure set point in the current pressure units 3 Press ENTER to accept the entry or press CLEAR to clear the numeric scratchpad NOTE The set point can also be changed using either the Step or the Jog function Please see Section 4 5 4 3 2 ENTERING EXITING CONTROL MODE 1 The Control mode is set from the Main Menu Press PREVIOUS until the Main Menu appears 2 Press CONTROL F2 to enter Control mode ENTER must be pressed to confirm entry into Control mode Note that any entry in the numeric scratchpad will also be taken as the new pressure set point On DPC s with full scale pressure ranges less than 1000 psi 6 9 MPa the DPC controls its internal pressure to the test port pressure before opening the isolation valve and entering the Control mode During this period the Control mode indicator flashes 3 Press MEASURE key found in the keypad to exit Control mode No confirmation is necessa
9. inqueue inq ch if inq in QUEUE SIZE inq in 0 outportb 0x20 0x20 serial initialize initialize serial port Ky My void serial initialize char msg 10 int divisor unsigned v portbase Ox3F8 COMI Ox3F8 COM2 Ox2F8 intnum 4 COMI 4 COM2 3 outportb portbase 3 0x80 outportb portbase 1 0 outportb portbase 0x0C 9600 Baud outportb portbase 3 3 8 Databits No Parity 1 Stopbit old vector getvect intnum 8 Save old interrupt vector setvect intnum 8 serial int Set new interrupt vector v inportb 0x21 Enable interrupt V amp 1 lt lt intnum outportb 0x21 v outportb portbase 1 0x01 Enable receive interrupt outportb portbase 4 0x0B Enable Interrupt DTR RTS CLEAR serial write 5 19 REMOTE OPERATION serial close turn off serial receive interrupt void serial close unsigned outportb portbase 1 0 outportb portbase 4 0 v inportb 0x21 v 1 lt lt intnum outportb 0x21 v setvect intnum 8 old vector mme Se ee m a SS See Vea cases eee serial write write single character to serial port por RR PEU PUMP Wer Up ee RUM V IUE MP DERE MN ult while
10. transmit_enabled while inportb portbase 5 amp 0x20 0 outportb portbase ch muLIIILLILILIBcLIlzlllullllllLacclicullaeldllalllencucllcllaellllLzllhlccLclclocucc write 7000 serial write a string to the correct 7250 Xp crc EE Dc ET ER Tn ERN void write 7000 serial char s if address 1 serial write CLEAR Disable Addressing else serial write DLE Enable Addressing serial write address 0x20 Address while s Write string serial write 5 ai request 7000 serial write a commmand and read the respons Ey Se eA eee int request 7000 serial char s char ch clock_t start current write 7000 serial 5 Write Command 0 while i lt QUEUE SIZE 1 start clock while inq in inq out Wait for a character current clock if current start current CLK 86400 if current start TIMEOUT Check for timeout buffer i 0 return FALSE REMOTE OPERATION 5 20 ch xf if els buffer Q return F inqueue inq out inq out ch Ox buffer return 1 UEUE SIZE ALSE ing out Put character in buffer QUEUE_SIZE 0
11. 1997 by Ruska Instrument Corporation All rights reserved This document may not be reproduced in part or in whole without the express written consent of Ruska Instrument Corporation DISCLAIMER No representations or warranties are made with respect to the contents of this user s manual Further Ruska Instrument Corporation reserves the right to revise this manual and to make changes from time to time in the content hereof without obligation to notify any person of such revision TRADEMARK NOTICE P M RUSKA is a registered trademark of Ruska Instrument Corporation Trademarks or tradenames are subject to state and federal laws concerning their unauthorized use or other infringements The fact that the product marks or names in this manual do not bear a trademark symbol DOES NOT mean that the product name or mark is not registered as a trademark or tradename Any queries concerning the ownership or existence of any trademarks or tradenames mentioned in this manual should be independently confirmed with the manufacturer or distributor of the product iii INTRODUCTION REVISION NOTICE RELEASE REV DATE OF DESCRIPTION NUMBER RELEASE 7252 1D01 A 09 16 03 Original release See DC RO 23958 INTRODUCTION REVISION HISTORY RELEASE 7252 1D01 Revision A 09 16 03 Original release See DC RO 23958 INTRODUCTION 7252 Change Language Hold key for 5 seconds Misure 0 000 D
12. 2 Use the rotary knob to highlight the desired parameter 3 Use the numeric keypad to enter the address use the rotary knob to change the other parameters The ENTER key must be pressed after entering the address REMOTE OPERATION 5 2 4 Repeat steps 2 and 3 to set all parameters needed 5 4 DEVICE MESSAGES 5 4 1 SCPI COMMAND FORMAT SCPI mnemonics have two forms long and short The short form is all in capital letters The long form is the entire mnemonic Commands may use either the short form or the entire long form No other forms are accepted SCPI ignores case uppercase and lowercase are equivalent SCPI command is made by following the command tree as presented in the command summary Each level adds a mnemonic to the command separated by colons Mnemonics enclosed in square brackets are optional and may be omitted Some mnemonics are followed by an optional numeric suffix If omitted the suffix defaults to 1 Multiple commands may be placed in a single message separated by semicolons Each command starts at the same level of tree where the last command stopped unless the command starts with a colon The first command in a message and any commands starting with a colon start at the root of the command tree IEEE 488 2 commands may occur between SCPI commands without affecting the tree level Command parameters are separated from the command name by one or more spaces Multiple parameters are separated by com
13. Check for GPIB Interface Errors if ibsta amp ERR printf GPIB Status 4X Error d n return 1 ies Check for 7250 Errors retval 0 while kbhit ibrsp device amp status7 Serial poll if status7 amp 4 0 Check error bit break retval 1 request 7000 SYST ERR Nn Get error message printf buffer return retval RE d 6226 write 7000 write a command to the 7250 x Nu void write 7000 char s ibwrt device 5 strlen s ft request 7000 write a query command and read the response void request 7000 char s ibwrt device 5 strlen s ibrd device buffer sizeof buffer xy 5 6 2 SAMPLE PROGRAM 2 7250 GPIB IEEE 488 ZERO SEQUENCE Jp Sample Program 2 7250 GPIB IEEE 488 Xy KY Zero Sequence EA include lt stdio h gt include lt stdlib h gt include lt string h gt include lt conio h gt include decl h yy int device GPIB Device descriptor char buffer 256 buffer for input output strings 5 13 REMOTE OPERATION double pressure int status int void TUE void void check errors zero void write 7000 char s request 7000 char s void main void char p Initialize GPIB Interface
14. 0 Line Feed End of response i 0 TRUE ch Sh vas 0 Buffer full 5 6 4 SAMPLE PROGRAM 4 QBASIC EXAMPLE FOR 7250 E C GP REM SINCLUD DIM READING CALL IBDEV CALL IBCLR CALL IBWRT CALL IBRD R PRINT READI CALL IBONL END AS STRIN 0 4 0 12 R7010 7010 REA NG R7010 0 IB PC QBDECL BAS G 30 1 amp H40A R7010 R7010 MEAS chr amp H0A DINGS Note EOM amp EOS are linefeed 5 21 REMOTE OPERATION THIS PAGE INTENTIONALLY LEFT BLANK REMOTE OPERATION 5 22 SECTION 6 0 MAINTENANCE 6 1 INTRODUCTION Very little maintenance is required for the DPC This section of the manual discusses suggested maintenance procedures 6 2 OBSERVING THE SOFTWARE VERSION NUMBER Follow the steps below to observe the DPC s software version number 1 If necessary press PREVIOUS several times to return the display to the Main Menu 2 Select MODE MENU SETUP SYSTEM The software version number will appear on the screen 3 Press PREVIOUS to return to the previous screen 6 3 PREVENTIVE MAINTENANCE Although the DPC is designed to be nearly maintenance free occasional preventive maintenance is required to keep the DPC s performance optimal 6 3 1 INITIATING THE DPC S SELF TEST To test the DPC s hardware and software follow the steps below 1 If necessary press PREVIOUS several times to retur
15. 4 6 5 MENU DISPLAY The Menu Display is used to conveniently monitor most of the sensor output parameters It is primarily used for troubleshooting This display screen shows all available sensor readings from both channels LOCAL OPERATION 4 28 CHANNEL A MENU DISPLAY MENU 4 6 5 1 Menu Display Blank This is used as a screen saver in the 7252 4 29 LOCAL OPERATION THIS PAGE INTENTIONLLY LEFT BLANK LOCAL OPERATION 4 30 SECTION 5 0 REMOTE OPERATION 5 1 CAPABILITIES The DPC can be operated remotely by a computer Two interfaces are supported IEEE 488 and RS 232 Both interfaces support SCPI Standard Commands for Programmable Instruments The IEEE 488 interface additionally supports emulation of a Ruska Single Channel Interface Panel Models 6005 701 and 6005 761 The IEEE 488 interface conforms to the following standards ANSI IEEE Std 488 1 1987 IEEE Standard Digital Interface for Programmable Instrumentation ANSI IEEE Std 488 2 1987 IEEE Standard Codes Formats Protocols CommonCommands SCPI 1991 0 Standard Commands for Programmable Instruments 5 1 1 488 The following identification codes define the interface capabilities of the DPC Identification codes are described in the IEEE 488 standard SH1 Source Handshake Complete Capability 1 Acceptor Handshake Complete Capability T5 Talker L3 Listener SRI Service Request Complete Capability RL1 Remote Local Complete Capability
16. 6 3 1 Preparing fo Program caet eret 4 19 4 6 3 2 Entering a New Program ioris tae et e tides 4 20 4 6 3 3 Automatically Generating a Program 4 21 4 6 3 4 Changing the Name of a 4 22 4 6 3 5 Changing an Existing Program octets 4 23 4 6 3 6 Changing the Configuration Stored with a Program 4 24 4 6 3 7 Running a Program 4 25 4 25 4 6 4 1 Menu Test Sweep 4 26 4 6 4 2 Menu Test Sell Test ores eroe toros 4 27 4 6 4 3 Menu Test Remote 4 27 4 6 4 4 Menu Test Shop 4 27 4 6 4 5 Menu Test Control 4 28 DISPLAY 4 26 4 6 5 1 Menu Display Blank 4 29 INTRODUCTION SECTION 5 0 REMOTE OPERATION 5 1 5 2 5 3 5 4 5 5 5 6 6 1 6 2 6 3 6 4 CAPABILITIES 5 1 ae ete b P etu 5 1 85 232 Auri RUE o dr rti ERE At ate ee 5 REMOTE LOCAL 5 2 sei EIER EUER ERR ER UE EU 5 2 DEVICE MESSAGES s e erra ed eta e v C HD p RO OR E S 5 3 5 4 1 SCPI COMMAND FORMAT 5 3 5 4 2 SCPERESPORNSE FORMAT ect tesi SU
17. 7000 serial char s void serial close void int request 7000 serial char s void serial write char ch gs void main void char Le Initialize Serial Interface gcc TEM a es address 4 serial initialize Reese Ung cines soe esse ees sew ese Initialize 7250 Interface pm UNIT FS Set units to percent of full scale PRES 20 0 Set control setpoint to 20 5 PRES TOL 0 001 Set control tolerance to 0 001 FS OUTP MODE CONTROL Enter control mode BS el O Oe i IUe ro ie ee write 7000 serial UNIT FS PRES 20 0 TOL 0 001 OUTP MODE if check errors 5 17 REMOTE OPERATION Tur XE CONTROL n serial close return E EE er ed me er ie ee es T E RE Read pressure status until setpoint is reached es ih MEAS Read pressure X COND Read status setpoint n ee acs Ge e cas EE es ee an oe ee EO E ee ee eee while kbhit if request 7000 serial MEAS STAT OPER COND n printf Timeout n continue pressure strtod buffer amp p status atoi p if check errors continue if status amp 0x10 printf Pressure 9 31f n pressure
18. DPC will generate an Oven Control Failure error messages The operator can review the temperature and duty cycle of the oven by pressing the MENU DISPLAY keys The unit must be have been warmed up for a minimum of 3 hours prior to determining the condition of the oven temperature control The temperature of the sensor should be controlled to 50 C The Duty Cycle indicates the amount of time in units of percentage that the oven control is turned on in order to maintain the oven at the proper set point of 50 C A unit that is operating properly after it has fully warmed up should indicate a sensor temperature of 50 C and a duty cycle between 10 to 90 If operating the instrument in a very cold environment and the oven duty cycle is at a high percentage gt 90 you will need to turn the fan off If you are operating in a warm environment or when multiple systems are housed in consoles without adequate ventilation the system may become too hot and generate the oven control failure error message If operating the instrument in a warm environment and the oven duty cycle is at a low percentage gt 10 you will need to turn the fan on See Section 6 7 for fan operation When the operator changes the status of the fan it will remain in that condition until the operator changes the setting MENU DISPLY MENU 2 7 1 5 Pressure Reading and Correction The sensor s analog output is processed by an analog to digital circuit that results
19. It also stops the current program sequence or calibration process PREVIOUS key exits the current menu and returns to the previous menu Figure 4 2 is a menu tree showing the relationship between all the menus in the system Refer to it for selections available under the menu To move to a lower menu press the function key with the correct label move towards the main menu press the PREVIOUS key In the Single channel Main Menu screen the F2 key places the unit in Control mode ENTER must be pressed to actually enter the Control mode 4 1 LOCAL OPERATION Limits gt User gt Units Remote gt System gt Zero gt Program gt 1 gt Delete gt Config gt Edit gt ne JEN Sweep JN Vu d E Control gt Enter Menu State Enter Setup Menu Set high low amp slew limits control mode control band and access code Set step size head correction filter and display digits Define user defined units of measure Set baud parity data bits stop bits GPIB address Set date and time reset machine view software version Enter calibrate menu Zero Sensor Enter Program menu Run programmed test sequences Delete a saved program Change the configuration of a program Limit slew etc Edit program instruction pressure tolerance dwell etc Change program name Enter Test menu Sweep pressu
20. Menu appears press Menu F6 then Test F5 and then Sweep F2 3 Enter the high and low pressure points the control tolerance dwell time and the number of cycles Sweep Cycle 0 Timer 0 Pressure Low psi Pressure High 0 00 Continue Tolerance 0 00 Dwell 0 seconds Cycles CHANNEL A MENU TEST SWEEP MENU 4 Press Run F2 to initiate the test 5 To pause the program press Pause F3 Pause will now be highlighted and the DPC will continue controlling to the current set point The DPC will maintain control of the current set point until further instructions from the user Press Continue F4 to resume the program LOCAL OPERATION 4 26 6 To stop the program press Stop F5 The program will stop running but the DPC will continue controlling to the current set point 4 6 4 2 Menu Test Self Test The DPC can perform electrical and pneumatic self test to assist in trouble shooting potential problems Please refer to the Maintenance Section 6 0 for more details NOTE In order to perform a pneumatic self test the supply port must be connected to a properly set supply pressure and the test port not open to atmosphere For absolute units a vacuum supply must also be connected to the exhaust port 4 6 4 3 Menu Test Remote Test The Menu Test Remote section of the system is used to perform a number of the diagnostic functions on the remote interface It can be used to display the transmitted and re
21. PPO Parallel Poll No Capability Device Clear Complete Capability DTO Device Trigger No Capability CO Controller No Capability The IEEE 488 interface is installed next to the processor board The interface is identified by the IEEE 488 standard connector on the back panel of the unit NOTE Do not change any jumpers or switch settings on the IEEE 488 interface board The IEEE 488 address is set by the MENU SETUP REMOTE screen 5 1 2 RS 232 The RS 232 interface supports standard serial operation from a computer to a single DPC RS 232 supports the IEEE 488 2 5 commands The DPC allows the following port setups Baud Rate 1200 2400 9600 or 19200 Data Bits 7 or 8 Parity Even Odd or None Stop Bits 2 Handshaking XON XOFF 5 1 The RS 232 connection is DB 9P connector found the back panel of the DPC It is located on the processor board The following pins are used all other pins are reserved Pin Direction Signal 2 In RXD Receive Data 3 Out TXD Transmit Data 5 GND Ground 7 Out RTS Request to Send 5 2 REMOTE LOCAL OPERATION In Local mode the DPC is operated manually through the front panel Section 4 0 covers local operation The DPC always powers up in the Local mode In Remote mode the DPC is operated by a computer connected to an interface Most functions that can be performed in Local mode can also be performed remotely Remote mode does n
22. REMOTE OPERATION EVENT CONDition ENABle number QUEStionable EVENT CONDition ENABlIe PRESet SYSTem BEEPer lt freq gt lt length gt DATE lt year gt lt month gt lt day gt ERRor ON OFF 1 0 TIME lt hour gt lt minute gt lt sec gt VERSion LANGuage COMP 6000 SCPI PRESet COMMunicate SERial RECeive TRANsmit BAUD lt number gt PARITY EVEN ODD NONE BITS 78 SBITs 1 2 GPIB ADDRess number TEST ELECtronic PNEumatic PNEumatic 5 UNIT DEFine lt n gt lt name gt lt number gt LENGth MMIIN PRESsure lt name gt TEMPerature C CEL F FAR K 5 4 5 EXAMPLE SCPI COMMANDS read clear operation event register read operation condition register set operation enable mask read clear questionable event register read questionable condition register set questionable enable mask clear enable masks lt Freq gt ignored system date returns lt error descr info gt or 0 No Error keyboard lock system time SCPI protocol version returns 1991 0 set interface emulation reset pressure control Run Elec Self Test amp Return Result Start Pneu Self Test Get Pneu Test Results Abort Pneu Volume or Leak Create Unit set length units set pressure units set temperature units To request the current pressure reading all of the following commands are equivalent MEASURE PRESSURE measure pressure MeASUrE pReSsUr
23. Stable else if tstat 0 cprintf Out of Range else if tstat 0 cprintf Unstable 2d minutes tstat gotoxy 20 7 if rstat 0 cprintf Stable else if rstat 0 cprintf Out of Range else if rstat 0 cprintf Unstable 2d seconds rstat while pstat 0 tstat 0 rstat 0 fo Se eee SS Start Zero Adjust CAL ZERO RUN s write 7000 CAL ZERO RUN n ee See Wait for zero to complete COND request 7000 STAT OPER COND n sscanf buffer Sd amp status if check errors return 0 gotoxy 1 9 cprintf Zeroing while status amp 1 0 gotoxy 1 9 cprintf Zero Complete return 1 5 15 REMOTE OPERATION check errors display all GPIB and 7250 error messages return TRUE if any errors were found as Xy int check errors void unsigned char status7 int retval Check for GPIB Interface Errors if ibsta amp ERR cprintf GPIB Status 4X Error d r n ibsta iberr return 1 5 Check for 7250 Errors 5 retval 0 while kbhit ibrsp device amp status7 Serial poll if status7 amp 4 0 Check error bit break retval 1 request 7000 SYST ERR n
24. The operator can then read the higher resolution DPC to determine the actual pressure value when the mechanical gauge is indicating a cardinal point The Step Jog the F5 key toggles between Step and Jog to switch between these modes press the function key 5 F5 4 5 1 STEPPING Assure that the word Step is highlighted in the Step Jog the F5 key Using the rotary knob rotate the knob clock wise to increase the set point or counter clock wise to decrease the controller set point The scratchpad will be updated to a new set point The step size defaults to 10 of full scale Press ENTER to accept the new set point 4 5 1 1 Setting Step Size From the Main Menu press Menu F6 Setup F2 and then User F2 Using the rotary knob move the cursor to highlight Step Size Enter the desired step size in the current pressure units and press ENTER 4 5 2 JOGGING Assure that the word Jog is highlighted in the Step Jog the F5 key From the Main Menu the pressure set point can be modified by rotating the rotary knob clockwise to increase pressure and counterclockwise to decrease pressure Each increment or decrement will change the pressure in the least significant digit Continually rotating the rotary knob the pressure will continue to change until the rotation is stopped 4 6 MENU The menu key is used to access the less commonly accessed configuration type functions This accesses the Setup Calibration Program Test and Displa
25. Tolerance Each set point in the program requires both a pressure and a tolerance in the current units of measure For example one set point might require a tolerance as low as 0 05 psi 0 35 kPa whereas another set point in the same program could be satisfied with a tolerance as high as 5 psi 0 35 kPa Dwell Time Once the pressure is within the specified tolerance the DPC starts a timer that runs for a user defined number of seconds This is referred to as dwell time As long as this timer is running the DPC will remain at the designated set point unless the max time see below elapses When the dwell time expires the DPC will proceed to the next step Typically the dwell time should be set to a value less than the max time Usually dwell time has a value of a few seconds but a value of can be used to create a pause in the program When the dwell time is set to zero the DPC switches to manual control once it is within the tolerance value of the set point pressure The user must then press a key on the front panel to continue the program MaxTime The max time is the maximum time in seconds including the dwell time that the DPC can spend on one step of the program After the max time elapses the DPC will automatically proceed to the next set point in the program even if the current set point has not been achieved Thus the max time selection limits the amount of time that the DPC can spend on any one set point Typically the max ti
26. and connected to the reference port of the DUT The test port of the DUT must be connected to the bell jar with a cutoff valve to isolate it from the DUT Additionally there must be a cutoff valve located between the Vacuum pump and the bell jar Close the Cut off valve to isolate the DUT test port from the bell jar Open the Vacuum Pump Valve to pull a hard vacuum on the bell jar to seal the bell jar and to float the masses Once the masses have risen in response to evacuation of the bell jar close the reference vacuum pump cutoff valve Use the metering valve on the bell jar to adjust vent the bell jar vacuum towards atmosphere until the masses begin to float Close the metering valve as soon as the masses begin to float Open the bell jar cutoff valve to the test port of the DUT close the exhaust Vent valve and use the pressure adjuster handwheel to adjust float position of the deadweight gauge to float the piston at mid float position 6 4 3 RPT CALIBRATION SIMULATED ABSOLUTE 6 7 MAINTENANCE span correction be applied to the RPT barometric sensor This correction is done using the DPC software and can be performed without removing the RPT from the DPC chassis 1 2 10 11 12 Place the in Measure mode Remove all pressure sources from the system Connect a pressure standard to the Reference Port of the DPC Note on the 7252 there are two reference ports Typically the RPT is connected to the t
27. appear NOTE To exit the calibration procedure before the calibration coefficients have been changed press CANCEL any time during the procedure Canceling restores all previous calibration values MAINTENANCE 6 4 Step 1 1 1 The first step automatically performs the sensor zeroing routing 1 2 Wait until the zero procedure finishes This may take several minutes When the DPC completes step 1 the calibration screen will appear On High Pressure Models pressure must be removed from the test port If zeroing an Absolute unit then the Test Port must be isolated Step 2 1 1 To begin step 2 use the calibration standard to apply the various pressures that will be requested by the 7252 The number of pressure points required to calibrate the DPC will vary based on whether the DPC is a 7252 or 7252 and if it has a vacuum negative gauge option The screen will display a table noting the following information Step The pressure step in the calibration sequence Apply The pressure that the standard is to generate to the DPC Tolerance The tolerance about the apply value that can be generated by the standard and still accepted by the DPC Actual The actual pressure value that was generated by the standard when the point was accepted Adj FS Depicts the amount that the DPC corrected its output to align to the standard This is used as a trouble shooting tool If one point has a significantly higher adjustmen
28. available use a double walled corrugated carton with a 275 rating The recommended carton size is 25 1 2 x 19 1 2x 12 3 8 inches Insert one foam cradle from the original shipment onto the floor of the box The original foam cradles are of the same type of construction and are completely interchangeable If the foam cradles are not available cover the bottom and sides with no less than 3 inches of N 95 foam strips Arrange the strips in the configuration illustrated in figure 7 1 Before sealing the carton include the following a Statement of the problem or service needed Be specific Include the name and telephone number of a knowledgeable technician for consultation b The part number serial number return address and purchase order number Seal the carton using gummed tape Address the carton to RUSKA INSTRUMENT CORPORATION 10311 WESTPARK DRIVE HOUSTON TX 77042 USA Label the carton with the following labels THIS SIDE UP HANDLE WITH CARE DO NOT DROP and FRAGILE If the original Ruska shipping carton is utilized for this shipment the above markings are preprinted on the carton STORAGE amp SHIPMENT 7 2 FIGURE 7 1 7 3 SHIPPING INSTRUCTIONS Ruska recommends using air freight for transportation Surface transportation subjects the shipment to more frequent handling and much more intense shock In most cases if surface transportation is the mode of transport employe
29. be scaled to match the device under test by setting the full scale value of the bar graph 4 6 1 2 3 Ready Tolerance A Ready indication is generated when in control mode and the measured pressure is reading within this ready tolerance value When running an internal program the ready indicator is shown when the measured pressure is within the tolerance stored in the program 4 6 1 2 4 Gas Head Pressure Correction The term head height refers to the vertical distance between the sensing element in the device under test and the DPC s pressure reference plane Once the user inputs the head height and selects air or nitrogen the DPC automatically corrects for head pressure 1 The Pressure Reference Line on the DPC is defined as the bottom of the color display where the display and the front panel join This provides the reference plane against which the device under test DUT pressure is measured 2 Determine the vertical distance between the DPC Pressure Reference Line and the reference plane of the device under test 3 Press the Unit key found in the keypad and press in mm F1 to select either inches in or millimeters mm for the head height entry 4 The head height is set from the Setup User Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 and then User F2 5 Press Medium F3 to select either Air or Nitrogen The selected units will be highlight
30. destroyed because electrostatic discharges at levels less than 4 000 volts cannot be seen felt or heard COMPRESSED GAS Use of compressed gas can create an environment of propelled foreign matter Pressure system safety precautions apply to all ranges of pressure Care must be taken during testing to ensure that all pneumatic connections are properly and tightly made prior to applying pressure Personnel must wear eye protection to prevent injury PERSONAL PROTECTIVE EQUIPMENT Wear eye protection approved for the materials and tools being used INERT GASES Operation of pressure equipment may be accompanied by the discharge of inert gases to the atmosphere The result is a reduction of oxygen concentration Therefore it is strongly suggested that exhaust gases not be trapped in the work area vii INTRODUCTION TABLE OF CONTENTS WARRANTY os ete t E pr E RERUM D ah xp ii COPYRIGHENOTIGE ada oe edat dota Reb duet aod nidi iii REVISION NOTIGE RD ue ONE iv REVISION HISTORY laden Pe bd v CHANGE TANGUAGE rit e Ee o ec ce SR vi SAFETY SUMMARY delia stes eos cn vii TABLE OF CONTENTS viii SECTION 1 0 GENERAL INFORMATION 1 1 INTRODUCTION 3 ene da UENIRE EON DE FB RU 1 1 1 2 GENERAL INFORMATION eene enne 1 1 13 FEA
31. display 1 Turn off the DPC and disconnect the power cord from the DPC 2 Locate and unscrew the four screws that secure the cover to the back panel 3 Place your hands near the middle of the cover and slide the cover towards the DPC s back panel 4 Lift up on the cover With the cover removed use typical electronic cleaning tools to remove any accumulated dust from inside the instrument 5 Replace the cover before resuming operation 6 3 3 MOISTURE FILTER The Bourdon tube sensor is hydroscopic An external desiccant filter prevents introduction of moisture and is strongly recommended for high humidity areas The filter should be replaced annually The moisture filter is used with the reference port only absolute only instruments do not need a moisture filter 6 3 4 PARTICLE FILTERS Refer to Appendix A for air supply quality requirements During normal operation the DPC transfers gas both into and out of the device under test DUT When necessary the user is expected to use and maintain an in line disposable particle filter to protect the DPC s pneumatics from any contamination that may exist in the DUT 6 3 5 VACUUM PUMPS Periodic checks of the user s vacuum pumps for oil levels It is very highly recommended that a power down vacuum venting valve is installed onto the vacuum pumps to ensure minimal chances of oil contamination from the vacuum sources These are normally MAINTENANCE 6 2 open solenoid valves that ar
32. down close to O psig For permanently absolute systems a vacuum pump capable of producing a vacuum level of 200 mTorr or less at the sensor reference port is required used to zero the sensor INSTALLATION 3 4 See Appendix for vacuum pump requirements See also Section 3 5 2 1 for Absolute mode requirements For instruments that have a barometric reference sensor option the barometer is tied to the reference port When operating in the gauge mode the reference port should be connected as noted above When operating in the absolute mode sealing the reference port from atmosphere will improve the stability of the DPC 7 0 O 3 5 5 d m SUPPLY TEST REF CO 7 RANGE A Nays _ x p 9 Se e 88 SUPPLY EXHAUST TEST RF e OO ms p P L gt oT Q MODEL 7252 BACK PANEL VACUUM TRANSDUCER INSTALLATION On permanent absolute models of the DPC s 15 50 psia a vacuum sensor is required to zero the instrument Some units are purchased with a vacuum sensor option which performs this task If this option was not included then the user should use the following procedure to install their vacuum sensor 1 2 3 4 Relieve all pressure from the DPC by venting the instrument Turn the power off and
33. enabled enter it at the prompt The first calibration screen will appear NOTE To exit the calibration procedure before the calibration coefficients have been changed press CANCEL any time during the procedure Canceling restores all previous calibration values Use the rotary knob to highlight the coefficient to be edited The terms are coefficients of a linear regression analysis Use the numeric keypad and the ENTER key to enter a new value To correct a mistake in the edit field use the CLEAR key 7 Repeat steps 4 and 5 until all coefficients are correct NOTE addition to saving the calibration coefficients to the DPC s memory separately record the calibration coefficients and store this backup in a safe place 8 To exit the editing procedure without storing the calibration coefficients in memory press CANCEL To store the calibration coefficients in memory select DONE F6 9 Press PREVIOUS to return to the Main Menu Once the calibration coefficients are input the user should record several pressure readings If there are any variances beyond the stated precision at these points then the calibration procedure should be performed MAINTENANCE 6 10 6 4 6 ZEROING The zeroing procedure is performed to correct for system zero shift and does not require full calibration The most important requirement for performing a valid zeroing procedure is to guarantee that there is not a pres
34. head height gas head medium B sets pressure display resolution returns to default resolution MODE ABSolute DIFFerential GAUGE TARE RANGE UPPer LOWer HEIGht lt number gt MEDium N2 AIR SOURCE PRESsure LEVel IMMediate AMPLitude number MODE FIXed LIST TOLerance lt number gt SLEW lt number gt CONTrol lt number gt ON lt number gt lt number gt OVERshoot ON OFF 1 0 PRESsurel 1 LEVel IMMediate AMPLitude number MODE FIXed LIST TOLerance lt number gt SLEW lt number gt CONTrol lt number gt ON lt number gt OFF lt number gt OVERshoot ON OFF 1 0 LIST PRESsure lt number gt lt number gt POINts DWELI number lt number gt POINts TOLerance lt number gt lt number gt POINts DIRection UPIDOWN COUNt lt number gt STATus OPERation 5 7 full scale value in units calibrated returns low cal point gas head height gas head medium A pressure control setpoint set control mode specifies output tolerance set slew rate control band overshoot limit B pressure control setpoint set control mode specifies output tolerance set slew rate control band overshoot limit set list of pressure values number of points defined specifies dwell times number of dwell times specifies tolerances number of tolerances direction to go through list number of times to go through list
35. if status amp 2 0 break 7 Reset 7250 to Measure mode T y OUTP MODE MEASURE Enter Measure mode Ll mre yea a ee et et a ee n m eer E et ae he et write 7000 serial OUTP MODE MEASURE n check_errors Se See ee a Reset Serial Interface Jet N serial close eee check errors display all 7250 error messages return TRUE if any errors were found Jeon bess eee eee eee int check errors void unsigned char status7 int retval a Check for 7250 Errors Lr RID PIA MET MN T retval 0 while kbhit if request 7000 serial STB n printf Timeout n return TRUE status7 atoi buffer REMOTE OPERATION 5 18 if status7 amp 4 break retval S50 Check error bit request 7000 serial SYST ERR n Get error message UA printf buffer return retval M cp pr DI DITE oru See ee TT serial int receive interrupt for serial port UA void interrupt serial int char ch if inportb portbase 2 amp 0x07 0x04 ch inportb portbase if ch XON transmit enabled TRUE else if ch XOFF transmit enabled FALSE else
36. in an output referred to as counts This output is corrected for the applied effects listed below The counts are linearized and the resulting pressure value is corrected for the variations in head pressure vacuum case effect and oven temperature effects 2 13 THEORY OF OPERATION The following equations are used the control algorithm to adjust and correct the pressure signal Zero Coefficients CsH CsL HsZ SsZ Zero correction for High FSR Full Scale Resistors Value is in counts 7 381 975 full scale of current sensor Zero correction for Low FSR Value is in counts 7 381 975 full scale of low FSR Hardware zero correction to 4095 center is 2048 Zero corrections scaling factor Ratio of High FSR to Low FSR Used only when Case Effect Coefficient or Oven Temperature Coefficient are non zero s 0 for high range sensor s 1 for low range sensor Range Coefficients KnF O Range Unused 4 Valid High FSR Range 5 Valid Low FSR Range KnO Kn1 Kn2 Calibration constants for range E s Ku 2 Kn Bba To hada Where is the zero corrected counts 7 381 975 full scale of current range and B is the calibrated counts 7 381 975 full scale of current sensor KnH Zero corrected counts for upper limit of range When the zero corrected counts from the A D exceed this value the next higher range will be used if possible 7 381 975 full scale of current range KnL Zero corrected counts for lower li
37. not physically vented to the atmosphere therefore the unit would not be measuring atmospheric pressure following a vent 2 42 CONTROL MODE PNEUMATICS 2 4 2 1 Pressure Supply Port The Pressure Supply Port connects the user s regulated gas supply to the Pneumatics Module Please refer to Appendix A for gas specifications and supply pressure limits On the 7252 there are two supply pressure ports one for each channel A separate regulated pressure supply will need to be connected to each individual supply pressure ports Each supply pressure should be regulated to the pressure defined in Appendix A 2 4 2 2 Vacuum Supply Exhaust Port For many applications a vacuum pump is not necessary The Exhaust Port includes a solenoid valve that is open only when the DPC is controlling pressure In Gauge mode if the will not be used to control pressures at or very near atmospheric pressure then the Exhaust Port should simply be left open to atmosphere Likewise in Absolute mode if the DPC will not be used to control pressures at or below atmospheric pressure the same rule would apply However if the DPC will be required to control to atmosphere in Gauge mode or sub atmospheric pressures in Absolute mode then a vacuum pump must be connected to the Exhaust Port Select a vacuum pump with the test port volumes and system slew rates in consideration The minimum requirements are noted in Appendix A 2 7 THEORY OF OPERATION 2 4 2 3
38. oreet t e a seabed te 6 3 6 4 1 CALIBRATION INSTRUCTIONS 6 3 GANN Preparation oed 6 4 6 4 1 2 HR Genet etie 6 6 6 4 2 VACUUM NEGATIVE GAUGE CALIBRATIONS 6 7 6 4 3 RPT CALIBRATION SIMULATED ABSOLUTE 6 8 6 4 4 VACUUM SENSOR CALIBRATION OPTIONAL CASE REFERENCE SENSOR 6 9 6 4 5 EDITING THE CALIBRATION 6 9 ZEROING etia nate ret UI MERE 6 11 6 4 6 1 Gauge and Vacuum Negative Gauge Instruments 6 11 6 4 6 2 Absolute Instruments 2 6 12 xi INTRODUCTION 6 4 6 3 RPT Simulated Absolute Instruments 6 13 6 5 SENSOR PHOTOCELL 2 6 13 6 6 OPTIMIZING CONTROL i cesdesiguideaceiecala sfednelessias 6 15 6 7 FAN OPERATION oio bene e y oo 6 17 6 8 SYSTEM SOFTWARE UPDATE PROCEDURE 6 18 6 9 REPLACEMENT PARTS cinereus 6 19 SECTION 7 0 PREPARATION FOR STORAGE amp SHIPMENT 7 1 DISCONNECTING THE 7 1 7 2 PACKING 5 65 7 1 7 3 SHIPPING INSTRUCTIONS iieri eth eee too
39. pressure separately every time a multipoint test or calibration routine is performed Another benefit is that the user can specify a tolerance for each set point pressure Once a tolerance is set the dwell timer will start counting down instead of waiting until the pressure is at the exact set point to start the dwell timer This gives the user a time advantage compared to manual mode operation and provides a degree of automation without the use of an external computer LOCAL OPERATION 4 18 The DPC can store up to 1 000 program steps that may be divided among a maximum of 20 named programs The Program menu operates only on the current channel The other channel will be in measure mode while the program is running 4 6 3 1 Preparing to Program Before entering a test sequence consider the items discussed below Program Name Valid program names range from one to eight characters in length can include numbers upper case letters and the and symbols For example Exer 14 and FStest are both valid names Configuration Since a program will depend on the current setup of the DPC the current configuration is stored with the program the user should set the units limits control parameters etc to the desired values before creating a program Number of Set points Before entering the sequence the user should determine the number of upscale and downscale set points required to complete the exercise Set point Pressure and
40. principle behind the operation of the DPC s sensing element Ideally this pressure current relationship would be a linear equation of the form I kP where l is current k is a constant of proportionality and P is pressure However due to certain mechanical characteristics of the helical tube and its supporting structure this pressure current relationship is slightly nonlinear The nonlinear portion of this pressure current relationship closely follows the form of a second order polynomial or I aP bP c where again P is pressure and a b and c are coefficients generated during the calibration procedure as discussed below When the user performs a three point calibration the DPC s software creates the three coefficients based on the user s zero mid point and full scale adjustments From then on the nonlinear term given above is subtracted from the total pressure current curve to achieve the desired linear pressure current relationship On the 7250i and 7250xi multiple quartz sensor ranges are used in order to provide the percent of reading specification In these instruments a total of three points per range with one point shared between two ranges is required Therefore for the 7250i a 5 point calibration is performed and for the 7250xi a 9 point calibration is performed to fully characterize the Ruska quartz sensors 2 1 THEORY OF OPERATION 2 6 4 AUXILIARY SENSORS Auxiliary sensors are sensors such as the oven tem
41. properly once the download is complete Finally the main software only reads the software versions on power up So following the controller code upgrade pressing the MENU TEST REMOTE SERIAL2 keys will only show the new revision level of the controller code after power is cycled on the 7252 6 9 REPLACEMENT PARTS The following is a list of the common replacement parts used in the Model 7252 DPC Low Pressure Manifold High Pressure Manifold Valve Maximum Full Scale Maximum Full Scale Identification Pressure Range 1000 psi Pressure Range 1000 2500 6895 kPa psi 6 9 20 7 MPa Valve Body Valve Coil Valve Body Valve Coil Supply Pressure 88 1074 88 1081 88 1054 88 1055 Vent 88 1074 88 1081 88 1054 88 1055 Test Port 88 1076 88 1078 Reference Port 88 1076 88 1078 7252 109 88 1055 6 19 MAINTENANCE Part Number Description 7252 109 7252xi isolation manifold valve body 88 1055 7252xi isolation manifold valve coil 11 763 TFT Display 11 764 Display Inverter Electronic Board 7000 70 Sensor LED Lamp Assembly 7000 71 Sensor Photocell 7252 111 Photocell Adjustment Tool 62 293 Power Supply 23 906 Fan 7252 100 005 Rotary Encoder 7215 Front Panel Keyboard Electronic Card MAINTENANCE 6 20 SECTION 7 0 PREPARATION FOR STORAGE amp SHIPMENT NOTE The procedures given in sections 7 1 through 7 3 must be strictly a
42. single vacuum pump Using 4 inch NPT fittings connect tubing with a minimum I D of inch to the Exhaust port and the Reference port Larger 1 0 pressure line is recommended if available Using appropriate pneumatic fittings connect the other end of the tubing to the vacuum supply line s This allows the system to function with a single vacuum pump The system will use the vacuum source for control or zeroing as required 3 5 3 TEST PORT The device s under test is connected to the test port The DPC controller is designed to operate within its specification limits into load volumes from 5 to 60 in 80 to 1000 cc Excessive leaks in the test volume will cause measurement errors in the device under test and may possibly affect control stability Tubing connected from the test port to the load volume should have an internal diameter greater than 1 8 inches 3 mm Tubing should be shorter than 15 feet 5 meters when minimum diameter tubing is used 3 5 3 1 SINGLE TEST PORT OPERATION OPTION Some versions of the 7252 allow the instrument to be set up where the test port of both controllers are connected together A flag must be set in the MODE MENU Setup User menu to allow the system to operate in this mode With the test ports connected the instrument will then allow the operator to control either of the two channels to a single test port When set up in this mode the system software uses an internal valve to isolate 3 3 INSTALLA
43. the green bar 9 Tighten the Allen screw 10 Often when the Allen screw is tightened the zero will move Review the width of the yellow line again loosen the Allen screw and now offset the yellow bar the MAINTENANCE 6 14 14 15 6 6 same width that you observed it moving from tightening the Allen screw and now offset it in the opposite direction by this same width Again tighten the Allen screw Now the width of the yellow line should be minimized Tap on the bracket with a screwdriver handle to relieve mechanical stress Continue to tap on the bracket until the counts stop changing If the zero moved significantly as a result from tapping the bracket repeat this procedure as necessary Reinstall plastic zeroing plug After the unit has become thermally stabilized perform a normal instrument zeroing procedure Refer to Section 6 4 5 FIGURE 6 5 PHOTOCELL LOCATION OPTIMIZING CONTROL The performance of the controller may be optimized for certain environments or performance criteria by adjusting the values available in the Control screen The Control screen is available from the Main Menu by pressing Menu F6 Test F5 Control F6 The Control screen is shown below 6 15 MAINTENANCE AutoTune Full its Calibrate MODE MENU TEST CONTROL MENU NOTE Be sure the Control Band parameter is set to zero Section 4 6 1 1 3 If the c
44. the standard that the calibration service provider used to perform the calibration would need to be substituted for the manufacturers calibration uncertainty that was used in the original uncertainty analysis Environmental or Installation Influences that could cause errors in the transfer standard This includes influences such as ambient temperature line pressure head pressure time response and controller effects It may include other influences that are very specific to one manufacturers instrument t is recommended that the intended application is reviewed to assure that the environmental does not impact the instruments performance or that the impact from the environment is accounted for in the uncertainty analysis For instance if an instrument has a 0 001 FS per degree Celsius temperature effect from a calibrated temperature of 20 degrees Celsius and the instrument is to be used in an environment where the temperature will vary from 15 to 25 degree Celsius then a 0 00596 of full scale uncertainty should be included in the uncertainty analysis for ambient temperature effects Combining the Uncertainty Components into an Expanded Uncertainty Statement Once all of the uncertainty components are identified they can be combined into an overall Expanded Uncertainty Statement for the instrument The vast majority of the measurement community has adopted a statistical approach to uncertainty analysis such as the International Organizati
45. the user can calibrate more frequently NOTE The calibration procedure automatically generates coefficients that are stored in memory on the DPC s If these constants are lost for any reason the calibration procedure must be performed regardless of the last calibration date If the calibration coefficients have been recorded they may be restored to the DPC at any time by editing the coefficients Section 6 4 3 6 4 1 CALIBRATION INSTRUCTIONS To calibrate the DPC the user connects a calibration standard such as the Ruska Instrument Model 2465 or 2470 for high pressure ranges Gas Piston Gauge to the DPC s test port then follows the multi step calibration procedure on the DPC s display The standard DPC requires a positive pressure calibration A vacuum negative gauge option is available and requires special calibration per Section 6 4 2 No disassembly is required and there are no potentiometers to tune NOTE The uncertainty of the final calibration must include the uncertainty of the pressure standard being used 6 3 MAINTENANCE 6 4 1 1 Preparation 1 Verify that the DPC s Reference Port is open to atmosphere for gauge calibrations and that the calibration standard is connected to the Test Port 2 For DPC s with pressure ranges greater than 100 psi 690 kPa verify that the supply pressure port is plugged or a supply pressure is connected to the supply port and adjusted to 110 of the full scale of the DPC
46. 1 OUTP MODE printf GPIB Driver not installed n return Sa Initialize 7250 Interface UNIT FS Set units to percent of full scale PRES 20 0 Set control setpoint to 20 FS PRES TOL 0 001 Set control tolerance to 0 001 5 OUTP MODE CONTROL Enter control mode x CONTROL n if check errors ibonl device 0 return Read pressure status until setpoint is reached Sh 5 Read pressure pe STAT OPER COND Read status setpoint is E E gt while kbhit request 7000 MEAS STAT OPER COND n pressure strtod buffer amp p status atoi if check errors continue if status amp 0x10 printf Pressure 9 31f n pressure if status amp 2 0 break cac Cred Be Pare nde M Reset 7250 to Measure mode Jet OUTP MODE MEASURE Enter Measure mode es 04 write 7000 OUTP MODE MEASURE n check_errors Reset GPIB Interface ILLI ibonl device 0 i check errors display all GPIB and 7250 error messages return TRUE if any errors were found a E Em int check errors void REMOTE OPERATION 5 12 unsigned char status7 int retval
47. 1 Same as PRESsure2 above TEMPerature 12 Same as PRESsure2 above DISP 1 ON OFF 1 0 lt text gt PRESsure BGRaph lt number gt PRESsurel 1 BGRaph lt number gt OUTPut PRESsure 5 10 MODE MEASure CONTrol VENT PRESsurel1 5 ON OFF 1 0 MODE MEASure CONTrol VENT PROGram CATalog SELected DEFine program block DELete SELected ALL program name gt STATe RUN PAUSe STOP CONTinue CONFigure RECall SAVE SENSE PRESSure RESolution lt number gt AUTO ONCE A Vacuum B Vacuum A Gas Temperature A Sensor Temperature B Gas Temperature B Sensor Temperature turns front panel display on off display message on front panel sets A bar graph maximum sets B bar graph maximum A off MEASure on CONTrol A sets mode off MEASure on CONTrol B sets mode returns list of defined programs lt step press toler dwell max gt deletes current program deletes all programs select current program change program state load program configuration save current configuration into program A sets pressure display resolution returns to default resolution MODE ABSolute DIFFerential GAUGE TARE UPPer REMOTE OPERATION 5 6 full scale value in units calibrated LOWer REFerence HEIGht number MEDium N2 AIR PRESSurel 1 RESolution lt number gt AUTO ONCE returns low cal point gas
48. 2 VALue lt n gt number DATA POINts VALue lt n gt VALue lt n gt lt number gt CALibration VALue lt n gt POINts ZERO lt number gt PRESsure3 Same as PRESsure2 above PRESsure4 Same as PRESsure2 above PRESsure1 1 Same as PRESsure above PRESsure12 Same as PRESsure2 above PRESsure14 5 5 get set tare value set tare state using current press low pressure limit slew rate limit high pressure limit auto vent limit calibration edit enabled request calibration edit A Pressure Perform calibration point return number of calibration constants returns label value 0 0 123 sets calibration constant return nominal calibration point return number of calibration points last calibration date last calibration time last zero date last zero time sets vacuum value microns mtorr enter zero calibration mode returns status for cal press temp ref start zero calibration abort zero calibration A Case Ref Perform calibration point return number of calibration constants returns label value 0 0 123 sets calibration constant return nominal calibration point return number of calibration points Zero sensor RPT Sensor PDCR B Pressure B Case Ref PDCR REMOTE OPERATION Same PRESsure2 above VACuum Same as PRESsure2 above 11 Same PRESsure2 above TEMPerature Same as PRESsure2 above TEMPerature2 Same as PRESsure2 above TEMPeraturel
49. 4 6 1 1 3 Auto Vent iret ent ri E ERI PEE PISIS ERES 4 11 4 6 1 1 4 Control reor ee qus 4 11 Gon ol hee aot im deep 4 12 A61 T6 4 12 4 6 E Sew LAMAN erini a a RAA 4 12 4 6 1 158 ACCESS i t E uo ea REEE 4 12 4 6 1 2 Menu Setup rte Etre rn ER EUR dd 4 12 4 6 1 2 T temp 4 13 4 6 1 2 2 Bar Graph MAXIMUM ss eoe etta 4 13 4 6 1 2 3 Ready Tolerance 4 13 4 6 1 2 4 Gas Head Pressure 4 13 4 6 1 2 5 Almosplhiete 4 14 4 6 1 226 Pressure Filter 4 14 4 6 1 2 7 Changing the Number of Decimals 4 14 A6128 4 14 4 6 1 3 Menu Setup Utile oos tes eet rrr rn esas 4 14 4 6 1 4 Menu Setup Remote eicere eene tnb eei 4 16 456 14 iioi pe rint e teres 4 16 4 6 1 4 2 PIOtOCOl eed 4 16 4 6 1 4 3 Serial Interface Set Up eee 4 16 4 6 1 5 Menu Setup System Pr ro deed 4 16 4 0 1 5 1 Date iiec oper ror reto oen 4 17 AsO 1 9 2 ReSel su 4 17 MENU CALIBRATE 4 17 4 6 2 1 Calibration PassWwoftl 4 17 4 18 MENU PROGRAM STORING A SEQUENCE IN MEMORY 4 18 4
50. 6 to 2500 psig 2 5 kPa to 17 2 MPa Full Scale Ranges Note this diagram depicts only one of the two 7252 channels THEORY OF OPERATION 2 4 SUPPLY EXHAUST PORT PRESSURE PORT PORT Control Section 477 VACUUM gt SENSOR Option FIGURE 2 2B MODEL 7252 DPC ABSOLUTE PNEUMATICS DIAGRAM TO 50 PSIA 340 kPa FS Note this diagram depicts only one of the two 7252 channels Control Made Zeroing TABLE 2 2 SOLENOID VALVES STATES 2 4 1 MEASURE MODE PNEUMATICS Figures 2 2 and 2 2 summarizes the Pneumatics of the DPC 2 4 1 1 Reference Port For gauge measurements the Reference Port is normally left open to atmosphere The Reference Port is isolated from the Test Port by a solenoid valve that is closed during the DPC s Measure and Control modes When the user commands the DPC to perform the zeroing process the solenoid automatically opens and the pressures on the Reference Port and Test Port become equal On permanent absolute instruments it is recommended to tie the reference port to the exhaust port and then connect them to the vacuum pump Therefore when the unit is zeroed the reference port valve opens and a vacuum is pulled onto the test port allowing the instrument to zero at a low vacuum level 2 5 THEORY OF OPERATION The Reference Port is protected a relief valve 2 4 1 1 1 Barometric Sensor Optional For Simulated Absolute instruments the Reference Po
51. BLE Calibrating Currently performing a calibration Bit 1 Settling Control setpoint has not been reached Pressure tolerance set by SOUR PRES TOL Bit2 Reserved 0 Bit3 Reserved 0 Bit4 Measuring The instrument is actively measuring Bit5 Reserved 0 Bit 7 Reserved 0 Bit8 Self test in progress Bit9 Reserved Bit 10 Reserved 0 Bit 11 Reserved 0 Bit 12 Reserved 0 Bit 13 Reserved 0 Bit 14 Program running Bit 15 Reserved 0 Questionable Status QUES EVENT QUES CONDITION QUES ENABLE Reserved Bit 1 Reserved 0 Bit2 Time is questionable Set when the clock has not been set Bit 3 Temperature is questionable Sets when oven temperature is not within range Bit4 Reserved 0 Bit5 Reserved 0 Bit6 Reserved 0 Bit 7 Calibration is questionable Set when the unit has not been calibrated Bit 8 Pressure is questionable Set when the pressure is overranged Bit9 Reserved 0 Bit 10 Reserved 0 Bit 11 Reserved 0 Bit 12 Reserved 0 Bit 13 Reserved 0 Bit 14 Command warning Set whenever a command ignores a parameter Bit 15 Reserved 0 REMOTE OPERATION 5 10 5 5 SERIAL OPERATION The RS 232 port accepts the same SCPI commands as the IEEE 488 The commands can be terminated by a carriage return hexadecimal OD or a line feed hexadecimal The responses are always terminated by a carriage return followed by a line feed The serial port also supports XON XOFF When the XOFF hexadecima
52. DIGITAL PRESSURE CONTROLLER MODEL 7252 MODEL 72527 USER S MANUAL RUSKA INSTRUMENT CORPORATION 10311 WESTPARK DR HOUSTON TEXAS 77042 713 975 0547 FAX 713 975 6338 e mail ruska ruska com E http www Ruska com Release 7252 1D01 Revision A Date 09 16 03 WARRANTY Ruska Instrument Corporation warrants its products to conform to or exceed the specifications as set forth in its catalogs in use at the time of sale and reserves the right at its own discretion without notice and without making similar changes in articles previously manufactured to make changes in materials designs finish or specifications Ruska Instrument Corporation warrants products of its own factory against defects of material or workmanship for a period of one year from date of shipment Liability of Ruska Instrument Corporation under this warranty shall be limited to replacing free of charge FOB Houston Texas any such parts proving defective within the period of this warranty but will not be responsible for transportation charges or consequential damages This warranty is not made for products manufactured by others which are illustrated and described in Ruska catalogs or incorporated in Ruska products in essentially the same form as supplied by the original manufacturer However Ruska Instrument Corporation agrees to use its best efforts to have original suppliers make good their warranties ii INTRODUCTION COPYRIGHT NOTICE Copyright
53. E meas pres measure REMOTE OPERATION MEAS To set the control pressure setpoint to 50 all of the following commands are equivalent SOURCE PRESSURE LEVEL IMMEDIATE AMPLITUDE 50 SOUR PRES LEV IMM AMPL 50 0 PRESSURE 50 PRES 50 To zero the unit via the remote interface use the following sequence CAL ZERO INIT Enter Zero Mode CAL ZERO INIT Read Status Mode Pressure Temperature Reference and Wait Until Stable CAL ZERO RUN Start Zero Adjust Sequence STAT OPER COND Wait Until Complete Bit O O 5 4 6 SCPI STATUS REGISTERS Three type of status registers are available Condition Event and Enable Condition registers always show the current status of the instrument Bits may turn on and back off between reads The status read is the status of instrument at the moment of the read Condition registers include STB Status Byte Register ESR Standard Event Status Register STAT OPER COND Operation Status Condition Register STAT QUES COND Questionable status Condition Register Event registers do not show the current state but flag the bits in the condition registers that have changed since the last time the event register was read When an event register is read it is reset to zero STAT OPER EVENT Operation Status Event Register STAT QUES EVENT Questionable Status Event Register Enable registers are set by the user to create summary bits If the user sets a bit in the enable register
54. ECTRONICS MODULE 2 3 1 BACK PLANE BOARD The Back plane Board is used to interconnect all of the plug in electronic boards and distribute power The Microprocessor Board the Digital Control Board and the IEEE 488 Interface all plug into the Back plane Board The Front Panel communicates with the Microprocessor Board via cables The Sensor Board communicates with the Microprocessor board through an internal RS 485 serial communication bus 2 3 2 MICROPROCESSOR BOARD All of the DPC s software resides in nonvolatile programmable read only memory Flash EPROM on the Microprocessor Board which plugs directly into the Back plane Board This software contains all of the instructions that operate the DPC as well as the conversion factors that the DPC uses to translate the internal pressure unit of measure of kPa into the units selected by the user These factors are given in Table 2 1 Data that is subject to change after the DPC leaves the factory are held in electrically erasable programmable read only memory EEPROM This includes the current units of measure the coefficients from the zeroing process the current pressure medium calibration coefficients and the conversion factors for the four user defined units of measure When the DPC powers up its software is loaded into random access memory also on the Microprocessor Board At the same time the values stored in EEPROM Board are restored to memory Another important com
55. Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 then System F5 and then Reset F1 4 6 2 MENU CALIBRATE The Menu Calibrate command is used to perform the calibrations on all of the sensors utilized by the DPC The 7252 can be completely calibrated using the front panel interface It does not require any external computer or software in order to perform a successful calibration also has the capability of being calibrated remotely through either the RS232 or IEEE 488 interface The 7252 will guide the operator through a menu driven calibration procedure identifying the pressures that should be supplied by a standard Following the calibration procedure the 7252 calculates and saves its own coefficients The calibration coefficients are date stamped so the user can easily identify the last time the instrument went through a full calibration when the coefficients were last edited or when the DPC was re zeroed The calibration section in the DPC can be password protected to prevent any unauthorized entry into the calibration section of the system Please refer to the Maintenance Section Section 6 0 of the manual for more detailed information regarding the calibration of the DPC The calibration menu is identical in both channels Press the Sensor function key to select the correct sensor from either channel 4 6 2 1 Calibration Password The calibration password allows the user to protect access to D
56. PC calibration constants and the calibration procedure the calibration password is set to any number other than zero it is required before the user is allowed to calibrate the DPC or manually change the calibration constants IMPORTANT It is recommended that the access password be recorded and filed in a secure location 4 17 LOCAL OPERATION 1 The calibration password is set from the Calibration Menu From the Menu press PREVIOUS until the Main Menu appears press Menu F6 then Calibrate F3 2 Press the Access F4 key If there is a password in the system other than 0 then you must enter the current valid password into the 7252 before it will allow you to modify the password 3 Use the numeric keypad to enter the new calibration password Setting the calibration password to zero allows free access to DPC calibration and constants Press ENTER 4 Press Yes F4 to acknowledge changing the calibration password Press No F5 to reject changing the calibration password 4 6 2 2 Zeroing Ruska recommends that the DPC be zeroed once a day to maintain optimal performance The zero drift specification is defined in Appendix A under General Specifications Refer to Section 6 4 5 for the zeroing procedure On gauge mode instruments the zeroing procedure automatically ties both test and reference ports of the Ruska quartz sensor together and performs the zeroing routine On permanent absolute instruments a va
57. Pressure Control Pressure control is performed by a dual loop control system The inner loop is a digital loop using a high frequency response silicon strain gauge sensor a digital controller and two pulse width modulated solenoids The two solenoids either add gas to the test port or remove it The outer loop provides closed loop control based on feedback from the quartz Bourdon tube and an analog output setting which provides the desired set point for the inner loop 2 5 CONTROL STRATEGY 2 5 1 INNER VS OUTER LOOPS The inner loop accepts a signal from the outer loop and uses this signal as the pressure set point The inner loop uses a high frequency response strain gauge sensor as its reference The frequency response of this transducer allows for high speed modulation of the solenoids This sensor is aligned to the high accuracy quartz sensor when the system is Auto tuned The outer loop is a lower frequency response analog digital loop The outer loop uses a calibrated forced balanced sensor This sensor is used to monitor the pressure of the system The results are used for the displayed pressure The outer loop is responsible for adjusting the signal sent to the inner loop to compensate for temperature and time drifts associated with the inner loop sensor 2 5 2 NORMAL MODE In the Normal mode minimizing pressure overshooting takes precedence over control speed In the Fast Mode control speed takes precedence over overshooting the se
58. Program For the DPC to automatically generate a program the user must input the first set point pressure the last set point pressure and the number of steps in between as well as the dwell time max time and tolerance common to all set points 1 Ensure that the units limits and control parameters are set to their desired values 2 The program is entered from the Program Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Program F4 3 Use the rotary knob to highlight new If these steps are used on an existing program all program steps will be deleted and replaced with the automatically generated program 4 Press Edit F4 Since new was highlighted the DPC will create a new program and give a default name of NAMEnn where nn is a two digit number The program editing screen will appear displaying the first step 5 Press Auto F3 4 21 LOCAL OPERATION Program NAMEO0 Stop Tolerance Dwell Time Max Time Points Up Points Down CHANNEL A MENU PROGRAM EDIT AUTO MENU 6 Using the numeric keypad enter the values for Start Stop Tolerance Dwell time Max time number of pressure Points up and number of pressure Points down pressing ENTER after each value The rotary knob may be used to skip fields 7 Press Program F1 The program will be generated and the display will show the first step 8 Press the Name F6 key to edit t
59. R 2 8 2 5 3 FAST MODE eti eR OD 2 8 2 5 4 ALIGNMENT OF INNER LOOP WITH OUTER LOOP 2 9 220 5 PID CONTROL 5 2 9 2 6 TRANSDUCER MODULE 2 10 2 6 1 QUARTZ BOURDON TUBE SENSOR TRANSDUCERO 2 10 viii INTRODUCTION 2 7 4 1 4 2 4 3 4 4 4 5 4 6 2 0 2 SENSOR BOARD 2 11 2 6 3 LINEARIZATION TERM nette td 2 11 2 A AURILIARY SENSORS ans Serres lii oa re Rar e AIRE 2 12 2 6 4 1 Case Reference Vacuum Sensor Option 2 12 SOFTWARE trip ine NES EH 2 12 2 7 1 SOFTWARE SAFETT CONTROLS decetero e trees 2 12 2 7 1 1 Preventing Operator 2 12 2 7 1 2 Pneumatic Er OTS a rrt Pete 2 12 Dial cls 2 12 ZA NA 2 12 2 7 1 5 Pressure Reading and Correction 2 13 SECTION 3 0 INSTALLATION INTRODUCTION ar 3 1 UNPACKING THE DPC e ola 3 1 CAUTIONS inia tam d ict id uet DI an DEG 3 2 POWERING UP THE DPC eon otro n tenete a e eid 3 2 3 4 1 OBSERVING THE DPC S FULL SCALE RATING anita eate 3 2 PNEUMATIC 65 3 2 9 5 E PRESSURE SUPPBYSPORT a
60. RAL SPECIFICATIONS GENERAL PARAMETERS Storage Humidity Operating Temperature 18 36 C Storage Temperature 20 to 70 C Electrical Power 90 260 VAC 150 W Warm up Period If there is any condensation when storing the DPC it must be thoroughly dried before power is applied It is also recommended to connect the reference port to the test port and evacuating these simultaneously to remove any moisture from the sensor 3 1 INSTALLATION 3 3 CAUTIONS The following cautions should be heeded at all times to ensure safe operation of the DPC 1 Never operate the DPC with the cover removed The power supply has internal voltages near 400 volts 2 For each channel never apply more than 120 of the DPC s channel full scale as a pressure supply Both pressure supplies must be regulated and meet all of the criteria stated in Appendix A of this manual 3 Never apply more than 110 of the DPC s full scale to the test port of each channel Never try to control while a pressure source is connected to the test port 4 Do not expose the instrument to thermal and mechanical shock or vibration This may affect performance and require rezeroing 5 See the safety summary in the introduction 3 4 POWERING UP THE DPC First plug the power cord supplied with the DPC into the power connector on the DPC s back panel CAUTION Grounding for the DPC is provided through the power cord Next plug the power cord into a receptacle rated
61. TION the lower pressure channel from the higher pressure channel when controlling pressures that are greater than the full scale range of the low pressure channel This option is only available with instruments where both channels have a full scale pressure range that is greater than 10 psi 69 kPa and less than or equal to 1000 psi 6 9 Mpa WARNING The software protects the lower pressure sensor from overpressurization when this mode is activated If this feature is turned on make sure that the test ports are disconnected prior to turning this feature off 3 5 4 REFERENCE PORT The reference port is open to atmosphere for gauge measurements or it can be connected to the Reference Port of the Device Under Test Instruments with a low full scale pressure range require special handling to assure the performance of the instrument These instruments are very sensitive to atmospheric pressure changes including disturbances in the atmospheric pressure The reference side must be very carefully controlled or changes due to wind air handlers doors shutting etc will cause major variations The DPC tracks these changes but it may not track in the same way as the device under test To control these changes it is recommended that the reference port of all relevant devices be tied to the reference port of the DPC The reference port can be sealed from atmosphere in most applications where the test times are relatively short This isolates the por
62. TRODUCTION The DPC s power supply electronics pneumatics and sensor combine to form a complete stand alone measure and control instrument This section of the manual describes the DPC s component modules Figure 2 1 and provides a general discussion of each Reference Port 1 1 1 1 1 1 PNEUMATICS 1 Test Port 1 1 1 1 1 SENSOR Supply Pressure Port Exhaust Port Section Section 2 4 1 1 1 1 Reference Port Test Port 1 1 1 1 1 PNEUMATICS SENSOR Supply Pressure Port N Exhaust Port Section 2 6 1 2 4 INNER LOOP SENSOR BACKPLANE POWER BOARD SUPPLY DIGITAL CONTROL BOARD 1 Section Section 2 3 1 2 2 Section 2 3 3 AC FRONT IEEE POWER PANEL CARD Section Section Section 22 2 3 5 2 3 4 Electronic Module FIGURE 2 1 DPC BLOCK DIAGRAM 2 2 POWER SUPPLY 2 1 Section 2 3 2 The 7252 has two pneumatic control and two primary transducer modules A SENSOR BOARD 1 1 Section 2 6 2 1 1 SENSOR BOARD Section 2 6 2 DIGITAL CONTROL BOARD 2 Section 2 3 3 MICROPROCESSOR BOARD RS 232 IEEE 488 THEORY OF OPERATION The DPC s universal power supply accepts AC voltages from 90 to 260 volts at 47 63 Hz and DC voltages from 100 to 370 volts This quad output supply produces 5 VDC 12 VDC and 24 VDC which are distributed to the Control and Backplane Boards 2 3 EL
63. TURES t tet mea ueri di M d dva Gi 1 1 1 4 STANDARD EQUIPMENT amp OPTIONS 1 3 SECTION 2 0 THEORY OF OPERATION 2 1 INTRODUCTION cere es EHE 2 1 2 2 POWER 50 2 2 2 9 ELECTRONICS MODULE ED UR EE CR HRS 2 2 2 9 1 BACK PEANE BOARD ete 2 2 2 3 2 MICROPROCESSOR BOARD pier e E 2 2 2 3 3 DIGITAL CONTROL BOARD 2 3 2 3 4 IEEEZASS INTERFACE OE 2 3 24825 FRONT PANEL a d ident d ER ER I e e 2 3 2 4 PNEUMATICS MODULE iiec t one eee Hn EE E Hr eee 2 4 2 4 1 MEASURE MODE PNEUM ATIGS rst b o eti Re 2 5 2 4 1 1 Reference coa ec eH ere EO HO 2 5 2 4 1 1 1 Barometric Sensor 2 6 2 4 1 1 2 Absolute with Evacuated Reference Optional 2 6 224 152 WEST POP e 2 6 2 4 1 2 1 Single Test Port Operation Option 2 6 2 4 1 3 Vent Procedure 2 7 2 4 2 CONTROL MODE PNEUMATICS 2 7 2 4 2 1 Pressure Supply 2 7 2 4 2 2 Vacuum Supply Exhaust Port e e etas 2 7 2 4 2 3 Pressure Control oi oi rt ee det eds s 2 8 2 5 CONTROL STRATEGY cj netic Gee 2 8 2 5 1 556 2 8 2 5 2 NORMALD MODE assist OE S RR R
64. act rating of 275 and be of double walled construction This type of box will sustain most types of damages incurred during the shipping and handling process but ensures that the contents remain intact and damage free The foam cradle ensures that a minimum of 3 inches of foam separates the inner surface of the box and any portion of the DPC Wood or metal boxes do not absorb shock when dropped and therefore are not recommended If the original packaging and shipping materials have been retained use them for packing the DPC If the DPC is being packed for long term storage more than 30 days place a desiccant bag inside the box 7 1 STORAGE amp SHIPMENT The must be prepared for shipment in the following manner 1 Ruska Instrument has RMA procedure place Please contact the Customer Service Center to obtain an RMA number prior to returning any equipment to Ruska Have the following information available when contacting Ruska the part number the serial number the purchase order number the billing and ship to address and the buyer s name and telephone number panre This information plus the RMA number must be attached to the unit when it is shipped to Ruska Instrument There will be a minimal charge for inspection and or evaluation of returned goods Enclose the DPC in plastic any good water barrier material Antistatic material is recommended If the original shipping carton is not usable or
65. al value of the applied pressure generated by the standard and press ENTER Generate the second pressure Enter the actual value of the applied pressure generated by the standard and press ENTER The RPT sensor is now linearly compensated Once the calibration procedure is complete the user should verify several pressure readings against the pressure standard If there are variances beyond the stated precision then an error was probably made in generating one of the calibration pressures and the calibration procedure should be repeated Remove the pressure source from the Reference Port 6 4 4 VACUUM SENSOR CALIBRATION OPTIONAL CASE REFERENCE SENSOR MAINTENANCE 6 8 span correction can be applied to the vacuum sensor This correction is done using the DPC software and can be performed without removing the vacuum sensor from the DPC chassis 1 2 12 13 14 6 4 5 Place the DPC in Measure mode Remove all pressure sources from the system The Vacuum sensors are located inside the black sensor oven assembly Connect a pressure standard physically as close to the vacuum sensor as possible You may wish to remove the top cover of the instrument and connect directly to the pressure ports going into the quartz sensor oven assembly Note on the 7252 each sensor will have its own independent vacuum sensor If desired change the DPC s units of measure see Section 4 to match those of the calibration standard
66. ar Maximum to 3000 psi to 200 bar 6 4 inch TFT Active Matrix Color User selectable up to 1 1 000 000 90 260 VAC 47 63 Hz 50 400 Hz for i xi models 150 W 18 36 C 20 70 5 95 relative humidity non condensing 5 60 in 80 1000 cc s 7 16 5 W x 19 D 17 8 cm x 41 9 cm x 48 3 20 Ib 9 kg inHg at 0 C and 60 F kPa bar psi at 4 C 20 and 25 C kg cm mmHg at 0 C cmHg at 0 C and cmH O at 4 C 1 inch NPT female Test Port 12096 of Maximum Scaled Quartz Sensor Range Reference 10 Psig where applicable 115 FS for units greater than 100 psi of each channel 100 FS plus 15 psi for units less than or equal to 100 psi for each channel A 5 APPENDIX A TABLE 1 PERFORMANCE SPECIFICATIONS 7252 Pressure Range 5 1000 psi 1000 2500 psi 15 50 psi 3000 psi 0 34 68 9 bar 68 9 172 bar 1 3 45 bar 210 bar Mode Gauge Gauge Absolute Gauge Precision 0 003 FS 0 003 FS 0 003 FS 0 01 FS Stability Over 3 Months 0 0019 RDG 3 months Over 1 Year 0 0075 RDG year 0 01 FS Zero Drift lt 0 004 FS lt 0 004 FS lt 0 004 FS Limits 0 15 psia 0 15 psia 0 15 psia lt 20 Seconds lt 20 Seconds lt 20 Seconds lt 60 Seconds Test Port Standard none standard none Isolation PERFORMANCE SPECIFICATIONS 7252i MODEL 7252i 2 GAUGE From 25 to 100 FS 0 005 RDG Below 25 FS 0 005 of 25 FS Ne
67. asurement and control processes 2 3 5 FRONT PANEL The Front Panel contains the active matrix TFT color display rotary knob and rubberized keys used to operate the DPC 2 3 THEORY OF OPERATION 2 4 PNEUMATICS MODULE The DPC s Pneumatics Module varies depending on whether the DPC is a Gauge mode Absolute mode or a Simulated Absolute mode instrument Gauge mode DPC s reference their measurements to atmospheric pressure whereas Absolute mode DPC measurements are made with respect to sealed vacuum A Simulated Absolute mode DPC has a barometric sensor in addition to a gauge Bourdon tube sensor The DPC adds the barometric reading to the Bourdon tube reading to obtain a Simulated Absolute value It can operate as a Gauge mode instrument if the user selects to not add the reference pressure The valves filters and transducers that make up the pneumatics module of a Gauge mode or Simulated Absolute DPC are shown in Figures 2 2a The schematics for the Absolute mode DPC is shown in Figures 2 2b In the sections that follow the Zero Isolation Apply and Release valves are all 24 volt DC solenoid valves that are either open or closed depending on the DPC s operational mode Their behavior is summarized in Table 2 2 REFERENCE SUPPLY EXHAUST PORT PRESSURE PORT PORT BAROMETRIC REFERENCE SENSOR SIMULATED ABSOLUTE OPTION Control Section VACUUM SENSOR Option FIGURE 2 2 MODEL 7252 DPC GAUGE PNEUMATICS DIAGRAM 0 3
68. ate the second vacuum sensor Remove the vacuum standard from the instrument Reinstall the cover onto the 7252 EDITING THE CALIBRATION COEFFICIENTS If the DPC s memory is erased but the calibration coefficients are known the user can restore the coefficients to the DPC by following the directions below 6 9 MAINTENANCE CAUTION Never randomly adjust the calibration coefficients Only qualified personnel with valid backup data should be allowed to edit the coefficients If the backup coefficients are questionable perform the calibration procedure in its 1 2 entirety Verity that the DPC is in Measure mode Section 4 0 Enter the Calibration screen by selecting MODE MENU CALIBRATE When you first enter the Calibration menu the top line of the display will indicate which sensor is being the viewed The sensors coefficients are then shown below the sensor label The first sensor that is shown is the primary measuring sensor This is indicated by the word Primary displayed in the top of the display To cycle through the various sensors that exist in the system you would press the Sensor F6 function key The two common sensors that would be calibrated would be the Ruska sensor which would be labeled as Primary and if the unit has the optional Barometric Reference sensor this would be labeled as Atmospheric Sensor To edit the calibration coefficients press the EDIT button If the calibration access code is
69. ay Complete AUN 6 8 1 Model 7252 Controller Software Upgrade In addition to the main code the 7252 include code for the pressure controller The controller software version can be viewed by pressing the MENU TEST REMOTE SERIAL2 MAINTENANCE 6 18 keys The controller software version is displayed next to Ctrl This code can be upgraded through the RS 232 port on most units Press the MENU TEST CONTROL key and check for Download Yes If Download No is displayed the chip must be replaced to upgrade software If Download is not displayed upgrade the main software to 7252 1R17 or higher first The digit in front of the R increases with revision levels and the last two digits will increment upwards as the revision level increases e g OR99 is older code than 1RO1 which is older than 1 8 etc 1 Connect a PC to the RS 232 port on the 7XXX using a null modem cable 2 The zip file labeled 7252 Control XRXX contains files UPDATE7 EXE and lt version gt IMG Unzip these files into a directory Set the 7XXX to 9600 baud 8 databits no parity 1 stopbit Run the program Update7 Follow the prompts to select the communications port and the image file 6 Update7 should display Complete Note when updating the controller code the 7252 will display various error messages This is expected The front display will freeze on the 7252 when the controller code is being downloaded lt will operate
70. cd ipic Dn D IURE eit 3 2 3 5 2 EXHAUST PORT eoe Fa pa s repa 3 3 Absolute Models cenobii hU e SEU ERAN cane 3 3 5 LOUNGE TT 3 3 3 5 3 1 Single Test Port Operation Option 3 3 2 944 REFERENCE PORT atem ter roe iia 3 4 3 5 5 VACUUM TRANSDUCER INSTALLATION eco era aea 3 5 3 5 6 VACUUM SENSOR tau re deb eot 3 6 SECTION 4 0 LOCAL OPERATION PUTORIAL 4 3 4 1 1 SELECTING LANGUAGE a She tones 4 6 4 1 2 SELECTING MODE OF OPERATION s c Hern teeth ees 4 6 4 1 2 1 Simulated Absolute Instruments eerte 4 6 MAIN MENU eo ERE Ph 4 7 CONTROLLING 55 4 7 4 3 1 SETTING THE PRESSURE SETPOINT e ere e oo er tede 4 8 4 3 2 ENTERING EXITING CONTROL eter reris 4 8 C Re Gee tue ea E dO SM AE 4 8 0 4 8 2 3 i Oe Dee 4 9 4 5 1 Step S126 4 9 4 5 2 JOGGING 4 9 MENU duct 4 9 MENU SETUP 4 10 4 6 1 1 Men Setup Elec to 4 10 Ix INTRODUCTION 4 6 2 4 6 3 4 6 4 4 6 5 2 6 T High shoes 4 10 4 6 1 1 2 ep e Acton nei Senis 4 11
71. ceived messages that are sent across the interface This can be a powerful tool to assist in identifying the source of communication problems The Menu Test Remote menu displays information from the IEEE 488 interface Pressing the Serial 1 F2 or Serial 2 F3 keys will display information from the serial ports Serial 1 S nt GPIB Not Installed Msgs 0 Serial 2 Ints 0 SPoll 00 Status 00 00 CHANNEL A MENU TEST REMOTE GPIB MENU 4 6 4 4 Menu Test Shop The Menu Test Shop1 menu of the system is used to display the current status of the various valve positions in the system This menu is primarily used for diagnostics and will be discussed further in the Maintenance Section 6 0 4 27 LOCAL OPERATION Test Closed Zero Closed Low Closed CHANNEL A MENU TEST SHOP1 MENU 4 6 4 5 Menu Test Control The Menu Test Control menu of the system is used to tune the controller On new instruments the controller is tuned at the factory and therefore the user should not need to access or make any adjustments to the controller using this menu This menu is user accessible in order to provide a means to set up the controller when control valves are replaced or to perform maintenance on the controller This menu is primarily used for diagnostics and repair and will be discussed further in the Maintenance Section 6 0 AutoTune Full ME Calibrate CHANNEL A MENU TEST CONTROLLER MENU
72. configuration screen will appear Press Recall F2 The DPC will be set to the configuration stored with the program Program 5701 Configuration High Limit 110 000 psi Low Limit 20 305 Control On Band 0 001 Control Off Band 0 000 Bargraph Max 100 000 Slew Rate 9999 997 psi min Slew Limit 9999 997 Gas Head 0 0 mm Ne Control Normal Display Digits 1 Type Diff CHANNEL A MENU PROGRAM CONFIG MENU Press PREVIOUS until the Main Menu appears Press Setup F2 then Limits F1 Change the desired parameters using the normal procedures Return to the Main Menu by pressing PREVIOUS three times Press Menu F6 then Program F4 Use the rotary knob to highlight the name of the program Press Config F3 then Save F1 The configuration of the DPC will be changed to the current settings and stored in the program s configuration 4 6 3 7 Running a Program LOCAL OPERATION 4 24 1 Programs are the Program Menu From the Menu press PREVIOUS until the Main Menu appears press Menu F6 then Program F4 2 Use the rotary knob to highlight the name of the program 3 Press Run F1 The program run screen will appear Stop will be highlighted showing that the program is not currently running CHANNEL A MENU PROGRAM RUN MENU 4 Press Run F2 The configuration of the DPC stored with the program is restored the pressure set point is set to the pressure valu
73. cuum pump and vacuum gauge is required to zero the instrument The optional vacuum gauge sensor should be installed in a port that is located internally to the DPC very near to the Ruska quartz sensor See Section 3 5 5 for proper vacuum gauge installation instructions When initiating the zeroing command in the DPC it will cycle the internal valves allowing the external vacuum pump to pull a hard vacuum on the Ruska sensor It is recommended that the sensor be pulled down to a vacuum of less than 200 mTorr preferably less than 100 mTorr in order to obtain a proper zero The DPC can be zeroed at higher vacuum levels however the uncertainty of vacuum sensors tend to increase at higher vacuum levels therefore the uncertainty in the DPC would also increase if zeroed at higher vacuum levels Once the vacuum level is stable the user enters the vacuum level as indicated by the vacuum gauge and then the zeroing procedure completes Please refer to the Maintenance Section Section 6 0 of the manual for more detailed information regarding the zeroing procedure of the DPC 4 6 3 MENU PROGRAM STORING A SEQUENCE IN MEMORY A program can be run on only the one selected channel at a time Consider an exercise that requires the DPC to start at 30 psi increase to 50 psi then decrease to 20 psi Test sequences like this may be stored in the DPC s memory as a program One benefit of storing a sequence in memory is that the user does not have to command each
74. d handling damage is likely Again it is essential that the procedures mentioned in sections 7 1 through 7 3 be strictly adhered to in order to prevent any shipping and handling damage to the instrument 7 3 STORAGE amp SHIPMENT NOTES STORAGE amp SHIPMENT Jed APPENDIX SUMMARY OF SPECIFICATIONS A 1 UNCERTAINTY ANALYSIS To perform an Uncertainty Analysis on a measurement device you must be able to identify all of the parameters that influence the measurement You must be able to quantify the magnitude of the potential error source and combine these into an overall uncertainty statement To determine the expanded uncertainty on any manufacturers pressure Transfer Standard TS you must identify the following four primary influences 1 Performance specifications of the TS 2 Long term Stability of TS 3 Uncertainty of the standard used to calibrate the TS 4 Environmental or installation influences that could cause errors in the TS Performance Specifications are the short term measurement properties of the device These traditionally include linearity hysteresis and repeatability properties of the transfer standard There often is considerable contusion with the performance specification because different manufacturers use different terms to describe the performance characteristics of their instruments The two most common terms used are Accuracy and Precision In both cases as a minimum the manufacturer
75. d absolute DPC s contain two sensors that require periodic zeroing The primary sensor is zeroed according to the instructions in Section 6 4 5 1 or 6 4 5 2 The barometric sensor is zeroed according to the following instructions 1 Verify that the Reference Port is open to atmosphere 2 Enter the Calibration screen by selecting MODE MENU CALIBRATE 3 Select the Atmospheric Sensor by pressing the Sensor F6 key until the words Atmospheric Sensor is displayed above the calibration coefficients 4 To begin the zeroing process press ZERO If the calibration access code is enabled enter it at the prompt The zeroing screen will appear NOTE The next step requires the use of a properly calibrated standard This zeroing process does contribute directly to the overall accuracy of the system since the pressure applied to the sensor is a non zero differential pressure 5 Enter the current barometric pressure Press ENTER 6 5 SENSOR PHOTOCELL ZEROING If the error message Mechanical Zeroing Needed is displayed the sensor photocell must be zeroed The following steps describe this process Press the MODE key to select the desired channel CAUTION The DPC should only be opened by qualified electrical mechanical service technicians Lethal voltages are present and exposed in the power supply and display NOTE The sensor MUST have zero differential between the Test port and Reference port For Gauge DPCs apply atmospheric
76. decay curve V p 5 A i S 5 4 S Set point A Actual V Control Output p i d Control Coefficients Figures 2 3 and 2 4 show typical Control mode operation Pressure in percent of full scale is plotted versus time to show the change in pressure as the instrument steps from one control point to the next pressure Time seconds FIGURE 2 3 PRESSURE CONTROL NORMAL MODE pressure Time seconds FIGURE 2 4 PRESSURE CONTROL FAST MODE 2 9 THEORY OF OPERATION 2 6 TRANSDUCER MODULE 2 6 1 QUARTZ BOURDON TUBE SENSOR TRANSDUCERO1 The quartz Bourdon tube sensor is mounted in a machined aluminum housing The sensor consists of a helical quartz tube with a mirror affixed to one end as shown in Figure 2 5 A rigid beam is attached transverse to the axis of the helical tube Attached to both ends of this beam are electromagnetic coils Mounted beneath the coils are permanent magnets A lamp assembly directs light through a quartz or sapphire window onto the mirror affixed to the helical tube as shown in Figure 2 6 The mirror reflects the light back through the window and strikes two matching photodiodes When there is zero pressure differential across the helical tube the photodiode assembly is mechanically adjusted so that the light spot is centered between each photocell In this zero position the outputs of the two photodiodes provide energy used to maintain the quartz assembly in its zero p
77. defined limit the unit will not accept the value and it will generate an error code informing the user that they have entered a set point that is LOCAL OPERATION 4 10 greater than the high pressure limit In control mode if for any reason the pressure exceeds the user defined limit it will change into the measure mode and again display an error message to the operator informing them of the error that occurred This value can be edited using the rotary knob to highlight the High Limit Then enter the new value using the keypad This will show up in the scratch pad on the lower portion of the screen Press the Enter key and the value for the high limit will be updated to the value that was typed into the scratchpad 4 6 1 1 2 Low Limit User defined Minimum pressure limit This is the same as the high limit except it is to protect the DUT from low pressure limits 4 6 1 1 3 Auto Vent User defined maximum pressure that the DPC can reach prior to venting the test port to atmosphere 4 6 1 1 4 Control Band There are two common pressure control approaches that are available with the Ruska 7252 DPC One of the most common control styles is an Active controller where the controller remains operative and holds the pressure at a commanded set point This allows the system to hold the pressure at a set point within the control stability specification See Appendix A In addition to possible leaks in a system following a pressure step the press
78. dhered to in order to prevent damage to the instrument Failure to follow these procedures will likely result in damage to the DPC during shipment This damage is not covered by the carrier s insurance 7 1 DISCONNECTING THE DPC Relieve all pneumatic pressure from the DPC Turn the DPC power switch to the off position Disconnect the power cable from the DPC power receptacle Disconnect all pneumatic lines from the DPC s back panel Plug all ports 7 22 PACKING INSTRUCTIONS To prevent shipping and handling damage to the instrument adhere to and strictly follow the instructions below The governing discipline in ensuring a damage free shipment is to ensure that the possibility of handling shocks to the DPC is minimized and or prevented during transit Ruska accomplishes this task by cradling the DPC within two foam cradles that are encapsulated within a double walled corrugated box The DPC is restrained and supported but still has resilience The materials used in the packaging operation are foams that have a minimum impact rating of not less than N 95 Styrofoam poured foam place mixtures and other rigid foams are not recommended If polyfoam or rubber foam other than that used in the original packaging is to be used cut it into strips so that it will not present a large rigid surface to the DPC Ruska has found that corrugated cardboard boxes provide the best packaging exterior The box must have an imp
79. e Section 3 5 5 for vacuum sensor installation 1 Select the desired pressure units using the UNITS key You can change both the unit of measure that the DPC is displaying Pressure and the unit of measure for the vacuum sensor It is not required to have the DPC displaying pressure in the same unit of measure as the vacuum sensor To change the unit of measure for the Vacuum sensor press the UNIT key and then the Vacuum F2 key Enter the Calibration screen by selecting MODE MENU CALIBRATE Select Zero F1 Do NOT press the Calibrate button When initiating the zeroing command in the DPC it will cycle the internal valves allowing the external vacuum pump to pull a hard vacuum on the Ruska sensor It is recommend that the sensor be pulled down to a vacuum of less than 200 mTorr preferably less than 100 mTorr in order to obtain a proper zero The DPC can be zeroed at higher vacuum levels however the uncertainty of vacuum sensors tend to increase at higher vacuum levels therefore the uncertainty in the DPC would also increase if zeroed at higher vacuum levels Wait for the vacuum level on the test port to stabilize Enter the vacuum level as read by the external vacuum gauge and press OK F6 Do not disturb the instrument while zeroing is in process Wait for the zeroing procedure to finish Press PREVIOUS to return to the Main Menu MAINTENANCE 6 12 6 4 6 3 Simulated Absolute Instruments Simulate
80. e Units Define Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 then Units F3 2 Use the rotary knob to highlight the desired user defined unit and then select the Edit Name F1 function key 3 The following sequence is used to change the name of the selected unit CHANNEL A MENU SETUP UNITS EDIT NAME MENU a Use the lt F4 or gt F5 key to highlight the desired character in the matrix b Use the rotary knob to change the character c Repeat steps a and b until the desired name is entered Press the Clear key to start over d Press the Done F6 key when the name change is completed 4 Use the rotary knob to highlight the desired user defined unit that has just been renamed 5 Use the numeric keypad to enter the conversion factor and press ENTER to accept 4 15 LOCAL OPERATION Press PREVIOUS three times to return to the Menu The new unit definition may now be selected using the units key 4 6 1 4 Menu Setup Remote The Menu Setup Remote screen is where the remote communication interface is set Default 4 Protocol 6000 510 Baudrate 1200 2400 19200 Data Bits 7 Parity 1 Stop Bits 2 CHANNEL A MENU SETUP REMOTE MENU 4 6 1 4 1 GPIB Address Sets the IEEE 488 interface address 4 6 1 4 2 Protocol The Protocol defines which protocol should be used by the remote interface The opt
81. e a powertul tool when you are trying to improve the measurement performance of a standard By reducing the calibration interval the expanded uncertainty would also reduce On the other hand some manufacturers do not claim that their stability specification is proportional with time This would be the case for instance if the instrument naturally drifted in a sinusoidal fashion This would suggest that the sensor 1 APPENDIX could drift to its maximum stability limit at any time and therefore reducing the calibration interval would not improve the expanded uncertainty of the device Uncertainty of the Standard used to calibrate the transfer standard This is the expanded uncertainty of the calibration standard that was used by the manufacturer to calibrate the digital transfer standard This should be the expanded uncertainty of the calibration standard and include all sources of uncertainty that would influence the calibration standard including the uncertainty from the National Standards Laboratory that the standard is traceable It should also be noted that when the instrument is re calibrated the uncertainty of the device is influenced by the uncertainty of the calibration standard that will be used to perform the re calibration Therefore the uncertainty analysis should be evaluated following each re calibration If the instrument is re calibrated using a different calibration service provider than the manufacturer the uncertainty of
82. e an indication that the inner loop control sensor needs to be realigned with the high accuracy quarts sensor This is achieved by running the Calibrate Auto Tune function NOTE Prior to performing any Auto Tune functions in an effort to improve the controller performance confirm that the system is a leak free system and the volume attached to the test port is within the recommended range see Appendix A Additionally assure that the system has adequate pressure and vacuum supply when required MAINTENANCE 6 16 To perform these Auto Tune functions the instrument must be connected to a pressure supply with the pressure supply set to the proper supply pressure please refer to the specifications in Appendix A On absolute instruments a vacuum pump must be connected to the exhaust port Disconnect any device under test from the test port The test port must be connected to a sealed volume of 5 to 15 cubic inches 80 to 240 cc s Use the Rotary knob to select which Auto Tune procedure is to be performed and then press the enter key The Full performs the complete Auto Tune sequence If selected you are not required to run any of the other Auto Tune functions Press the enter key The DPC with go through a sequence of controlling to various pressures and automatically adjusting the control parameters of the valves The DPC will display a message indicating when it is complete with the Auto Tune procedure The time required to comp
83. e in the first step and the DPC is placed in Control mode Run will now be highlighted and the program will proceed through its steps 5 To pause the program press Pause F3 Pause will now be highlighted and the DPC will continue controlling to the current set point The DPC will maintain control of the current set point until further instructions from the operator Press Continue F4 to resume the program 6 To stop the program press Stop F5 The program will stop running but the DPC will continue controlling to the current set point 4 6 4 MENU TEST The Menu Test section of the system is used to perform a number of the diagnostic and tuning functions that are available with the 7252 The Sweep and Control test operate on the current selected channel The other screens are independent of the selected channel 4 25 LOCAL OPERATION Remote CHANNEL A MENU TEST MENU 4 6 4 1 Menu Test Sweep Test The sweep function can be used to automatically exercise the elastic sensing element of the device under test prior to performing a calibration For the DPC to perform the sweep test input the high and low set point pressures the pressure control tolerance the dwell time at set point and the number of cycles to perform 1 Ensure that the units limits and control parameters are set to their desired values 2 The sweep test is entered from the Sweep Test Menu From the Main Menu press PREVIOUS until the Main
84. e powered through the vacuum pump power switch When the vacuum pump is turned on the solenoid valve is energized and closes allowing the pump to operate normally When the pump is turned off power is removed from the solenoid and the vacuum is vented to atmosphere Periodic changing of vacuum pump oil as recommended by the vacuum pump manufacturer should also be done 6 3 6 PROCESSOR BATTERY The processor board uses a lithium battery to maintain time and date information This battery has a varying life If the instrument is left on 24 hours a day it may last 5 to 10 years If the instrument is stored it may only last one year Annual replacement is recommended To replace the battery 1 Turn off power and remove the instrument cover See Section 6 3 2 2 Remove the processor card by removing the screw and the bracket that locks the display cable in place and gently rock the card upward 3 Holding the processor card remove the battery the round silver object by caretully pulling on the battery 4 Plug in a new battery RIC 4 725 5 Reinstall the processor card the bracket that locks the display cable in place and the screw Replace the instrument cover 6 The time and date may have to be re entered See Section 4 6 1 5 6 4 CALIBRATION To keep the DPC operating within its specified precision the calibration procedure described below should be performed once every year If a higher level of overall performance is desired
85. ed 4 13 LOCAL OPERATION 6 Press Position F4 to select if the position of the Device Under Test is either Above or Below the 7252 The selected units will be highlighted and appear in the Gas Head description 7 Use the rotary knob to highlight the label Gas Head 8 Use the numeric keypad to enter the height in the selected unit 9 Press ENTER to accept the entry 4 6 1 2 5 Atmosphere The nominal barometric pressure value for the location that the DPC is utilized should be entered for atmosphere On gauge mode instruments this number is used to calculate the density of the test port pressure medium and to correct for head pressure variances between the reference port of the DPC and the DUT 4 6 1 2 6 Pressure Filter is used to adjust the degree to which the front display pressure value is filtered A value of four 4 is the default value As the value increases the filtering level increases however the display update rate reduces Typical filter values would range between 1 to 10 For pressure sensors with full scale ranges of 1 psi 7 kPa or less a filter value up to 30 is typically recommended 4 6 1 2 7 Changing the Number of Decimals Each unit has a default number of decimal places used for pressure display This may be adjusted up or down by one decimal place 1 The decimal digits are set from the Setup User Menu From the Main Menu press PREVIOUS until the Main Menu appears press M
86. enu F6 then Setup F2 and then User F2 2 Turn the rotary knob until the label Display digits is highlighted 3 Turn the rotary knob further until the desired number of digits from the default resolution is highlighted 1 0 1 and then press the ENTER key to select 4 6 1 2 8 Key Click The DPC can be configured to emit a clicking sound each time a key is pressed 1 The key click is set from the Setup User Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 and then User F2 2 Turn the rotary knob to highlight Key click and then highlight either on or off 3 Press the ENTER key to select 4 6 1 3 Menu Setup Units In addition to the standard units of measure provided by the DPC four user defined units are available To create a user defined unit the user enters a name that is one to ten characters long and a conversion factor that is a multiple of kiloPascals kPa For example using the information from table 2 1 the conversion factor for millitorr or one micron of mercury at C is calculated as follows 1000mTorr lTorr Hg 0 0 145037 7psi mTorr kPa x 7 ImmHgo o 77 00193377psi TkPa LOCAL OPERATION 4 14 thus the conversion factor simplifies to mTorr kPa x 7500 6180 Edit Name kPa 750061800 0 0 0098692 10 CHANNEL A MENU SETUP UNITS MENU 1 The pressure units are defined from th
87. for any AC voltage between 90 and 260 volts If a different power cord is necessary for your receptacle consult Table 1 1 for available power cords Finally turn on the DPC by toggling the power switch on the back panel When the MEASURE screen appears on the display the front panel will be fully operational 3 4 1 OBSERVING THE DPC S FULL SCALE RATING The full scale pressure range of each channel of the DPC is noted on a label on the front panel of the instrument The label denotes the pressure range for channel A and for channel B 3 5 PNEUMATIC CONNECTIONS The following sections discuss each port All ports are NPT pipe fittings See Figure 3 1 Remove all plastic shipping plugs from the back panel pneumatic ports 3 5 1 PRESSURE SUPPLY PORT Each channel has its own individual pressure supply port which must be connected to an independently regulated source of clean dry nitrogen or air Shop air should not be used Refer to Appendix A for supply port gas purity and pressure regulation requirements Warning Make sure that you connect the proper pressure supply to the correct pressure channel The pressure range for each channel is identified on the front panel of the 7252 This is depicted using the letter A and B for the two channels and the pressure INSTALLATION 3 2 associated with these ranges On the rear of the instrument there are two manifolds one for channel A and one for channel B Verify that the press
88. g Gauge Greater of 0 005 of 25 FS or 0 0075 psi 0 05 kPa Precision opt Stability Over 3 Months 0 001996 RDG months Over 1 Year 0 0075 RDG year lt 0 002 5 24hrs Control Stability 0 00196 of maximum FS Control Low Limit 0 psig 0 15 psia Slew Rate 20 Seconds Test Port Isolation Precision is defined as the combined effect of linearity repeatability and hysteresis throughout the operating temperature range Some manufacturers use the word Accuracy in place of Precision however the meaning is identical 3 Requires vacuum pump to control 0 psig or the vent mode can be used to obtain 0 psig Zero drift typically improves with sensor age Defined as 1096 FS increments into a 15 cubic inch volume APPENDIX A 6 GAS SPECIFICATIONS Pressure Source Medium Pressure Source Particle Size Contamination Pressure Source Max Moisture Content Clean Dry Air or Nitrogen lt 50 microns 50 C dew point Pressure Source Max Hydrocarbon Content 30 ppm VACUUM REQUIREMENTS Supply Vacuum 50 liters per minute minimum with auto vent feature absolute units only Bypass Supply Vacuum Valve for High Pressure Gauge work Industrial grade nitrogen 99 5 pure APPENDIX A THIS PAGE INTENTIONALLY LEFT BLANK APPENDIX A A 8 APPENDIX SUMMARY OF ERROR MESSAGES Negative error numbers are from the Standard Commands for Programmable Instruments Version 1991 0 Description and Cor
89. have been completed The DPC should display a screen similar to the one shown above The right hand side of the display should show the options At power up there may be errors relating to the default settings an error message is displayed in red at the bottom of the screen press F6 then press PREVIOUS If multiple errors exist you will need to press the F6 key multiple times to clear all of the errors It is generally easier to first operate the system in the Single Channel Display Screen as opposed to the Dual Screen Press the Menu function key to go to the Channel A only screen Press the Mode key to go to the Channel B only screen Pressing the Mode screen toggles between the two channels Channel A is recognizable by the dark blue background color and channel B has a lighter background color Select Channel A to proceed with the tutorial 4 3 LOCAL OPERATION Control Setpoint CHANNEL A MAIN MENU This is the channel A Main Menu The double sized numbers in the top center of the display shows the current measured pressure 0 00 psi diff The upper left corner shows the current mode of the DPC MEASURE CONTROL or VENT The right side of the screen shows a bar graph displaying the current pressure relative to a user configurable full scale value Below the pressure is the pressure control set point below this is the difference between the set point and the actual value Below this is a numeric scratchpad for enter
90. he name of the program See Section 4 6 3 4 for creating a user defined program name 4 6 3 4 Changing the Name of a Program 1 The name of an existing program is changed from the Program Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Program F4 n addition to changing the name of an existing program a new program may be initiated by selecting new and performing the same steps as outlined to change the name of a program 2 Use the rotary knob to highlight the current name For a new program name select new 3 Press Edit FA The program editing screen will appear displaying the first step 4 Press Name F6 LOCAL OPERATION 4 22 sc un CHANNEL A MENU PROGRAM EDIT NAME MENU Use the F4 and F5 keys to highlight a character Turn the rotary knob to select the character from the character set To correct a mistake press Clear F4 and return to step 5 Repeat steps 5 and 6 until the name is complete Press Done F6 to store the contents of the scratchpad as the new name of the program 4 6 3 5 Changing an Existing Program Instructions for changing an existing sequence are given below Both manually and automatically generated programs may be edited 1 4 Programs are changed from the Program Menu From the Menu press PREVIOUS until the Main Menu appears press Menu F6 then Program F4 Use the ro
91. his manual and a power cord Although the standard DPC is fully functional with just these items and the appropriate pressure and vacuum supplies the following options are also available NVLAP Accredited Calibrations Ruska received formal accreditation from the National Voluntary Laboratory Accreditation Program NVLAP which is administrated by the National Institute of Standards and Technology NIST NVLAP has assigned Ruska laboratory code 200491 0 to indicate that our accredited calibration services are in compliance with all relevant requirements of ISO IEC 17025 1999 and ISO 9002 1994 Ruska s calibration laboratory can provide an optional accredited pressure calibration The NVLAP calibration certifications are optional and must be requested at time of order Rack Mount Kit This 6 969 kit meets ANSI EIA requirements for a 4U 19 rack mount kit Additional Power Cords Additional power cords are available for most countries All options are summarized in Table 1 1 To order these items please contact Ruska Instrument Sales in the U S at 713 975 0547 TABLE 1 1 OPTIONS LIST FOR THE MODEL 7252 DPC Ruska Instrument Corp Part Number RIC LabView Driver National Instruments Downloadable from World Wide Web Rack Mount Kit Cabinets 18 24 inches deep 7250 903 Vacuum Pump 115 VAC 50 60 Hz 99877 800 230 VAC 50 60 Hz 99877 860 1 3 INTRODUCTION NOTES INTRODUCTION 1 4 SECTION 2 0 THEORY OF OPERATION 2 1 IN
92. ifferenz psi vi INTRODUCTION SAFETY SUMMARY The following are general safety precautions that are not related to any specific procedures and do not appear elsewhere in this publication These are recommended precautions that personnel must understand and apply during equipment operation and maintenance to ensure safety and health and protection of property KEEP AWAY FROM LIVE CIRCUITS Operating personnel must at all times observe safety regulations Do not replace components or make adjustments inside the equipment with the voltage supply connected Under certain conditions dangerous potentials may exist when the power control is in the off position due to charges retained by capacitors To avoid injuries always remove power from discharge and ground a circuit before touching it DO NOT SERVICE OR ADJUST ALONE Do not attempt internal service or adjustment unless another person capable of rendering aid and resuscitation is present RESUSCITATION Personnel working with or near dangerous voltages shall be familiar with modern methods of resuscitation Such information may be obtained from your local American Medical Association ELECTRO STATIC DISCHARGE SENSITIVE PARTS CAUTION Electrostatic discharge sensitive ESDS is applied to low power solid state parts which could be damaged or destroyed when exposed to discharges of static electricity Maintenance personnel are often not aware that an ESDS part has been damaged or
93. imits When these limits are exceeded the DPC is returned to Measure mode shuts off the apply and exhaust control valves and an error message is generated Additionally a vent limit may be set The DPC will go to Vent mode when the pressure exceeds this limit 2 7 1 3 Shut Offs Measure mode can be entered at any time by pressing the Measure key on the main keypad with no further acknowledgment required The DPC will turn off the controller 2 7 1 4 Oven Control The oven temperature is controlled via a pulse width modulated signal The time the heater is on can be varied from 0 to 100 The pulse width at startup is initialized to the previous value which was stored in battery backed CMOS RAM The oven control is a PID controller updated approximately every 7 seconds The sensor readings are accessed by pressing MENU DISPLAY With an exception of the 3000 psi 20 7 MPa version 7250 the high accuracy quartz sensor is housed in a temperature controlled oven There is a 3 hour warm up time required prior to the DPC operating at its optimum precision The user can verify when the instrument is thermally stable by THEORY OF OPERATION 2 12 viewing the MENU DISPLAY screen and verifying that the temperature is at 50 In addition to the temperature this screen will show the duty cycle of the oven When operating the system in either a very cold or hot environment if the oven in unable to maintain the temperature of the internal oven the
94. ing a new set point value The highlighted label on the right hand side of the screen displays the current assignments of the function keys F1 through F6 that are located beside the display Step 1 Change the pressure units The units are changed by selecting the UNITS key on the keypad Vacuum kPa psi kgf cm mmHg 0 C cmHg 0 C inHg 0 C inHg 60 F 204 4 C 20 C inH2O 25 C user1 2 atm mbar FS feet meters knots km hr Pa hPa MPa kgf cm mmHg 0 C cmHg 0 C inHg 0 C inHg 60 F 204 4 C 20 C inH2O 25 C user1 user2 atm mbar FS feet meters knots km hr Pa hPa MPa UNITS MENU Step 2 Use the rotary knob located to the right of the display to move the highlight bar to the desired unit Note the highlighted curser initially shows the current unit of measure When the rotary knob is moved the current unit remains highlighted in a gray color and the new unit is highlighted in a light blue color LOCAL OPERATION 4 4 Step 3 When the unit desired is highlighted press the ENTER key the far right side of the front panel under the numeric keypad The display will return to the MAIN screen with the current units The second part of this tutorial uses the DPC to generate pressure The pressure supply must be connected and the test port must be connected to a closed volume in accordance with Section 3 5 of this manual Step 4 Step 5 Step 6
95. ing in a warm environment or when multiple systems are housed in consoles without adequate ventilation the system may become too hot and generate the oven control failure error message If operating the instrument in a warm environment and the oven duty cycle is at a low percentage gt 10 you will need to turn the fan on When the operator changes the status of the fan it will default to that condition until it is changed by the operator Test Closed Zero Closed Low Closed MODE MENU TEST SHOP 1 MENU To turn the fan on or off press Menu F6 from the Main Menu then Test F5 then Shop F5 Use the rotary knob to highlight either fan Off or On Press ENTER to select 6 8 SYSTEM SOFTWARE UPDATE PROCEDURE NOTE Calibration and other stored constants are not affected by program updates The update procedure requires a PC connected to the RS 232 port on the 7 9 pin to 9 pin null modem cable minimum pinout 2 3 3 2 5 5 1 When appropriate Ruska can e mail the latest version of the software for upgrading instruments The e mail will have a zip file attached contains two files UPDATE7 EXE and lt version gt IMG Unzip these files into a directory on the PC Set the 7XXX to 9600 baud 8 databits no parity 1 stopbit Run the program Update7 Follow the prompts to select the communications port and the image file When the upgrade is finished Update7 running on the PC and the 7XXX should both displ
96. ions are Standard Communication for Programmable Instruments SCPI which is the only interface available for the 7252 4 6 1 4 3 Serial Interface Set Up The operator can set up the Baud Rate Data Bits Parity and Stop Bits for the Serial Interface 4 6 1 5 Menu Setup System The System Menu identifies the Software release version that is being operated in the DPC It also stores and allows the operator to edit the Date and Time Ruska Instrument Model 7250x Software Version 2002 09 06 10 49 32 0 03 2002 09 11 Time 15 56 56 CHANNEL A MENU SETUP SYSTEM MENU LOCAL OPERATION 4 16 4 6 1 5 1 Date Time The DPC s system clock is continuously updated If the date or time requires editing the following applies 1 The date and time are set from the Setup System Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 and then System F5 2 To set the system date turn the rotary knob until Date is highlighted Use the numeric keypad to enter the current four digit year month and day yyyymmdd All digits must be entered Press ENTER to accept 3 To set the system time turn the rotary knob until Time is highlighted Use the numeric keypad to enter the current hour minute and second hhmmss All digits must be entered Press ENTER to accept 4 6 1 5 2 Reset The Reset F1 command is used to re boot the DPC 1 To reset the system from the Main
97. ive matrix TFT display combines a bright low glare readout with a wide viewing angle During normal operation the measured pressure is easily visible from a distance of 10 feet 3 meters Adjustable Pressure Display The pressure display may be adjusted to show one decimal greater than or less than the default resolution Ease of Operation An intuitive menu driven interface makes the DPC easy to use Frequently used selections such as the units of measure are restored to memory each time the DPC powers up Easily Programmable The DPC s powerful microprocessor provides the basis for smart electronics With a few simple keystrokes the user can set limits on the system pressure create unique units of measure program a test sequence and more Modular Design The sensing element pneumatics electronics and user interface are separated into modules making maintenance faster and easier Attractive Desktop Packaging A sturdy aluminum case houses all of the DPC s pneumatics electronics and user controls With the optional rack mount kit this standard 19 EIA chassis fits easily into a rack mount system Power On Self Test Upon power up the DPC quickly tests its hardware and software After the DPC completes this test the user can select more extensive self tests for the pneumatics and electronics Ease of Calibration Calibration may be performed either remotely or entirely from the front panel No disassembly is required and the
98. l 13 command is received the DPC will stop transmitting Transmission is restarted when the XON hexadecimal 11 command is received When only one unit is attached the Control C hexadecimal 03 command will clear the transmit and receive buffers and disable addressing When addressing is disabled the unit will respond to commands without being addressed 5 6 SAMPLE PROGRAMS 5 6 1 SAMPLE PROGRAM 1 7250 GPIB IEEE 488 CONTROLS PRESSURE TO 20 000 FS fe Sample Program 1 7250 GPIB IEEE 488 gt Af Controls pressure to 20 000 5 x tof include lt stdio h gt include lt stdlib h gt include lt string h gt include lt conio h gt include decl h int device GPIB Device descriptor char buffer 256 buffer for input output strings double pressure Pressure read from unit int status Status register from unit int check errors void void write 7000 char s void request 7000 char s void main void char p Initialize GPIB Interface PX device 0 First GPIB Board 4 GPIB Address of 7010 NO_SAD No secondary addressing Tis 1 Second Timeout 0 No automatic EOI for transmit REOS LF Terminate read on Line Feed if ibsta amp ERR 5 11 REMOTE OPERATION write 7000 UNIT FS PRES 20 0 TOL 0 00
99. lete the Auto tune procedure can range anywhere from 15 to 45 minutes AutoTune State 2 Inner 0 00 Setpoint 0 000 AAdj Control 0 R Bias R Adj 0 0 Release 0 If any control valves or the high speed inner loop pressure sensor has been replaced the Auto Tune should be run to characterize the new hardware 6 7 FAN OPERATION The fan in the 7252 can be turned on or off It is recommended to keep the fan ON since this will extend the life of the power supply When operating the system in either a very cold or hot environment if the oven is unable to maintain the temperature of the internal oven it will generate error Oven Control Failure Error messages The operator can review the temperature and duty cycle of the oven by pressing the MODE MENU DISPLAY keys The unit must have been warmed up for a minimum of 2 hours prior to determining the condition of the oven temperature control The temperature of the sensor should be controlled to 50 C The Duty cycle indicates the percentage of time that the oven control is turned on in order to maintain the oven at the proper set point of 50 C A unit that is operating properly after it has fully warmed up should indicate a sensor temperature of 50 C and a duty cycle between 10 to 90 6 17 MAINTENANCE If operating the instrument a very cold environment and the oven duty cycle is at a high percentage gt 90 you will need to turn the fan off If you are operat
100. mas SCPI accepts numeric parameters with optional sign decimal point and exponent OFF is equivalent to zero and ON is equivalent to one Floating point numbers are rounded to the nearest integer for commands accepting integer values only A message is terminated by a line feed hexadecimal OA Carriage returns tabs and other control characters are ignored 5 4 2 SCPI RESPONSE FORMAT Most values can be queried by appending a question mark to a command and not specifying any parameters Commands ending with a question mark in the command summary cannot be set only queried Multiple values from a single command are separated by commas Responses from different commands in the same message are separated by semicolons The response message is terminated by a line feed hexadecimal OA Integer responses are returned as one or more digits Boolean values ON and OFF values are always returned as numbers with zero for OFF and one for ON Floating point values are returned in the format d ddddddddE dd 5 3 REMOTE OPERATION 5 4 3 ANSI IEEE 488 2 1987 COMMAND SUMMARY CS 2 ESE number ESR2 IDN OPC OPC RST SRE SRE number STB TST WAI 5 4 4 SCPI COMMAND SUMMARY Clear Status Event Status Enable Query Event Status Enable Event Status Register Identification Operation Complete Query Returns 1 Operation Complete Reset Service Request Enable Query Ser
101. me should be set to a value greater than the dwell time If the max time is set to zero the DPC will attempt to achieve the set point indefinitely i e the max time function is disabled Mode of Entry f the upscale portion of the desired pressure step sequence and the downscale portion of the sequence both have the same highest and lowest set points and consist of evenly spaced steps the Auto option can be used to automatically generate the program However if any part of the sequence includes unevenly spaced steps or ihe starting and ending set points are not the same each step must be programmed individually In the example given at the beginning of Section 4 6 3 each step must be 4 19 LOCAL OPERATION programmed individually since the starting set point is 30 psi and the ending set point is 20 psi Detailed instructions for entering these items are given in the sections that follow 4 6 3 2 Entering a New Program To program the DPC use the keys on the front panel to change values on the DPC s program editing screen Instructions for entering each step of a new program are included below 1 Ensure that the units limits and control parameters have been set to the desired values 2 The program is entered from the Program Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Program F4 Named Programs CHANNEL A MENU PROGRAM MENU 3 Use the rotary knob to highlight ne
102. mit of range When the zero corrected counts from the A D are below this value the next lower range will be used if possible 7 381 975 full scale of current range Range number 1 4 for high range sensor 5 8 for low range sensor THEORY OF OPERATION 2 14 SECTION 3 0 INSTALLATION 3 1 INTRODUCTION This section of the manual discusses initial installation for the Model 7252 DPC Installing the DPC involves connecting the supply and test pressure tubing powering up the unit and configuring the system through the front panel 3 2 UNPACKING THE DPC Carefully unpack all components checking for obvious signs of damage The shipment contains the following items Model 7252 or 72521 DPC power cord user s manual pec MPa calibration report 5 user specified instrument options If necessary report any shipping damage to the freight agency Remove all shipping and packing materials including the shipping plugs from all components If possible save the packing materials for future shipping needs Finally install the DPC in a location that meets the requirements listed in Table 3 1 NOTE The DPC should be handled in such a way as to minimize mechanical shocks or vibration during installation or use It should be mounted on a rigid bench or in a sturdy 19 rack Although the zeroing process will compensate for a slightly unlevel mounting the DPC should be mounted to within 5 of level TABLE 3 1 GENE
103. n the display to the Main Menu then press the MODE key to select the channel main menu 2 Select MODE MENU TEST SELF ire MODE MENU TEST SELF MENU 3 Press ELECTRICAL F1 The electronics self test will run and display the results The electronics test runs eight sets of tests on various parts of the electronic modules Table 6 1 describes these tests and the possible actions needed if a test fails The pneumatics test runs nine tests on the pneumatics module Table 6 2 describes these tests and the possible actions needed if a test fails 6 1 MAINTENANCE TABLE 6 1 ELECTRONICS SELF TEST Action on failure RIC Part Replace processor board 7215 586 3 Tests the real time clock Replace processor board 7215 586 3 Tests the 10 ms interval timer Replace processor board 7215 586 3 EEPROM Tests the nonvolatile memory Replace processor board 7215 586 3 Oven Tests operation of the sensor oven Replace sensor assy Contact Ruska Allow oven to warm up 6 3 2 REMOVING THE DPC S COVER The DPC should be kept clean and completely assembled at all times Operating the DPC without its cover affects the DPC s thermal gradients and therefore may reduce precision If it becomes necessary to remove the DPC s cover follow the instructions below CAUTION The DPC should only be opened by qualified electrical mechanical service technicians Lethal voltages are present and exposed in the power supply and
104. n zero the 7252 The 7252 would zero the Ruska quartz sensor against an internal vacuum sensor measuring this residual vacuum level This vacuum sensor continuously monitors and update the pressure reading based on the reference vacuum level Following the absolute zero the channel would operate in the absolute mode If the 7252 requires to control sub atmospheric pressures then a second vacuum pump should be connected to the exhaust port for use in pressure control It is not recommended to use one pump connected to both the reference and the exhaust when operating in absolute mode since the controller could cause an unstable reference vacuum 2 4 1 2 Test Port The Test Port connects the DUT to the Pneumatics Module On systems with a full scale pressure range less than or equal to 1000 psi 7 MPa The Test Port is isolated from the DUT by a normally closed solenoid valve that is open during the DPC s Measure Control and Vent modes and closed during the zeroing process This test port isolation valve is not utilized in higher pressure range DPC s The 7252 has two test ports one for each pressure range in the system The Test Port is protected by a relief valve 2 4 1 2 1 Single Test Port Operation Option Some versions of the 7252 allow the instrument to be set up where the test port of both controllers are connected together A flag must be set in the MENU THEORY OF OPERATION 2 6 Menu Setup User menu to allow the system to o
105. nt panel The local interface front panel consists of a color TFT display a rotary knob and a set of keys The display shows the system status and menu options The keys are grouped according to function 1000 psi 10 psi FIGURE 4 1 MODEL 7252 FRONT PANEL Numeric Keypad This includes the number keys the decimal point and the change sign key The UNITS key changes between units of measure MODE held down for 5 seconds changes the language It also switches to the single display mode and toggles between the two channels in the single channel display mode MEASURE is used to place both channels into measure mode CLEAR key will clear the numeric entry field The ENTER key accepts the entered number or confirms a command Function Keys These are the six keys that run vertically beside the display The label shown in the display beside each key identifies their function These functions will change based on which screen you are operating For ease of communication throughout the manual we refer to these keys as F1 through F6 We consider the top key to be F1 and the bottom F Rotary knob The rotary knob select a field for editing and are used for small pressure changes pressure jog at the main menu of the single display mode CANCEL PREVIOUS These keys are used to stop undo or exit the current operation The CANCEL key returns all edited fields on the current entry screen to their original values
106. nto one instrument 1 3 FEATURES The following features are available on all Model 7252 DPC s Fused Quartz Bourdon Tube Technology 0 36 2500 psi full scale ranges Ruska s force balanced fused quartz Bourdon tube sensor makes use of the stability high elasticity low hysteresis and excellent fatigue strength of fused quartz This time proven technology eliminates the need for gear trains bearings shafts and other moving parts that can wear out or introduce hysteresis or deadband into the process Mercury Free All components in the DPC are mercury free NIST Traceability All DPC s are calibrated using Ruska deadweight gauges which are directly traceable to the National Institute of Standards and Technology NIST Ruska is also a NVLAP accredited laboratory and therefore can provide an optional NVLAP accredited calibration Universal Power Supply The DPC s universal power supply accepts AC voltages between 90 and 260 volts and DC voltages between 100 and 370 volts To reconfigure the DPC for use in another country the user simply changes the power cord Measure While Control The DPC simultaneously digitally displays the commanded pressure the actual pressure and the difference between the two A bar graph indicates 1 1 INTRODUCTION how close the actual pressure is to the commanded pressure as well as how close the commanded pressure is to the DPC s full scale pressure Friendly Display The DPC s color act
107. ntrol in Passive Control Mode 0 000 of Reading 2 sigma Expanded Uncertainty RSS 0 0055 of Reading per 90 days Uncertainty Analysis One Year Calibration Interval Uncertainty Ruska Model 7252i from 25 to 100 of Range 2 sigma A Performance Linearity Hysteresis Repeatability 0 005 of Reading and Temperature B Stability 1 year 0 0075 of Reading year Calibration Standard Ruska Model 2465 DWG 0 0010 of Reading Temperature Included A above 0 000 of Reading Control in Passive Control Mode 0 00096 of Reading 2 sigma Expanded Uncertainty RSS 0 009 of Reading per year A 3 APPENDIX A The following two tables are uncertainty analysis examples for a single range 7252 based on a three month and a yearly calibration Uncertainty Analysis 3 Month Calibration Interval Uncertainty Ruska Model 7252 2 sigma A Performance Linearity Hysteresis Repeatability 0 003 of Full Scale and Temperature B Stability 3 months 0 001996 of Reading per 90 days C Calibration Standard Ruska Model 2465 DWG 0 0010 of Reading Lc m Temperature Included in A above 0 00096 of Reading Control in Active Control Mode 0 001 of Full Scale 2 sigma Expanded Uncertainty RSS 0 003296 of Full Scale RSS with 0 002496 of Reading per 3 months Uncertainty Analysis One Year Calibration Interval Uncertainty Ruska Model 7252 2 sigma A Performance Linearity Hy
108. on for Standards ISO Guild to the Expression of Uncertainty in Measurement This statistical approach combines all of the uncertainty components in quadrature RSS In this approach it is important to define the level of confidence that all of the uncertainty components are defined For instance all of the uncertainty specifications that Ruska Instrument Corporation publishes are at the 2 sigma level which would be at a 9596 confidence level Some manvfacturers may state their uncertainty at different confidence level and therefore you would need to be able to convert from one to the other in order to compare the two devices For instance if a manufacturer states that they have an uncertainty of 0 00596 FS and that the uncertainty is expressed at the 1 sigma level then APPENDIX A A 2 it would be doubled to express it at the 2 sigma level i e it would be an 0 01 FS device at a 2 sigma or 95 confidence level The following two tables are uncertainty analysis examples for a 7252i based on a three month and a yearly calibration Uncertainty Analysis 3 Month Calibration Interval Uncertainty Ruska Model 7252i from 25 to 100 of Range 2 sigma A Performance Linearity Hysteresis Repeatability 0 005 of Reading and Temperature Stability 3 months 0 0019 of Reading per 90 days C Calibration Standard Ruska Model 2465 DWG 0 0010 of Reading Temperature Included in A above 0 000 of Reading Co
109. ontroller does not control optimally it would be recommended to first assure that the system is free of leaks and is operating within the external volume specifications see Appendix A You should verify that the instrument is fitted with the proper sized pressure lines to minimize flow restrictions see Section 3 5 Verify that the control band is set as intended see Section 4 6 1 1 3 For active control when testing the controller the Control Band Off and Control Band On values should be set to zero Finally verify that the control is set to Normal to minimum overshoot see Section 4 6 1 1 4 If the system continues to control improperly you can perform the Auto tune There are two options available to the operator Full This fully characterizes the control function of the 7252 It automatically adjust the control valve biases and aligns the inner loop high control pressure sensor to the high accuracy quartz sensor This should be performed any time major components are replaced in the controller such as the control valves or the high speed inner loop control sensor Additionally if the controller is not functioning properly a full Auto tune can be performed to optimize the control Calibrate This automatically aligns the inner loop high control pressure sensor to the high accuracy quartz sensor If in the Normal control mode as opposed to the fast control mode the controller overshoots the commanded pressure valve this could b
110. op reference port However this can vary based on the configuration of the 7252 If the barometric sensor does not react when changing the pressure in the top reference port try the lower reference port If desired change the DPC s units of measure see Section 4 to match those of the calibration standard To access the Calibration screen from the Main Menu select MODE MENU CALIBRATE Select the atmospheric sensor by pressing the Sensor F6 key until the words Atmospheric Sensor is displayed above the calibration coefficients To begin the calibration process press CALIBRATE If the calibration access code is enabled enter it at the prompt The first Calibration screen will appear You will use the calibration standard to apply the various pressures that will be requested by the 7252 The screen will display a table noting the following information a Step the pressure step in the calibration sequence b Apply The pressure that the standard is to generate to the DPC Actual The actual pressure value that was generated by the standard when the point was accepted The Actual value will be highlighted This is your first pressure point in the calibration procedure This calibration requires the generation of two pressures within the range of 700 to 1100 mbar absolute The selected pressures should be spaced as far apart as possible within the allowable range Generate the first pressure Enter the actu
111. osition thus a force balance is created As pressure is applied in the helical tube the entire apparatus attempts to rotate This causes the mirror to move the reflected light spot to shine more on one photodiode than the other The Sensor Board see Section 2 6 2 then responds by changing the current to the electromagnetic coils that through interaction with the permanent magnets force the helical tube to return to its zero position The amount of current required to do this is proportional to the pressure applied across the helical tube Thus the pressure is determined by the amount of current required to return the helical tube to its zero position On Absolute Models the process is similar except that the Bourdon tube is permanently evacuated to less than 0 1 mtorr and sealed at the factory and the test pressure is applied to the sensor case With this configuration all test pressures are measured with respect to vacuum FIGURE 2 5 SHAFT MAGNET SECTION THEORY OF OPERATION 2 10 FIGURE 2 6 PHOTOCELL LIGHT SPOT 2 6 2 SENSOR BOARD A temperature sensor and the quartz Bourdon tube pressure sensor are monitored by the Sensor Board The Sensor board is also used to control and maintain the sensor housing at 50 C 2 6 3 LINEARIZATION TERM As described in the previous section the relationship between the pressure being measured and the current required to keep the quartz Bourdon tube in its zero position is the main
112. ot automatically disable local operation The remote interface may be active while local operations are being done In cases where full remote control is required the following methods may be used 1 Issue a Local Lockout LLO interface message via the IEEE 488 interface The DPC will disable the local keyboard until the Go To Local GTL interface message is received or the REN Remote Enable line is unasserted This method cannot be used on the serial interface 2 Issue the SCPI command SYSTEM KLOCK ON to lock the local keyboard The DPC will disable the local keyboard until the command SYSTEM KLOCK OFF is received 3 Issue the SCPI command DISPLAY ENABLE OFF or DISPLAY TEXT lt string gt These commands will disable the local display in addition to locking the keyboard The command DISPLAY ENABLE ON will restore the local display and keyboard operation Local operation may also be restored by turning the DPC off and back on 5 3 CONFIGURATION The remote interface must be configured before it is connected The remote interface is configured using the local interface The parameters needed vary with the interface used IEEE 488 Address Protocol RS 232 Baud Rate Data Bits Parity Stop Bits To configure the remote interface 1 The remote interface is configured from the Setup Remote Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Setup F2 and finally Remote F4
113. perate in this mode With the test ports connected the instrument will then allow the operator to control either of the two channels to a single test port When set up in this mode the system software uses an internal valve to isolate the lower pressure channel from the higher pressure channel when controlling pressures that are greater than the full scale range of the low pressure channel This option is only available with instruments where both channels have a full scale pressure range that is greater than 10 psi 69 kPa and less than or equal to 1000 psi 6 9 Mpa 2 4 1 3 Vent Procedure The vent mode is implemented with a fast multi step procedure For gauge instruments the DPC controls pressure at the maximum rate towards zero psig When the primary sensor reads that the pressure is within 196 FS pressure of zero psig the controller is turned off and the reference zeroing solenoid is opened which vents the remaining test port pressure to atmosphere If the DPC is at a sub atmospheric pressure then the system will control to zero psig at maximum rate turn off the controller and open the zeroing solenoid Permanent absolute instruments do not have a valve that allows the test port to be vented to atmosphere Therefore these units will control the test port pressure to a value near atmosphere and then turns off the controller This allows the operator to safely disconnect the device under test from the test port However the instrument is
114. perature sensor These are reference sensors aligned at the factory and are utilized by the firmware 2 6 4 1 Case Reference Vacuum Sensor Option A case reference vacuum sensor is a user selectable option This option includes a vacuum sensor installed into the test port on absolute units and the sensor case reference port on differential units and can be read directly by the DPC On permanent absolute instruments this is used to zero the Ruska quartz sensor Please note that the uncertainty of the vacuum sensor used to zero the DPC must be considered in the overall uncertainty analysis of the DPC On units that have been purchased with the Absolute Mode with Evacuated Reference this sensor is used to zero the DPC and it is used to continuously monitor the DPC Case reference while operating in the absolute mode 2 7 SOFTWARE The DPC is a digital software based instrument The controlling software uses a PID algorithm and allows for user definable units and onboard programming The software control loop is an digital outer loop with a high speed inner loop 2 7 1 SOFTWARE SAFETY CONTROLS 2 7 1 1 Preventing Operator Errors The operator is required to verify a change to Control mode or Vent mode by pressing the Enter key Additionally the control set point is set to zero on power up or when any of the limit errors occur 2 7 1 2 Pneumatic Errors The DPC continually monitors the pressure for low high and slew rate of change l
115. point in the current unit of measurement The Controller will control the pressure to the commanded set point Once the actual pressure is within the user defined Control Off Band tolerance the controller will shut off The pressure will remain at this level only changing by the thermal influences or leaks in the system The controller will remain off until it reaches the Control On Band limit The controller will then re activate and control the pressure back to the Control Off Band tolerance This mode of operation removes 4 11 LOCAL OPERATION any added uncertainty in the measurement system due to the controller since the controller is Passive during the high accuracy pressure measurements As an example if a 100 psi 690 kPa full scale DPC was set up with the Control Off Band at 0 001 psi 0 007 kPa and the Control On Band set to 0 005 psi 0 035 kPa This would place the DPC in a Passive control mode If the DPC was placed into the control mode with a pressure set point of 10 psi 69 kPa it would control up to the 10 psi 69 kPa value Once it reached a pressure of 9 999 psi 68 993 kPa the active control would turn off Due to the thermal effects caused by pressurizing the system the pressure will start reducing in the system Once the pressure reaches 9 995 psi 68 965 kPa the active controller would automatically turn on and control the pressure back to 9 999 psi 68 993 kPa and then turn off After a few cycles the system
116. ponent on the Microprocessor Board is the lithium battery The battery continuously updates the DPC s date and time even when the unit is powered down This battery has a varying life If the instrument is left on 24 hours a day it may last 5 to 10 years If the instrument is stored it may only last one year The Microprocessor Board also supports the RS 232 serial interface that allows the user s computer to communicate with the DPC THEORY OF OPERATION 2 2 TABLE 2 1 CONVERSION FACTORS Unless specified otherwise conversion factors are based on ANSI 268 1982 mm E E LN LA KPa pounds per square inch kPa x 0 1450377 inches of water 4 C kPa x 4 014742 kilograms per square centimeter kPa x 0 0101972 Centimeters of water 4 C kPa x 10 19744 Millimeters of mercury 0 C kPa x 7 500605 7 2 3 3 DIGITAL CONTROL BOARD The Digital Control Board plugs directly into the Back plane Board This board reads a high speed silicon strain gauge pressure transducer PDCR connected to the pressure generation point A digital controller on the board drives two solenoids in the pneumatics section to form a high speed closed loop controller 2 3 4 488 INTERFACE The DPC s IEEE 488 GPIB interface card which plugs directly into the Back plane Board provides the DPC with 488 interface This interface allows the user to automate the me
117. pressure display To change mode from the keypad press Mode then select either Absolute 1 or Gauge F2 Please note that the available selection may vary from unit to unit For instance on a permanent absolute instrument the Gauge option would not be available but the simulated gauge is via the Tare function LOCAL OPERATION 4 6 Absolute CHANNEL A MODE MENU 4 2 MAIN MENU The Main Menu displays the measured pressure in double sized numbers Below the pressure reading is the current unit of measure and mode Gauge Differential or Absolute The Main Menu can always be reached by repeatedly pressing PREVIOUS The model 7252 is designed such that all of the commonly used functions are accessible by a direct key on the key pad or from a top level function key Less commonly used set up type functions are accessible through the menu function key Setpoint ud 1 CHANNEL MAIN MENU NOTE For DPC s with pressure ranges greater than 100 psi 700 kPa the supply pressure port must be plugged or connected to a properly set pressure supply in order to measure pressure greater than 100 psi 700 kPa 4 3 CONTROLLING PRESSURE The Control F2 function key is used to place the DPC into the Control Mode A pressure set point should be entered into the DPC prior to placing the unit into the control mode This is to assure that the operator is aware of the set point valve prior to entering into the control mode
118. pressure to the Reference port For Absolute DPCs apply a vacuum to the Reference port 200 1 Remove the DPC s top cover 2 Locate and remove the plastic zeroing plug located in the side of the sensor oven assembly 3 Enter the Zeroing screen by selecting MODE MENU CALIBRATE 4 Select the Primary sensor by pressing the Sensor F6 key until the words Primary is displayed above the calibration coefficients 5 Select Zero F1 Do NOT press the Calibrate button 6 Select the Mechanical Zero F1 key 6 13 MAINTENANCE 0 Out of Range Temperature 0 00 Stable Reference 0 000 Stable 7 Referring to Figure 6 5 slightly loosen the Allen screw on the back of the sensor bracket making sure to maintain a snug fit on the screw Using the T shaped Photocell Centering Tool RIC 7252 111 adjust the photocells by placing the tool in the hole in the back of the sensor and turning the tool slightly The screen will show a number of horizontal lines The top yellow bar represents the current zero setting The bottom portion of the bar has a green bar in the center and two red bars on either end If the top yellow bar is over the red bar then mechanical zeroing is required If the yellow is over the green bar then no adjustment is required 8 Adjusting the photocell will cause the yellow bar to reduce in width You want to adjust the photocell until the yellow line is as thin as possible over
119. re are no potentiometers to tune On single sensor units only a three point calibration is required to fully characterize the instrument On instruments that integrate multiple ranges such as the 72521 additional calibration points are required Automatic Zero Adjust At the user s request the DPC s software automatically performs the zero adjustment with no potentiometers to tune Automatic Head Correction The DPC automatically corrects for head pressure between the DPC and the device under test DUT taking into account the density of the test gas e g air or nitrogen Choice of Medium Although the DPC is not sensitive to the type of gas used within the system the user can select either instrumentation air or nitrogen allowing the DPC to automatically make pressure head corrections Choice of Display Units Standard units include inHg at 09 and 60 F kiloPascals bars psi inH O at 4 20 and 25 kilograms per square centimeter mmHg cmHg at 0 C and cmH O at 4 C Altitude and airspeed units include feet meters knots and kilometers per hour In addition to these predefined units four user defined units are programmable Communications Interface The DPC includes standard RS 232 serial and IEEE 488 interfaces The user s computer communicates with the DPC through the Standard Commands for Programmable Instruments SCPI protocol INTRODUCTION 1 2 1 4 STANDARD EQUIPMENT amp OPTIONS A standard DPC includes t
120. rease the set point or counter clock wise to decrease the controller set point The scratchpad will be updated with a new set point The step size defaults to 10 of full scale This step size is user defined and can be changed in the Menu Setup menu 4 5 LOCAL OPERATION L L 1 L L LE Setpoint 1 Press Enter to Confirm CHANNEL A MAIN MENU Step 9 Press ENTER to accept the new set point The DPC will move to the new set point Step 10 Press Measure key which is located in the key pad The DPC will change to Measure mode No confirmation is necessary to leave Control mode 4 1 1 SELECTING LANGUAGE The 7252 DPC can operate in a variety of different languages To select a different language press and hold the MODE key for 5 seconds The current language will be highlighted Use the rotary knob to highlight a new language and hit the ENTER key to select that language 4 1 22 SELECTING MODE OF OPERATION The 7252 DPC is offered in three different modes These are gauge only absolute only or simulated absolute which operates in both gauge and absolute modes 4 1 2 1 Simulated Absolute Instruments This 7252 DPC is a Gauge and Vacuum Negative Gauge instrument with a barometric reference sensor The summation of the pressure reading from the measurement sensor in the 7252 and the pressure reading from the barometric sensor provides for the simulated absolute
121. rective Action ee Invalid Separator Check punctuation in the SCPI command Data Type The type of parameter data is incorrect Missing Parameter No valid parameter was found for the SCPI command Command Header The command name is not valid Command Unknown The command specified does not exist Header Suffix The numeric suffix for the command name is out of range Settings Conflict The command could not be executed due to the current state of the DPC Some commands cannot be executed while a program self test or calibration is in progress 222 Out of Range The value is not within the valid range For pressures check high and low limits Cannot create program Program memory is full Illegal Program Name The name specified is not valid or does not exist Program Currently Running The command cannot be executed while a program is running Program Syntax Error The syntax of the program definition is not correct 286 Program Runtime Error An error occurred while running the program Usually the setpoint is out of range Calibration Data Lost The calibration data has been lost and the unit must be recalibrated Configuration Data Lost The configuration data has been lost Check all parameters to be sure they are correct 502 Low Limit Exceeded The pressure was less that the low limit 503 Oven Temp Overrange Either the transistor that drives the heater for the quartz Bourdon tube sensor
122. res a number of cycles between two points Perform self test Display remote status Display solenoid valve status Tune control valve parameters Disp gt Display transducer values Blank gt Screen Saver FIGURE 4 2 MENU TREE LOCAL OPERATION 4 2 The key places the unit Vent mode This opens the test port to atmosphere and rapidly reduces the pressure ENTER is required to confirm the operation The F5 key places the unit either the stop or the jog mode and the rotary knob is then used to set the control set point by the correct step or jog amount To go to one of the menus press the F6 key DUAL CONTROL SCREEN The DPC should display a screen similar to the one shown below at power up This is the top of the menu tree The rotary knob may be used to highlight a set point to edit Then enter the new value using the keypad This will show up in the scratch pad on the lower portion of the screen Press the Enter key and the highlighted value will be updated DUAL CONTROL SCREEN Press the Control and Vent function keys to change modes on the specified channel after Enter is pressed to confirm the change Press the Menu function key to go to the Channel A only screen Press the Mode key to go to the Channel B only screen Press the Mode key further toggles between the two channels 4 1 TUTORIAL To begin the tutorial first verify that the DPC is powered up and that the pneumatic connections
123. rt is monitored by a precision barometric sensor Figure 2 2A This sensor provides the barometric offset that allows the Gauge mode DPC to function in a Absolute system A 7252 must have a minimum full scale pressure range of 14 7 psig 101 kPa in order to be configured to operate in the simulated absolute mode using the barometric reference sensor On 7252 s that have two gauge mode sensors with pressure ranges greater than 14 7 psig 101 kPa and a barometric sensor option is installed both channels are able to operate in gauge or absolute modes However since the Barometric sensor is internally only tied to one of the reference ports it is recommended to externally tie the two reference ports of both channels together and have them vented to atmosphere 2 4 1 1 2 Absolute with evacuated reference Optional An option is available on the 7252 that will allow a gauge mode instrument to operate in the absolute mode by evacuating the sensors reference port with an external high capacity vacuum pump This option includes a vacuum sensor that is internally tied to the reference port of the pressure channel that is configured with this option Note for both channels to operate in this mode each sensor must have a vacuum sensor installed In gauge mode the reference port is open to atmosphere In the absolute mode a vacuum pump evacuates the reference port of the sensor Once a vacuum level of less than 200 mtorr is achieved the operator ca
124. ry 4 44 VENT The Vent F3 function is used to rapidly vent the pressure in the system to atmosphere This system does not have a designated internal vent valve Instead the vent mode is implemented with a fast multi step procedure For gauge instruments the DPC controls pressure at the maximum rate towards zero psig When the primary sensor reads that the pressure is within 1 FS pressure of zero psig the controller is turned off and the zero solenoid valve that ties the reference port to the test port is opened This physically vents the test port to atmosphere If the DPC is at a sub atmospheric pressure then the system will control to zero psig at maximum rate turn off the controller and open the zeroing solenoid valve again venting the test port to atmosphere This function is not available on permanent absolute versions of the 7252 4 5 STEP JOG This feature is only available when operating in the single channel mode In addition to entering the pressure set point through the key pad the pressure set point can be changed using either the step or the jog functions The Step function is used primarily when the operator is taking pressure steps in equal pressure increments The size of the LOCAL OPERATION 4 8 pressure step is user defined The Jog function is most often used when calibrating mechanical gauges such as a dial gauge and the operator wishes to change the pressure until the mechanical gauge indicates a cardinal point
125. s define these terms to be the combined effects of linearity hysteresis and repeatability Since the manufacturer defined the terms they used this should not be a problem However it is common that the users definition of these terms differ from the manufacturers and therefore cause considerable confusion For instance the user may believe that the term Accuracy includes all sources of uncertainty This would include items 1 through 4 listed above which would be an all encompassing specification The manufacturer may define Accuracy as the performance specification which consist only of item 1 above The result would be that the instrument would not be capable of meeting the users application because it would not meet the users definition of Accuracy Long Term Stability defines how the instrument drifts with time This specification can be utilized to define the calibration interval for the standard Some manufacturers will provide more than one stability specification for their instrument based on different calibration time intervals It is important to understand that you should not arbitrarily vary the manufacturers stability specification based on time without knowing the characteristics of their device Some manufacturers identify that their stability specification is proportional with time Therefore if the calibration interval were reduced in half the magnitude of the stability specification would also be halved This can b
126. section 2 or the oven temperature sensor itself is malfunctioning To observe the oven temperature select OK then select MENU DISP Check the transistor and sensor for malfunction requesting service B 1 APPENDIX B section 7 if necessary Case Pressure Overrange Select OK then reduce the pressure at the case 5 5 5 Mechanical Zeroing Needed The zero point of the quartz Bourdon sensor is beyond the range of the compensation circuit The zero is adjusted by the software but should be manually adjusted for complete accuracy reference port to 30 psia or lower Oven Control Failure The temperature controller is unable to keep the sensor at the proper temperature 545 Sensor Communication Error Unable to Communicate with 7215xi Sensor 546 Sensor Calibration Lost The 7215xi sensor has lost its calibration and must be recalibrated Factory Data Lost Internal factory constants have been lost Contact Ruska for more information Calibration Mode The Calibrate button must be pressed before SCPI calibration commands can be executed Error reading Barometric RPT Pressure Sensor Control Sensor out of range Controller Communication Error 804 Autotune Failed 40 42 45 800 Solenoid Over Temperature The control solenoids have over heated Wait until they have cooled before entering Control mode 804 APPENDIX B B 2
127. steresis Repeatability 0 003 of Full Scale and Temperature B Stability 1 year 0 007596 of Reading year C Calibration Standard Ruska Model 2465 DWG 0 0010 of Reading Lc tc Temperature Included in A above 0 00096 of Reading Control in Active Control Mode 0 00196 of Full Scale 2 sigma Expanded Uncertainty RSS 0 0032 of Full Scale RSS with 0 0076 of Reading per year Barometric Reference Sensor Option The two sigma expanded uncertainty of the barometric reference sensor is estimated to be less than or equal to 0 002 psi 13 8 Pa per year This uncertainty component should be combined RSS with the primary sensor uncertainty when operating in the absolute mode with a barometric reference sensor APPENDIX A A 4 Evacuated Reference Option The two sigma expanded uncertainty of the vacuum sensor used to monitor the reference pressure is estimated to be less than or equal to 10 mtorr 1 33 Pa per year This uncertainty component should be combined RSS with the primary sensor uncertainty when operating in the absolute mode with a evacuated reference vacuum sensor 2 SPECIFICATIONS GENERAL SPECIFICATIONS Pressure Range Display Display Resolution Electrical Power Operating Temperature Storage Temperature Humidity Nominal Control Volume Dimensions Weight Standard Pressure Units Pneumatic Ports Relief Valves Supply Pressure Minimum 0 to 5 0 to 700 mb
128. sure differential between the sensor s test port and case reference If during the zeroing procedure the message Mechanical Zeroing Needed appears the sensor photocell may need to be zeroed See Section 6 5 for more information The zeroing screen presents several pieces of information The screen will display the current status of the pressure sensor Stability and Temperature If any of the above are unstable then the system will delay until stability is achieved Pressing OK F6 will bypass this wait period NOTE Bypassing this wait period can have a negative effect on the zeroing procedure 6 4 6 1 Gauge and Vacuum Negative Gauge Instruments 1 Verify that the Reference Port is open to atmosphere 2 Enter the Calibration screen by selecting MODE MENU CALIBRATION 3 Select Zero F1 Do NOT press the Calibrate button Pressure 0 Out of Range Temperature 0 00 Stable Reference 0 000 Stable 4 Do not disturb the instrument while zeroing is in process 5 Wait for the zeroing procedure to finish 6 11 MAINTENANCE Performing Zero Adjust 6 Press PREVIOUS to return to the Main Menu 6 4 6 2 Absolute Instruments A vacuum pump must be connected to the reference port A vacuum gauge should be installed for measuring the case reference pressure This gauge should be installed as close to the sensor as possible There is an 1 8 inch NPT fitting available for this installation inside the DPC near the sensor Se
129. t point In the Normal mode the inner loop controls to the set point using maximum rate until close to set point and then slowing down as the set point is approached to minimize overshoot The outer loop continually adjusts the inner loop to compensate for temperature and drift 2 5 3 FAST MODE This mode of operation assumes that the inner loop sensor and the outer loop are aligned When a new set point is issued the outer loop sends a signal that was determined to be equivalent to the desired pressure When the system detects that the pressure is sufficiently close to the desired set point then the outer loop switches to the PID algorithm This control mode results in the highest speed pressure control 2 5 4 ALIGNMENT OF INNER LOOP WITH OUTER LOOP Since the control system of the DPC is based on the alignment between the inner and outer loop sensors there is a procedure that automatically aligns these sensors It is possible that during typical operation the alignment between the inner loop and the outer loop sensor can become miss aligned This can cause control problems such as overshoot This can be realigned using the Auto Tune feature See the Maintenance Section Section 6 0 for details on the Auto Tune functions of the 7250 THEORY OF OPERATION 2 8 2 5 5 CONTROL The outer loop pressure controller is a form of PID control executed every 100 milliseconds 10 times per second The pressure is controlled to an exponential
130. t from pressure changes in the atmosphere and results in very stable pressure measurement and control If the test times are relatively long in addition to connecting the reference ports together they should also be connected to a tank with a volume of 200 cubic inches or better The tank should be vented to atmosphere through a small orifice bleeder valve at the other end of the tank The entire reference assembly should be shielded from rapid fluctuations in air temperature and flow The vent valve should be set experimentally In an environment with no temperature change it would be closed In an environment with no pressure fluctuations it would be wide open The heat from the DPC oven and control valves will cause some temperature variations Thus the appropriate setting varies but a good compromise can be found To observe the variations connect the reference as discussed and open the test port to the atmosphere In measure mode the DPC will indicate the variations A good filter may be usable in place of the valve if it provides approximately the correct restriction of air flow One consideration is that if the reference port is completely sealed from atmosphere its pressure will change due to barometric pressure changes or temperature changes in the environment f the pressure in the reference port becomes lower than the barometric pressure then a vacuum pump would need to be attached to the exhaust port to allow the controller to control
131. t required than other points in the calibration this may indicate that there was an error in that specific calibration point The operator can re check this pressure point prior to completing and accepting the full calibration 1 2 The Step 1 actual value will be highlight This is your first pressure point in the calibration procedure NOTE f the DPC has the Vacuum Negative Gauge Option or the Barometric reference the first two points in the procedure will show the negative pressures that should be generated to calibrate the sensor in the negative gauge direction You are not required to perform both the negative and the positive gauge calibrations every time the unit is calibrated If you want to calibrate only the positive pressures using the rotary knob move the highlighted curser down to the first positive pressure step and generate all of the positive pressures in the procedure When you are complete with the positive points hit the Done key the unit will maintain the older coefficients for the negative gauge portion of the sensor and calculate new coefficients for the positive gauge ranges Conversely you can calibrate just the negative gauge section if desired However you must complete all of the positive or negative gauge steps in the procedure to complete a valid calibration 6 5 MAINTENANCE 2 3 Using your calibration standard generate the pressure shown in the Apply column When the measured pressure s
132. t rr itt rero dd 7 3 APPENDIX A SUMMARY OF SPECIFICATIONS A 1 UNCERTAINTY 1 5 1 A 2 SPECIFICATIONS 5 APPENDIX B SUMMARY OF ERROR MESSAGES B 1 LIST OF FIGURES FIGURE 2 1 DPC BLOCK DIAGRAM i iei tus Coe SEES Ron ex eno ed Ser eate ee Sa ees 2 1 FIGURE 2 2A MODEL 7252 DPC GAUGE PNEUMATICS DIAGRAM 2 4 FIGURE 2 2B MODEL 7252 DPC ABSOLUTE PNEUMATICS DIAGRAM TO 50 PSIA 2 5 FIGURE 2 3 PRESSURE CONTROL NORMAL 2 9 FIGURE 2 4 PRESSURE CONTROL FAST 2 9 FIGURE 2 5 SHAFT MAGNET I tede rena eren d 2 10 FIGURE 2 6 PHOTOGELL UKGHT SPOT ehe EE Es 2 11 FIGURE 3 1 MODEL 7232 BACK PANEL x t ier rer eus 3 5 FIGURE 4 1 MODEL 7232 FRONT PANEL tene E ed ede e ee 4 FIGURE 4 2 MBINU TREE oe eb e sb e e Er dtes dee 4 2 FIGURE 6 4 VACUUM NEGATIVE GAUGE CALIBRATION 6 7 FIGURE 6 5 PHOTOCELL LOCATION 6 15 LIST OF TABLES TABLE 1 1 OPTIONS LIST FOR THE MODEL 7252 1 3 TABLE 2 1 CONVERSION FAGCTONRS dites tee au en ue a iy Sever er eu cub cte 2 4 TABLE 2 2 SOLENOID VALVE STATES uet ette eb estas bt dete
133. tabilizes use the DPC s numeric keypad to enter the actual pressure applied by the calibration standard and then press ENTER Do not enter the measured pressure reported by the DPC If necessary use the CLEAR key to correct a mistake in the edit field If the actual pressure applied is within the indicated tolerance the unit will accept that point and the highlighted curser will automatically scroll down to the next calibration step If the actual pressure is outside of the tolerance for the requested mid point pressure Error 222 Data out of range will occur Acknowledge this error by selecting OK F6 then re enter the actual pressure repeating step 2 1 if 1 2 Generate the next pressure calibration point requested by the DPC Apply this pressure using calibration standard and follow the instructions in Step 2 3 entering the actual pressure applied Repeat this procedure until all of the calibration steps are complete Review the Adj FS field to see if one point has a significantly higher adjustment required than other points in the calibration This may indicate that there was an error in that specific calibration point The operator can re check this pressure point prior to completing and accepting the full calibration To re enter a point use the rotary knob and move the highlighted curser to the actual pressure values in the step in question Generate the requested apply pressure using the standard and enter then new act
134. tary knob to highlight the name of the program Press Edit F4 The program editing screen will appear as a table showing all of the steps Program TESTO1 Cycles 1 Pressure Tolerance Dwell Max Step psi Sec sec 0 0000 0 0010 100 20 0000 0 0010 100 40 0000 0 0010 100 60 0000 0 0010 100 100 0000 00010 100 50 0000 0 0010 100 0 0000 0 0010 100 1 2 3 4 80 0000 0 0010 100 6 7 8 0 0 0000 CHANNEL MENU PROGRAM EDIT MENU The rotary knob can be used to move through the program and highlight the value you wish to edit Use the keyboard to enter a new value This value will 4 23 LOCAL OPERATION show up in the scratch pad located at the bottom of the window Press Enter to accept the edited value To add a step to the program first move to the step after the new step For example to insert a step between steps 3 and 4 move to step 4 Press Insert F4 To delete a step in the program first move to the step to be deleted then press Delete F5 When all changes have been made press PREVIOUS to return to the Named programs screen The DPC automatically saves the changes that were made in the program 4 6 3 6 Changing the Configuration Stored with a Program 1 m Programs are configured from the Program Menu From the Main Menu press PREVIOUS until the Main Menu appears press Menu F6 then Program FA Use the rotary knob to highlight the name of the program Press Config F3 The
135. tory default it is required before the user is allowed to change the limits control parameters or programs IMPORTANT It is recommended that the access password be recorded and filed in a secure location 4 6 1 2 Menu Setup User The Menu Setup User menu is used to setup all of the user specific configurations This includes setting the control step size range of bar graph pressure gas head display pressure filter display resolution digits and audible key click The step size bar graph max ready tolerance and gas head are defined separately for each channel All other entries are common for both channels LOCAL OPERATION 4 12 10 00 psi Bargraph Max 100 00 psi Ready Tolerance 0 01 psi Gas Head 0 0 mm above 250x Atmosphere 101 325 kPa Pressure Filter 4 Display Digits 0 1 Key Click Yes CHANNEL A Menu Setup User Menu 4 6 1 2 1 Step Size In addition to entering the pressure set point by the key pad the pressure set point can be changed using the step function The step function is used primarily when the operator is taking pressure steps in equal pressure increments The size of the pressure step is user defined From the Main Menu press Menu F6 Setup F2 and then User F2 Using the rotary knob move the cursor to highlight Step Size Enter the desired step size in the current pressure units and press ENTER 4 6 1 2 2 Bar Graph Maximum The bar graph on the Main Menu screen can
136. ual value when stabilized 6 4 1 2 Storing the Coefficients Step 4 4 1 NOTE Calibration is complete To exit the calibration procedure without storing the calibration coefficients in memory press CANCEL To store the calibration coefficients in memory select the Done F1 key and the DPC will calculate all of its new coefficients In additional to saving the calibration coefficients to the DPC s memory the user is advised to separately record the calibration coefficients and store this backup in a safe place Step 5 5 5 2 Press PREVIOUS to return to the Main Menu Once the calibration procedure is complete the user should verify several pressure readings against the pressure standard If there are variances beyond the stated precision then an error was probably made in generating one of the calibration pressures and the calibration procedure should be repeated MAINTENANCE 6 6 6 4 2 VACUUM NEGATIVE GAUGE CALIBRATIONS Vacuum mode is an available option The following configuration should be used when calibrating in the Vacuum mode saa PRESSURE CONTROLLER SYSTEM PRESSURE amp VACUUM FIGURE 6 4 VACUUM Negative Gauge CALIBRATION To calibrate in Vacuum mode with the configuration shown in Figure 6 4 the following actions should be taken The system pressure and vacuum inlet valve should remain closed The bottom side of the piston must be open vented to atmosphere
137. unplug the power cord from the DPC Remove the cover The large black box inside the DPC is the oven assembly that houses the pressure sensor On permanent absolute units there will be one pressure line extending out from the sensor oven assembly Along this pressure line there will be a tee with one side plugged with a 1 8 inch NPT stainless steel pipe plug Locate and remove the 1 8 inch NPT stainless steel pipe plug using a 3 16 inch Allen wrench Make two wraps of Teflon tape on the 1 8 inch NPT fitting threads of the vacuum transducer Apply a small amount of vacuum grease to the tape Install the vacuum transducer in the fitting in the DPC Plug the cable from the vacuum gauge into the vacuum transducer Route the cable into the U shaped slot on the top left side of the back panel 3 5 INSTALLATION 10 Replace the DPC s cover plug the power cord back into the DPC and turn the power on 3 5 6 VACUUM SENSOR OPTION The DPC is also available with a vacuum sensor option On a permanent absolute instrument this sensor is used to zero the Ruska quartz sensor at a high vacuum On a DPC that has the Evacuated Reference Option this vacuum sensor is used to monitor the vacuum level in the reference port when the reference port is pulled to a hard vacuum allowing the DPC to operate in the absolute mode INSTALLATION 3 6 SECTION 4 0 LOCAL OPERATION This section of the manual describes operation of the DPC using the fro
138. ure in the system changes due to temperature effects When operating an Active control system the controller continuously monitors any pressure variances in the system and compensates for these effects to hold the pressure at the set point The benefit of the Active control is that it can maintain the pressure at the commanded set point even when there are slight leaks in the system or the system is not thermally stable The second approach is to control the pressure in the system to a set point and then to shut off the Active controller We describe this as a Passive control mode Following a pressure step and the controller becomes passive the pressure will continue to change in the system due to thermal effects However these thermal effects will stabilize over time Once the system has thermally stabilized pressure measurements can be made in the system without any pressure noise injected into the system as a result of having an Active controller in the system The result would be that the controller would not add any additional uncertainty to the pressure measurement since it would be inactive during the measurement process For this method pressure will not be at a cardinal set point When the Control Off Band and Control On Band are set to zero the DPC operates in ihe Active control mode Setting a Control On and Off Band places the DPC in the Passive control mode The Control On and Off Band provides a tolerance around the pressure set
139. ure supply is regulated to the proper pressure based on the actual full scale pressure range of each channel Tubing must be of at least 1 8 inch 3 mm inside diameter and of a sufficient wall thickness for the pressure Either stainless steel or copper tubing is acceptable 3 5 2 EXHAUST PORT The exhaust port may be left open to atmosphere under most conditions A vacuum pump is required in Absolute mode for controlling pressure below atmospheric pressure and will allow lower pressure control in Gauge mode i e to control to psig Supply vacuum lines must have minimum restrictions Tubing should have a minimum I D of inch In small rooms the exhaust port should be piped outside to prevent an accumulation of nitrogen It is also very important to install an auto vent valve to the vacuum pump The purpose of the valve is to vent the vacuum to atmosphere when the pump is turned off The addition of tubing to direct discharged gas out of the work area will also significantly reduce audible noise is acceptable to add tubing to the exhaust port for the primary purpose of reducing noise Care should be used to prevent blockage of the exhaust tube If the exhaust tube is significantly restricted then the exhaust tube can be exposed to full scale pressures 3 5 2 1 Absolute Models When the DPC is a permanent absolute system the Exhaust port and Reference port should be externally connected together to allow the system to function with a
140. vice Request Enable Status Byte Query Self Test Query Wait No operation The current value associated with SCPI command may be read by appending question mark to the command upper pressure limit MEASure PRESsure SLEW PRESsure2 PRESsure3 PRESsure4 PRESsurel1 SLEW PRESsure12 PRESsure14 VACuuml 1 TEMPerature TEMPerature2 TEMPeraturel1 TEMPerature 12 CALCulate PRESsure lt number gt 5 ON OFF LIMit LOWer number SLEW number UPPer number VENT lt gt PRESsurel 1 REMOTE OPERATION For example CALC LIM UPP will return the current A Pressure A Slew Rate A Case Ref RPT Sensor A PDCR B Pressure B Slew Rate B Case Ref B PDCR A Vacuum B Vacuum A Gas Temperature A Sensor Temperature B Gas Temperature B Sensor Temperature get set tare value set tare state using current press low pressure limit slew rate limit high pressure limit auto vent limit 5 4 lt number gt 5 LIMit LOWer number SLEW number UPPer number VENT number CALibration MODE MODE number PRESsure VALue lt n gt number DATA POINtS VALue lt n gt VALue lt n gt lt number gt CALibration VALue lt n gt POINts DATE TIME ZERO DATE TIME VALue number INITiate INITiate RUN 5 PRESsure
141. w 4 Press Edit F4 Since new was highlighted the DPC will create a new program and give a default name of NAMEnn where nn is a two digit number The program editing screen will appear displaying the first step Program Cycles 1 Pressure Dwell Step psi sec sec 0 0 000 Delete CHANNEL A MENU PROGRAM EDIT MENU LOCAL OPERATION 4 20 5 Using the numeric keypad enter the values for Pressure Tolerance Dwell time and Max time pressing ENTER after each value The rotary knob may be used to skip fields 6 At the O step enter the next pressure and the DPC will automatically insert a new pressure step 7 Repeat steps 5 and 6 until the test sequence is complete The Tolerance Dwell time and Max time will default to the value programmed in the first program step and only need to be changed if a different value is desired for a particular step 8 It is often suggested that the last point in a calibration program is to vent the pressure to atmosphere This can be achieved by selecting the VENT function key as the pressure set point Note you can use the vent as a set point at any point in the program The dwell and max time function with vent just as they would at a controlled set point 9 When all steps have been entered press PREVIOUS to return to the Named programs screen See Section 4 6 3 4 for creating a user defined program name 4 6 3 3 Automatically Generating a
142. when the instrument sets the corresponding bit in the event register a summary bit in the Status Byte Register is set ESE STAT OPER ENAB STAT QUES ENAB The Service Request Enable Register SRE is used to generate service requests on the IEEE 488 bus If a user sets a bit in this register when the instruments sets the corresponding bit in the Status Byte Register STB a service request is generated SRE Status Byte Register STB Service Request Enable Register SRE Bit7 Operation status summary Set when an event enabled in OPER ENABLE occurs Bit6 Service request Set when an event enabled in SRE occurs This bit is not used in SRE 5 9 REMOTE OPERATION Bit5 EBS Event status bit Set when an event enabled in ESE occurs Bit4 Message available Set when a response is ready to be sent Bit3 Questionable status summary Set when an event enabled in QUES ENABLE occurs Bit 2 queue not empty Bit 1 Reserved 0 BitO Reserved 0 Standard Event Status Register ESR Standard Event Status Enable Register ESE Bit 7 Power on Set at power up Bit6 Reserved 0 Bit5 Command error Error in command syntax Bit4 Execution error Error in command execution Bit3 Device dependent error Device error independent of commands Bit2 Query error Output queue empty when request received Bit 1 Reserved 0 Operation complete Set for OPC command Operation Status OPER EVENT OPER CONDITION OPER ENA
143. will thermally stabilize and the pressure will hold between the Control On and Control Off Bands 4 6 1 1 5 Control The DPC has two control modes of operation Normal and Fast In the Normal mode minimizing pressure overshooting takes precedence over control speed In the Fast Mode control speed takes precedence over overshooting the commanded set point 4 6 1 1 6 Slew Rate User defined maximum pressure rate of change The DPC is designed to control with minimum overshoot into a wide variety of external volumes at its highest slew rate Therefore in most applications it is recommended that the slew rate be set at its maximum rate value This provides the highest speed control without jeopardizing overshoot or control stability properties The only application where the operator may wish to slow down the slew rate control speed is in applications where the device under test could be damaged by high rate of pressure change The DPC control algorithm tries to limit the rate of pressure change to the slew rate 4 6 1 1 7 Slew Limit The slew limit is used by the system to assure that the slew rate is not exceeded If the slew rate is exceeded the DPC will change from the control mode to the measure mode and it will generate an error message to the operator 4 6 1 1 8 Access The test access password allows the user to protect access to DPC configuration and programs If the test access password is set to any number other than zero fac
144. y functions Calibrate Program Display CHANNEL A MENU 4 9 LOCAL OPERATION 4 6 1 MENU SETUP Setup is used to configure the system It includes setting all of the limits user parameters user defined units of measure remote interface and system setup On the 7252 the User and Limits screens are separate for each channel and must be set up independently The Units Remote and System screens are identical in each channel Any changes made in one channel immediate affects the other channel Limits Remote CHANNEL A MENU SETUP MENU 4 6 1 1 Menu Setup Limits The Menu Setup Limits menu is used to setup all of the limits in the system The pressure limits can be used to protect the device under test DUT from overpressure All limits are defined separately for each channel Press the Mode key to switch between two pressure channels The Access code is common and is used for both channels 110 00 psi Low Limit 20 31 Auto Vent 400 00 Control On Band 0 00 Control Off Band 0 00 Control Fast Slew Rate 10000 psi min Slew Limit 10000 Access CHANNEL A MENU SETUP LIMITS MENU 4 6 1 1 1 High Limit User defined Maximum pressure limit This is often set just over the full scale pressure of the device under test DUT in order to protect the DUT The DPC will then prevent the pressure from exceeding the high limit If the user enters a value greater than the user

DIGITAL PRESSURE CONTROLLER

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