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DSCUSB Manual

1. Physical Mounting OEM PCB EIS 8 00000 Ngee TI ge e Ts 27 05 24 HE 241 o C26 E lo M R23 BS 1c5 9 98 8 CE OH 999 be ga 15 7 X ae aoe Bi 9 o o Dis a oaa Datum 0 0 0 127 5 46 Dimensions in mm The PCB can be fitted to a motherboard by fitting in line pins to the 6 way 4 way and 5 way rows of holes and plugging them into corresponding sockets on the motherboard or directly soldering through holes The 6 way and 4 way holes are on a 0 1 pitch the 5 way holes are on a 2mm pitch OEM Module 4 holes 3 5mm dia Wagsn daasn SOCKET DSCUSB PCB NI oxa HS joooooo U 63 Mantracourt Electronics Limited DSCUSB User Manual The OEM Module can also be DIN rail mounted by means of suitable clips e g Wago 209 120 fitted to a separate base plate Ideally the DSCUSB should be installed in a protective enclosure such as a metal box Electrical Protection Electrostatic protection is sufficient for installation purposes only No over current or over voltage protection is provided in case of faults the supply arrangements should therefore employ adequate power l
2. SOUT selected output foat b SYS main output temperature float RO 11 23 SRAW raw system output float RO 12 25 CELL celloutput Ww FLAG int CRAW rawcellouput ffloat 5 Bi ELEC float Ro B3 SZ system zero float RW 22 45 SYSN snapshot result float RO 23 47 PEAK Peakvalue Float RO 05 VER software version SERL serial number low int RO 31 63 SERH serial number high int RO 32 65 STN int BAUD byte RW OPCL RATE DP digits after point byte RW 37 75 DPB digits before point byte RW 38 77 NMVV CGAI float COFS CMIN float Rw M e9 CLN lin n points byte RW 50 101 CLX1 7 CLK1 7 flin corrections l61 67 SGAI SOFS float SMAX system range max float RW 75 151 USR1 9 FFLV Float FFST RST b X 100 SNAP X 103 RSPT X 104 SCON ShuntcalON p Jx n O SCOF ShuntcalOFF F K n O OPON Digital Outputon K p5 OPOF Digital output off X 108 217 61 Mantracourt Electronics Limited DSCUSB User Manual CTN tempco n points byte RW 110 221 1 5 CTG1 5 tempco gain adjust float RW 116 120 233 241 CTO1 5 tempco offset adjust float RW 121 125 243 251 Table Key Denotes a range e g CLK1 7 means CLK1 to CLK7 Access RW RO WO X read write read only w
3. 76 Mechanical Specification for DSCUSBS and DSCUSBH scsccsccsscsccsccccccscsnssscescesccsesssssesscesseseeass 77 dec 77 E EE ote UID p 77 Environmental Approvals n ee vul rra ra RO VERE EROS 78 3 X Mantracourt Electronics Limited DSCUSB User Manual Den onze ere Tae aes qe Dessen 78 Warranty arredor eraai raet e aa eaaa ae ae eaaeo aaa Ea araa e a aaaea nM Mantracourt Electronics Limited DSCUSB User Manual 4 Chapter 1 Introduction This chapter provides an introduction to the DSCUSB products describing the product range main features and application possibilities Overview The DSCUSB products are miniature high precision Strain Gauge Converters converting a strain gauge sensor input to a digital USB serial output They allow high precision measurements to be made and communicated directly to a PC With the appropriate drivers installed the DSCUSB appears as a virtual communication port to the Key Features Three Form factors The product is available in three formats depending on how it is to be integrated PCB Only for OEM integration into the customer s own products This can include fitting into a load cell body
4. DSJ2 OEM Module Cased version DSCUSBS and DSCUSBH USB Strain Gauge or Load Cell Digitiser Modules User Manual www mantracourt co uk FOR ENTERPRISE MC mantracourt Contents Chapter 1 Introduction seces eoe sero ves odes ode roro Se cede veo esis Sus en te oie veo Nadie due reve ese ene se sce 5 OVEPVIEW 22 5 Key Features ches edeceaeresadasden ated bavands eens eTa 5 Special Facilities 6 THE Product UE ICT tee eas 7 Chapter 2 5 ere era eoe Veoh eee dere Ape EVE Ve e Ee Vea Ye eases 8 Communications Interface Information eee sheets he hse sesso sese sse eee 8 Checking the Device Protocol Typer ios e dede e aed eee voee nre end eua eroe er ees a Deae esee ao eer eee eer 9 Iristrument EXplorert ziii eo es eee se ee aa eens eU RES Ke eu E eau eu cede segue eure exea dant 9 What Can Instr mert Explorer eo exer en ees eR err Ra eb Dur DE ee eer eau e V
5. RIB 9o nc dh De Tot Load 100mA max Power supply 30V max Switch or relay contacts Mantracourt Electronics Limited DSCUSB User Manual 34 OEM Module Wdasn Q Q Q USB SOCKET e I m x i z m x Q z GND TEMP DIN DOUT Load 100mA max Power supply 30V max Switch or relay contacts Cased version Digital Output Power supply 30V max Load 100mA max To change the cased version to accept a digital input the PCB must be modified This requires removing one 0603 SM zero Ohm resistor and re fitting it in another location The PCB must be removed from its housing by unscrewing the four screws and withdrawing the PCB from the case A fine tipped temperature controlled soldering iron should be used to avoid damage to the PCB and surrounding components Remove R30 zero Ohm link re fit in position R29 or link across R29 35 Mantracourt Electronics Limited DSCUSB User Manual Switch or relay contacts Flags Diagnostics Flags FLAG and STAT All the self diagnostics rely on the FLAG amp STAT parameters which are 16 bit integer register in which different bits of the value represent different diagnostic warnings FLAG is stored in EEPROM and is therefore non volatile STAT is stored in RAM and reset on power up to 0 FLAG is latching and needs to be res
6. Instrument Settings Mantrabus 2 DSC USB nstrument Virtual Serial Port Port 7 Y Devices have been detected on the following virtual serial ports COM Cancel As can be seen in the above screenshot the dialog message will indicate whether a device was detected and at what COM Port In this example it is at COM7 so select Port 7 from the drop down list Clicking OK will start communications with the device Mantracourt Electronics Limited DSCUSB User Manual NOTE The screenshots have been taken from a computer running Vista so you may see windows that appear slightly different depending on your operating system Running the Instrument Explorer Software Having installed Instrument Explorer you can now run the application which the rest of this chapter is based on From the Windows Start button select Programs then Instrument Explorer or double click on the shortcut on your desktop Instrument Explorer Icon gs Shortcut to Instrumente The application should open and look like the following screen shot Instrument Explorer Window W Instrument Explorer i Communications rs Wal 5 Al Mantrabus 1 ADP15 standard ADW15 standard LCA15 standard UAB15 standard MantraASCII 2 DCell v3 wm DSC v3 eq DSC USE Mantrabus 2 DCell v3 2545015 mm DSC v3 oS
7. L3 e 059 bg o 1 D4 Tucci Revd end Diagnostic LED USB Rx Data The Diagnostic LED indicates the current status of the device and also its protocol If all is healthy the LED should flash ON for a period of 100ms The rate at which the LED flashes is used to indicate the protocol as indicated in the table below Protocol LED Flash Period ASCII 0 5 seconds MODBUS 1 second MANTRABUS II 2 seconds If an error conditions occurs which is based on any of the following error flags being set then the operation of the LED will invert i e the LED will flash off for 100mS at the rate set in the table above The flags in question are TEMPUR TEMPOR ECOMUR ECOMOR CRAWUR CRAWOR SYSUR SYSOR amp LCINTEG The USB Rx and Tx LEDs indicate the presence of USB traffic N B due to the nature of the USB waveform these LEDs are not very bright but do serve as diagnostic indicators Mantracourt Electronics Limited DSCUSB User Manual 50 Chapter 8 Communication Protocols This chapter gives details of communication protocols and bus connections There are effectively three layers involved in communicating with the DSCUSB 1 Internally all devices support the same command set as described in earlier sections 2 Command accesses are coded into actual byte sequences according to the communications protocol used Three protocols ASCII Mantrabus and Modbus
8. Select No not at this time so that the wizard does not try searching online for a driver Click Next Mantracourt Electronics Limited DSCUSB User Manual 10 Found New Hardware Wizard Welcome to the Found New Hardware Wizard This wizard helps you install software for USB DSC Bus If your hardware came with an installation CD lt or floppy disk insert it now What do you want the wizard to do zi O Install from a list or specific location Advanced Click Next to continue Select Install the software automatically Recommended and click Next Now the wizard will start searching for the drivers Found New Hardware Wizard Please wait while the wizard searches e USB DSC Bus Cancel The wizard should then proceed with installing the software drivers 11 Mantracourt Electronics Limited DSCUSB User Manual Found New Hardware Wizard Completing the Found New Hardware Wizard The wizard has finished installing the software for e USB DSC Bus Click Finish to close the wizard Please note that there are two interfaces to the hardware so that there are two drivers that will be installed The USB DSC Port and the USB DSC Bus So the next dialog box you will see will be for the USB DSC Port and the steps will be repeated from step 2 Found New Hardware Wizard Welcome to the Found New Hardware Wizard This wizard helps you install software for USB DSC
9. Unused 16384 unused reserved 15 32768 unused reserved N Oo A 2 nN 2 o SPSTAT indicates the state of the Open collector output 1 being output on 0 being output off IPSTAT indicates the state of the digital input If the bit is set it indicates input is closed to OV V or GND SCALON Used to indicate that the Shunt Calibration command SCON has been issued amp therefore the shuntcal resistor is now in circuit with the strain gauge bridge SCOF command resets this bit Note that when Shunt Calibration is active the Load Cell Integrity Error will also be generated OLDVAL is set when the device is read via the communications Thus indicating this value has already been sampled It is reset when a new result has been made available Output Update Tracking The OLDVAL flag can be used for output update tracking This allows sampling each result exactly once To achieve this poll the STAT value until OLDVAL is cleared to indicate a new output is ready then read SYS this reading will set the OLDVAL flag in STAT This scheme works as long as the communications speed is fast enough to keep up With faster update rates and slower baud rates it may not be possible to read out the data fast enough User Storage USR1 USR9 There are nine storage locations USR1 to USR9 These are floating point numbers which can be used for storage of data This da
10. applications it may be necessary to Disconnect then Call disconnect then re connect after cycling the power in order to re establish communications 1001 RST lt CR gt ho response Mantracourt Electronics Limited DSCUSB User Manual 56 1 Change the device settings in Instrument Explorer by selecting Change Settings from the Communications menu Select new baud rate The MODBUS RTU Protocol MODBUS is a proprietary standard of Modicom Inc The full specification is quite complex including a timeout based framing strategy and polynomial CRC calculation so full details are not given here Refer to Modicom documentation Knowledge of the MODBUS protocol is therefore assumed The MODBUS protocol is a partial implementation of the RTU binary form of the MODBUS standard sufficient to allow DSCUSB units to coexist on a serial bus with other MODBUS compliant devices NOTE Third party applications for MODBUS communications are readily available e g ModScan from Win Tech software www win tech com who offer a free trial version Modbus Messages All messages and responses are formatted and check summed according to the normal RTU rules The slave number is the device station number Slave 0 may also be used for broadcast writes The device command set is mapped into the MODBUS Output or Holding Registers Parameters read or write are mapped onto a pair of registers containing a 4 byte floati
11. e Separator always present As no checksum or message verification technique is used slaves use this as an extra check on message validity e Command Identifier up to 4 alpha numeric characters case insensitive giving the name of the required command e Access Code Defines what sort of response is expected z means write data is expected to follow means the host is expecting to receive read data back CR i e nothing more before end means the command is an action type execute e Data an ASCII decimal formatted number can include 0 9 and spaces This field can have a maximum length of 15 characters e End of frame a CR is always present to indicate the end of the message Summary e Acommand message begins with followed by a three digit station address then a and finishes with a CR e The and CR only appear at the beginning and end of commands respectively e From the to the final CR is the command instruction of read write or execute type All instructions begin with an alphanumeric command identifier of up to 4 characters and end with a non alphanumeric which may be the final CR Slave Response Message Formats 53 Mantracourt Electronics Limited DSCUSB User Manual Each slave monitors the bus for command messages It responds to any message that is addressed to it by sending a response message To be accepted by a slave device a m
12. in use note Unless you have physical COM ports at the destination you wish to use then you can ignore this The in use note will be shown against any COM port that has at some time ever been allocated as a virtual COM port Once changed select OK on all dialogs until they are closed You have now established which COM port your DSC device is connected to NOTE The selected COM port should now remain with the DSC device regardless of which USB port it is plugged into However plugging the device into a different USB port may depending on operating system result in a request for drivers again If this occurs follow the above procedure from the Found New Hardware Wizard section Plugging in a new DSC device will also result in a driver request on Windows XP Again follow the above procedure from the Found New Hardware Wizard section 15 Mantracourt Electronics Limited DSCUSB User Manual Instrument Explorer Launch Instrument Explorer and select the appropriate DSC USB device from the instrument list in the left hand pane You need to know whether you have a Mantrabus ModBus or ASCII device 43 Instrument Explorer File Communications Parameters Watt ag inxasusBo Select Instrument a Par al Mantrabus 2 s 5450 oca 0518505 DSCv3 DSC USB mi LLD After clicking on the device name the following dialog will appear r
13. operating During correct operation the LED should Flash ON for 100mS then repeat at a rate depending on the protocol as shown in the following table If this is not the case then follow the instructions below Protocol LED Flash Period ASCII 0 5 seconds MODBUS 1 second MANTRABUS II 2 seconds If the LED is OFF check the power supply polarity amp voltage 4 25 5 5V 009 St Sz BB I me 86 8 14 3 amp D4 O OC Teol Revco C25 o i If the LED is permanently ON then contact the factory If The LED is ON for the majority of time then Flashes OFF for 100mS then a fault exists This fault can be read back using the communications Likely causes of this are Strain Gauge Integrity Error or Limits reached for MVV CRAW SRAW or TEMP First check the connections to the strain gauge are correct Next check the input is not over range or the limits set for CMIN CMAX SMIN or SMAX have not been exceeded No Communications The majority of problems involve a failure to communicate as there are a number of optional settings that must be set to the same value at both ends of the link Fo
14. we can convert the output to the required range So if test load fA gt CMVV reading cA test load fB gt CMVV reading cB then calculate the following gain value CGAI fB fA cB cA and the offset is Mantracourt Electronics Limited DSCUSB User Manual 30 COFS cA x CGAI fA The outputs CELL should then be the true forces applied Calibration Methods There are a number of ways of establishing the correct control values Method 1 Nominal data sheet Performance Values This is the simplest method where the given nominal mV V sensor output is used to calculate an approximate value for CGAI Example 50 kN load cell has nominal sensitivity of 2 2mV V full scale To get 50 0 for an input of 2 2mV V set CGAI to 50 2 2222 7273 This assumes the output for is OmV V Method 2 Device Standard Calibration Values With some load cells you may have a manufacturer s calibration document This gives precise cell output gain and offset specifications for the individual cell These values can be used to calculate CGAI and COFS Example A 10 tonne load cell has a calibration sheet specifying 2 19053mV V full scale output and 0 01573mV V output offset CGAI is set to 10 2 19053 0 01573 4 532557 COFS is set to 0 01573 x 4 532557 0 0071297 NOTE Methods 1 and 2 require no load tests This means that systematic installation errors cannot be removed such as cells not being mounted
15. 05058 e DCell v3 a DSC v3 Modbus RTU j DCell v3 xm DSC v3 OSC USE ae CANBus VCI v2 ri 56 The layout of Instrument Explorer s window and child windows allows the user full customisation to their requirements If the application show a different arrangement of child windows than the above screen shot then load one of the default workspaces as follows 17 Mantracourt Electronics Limited DSCUSB User Manual Click File on the menu and select Open Workspace From the file dialogue window select Layout Standard iew This will ensure your application layout matches this document A list of available instruments is displayed in the Select Instrument pane of Instrument Explorer Select the relevant device and protocol to match the device you are working with by clicking on the device icon Instrument Settings One of the following dialogue windows will be displayed Modbus rZ Instrument Settings Modbus ATU DSC USB Name Virtual Serial Port Port aw x Devices have been detected on the following virtual serial ports COM3 MantraASCll r2 Instrument Settings MantraASCll 2 DSC USB Name In Virtual Serial Port Port E Devices have been detected on the following virtual serial ports COM3 MantraBus r2 Instrument Settings Mantrabus 2 DSC USB Name Virtual Serial Port Patt v Devices have been de
16. Cell Connections USB SOCKET ONS 9X4 NI NI OX3 HS O AOOO GND TEMP DIN DOUT 43 Mantracourt Electronics Limited DSCUSB User Manual OEM PCB DTEMP Connections Cz C 28 R23 IC4 o R24 C25 CIZ C18 C24 b BIB 9 99 am c o De a or Ha dud o DTEMP The temperature module is a small double sided PCB with an 8 pin SOIC integrated circuit mounted to it The dimensions are 10 5 x 7 6 x 2 5mm 0 413 x 0 299 x 0 098 There are two solder pads for connection to the DSCUSB A 2mm hole is used for fixing the temperature module to the body of the load cell The module should ideally be positioned as close as possible to the strain gauges The IC on the temperature module must also be in good thermal contact with the load cell body so the strain gauges and temperature sensor see the same temperature DTEMP DQ Control Parameters The temperature compensation parameters define a pair of lookup tables that contain adjustments to the cell calibration gain and offset over temperature The parameters concerned are the following CTN Number of temperature table points CT1 CT5 C Indicated TEMP val
17. Electronics Limited DSCUSB User Manual The Product Range The DSCUSBS and DSCUSBH modules are available in three physical formats OEM PCB DSJ2 OEM Module Cased version Description and dimensions OEM PCB with plated through holes for cable connections Dimensions PCB 43 x 28 x 4mm 1 6929 x 1 1024 x 0 4724 inches OEM PCB fitted to DSJ2 motherboard providing screw type field connections for load cell temperature digital 1 0 and USB plus type 4 pole USB connector Dimensions Module 82 x 60 x 20mm 3 2283 x 2 3622 x 0 7874 inches Free standing module fitted with 9 way D type socket for load cell temperature and digital I O connections Integral USB lead with type A connector Dimensions Case 86 x 57 x 26 5mm excluding connector 95mm 3 740 including 9 way D type socket with 136cm 4 462 feet USB cable 7 Mantracourt Electronics Limited DSCUSB User Manual Chapter 2 Getting Started This chapter explains how to connect up a DSCUSB for the first time and how to get it working If you have an ASCII device we supply a simple DSC Toolkit software application that is simple to use If you have any other type of device you must use Instrument Explorer to configure the device Note that Instrument Explorer can be used with ASCII devices as well so if you need more complex configuration than DSC Toolkit offers you can use Instrument Explorer For simplicity this chapter is based on
18. Flags eres rese eren eren 37 Dynamic Status Flags STAT es orae cere cea Le S rin x FU Er a RR 38 Meaning and Operation of Flags eee hne ehe ehe eher e eser hse re sheer enne 38 Output Update Tracking cites 322 eoe peor evite rere Len oo e evi me e eon o ore ec hae aes 38 User Storage reves iid fee ere soa vole c es ue io dn Fees dese 38 USRI USRI enaere 38 Reset roe i TT E E E E T A 39 TheR set command RST da se ee eroe dae ERE SE Mees E KE E REM MEX ERES 39 WARNING Finite Non Volatile Memory Life seesssesssscccesessssceeeeeeesecooseeeeeessooososessssssssooossssssssooe 39 Chapter 4 The Reading Processi 5 eee ee eo ee ee ee eren kane eo ri ee e pensons us 40 Flow diagralm eee ee esee aee eo a ro eene ns edere eee ee dude aera uere vio ood ue E 40 Cell andiSystem Scalihg iecore e ces obe ad VENE 41 Gc mc mE 41 oM 41 CMN e EON eee tee daveb ER UE EA EXE ET boned 41 FER Rea baa hike Seth e BN GES ON ees U
19. PC as a normal COM port device Mantracourt Electronics Limited DSCUSB User Manual 8 Checking the Device Protocol Before running the communications application you will need to know both the protocol to use and the Com Port number allocated to the USBDSC see the section Establishing the Assigned COM Port later in this chapter DSCUSB Order Description Can Use Can Use DSC Codes Instrument Toolkit Explorer DSCSUASC ASCII Protocol USB Industrial Stability DSCSUEASC Cased version ASCII Protocol USB Industrial Stability DSCHUASC ASCII Protocol USB High Stability DSCHUEASC Cased version ASCII Protocol USB High Stability DSJ2 Motherboard PCB with field terminals for uncased Instrument Explorer Instrument Explorer is Mantracourt s own communication interface for our range of standard products It provides communications drivers for the DCell DSC DSCUSB products A complimentary copy is provided on CD ROM with the DSCUSB Evaluation Kit Instrument Explorer can also be downloaded from Mantracourt s website www mantracourt co uk products_software html Instrument Explorer is a software application that enables communication with Mantracourt Electronics instrumentation for configuration calibration acquisition and testing purposes The clean contemporary interface allows full customisation to enable your Instrument Explorer to be moulded to your individual requirements What Can Instrument Expl
20. Port n If your hardware came with an installation CD lt gt or floppy disk insert it now What do you want the wizard to do O Install from a list or specific location Advanced Click Next to continue Connecting up the Evaluation Kit Simply connect to a spare USB port on the PC using the lead provided in the kit Initial Checks With no load cell connected the LED on the DSCUSB should flash OFF for 100ms every 0 5 1 or 2 seconds depending on the protocol according to the following table Protocol LED Flash Period ASCII 0 5 seconds Connect a load cell to the six way screw connector following the labelling on the DSJ2 PCB Note If there are no errors the LED will Flash ON for 100mS then OFF for the above period This is the normal healthy state Mantracourt Electronics Limited DSCUSB User Manual 12 Establishing the Assigned COM Port The DSCUSB device actually creates a virtual serial port COM port even though it is plugged into a USB port This allows the PC software to communicate with the devices as if they were connected to a serial port Unfortunately the PC will allocate a COM port to each device over which we have no control Therefore we need to perform the next step to establish which COM port has been assigned to the DSC device Instrument Explorer only supports COM ports 1 to 8 so if a COM port greater than this has been assigned it will need to be changed as follows Open the Dev
21. held within the device s non volatile memory FLAG parameter and the other being dynamic and volatile STAT parameter Latched Dynamic Instrument Explorer provides a simple method of displaying and resetting individual flags although these are held within the device in FLAG and STAT parameters 21 Mantracourt Electronics Limited DSCUSB User Manual Flags zl Latched FLAG 0 0 Reset To quickly clear all the flags simply write zero to the FLAG parameter If no problems exist all flags should remain in their off state If any flags remain on then refer to Chapter 8 for flag definitions Performing a System Calibration The values obtained so far are in mV V units these are factory calibrated and fixed to within 0 1 accuracy The device also contains two separate user adjustable calibration parameter groups termed Cell and System Cell is used to convert from mV V to a calibration value and System to convert this calibration value to the required engineering units The use of CELL is optional We shall be using System for the following exercise where we rescale the output value to read in units of your choice and to calibrate precisely to your load cell system hardware Instrument Explorer provides Wizards to allow quick and simple calibration operations to be undertaken without the use of a calculator Wizards can be activated by simply selecting the required item from the Wiz
22. numeric value hyphen then the description of the value mo A CFCT 140 2400 The numeric value is the value of the parameter and the description is I ASCII odi just there to help EC EE 2 9600 3 19200 4 38400 5 57600 6 76800 7 115200 8 230400 9 460800 Commands These commands have Click to execute displayed in the RSTEMPUR Click to execute right hand column Clicking here will display L J button Click this to issue the command to the device to ease al As parameters are changed the communications traffic is displayed in the Comms Traffic pane If any errors occur they will be shown in red in the Errors pane Once an error occurs it will need to be reset before any more communications can take place Reset errors by either right clicking the Errors pane and selecting Reset Errors from the pop up menu or select the Communications menu and click the Reset Errors item To manually refresh the parameter list click the amp button on the toolbar or select Sync Now from the Parameters menu Now you have successfully established communications with your evaluation device the next step is to perform a simple calibration Connecting a Load Cell You can now connect a strain gauge bridge load cell or simulator to the DSCUSB A suitable strain gauge should have an impedance of 350 5000 Ohms and at least for now a nominal output of around 2 5mV V DSJ2 Evaluati
23. that all data has been received amp the next two bytes will be checksum data This does not apply to the response from the remote device as the master knows how many bytes to expect in the reply to each of its commands ACK amp NAK Mantrabus ll supports ACK amp sending ACK 06h at the end of a successful operation and NAK 15h for unknown command or failed operation These are always preceded by the station number see examples below N B Mantrabus ll will not transmit a for invalid checksum data but instead remains silent This is different from the behaviour of the older Mantrabus l 59 Mantracourt Electronics Limited DSCUSB User Manual Writing to Variables Station number and command number are followed by 8 bytes of nibble data the last having its MS bit set followed by the two checksum nibbles Reading of Variables To read an individual variable the command number is sent with the MS bit set i e no data following Action Commands These are transmitted like read commands i e no data sent The response is identical to write commands Mantracourt Electronics Limited DSCUSB User Manual 60 Chapter 9 Software Command Reference This chapter contains tables of all DSCUSB commands with brief details of each Commands in Access Order ASCII name CMVV Temp Compensated mV V float s Omo STAT Status int RO 13 MVV Filtered amp factory calibrated float RO 17 mV V
24. value for SYS at this high input level 25 Mantracourt Electronics Limited DSCUSB User Manual Apply the high known test weight and enter the required SYS value for this weight In this case it will be 100 Click Next to continue SYS Calibration Auto Result Instrument calibration complete The new calibration values have been calculated and the instrument updated Click Finish to complete this Wizard The display below shows the value of SYS You can now apply the low and high inputs to check that the calibration was successful You can press the Back button to return to previous calibration stage to repeat it SYS 99 99995 NOTE Some instruments have parameters that clamp the output values If the SYS output seems incorrect you should first check the instrument manual to see if there are any parameters that can clamp this output The device is now calibrated However you may find SYS has been clamped if the resultant SYS is greater than SMAX or less than SMIN If this is the case then change these values to suitable limits In this example we may set SMIN to 0 5 Kg and SMAX to 110 0 Kg This would then provide clamping of SYS to these values and also a flags being set in FLAG and STAT For detailed information about calibration calculations please refer to chapter 3 Mantracourt Electronics Limited DSCUSB User Manual 26 Chapter 3 Explanation of Category Items Instrument Explorer shows the ca
25. A unrecognised command correctly addressed to station 173 1173 XYWR CR produces the general error response CR Continuous Output Stream ASCII ONLY For the ASCII protocol only there is a continuous output mode The SOUT value is continually broadcast at intervals set by the RATE parameter see Chapter 3 The maximum output rate is 300Hz with the baud rate set to a minimum of 115200 This feature is intended for outputting data to a single simple serial device such as a display or printer There are two continuous output streaming modes which are determined by the station number being set to either 998 or 999 see below for how to change the station number e When set to 999 streaming does not start automatically a ctrl Q 0x11 character must be sent to initiate it This means that if there is for example a brief power interruption then streaming will stop even when power is restored A further ctrl Q character must be sent to re start streaming e When STN is set to 998 the continuous output stream will start automatically from power up The streaming can be switched on and off by sending the standard ASCII XON XOFF control bytes 0x11 and ctrl S 0x13 Station Number STN The STN parameter controls the station number which specifies the device address for bus communications Historically this was introduced to allow multi dropping on RS485 versions of other DSC and DCell products in Mantra
26. BUS RTU Protocol e cae eese 57 The Mantrabuis ll Proto Class a Ea EN 59 Chapter 9 Software Command Reference esee esses 61 Commands in Access Order eie asa epe dev cess ese Pese edere eve 42 61 Chapter 10 Installation eee n teer aae cece n ER eX Pea a Pe Ru Ee RSEN Nga evens Vae bade tee quee vQe a eqs eue 63 Before Installations oe ree eee ree ee esee Sever ee coke esses se sonsshres 63 Physical Mounting iiie eric ease ei vo Co eeu ess ee seus erre rae 63 OEM duc ME 63 Mod le 5 7 ERE reve ORE 63 Electrical Protection 20 22 64 Moisture Protection a a 64 Soldering recie 64 Power SUPDlY cree ee sehe pae eae ee vale duds ee epo eruere tese Lo erue sube e 64 Cable Requirements sese voco voci eye aX vro coed erbe V sees Sa V OUT Ue DUET V v 65
27. CELL at this low input level Enter required value for SYS 0 01573 ia Click the Next button and enter the high values as shown below SYS Calibration Table Enter High Data Enter the high level input value and required output value Enter value for CELL at this high input level Enter required value for SYS 2 19053 10 Click Next the following window will be displayed showing the calibrated SYS value which is dependent on the current input values 23 Mantracourt Electronics Limited DSCUSB User Manual SYS Calibration Table Result Instrument calibration complete The new calibration values have been calculated and the instrument updated Click Finish to complete this Wizard The display below shows the value of SYS You can now apply the low and high inputs to check that the calibration was successful You can press the Back button to return to a previous calibration stage to repeat it SYS 5 514293 NOTE Some instruments have parameters that clamp the output values If the SYS output seems incorrect you should first check the instrument manual to see if there are any Parameters that can clamp this output The device is now calibrated However you may find SYS has been clamped if the resultant SYS is greater than SMAX or less than SMIN If this is the case then change these values to suitable limits In this example we may set SMIN to 0 5 tonne and SMAX to 12 0 tonne This would then provide
28. ES 65 QEM c 65 OEM POB ERR SEEN VEO RUNI PE HE Vor de EE VU ERR TTL PET SEO 65 Strain Gauge Input DSCUSB 5 ern true roten eer esto Vo operan 65 P wer and Commu niCatiom 1 edere sete dose erede Se ERI eae dere eese nc E Ei eae SO see ete Pe 65 SENSON E 66 Identifying Strain Gauge Connections ssssessssessssssssscccesesssecececeeeseoosoeseeeeoooooosooessssssosoossssssssooe 66 OEM PCDB 4 wire load cell o ii cese etre re rue noe SEU S AER OR OUT A creen A e a dur Sede 66 OEM PCD 6 wire load cell lt i cies ces rede rer dti wa eee ox ERE e x eR Eee e de yes a TRU ee E ERE Ry 66 QEM Module 4 wire load cell rete eet eee eh Ros aeg xr ee eee 67 OEM Module 6 wire load cell ee ene ehh enhn hne he there these rh ther eren 67 Cased Version 4 wire load 0 eher ern 68 Cased Version 6 wire load cell 42 ier t tt Pd Rh IRI ao voie auae ra PATER Ur re 68 Strain Gauge Cabling and Grounding RequireMents csscsccsccsscsscsscscccsccscessessescesceenssaeseesscesseeeees 69 DSC Strain Gau
29. Mantracourt Electronics Limited DSCUSB User Manual Chapter 4 The Reading Process This chapter gives an account of the reading process except for the linearity and temperature compensation processes which have their own chapters later on Flow diagram Electrical MMV NMVV x 100 CTGx Ctx CTOx Ctx 1 F CLKx CLXx The underlying analogue to digital conversion rate is 4 8kHz These results are block averaged to produce the required output rate set by the RATE control This block averaged result is then passed through the dynamic filter at the same rate and then into the chain of above calculations The named values shown in the boxes are all output parameters which can be read back over the comms link The diagram shows three separate calibration stages called the Electrical Cell and System This allows independent calibrations to be stored for the device itself the load cell and the installed system characteristics Electrical The Electrical calibration produces corrected electrical readings from the internal measurements This is factory set by Mantracourt during the production process The main outputs from this are e MVV is the factory calibrated output in mV V units e ELEC is the mV V in terms Where the 100 value is set using NMMV This is for backwards compatibility only e TEMP is a device temperature measurement in and requires an optional modul
30. Measurement 5 5 5 e ve id eese easo vino rateseecececssseovedesen S eYec s Yo kua cero eese oe VY P Rad cere eren aa 45 How to Set Up a Temperature Compensation cceccccscccsccescccsccescccesccesceecccesscessscessescceessceseeees 46 Parameter Calculations 5 22 9 9 sete zoe ee cote e Ee Sese seg D Ee ere ze EE ez a aa e 46 Chapter 6 Linearity Compensation 47 Purpose and Method of Linearisation 47 Control Parameters ovi eese E secchaneveveneses steateusbewevanes ste 47 Internal Calculation sos eoe eo Fe esteso 47 How to Set Up Linearity Compensation ceeeeeeeeeeeeeeeeeeeeee eene nee hesehheehnse eese theses esses esos 48 Parameter Calculations and dessns n ioner ote se stesse eere eren 48 Chapter 7 Self Di gnostics ee ee eI nono eee roe No SN ERA Nae Eae e Te NES Ease ae eaae esae een ese 50 Diagnostics Flags 4 iioee ee eaae pae en eyes ae yx deed oleae aera ee etie Ce Lev YT PE RNC 50 Diagnostics LEDS 50 Chapter 8 Communication Protocols sccecccecccecces
31. RES avr Re OR ED o T n oes v De I PEE ed 41 Mom P 41 EE 41 41 REA 41 SES 41 Calibration Parameters Summary and Defaults cccesccsccsccsscencsesccescencsesessescesceeesssseesscesseeeees 42 Chapter 5 Temperature Compensation iss see seeded vse dois peur ede dense 43 Purpose and Method of Temperature Compensation csscsscscccscsncscccsccsccscescescescesssssssaesscescessease 43 Temperature Module Connections and Mounting DTEMP enhn hne eher rero 43 OEM Mod le DTEMP Connections cr aeuo vanes S42 ca cams S RE eu ee Rr eU dne Ee 43 OEM PCB DTEMP CONNECTIONS soeone tnne i e Eee ne tote d Ve ee Tee erasa sio e eee da De eR gn diva ts 44 Cased Version DTEMP 5 EE EEE rese tenerse 44 Control Parart ieters aree ic ee eve ge sone ss Pese hind ess cele suesvecadededseeseei e to Gace ss Prove ecu et 44 Intern l Calculation 2 oir Sepe ad erre a S dees 45 The Temperature
32. SCUSB PCB S a NI NI 9X3 HS 50mm q 72mm Dimesions 72 x 50mm with 4 x 3 5mm dia holes 2 8346 x 1 9685 with 4 x 0 1377 dia holes The OEM Module can also be DIN rail mounted by using suitable clips e g Wago 209 120 below fitted to a separate base plate Ideally the DSCUSB should be installed in a protective enclosure such as a metal box 77 Mantracourt Electronics Limited DSCUSB User Manual Environmental Approvals CE Approvals European EMC Directive 2004 108 EC BS EN 61326 1 2006 BS EN 61326 2 3 2006 Output shall not exceed the sum of uncertainties when subjected to an electric field of 10V m over the frequency range 80 to 600MHz Warranty All DSC products from Mantracourt Electronics Ltd Mantracourt are warranted against defective material and workmanship for a period of 3 three years from the date of dispatch If the Mantracourt product you purchase appears to have a defect in material or workmanship or fails during normal use within the period please contact your Distributor who will assist you in resolving the problem If it is necessary to return the product to Mantracourt please include a note stating name company address phone number and a detailed description of the problem Also please indicate if it is a warranty repair The sender is responsible for shipping charges freight insurance and proper packaging to prevent br
33. SOR 2 eG Osc uss MangarPump MantraCAN VCI g DSC v3 Modbus RTU LX DSC v3 eg SC USB as CANBus VCI v2 Fhe DSC 1 CANOpen When an instrument has been selected from the Select Instrument window this parameter list window will become populated The parameters and commands which are available for the selected device will appear in this list in a structured hierarchic manner enabling the user to expand or contract categories by clicking the and amp buttons on the left of the list There are four types of parameters and commands Read write Numeric These parameter values are displayed in the right hand column and can be edited by clicking the value The value can then be changed and pressing the Enter key or moving away Frwy 0 0 from the edited value will cause the new value to be written to the device There are no checks on the data entered and it is up to the user to enter the correct data Read Only These parameter values are displayed greyed out and cannot be changed 19 Mantracourt Electronics Limited DSCUSB User Manual Read write Enumerated These parameters can only be changed by BAUD 0 selecting the new value from a drop down list Clicking in the right hand column will display a down arrow button which BAUD 0 e when clicked will display the parameter value options in a list Note that all enumerated data apart from on off will be displayed with a
34. V V output and it is this value that all other measurement output values are derived from Factory calibration is within 0 05 Nominal mV V level NMVV This is used to represent the nominal mV V value representing 100 of full scale This value is used solely for the generation of ELEC It is factory set for 2 5mV V If the electronic gain is adjusted by changing the gain resistor then if ELEC is used NMVV value must be changed to represent the new nominal mV V mV V Output In Percentage Terms ELEC This is mainly for backwards compatibility with Version 2 It is the mV V value represented in percentage terms 100 being the value set by NMVV Temperature Value TEMP If the optional temperature module DTEMP is fitted then TEMP will display actual temperature in Otherwise TEMP will display 125 TEMP is used by the temperature compensation See chapter 5 Output Rate Control RATE The RATE parameter is used to select the output update rate according to the following table of values RATE value 0 1 2 3 4 5 6 7 8 9 10 update rate readings per 1 2 5 10 20 50 60 100 200 300 500 second The default rate is 10Hz RATE 3 The other settings give a different speed accuracy trade off Invalid RATE values default to 3 10Hz The underlying analogue to digital conversion rate is 4 8kHz These results are block averaged to produce the required output rate To Change th
35. ad of xA 99 88 CELL reading cA 100 0112 For test load of xB 500 07Kg CELL reading cB 498 7735 Calculate gain value In this case put SGAI xB xA cB cA 0 50007 0 09988 498 7735 100 0112 0 001003580 1 003580x10 Calculate offset value In this case SOFS cA x SGAI xA 100 0112 x 1 003580x10 0 09988 0 00048924 Check Putting the values back into the equation results for the two test loads should then be For x 99 88Kg CELL 100 0112 so SRAW 100 0112 x 1 003580x10 0 00048924 0 09988 For x 500 07Kg CELL 498 7735 so SRAW 498 7735 1 003580x10 0 00048924 0 5006987 The remaining errors are due to rounding the parameters to 7 figures Internal parameter storage is only accurate to about 7 figures so errors of about this size can be expected in practice System Limits SMIN SMAX These are used to indicate that the desired maximum and minimum value of SRAW have been exceeded They are set in weight units On SRAW being greater than the value set in SMAX the SRAWOR flag is set in both FLAG and STAT the value of SRAW is also clamped to this value On SRAW being less than the value set in SMIN the SRAWUR flag is set in both FLAG and STAT the value of SRAW is also clamped to this value System Zero SZ SZ provides a means of applying a zero to SYS and SOUT This could be used to generate a Net value making SRAW in effect a gross value SYS SRAW SZ Care s
36. and uncompensated load cells are especially sensitive having a large overall temperature coefficient Temperature compensation adjusts the measured value in a way that depends on a temperature measurement so that ideally the output is independent of the current temperature In practice it is usual to refer to a calibration reference temperature The ideal output value is then what the reading would have been if made at the reference temperature The DSCUSB temperature compensation facilities make adjustments to the Cell calibration parameters i e gain and offset which depend on temperature according to a digitally programmed curve These adjustments are automatically applied based on the current device temperature measurement With some care this can remove the need for the usual electrical compensation components altogether Note that the temperature compensation will also remove the temperature drift of the DSCUSB itself if the temperature compensation data is collected when the DSCUSB and strain gauges are tested together as a system Temperature Module Connections and Mounting DTEMP The temperature module is a connected using only two wires The temperature sensor is the Dallas 1 Wire digital device 0518520 One connection is ground the other 15 the 1 wire DQ connection which provides the bi directional data line OEM Module DTEMP Connections Wagssn Q Q Load
37. and Trough values are also recorded against the value of SYS these are volatile and reset on power up A command SNAP records the next SYS value and stores in SYSN this is useful where there is more than 1 device in a system and to prevent measurement skew across the system the SNAP command can be broadcast to all devices ready for polling their individual SYSN values System Scaling SGAI SOFS The cell output value CELL is scaled with gain and offset using SGAI and SOFS respectively The gain is applied first and the offset the subtracted This would be used to give a force output in the chosen units this output being termed SRAW SRAW CELL X SGAI SOFS If we have two cell output CELL readings for two known test loads xA and xB we can convert the output to the required range So if Testload xA gt CELL reading cA Test load xB CELL reading cB Then we calculate the following gain value SGAI xB xA cB cA And then the offset SOFS cA x SGAI xA SRAW now indicates the true load applied Example of calculations for SGAI and SOFS Example A 2500kgf load cell installation is to be calibrated by means of test weights The cell calibration gives an output in kgf ranging 0 2000 A system calibration is required to give an output reading in the range 0 1 0 tonnes Calculations Mantracourt Electronics Limited DSCUSB User Manual 32 Take readings with two known applied loads such as For test lo
38. and never read negative i e read value ranges are 0 to 65535 0 and 0 to 255 0 For writing values written to integer and byte parameters are truncated to the nearest integer and negative or positive values are acceptable NOTE Floating point data is not always exact even when reading integral data e g could get 3 999974 instead of 4 e g for a byte write 240 240 1 and 239 66 are all the same value Rounding Although rounding is applied when writing to integral values data read from a device is not rounded off The ASCII Protocol The ASCII protocol uses only printable characters and carriage return lt CR gt which allows a dumb terminal device or a PC programme like Hyper Terminal to interrogate the device Host Command Message Format The basic command request structure is shown in the following example illustrating the message 1001 56 1 123 456 lt gt meaning write 123 456 to parameter SGAI on station 1 Framing Station Separator Command Access End of Identifier Code frame sid SGA 123 456 An of Each Field is as Follows e Framing Character a character is used to signal the start of a new message This character is only ever transmitted by the host for framing purposes e Station Address a three digit ASCII decimal number 0 999 determines which slave device s the command is intended for All three digits must be sent Address 000 is reserved for broadcast addressing
39. ard menu Since we are now calibrating at system level we have a choice of two calibration methods Sys Calibration Table This technique is used when a manufacturer s calibration document is available for the connected strain gauge This normally gives mV V to engineering unit values Sys Calibration Auto This technique is used when the input can be stimulated with real input values i e test weights or forces can be applied We will now describe each of these techniques with an example Sys Calibration Table method A 10 tonne load cell manufacturer gives the following data mV V output Force 2 19053 10 tonne 0 01573 0 tonne Start the wizard by selecting Sys Calibration Table from the Wizard menu Mantracourt Electronics Limited DSCUSB User Manual 22 SYS Calibration Table Instructions This Wizard will allow you to calibrate your instrument by entering input values and required values which can be based on manufacturers tables You will need to know two CELL levels and the required SYS values at these points The two levels of input should be around 25 or below of full scale for the lower value and a high level at around 75 or higher of full scale Press NEXT to continue with the calibration Cancel Click the Next button and enter the low values as shown below SYS Calibration Table Enter Low Data Enter the low level input value and required output value Enter value for
40. are available 3 Serial communications are carried out via a Virtual COM Port assigned by the PC The protocol type is fixed for a given device during production The communications baud rate and station number the bus address are configured for each device by the control parameters STN and BAUD see Chapter 2 Getting Started Bus Standards Serial Data Format Serial data formatting is the same for all the protocols and is fixed to e one start bit e one stop bit e 8 data bits e no parity Communications Flow Control Bus flow control is managed as part of the protocol managed differently by each No hardware or software flow control signals are to be used for any of the bus standards Communications Errors Serial data which does not conform to the expected format causes a serial framing error to be registered which increments the Communication Failure Counter CFCT What this actually means is that following a start bit 1 to O transition a stop 1 bit was not seen in the expected place This is obviously baud rate dependent the commonest cause being data transmitted at a lower baud rate than the unit was configured for Choosing a Protocol The current choices are ASCII Printable characters easy to drive direct output to printers displays MODBUS RTU Binary industry standard inter compatible with other devices such as PLCs MANTRABUS II Efficient binary protocol checksums give better security t
41. ased version 86 x 57 x 26 5mm 3 3465 x 2 2492 x 1 087 excluding connector 95mm 3 740 including 9 way D type connector with 136 cm 94 462 feet USB cable Notes 3 From original offset at any time 4 1st Year Mantracourt Electronics Limited DSCUSB User Manual 76 Mechanical Specification for DSCUSBS and DSCUSBH R26 o oB ppm ii eset oon me 12 Le CG se en En 27 05 24 ie cat C26 il lo of 1 5 9 o o R24 IC3 140 is Pp S 5 952 Be ris ooo 9 L3 G o o Iz gt Datum 0 0 x y 0 127 5 46 Dimensions in mm The PCB can be fitted to a motherboard by fitting in line pins to the 6 way 4 way and 5 way rows of holes and plugging them into corresponding sockets on the motherboard or directly soldering through holes The 6 way and 4 way holes are on a 0 1 pitch the 5 way holes are on a 2mm pitch The diagram shows the x y coordinates of one hole of each connector OEM Module 4 holes 3 5mm dia 99A Naasn aaasn ANO USB OQ SOCKET NV D
42. been set up Although the tests are generally simpler than testing over temperature the accuracy requirement is often greater See below for notes of possible difficulties to be avoided Control Parameters Refer to Chapter 9 for command numbers The lookup table based on parameters CLXi CLKi defines an offset adjustment based on the CRAW value which is then added in to give the final CELL output N B linearity correction is applied after any temperature compensation The Parameters Involved Are CLN Sets the number of linearisation points from 2 up to 7 CLX1 7 Raw input CRAW value points CLK1 7 Output CELL adjustments to apply at these points They are used like this e The number of calibration points is set by CLN from 2 up to 7 e Raw input value points are set by CLX1 CLX2 CLX7 or up to the number set by CLN These must be arranged in order of increasing input value e The output corrections at these points are set by CLK1 CLK2 CLK7 e Corrections are specified in thousandths of a cell unit i e a CLKi value of 1 0 actually adds 0 001 to the CELL output This due to a limitation in the ASCII conversion to floating point numbers Internal Calculation This uses the same basic interpolated table lookup method as for temperature compensation First a working table index i is derived from the current raw input CRAW x as follows n number of points used as set by CLN When x lt CLX1 t
43. ble limits CMIN or CMAX The tested value CRAW is the cell output prior to linearity compensation SYSUR and SYSOR are the system output range warnings These are triggered if the SYS value goes outside the SMIN or SMAX limits LCINTEG indicates a missing or a problem with the Load cell It is based on the common mode of the SIG being correct NOTE this flag will also be set when the shunt calibration has been switched on WDRST indicates that the Watchdog has caused the device to re boot If this error continually occurs consult the factory BRWNOUT indicates that the device has re booted due to the supply voltage falling below 4 1V the minimum spec for supply voltage is 5 6V and this must include any troughs in the AC element of this supply REBOOT is set whenever the DSCUSB is powered up and is normal for a power up condition This flag can be used to warn of power loss to device 37 Mantracourt Electronics Limited DSCUSB User Manual Dynamic Status Flags STAT Status flags are live flags indicating current status of the device Some of these flags have the same bit value amp description as FLAG Meaning and Operation of Flags The various bits in the STAT value are as follows Bit Value Description Name o 1 Setpoint output status SPSTAT 2 Digital input status STAT 32 Strain gauge input over range ECOMOR 64 128 256 512 System over range SRAW SYSOR 1024 unused reserved
44. ccessccesceseccesscessseeeseeeeesssseesseeaseeeseeseeesseesaeeees 51 Mantracourt Electronics Limited DSCUSB User Manual 2 Serial Data Format rns seb e ae io e assa Ae PERDE REESE 51 Communications Flow Control cece cece eee e eee eee eee e ence ence eee emen ehe eee ehe eret hse restes 51 COMMUNICATIONS 5 4 aeree ER It re Maes E Ede ubere deetese Ves aen e Eas 51 Choosin9 a ProtoCcOol regia ocd oh dade ng 51 Communications Software for the Different Protocols eene nennen he ehh 51 Common Feat res of AIUProtocols 3 2 prey etl ee Ie e sce tae e ere e vede ee Gane San oda teas dE IS 52 Data Type Conversions and 53 53 5 53 Continuous Output Stream ASCII ee eene e ehh ehh e hh e ehh hehe e ehh enhn 55 Station Number STN 55 Baud rate Control BAUD a EAE de erp ode Ta deas 56 The MOD
45. ccuracy of 0 5 C over the temperature range 10 to 85 C and 2 0 C over temp range 55 to 125 C The resolution of the measurement is 0 0625 C The temperature is sampled and the TEMP variable updated every 5 seconds 45 Mantracourt Electronics Limited DSCUSB User Manual How to Set Up a Temperature Compensation There are a number of ways of obtaining a temperature compensation curve The best possible compensation for a given piece of physical hardware can only be achieved by performing experiments on that particular unit DSCUSB and associated strain gauges to characterise the measurement output at a variety of different stable temperatures in the required operating range The basic choice of methods depends on trading off ideal accuracy against the complexity of the calibration procedure Method 1 Apply a simple linear drift correction i e for known constant gain and offset changes per degree by specifying zero correction at the calibration temperature and appropriately adjusted correction values at extreme temperatures above and below this This can be used when the measurement or sensor has known temperature coefficients Method 2 Where the temperature characteristics of the measurement are known but not linear a similar scheme to Method 1 can be used with a multi point table defining an approximation to the known ideal temperature curves of offset and gain variations NOTE Both of the above methods are bas
46. clamping of SYS to these values and also a flags being set in FLAG and STAT Mantracourt Electronics Limited DSCUSB User Manual 24 Sys Calibration Auto Method Assume we need to calibrate for kg output and we have available accurate 10 kg and 100 kg test weights Start the wizard by selecting Sys Calibration Auto from the Wizard menu SYS Calibration Auto Instructions This Wizard will allow you to calibrate your instrument by applying known low input followed by known high input You will need two levels of input at around 25 or below of full scale and a high level input at around 75 or higher of full scale You will also need to know the required value of SYS for both of these input levels Press NEXT to continue with the calibration Click Next SYS Calibration Auto Acquire Low Input Apply the low level input and enter the value required in the text box below Ensure that the low input is still applied when the Next button is clicked Enter required value for SYS at this low input level Apply the low known test weight and enter the required SYS value for this weight In this case it will be 10 as we want the units of SYS to be kg Click Next to continue SYS Calibration Auto Acquire High Input Apply the high level input and enter the value required in the text box below Ensure that the high input is still applied when the Next button is clicked Enter required
47. consumes typically 70mA with a 350 Ohm gauge connected An installation should therefore assume at least 80mA per unit and allow for extra current being taken at power on though supply voltage can safely drop temporarily and for possible voltage drops in long cables The DSCUSB can supply enough excitation current to drive up to four 350 Ohm gauges connected in parallel In this case Self powered mode must be used see note above for the OEM Module as the total supply current will rise to approximately 135mA taking it above the USB specification for Bus Powered devices Any power supply ripple should be below 100mV and supply arrangements should provide current limiting for fault conditions see Electrical Protection above Mantracourt Electronics Limited DSCUSB User Manual 64 Cable Requirements USB OEM Module USB Seger 1 Red 4 Black vec USBDM 2 White USBDP 3 Green Wagssn ddgsn GND e Q GA USB SOCKET 9X3 NI NI 2X3 S S DSCSUSB PCB S DAAA DSCUSB MOTHERBOARD 1 Red USBDM 2 White USBDP 3 Green GND 4 Black 4 Black USBDP 3 Green USBDM 2 White VCC 1 Red 4 way connector 5 way connector Issue 1 PCB Issue 2 PCB Strain Gauge Input DSCUSB For optimal performance twin twisted pair with individual shields is recommended this gives good noise immuni
48. court s product range As supplied devices have the station number factory set to 001 Please note because the DSCUSB communicates through a virtual comm port VCP its unique identity is determined by the assigned Comm Port number rather than its station number STN For this reason the station number can be left at its default setting of 001 unless the continuous streaming feature described above is required STN 998 or 999 Two DSCUSB devices with the same station number can co exist without any conflicts when connected to a single PC via separate USB sockets or a hub Please note The new value of STN does not take effect until the RST command is issued or the device is power cycled 55 Mantracourt Electronics Limited DSCUSB User Manual To Change the Station Number of your device 1 First set STN to the new value 1001 STN 999 lt CR gt assuming a device with STN 1 is present it will respond with lt CR gt 2 Send a RST command or power cycle the device for the change to take place If using Hyper Terminal or similar applications it may be necessary to Disconnect then Call disconnect then re connect after cycling the power in order to re establish communications 1001 RST CR no response The station number will now be set to 999 Subsequent commands should be addressed to 999 Please note if using Hyper Terminal or similar applications it may be necessary to Disconnect then Call disconn
49. e There are also two flags ECOMUR and ECOMOR not shown on the diagram which indicate an input electrical under or over range Mantracourt Electronics Limited DSCUSB User Manual 40 Cell The calibration converts the mV V output into cell force reading This can be used by an OEM sensor manufacturer to provide a standard calibrated output in force units which could be based on either typical or device specific calibration data This stage also includes the temperature and linearity corrections not covered here The outputs from this are CMVV is the temperature compensated mV V MVV e CRAW is the scaled temperature compensated value CMVV e CELL is a load cell force reading in Force units e g kN e CRAWUR and CRAWOR are two flags indicating under or over range for the force measurement System The System calibration converts the Cell output into a final output value in the required engineering units This is normally be set up by a systems installer or end user to provide whatever kind of output is needed independently of device specific information in the Cell calibration Making this split allows in service replacement without re calibration The outputs from this are SRAW is re scaled and offset adjusted output derived from CELL e SYS is the final output value after removing a final user output offset value SZ from SRAW e SRAWUR and SRAWOR are output warning limit flags In p
50. e Oe vede NOE d 9 Installing Instrument Explorer ehe eres 9 eire 9 Found New Hardware Wizatrd il sie Lee eg ere stale ors aSa eee 10 Connecting the Evaluation Kit eos coss cakes eue e aya cece iv aea eek aae reserve coro eR eae yea eve cese scere eere 12 7 ct 12 Establishing the Assigned COM 13 Open the Device Manager Leve aen pev a e ae LN UE vr ER Ve To eaa Vo Ee Er UE 13 Device Mariager 2 e eei eeee scene 14 Iristrument Explorer E EN Ne NEN Ea SE EAE Ee Ve Ne e ENSE E EAE de Ea ERST T 16 Running the Instrument Explorer Software ete ernst enne 17 Instrument Explorer lonse ide vives eco denen net ea eee AIRE ere xe gogo te deve 17 Instrument Explorer eee ee E DRAGS RARE ERR E VE SE USERS NEA Dex oTi d ae eee 17 listru rrient Settlrigs uasisee ee Soc Eur detegs 18 Viewing Pic 19 Instrument Explorer Parameter List sse eereccosecooscocseooossesos
51. e Output Rate 1 Set RATE to the new value 2 Click on the RST button to reboot the device 3 Wait for one second for the reset procedure to complete and measurement cycle to start With RATE set to 0 you should be able to see the SYS update rate slow down to once a second and the noise level should also noticeably decrease All the main reading output values are updated at this rate Rate does not change the rate at which temperature output TEMP is updated Dynamic Filtering FFST and FFLV The Dynamic filter is basically a recursive filter and therefore behaves like an circuit It has two user settings a level set in mV V by FFLV and the maximum number of steps up to 255 set by FFST Instead of outputting every new value a fraction of the difference between the new input value RMVV and the current filtered value MVV is added to the current filtered value MVV to produce the filtering action If this difference is less than the value set in FFLV then the fractional amount added each time is decremented until it reaches the minimum level set by FFST i e FFST is the limit of the divisor e g if FFST 10 the fractional part of the difference between the new value RMVV and the current filtered value MVV will be decremented as follows 1 1 1 2 1 3 1 4 1 5 1 6 1 10 1 10 1 10 before being added to the current filtered value MVV Mantracourt Electronics Limited DSCUSB User Manual 28 If a rapidly c
52. eakage in transit Mantracourt warranty does not apply to defects resulting from action of the buyer such as mishandling improper interfacing operation outside of design limits improper repair or unauthorised modification No other warranties are expressed or implied Mantracourt specifically disclaims any implied warranties of merchantability or fitness for a specific purpose The remedies outlined above are the buyer s only remedies Mantracourt will not be liable for direct indirect special incidental or consequential damages whether based on the contract tort or other legal theory Any corrective maintenance required after the warranty period should be performed by Mantracourt approved personnel only ISO 9001 REGISTERED FIRM THE QUEEN S AWARDS EU J FOR ENTERPRISE Fa P C In the interests of continued product development Mantracourt Electronics Limited reserves the right to alter product specifications without prior notice Designed and Manufactured In the UK Code No 517 180 Issue 1 6 25 06 12 Mantracourt Electronics Limited DSCUSB User Manual 78
53. ect then re connect after cycling the power in order to re establish communications NOTES e The valid range of STN for the ASCII protocol is 1 999 e f STN is set outside the valid range it behaves as if set to a default of 1 e Ctrl Q will cause the DSCUSB to start streaming its data Ctrl S will stop the streaming Baud rate Control BAUD The BAUD parameter is a read write byte value specifying a standard communications baud rate according to the following table BAUD 2 3 4 5 7 value 2400 4800 57k6 76k8 115k2 230k4 460k8 bps Default setting value 7 for BAUD rate 115200 BAUD only take the values shown above If set lt 0 or gt 9 the baud rate reverts to default of 115200 Warning When changing this setting it is possible to lose communication with the device As well as keeping track of the correct baud rate it is also essential in this case to be sure that your hardware supports the rate you are changing to The evaluation kit supports all possible DSCUSB baud rates The new value of BAUD does not take effect until the RST command is issued or the device is power cycled To Change the Baud Rate follow a similar sequence to changing the STN value 1 First set Baud to the new value 001 BAUD 4 lt CR gt assuming a device with STN 1 is present it will respond with lt CR gt 2 Send a RST command or power cycle the device for the change to take place If using Hyper Terminal or similar
54. ed on known characteristics which could come from datasheets but these methods would not compensate for the DSCUSB Method 3 Do a series of measurements at different temperatures and install the appropriate correction values to give exactly correct results at those same temperatures i e calculate ideal gain and offset corrections at the tested temperatures This method is the most common There is a wizard available in Instrument Explorer which will enable this method to be easily completed by calculating the gain and offset corrections for you Method 4 Use a set of test results to plan a best correction curve not necessarily perfect at test temperatures but slightly better overall NOTES All of these methods can be applied either to data from individual devices or to an average correction for a particular type of sensor hardware During testing temperatures should be measured using the internal TEMP measurement as this is the measurement used to do the corrections For in system tests the environment of the DSCUSB must always be as near as possible to the exact conditions of the eventual in system use Parameter Calculations Instrument Explorer provides a Wizard for the calculation of the parameters required by the DSCUSB This is based on Method 3 where data is collected The wizard allows for small changes in the sampled temperature point that may occur when taking a set of results for gain and
55. elected 9 Mantracourt Electronics Limited DSCUSB User Manual r 15 Setup Instrument Explorer Select Components Which components should be installed Select the components you want to install clear the components you do not want to install Click Next when you are ready to continue Custom M Explorer nent IXXAT CAN Drivers Required for CAN devices 3 7 MB F IXXAT CAN Driver Document 0 8 MB DSC USB Drivers Required for USB devices Current selection requires at least 14 7 MB of disk space If you already have an older version of Instrument Explorer installed or did not select this option when you installed the newer version you can safely install again without uninstalling first In the above example the CAN drivers have not been selected as they are not required The installation software is trying to pre install the required drivers so that they can be automatically found when the hardware is plugged in later on This will appear twice during the installation After installing the software you can connect the DSCUSB device to the computer The new hardware will be detected and the computer may display a dialog window asking whether to use Windows Update or the Internet to search for software Found New Hardware Wizard Once the software has been installed you can plug in the hardware The Found New Hardware Wizard should now appear
56. essage must start with the correct three digit slave address and and end with lt CR gt with no intervening extra The slave will then always respond There are three possible types of response acknowledge ACK acknowledge with data for a read and not acknowledge NAK ACK is a single lt CR gt character This confirms an execute or write command ACK with data is a decimal number followed by lt CR gt This confirms a read and returns the data value NAK is an CR sequence The device rejected the command There are several possible reasons for a NAK response Command identifier not recognised Badly formatted command Missing command identifier unrecognised access code character or unexpected character somewhere else Access attempted not supported by this command NOTES e The maximum time from receipt of the host s terminating CR to a response from the device if any will be 50mS After this time it can be assumed there is no response e There is no value checking A slave cannot a command because a write data value is unsuitable in some way only if write access itself is disallowed For the Ack with data i e a successful read command the returned value consists of printable ASCII characters finishing with a CR formatted according to the DP and DPB settings as follows Write Command If the device accepts the command then a CR is transmitted There is no e
57. et by the user whereas STAT is non latching showing the current error status Latched Warning Flags FLAG The flags are normally used as follows FLAG is read at regular intervals by the host like the main output value but generally at longer intervals If some warnings are active i e FLAG is non zero then the host tries to cancel the warnings found by writing FLAG 0 The host then notes whether the error then either remains i e couldn t be cancelled or if it disappears or if it re occurs within a short time and will take action accordingly The warning flags are generally latched indicators of transient error events by resetting the register the host both signals that it has seen the warning and readies the system to detect any re occurrence i e it resets the latch What the host should actually do with warnings depends on the type and the application sometimes a complete log is kept sometimes no checking at all is needed Often some warnings can be ignored unless they recur within a short time Warning flags survive power down i e they are backed up in non volatile EEPROM storage Though useful this means that repeatedly cancelling errors which then shortly recur can wear out the device s non volatile storage see Chapter 3 Basic Set up and Calibration Mantracourt Electronics Limited DSCUSB User Manual 36 Meaning and Operation of Flags The various bits in the FLAG value are as follows Value Descr
58. exactly vertically The accuracy is also limited by the DSCUSB electrical calibration accuracy which is about 0 1 The remaining methods require testing with known loads but are therefore inherently more reliable in practice as they can remove unexpected complicating factors relating to installation Method 3 Two Point Calibration Method This is a simple in system calibration procedure and probably the commonest method in practice as in the previous example Two known loads are applied to the system and reading results noted then calibration parameters are set to provide exactly correct readings for these two conditions eg a 10kN 1 tonne load cell has a CELL reading of 0 120721mV V with no load and 2 21854mV V with a known 100kg test weight To calibrate this to read in a 1 0 to 1 0 tonne range Calculate CGAI as 0 1 2 21854 0 120721 0 047669 Set COFS 0 120721 x 0 047669 0 005755 Method 4 Multi point Calibration Test For ultimate accuracy a whole series of point measurements may be taken to determine the best linear scaling of input to output Effectively a best line through the data is then chosen and the calibration is set up to follow the line Testing of this sort is also used to establish linearity corrections and similar tests at different temperatures are used to set up temperature compensation see Chapters on Temperature Compensation and Linearity Compensation Note Instrument Explore
59. ge Cabling tese 69 Key Req irem nts 5 dere ve eode rente erano e Tex sense 69 Strain Gauge Sensitivity Adjustmeht 4 eee ro eoa he ekle eu rou eaae pee ee espe up ue erae 70 Chapter 1 1 Troubleshooting eee tee rre rores enn han oce eoe see ure do s aseo ep Vevey epueesesec eU sve 72 LED Indicator tere eR ein a eei eee eese esas s 72 No Commu nications 4 10 eI pei dre e eser pe esaeedsevesesesesesesegetessevesssesosegetesesseseeeseeesebeseyess eese sees 72 Bad REadiNGS aenneren EE E ILIUM 73 Unexpected Warning Flags sre e ero eo rosse aureo e eeu ee aea eeu eaae uvae tees VPE E ede PS 73 Problems with B s Baud Rate eye eee ee nre trae euo ere deve etae se eere porous eue ceto i e ro vE ee Eae Ee eoe ERO PEN TS 74 Recovering lost DSCUSB ooi sese eee re eee uersa ye e eo aee ea Ya vage veo ve ee a EE eye Ver Ue e Vea un es 74 Chapter 12 Specifications Pene FEN SEES SER EE YEARS FORAS ETE EIS ENS TIEN FE FORTE 75 Technical Specificatioris DSCUSBS eroe erae eae ee eroe dese eua eos desea so dened duse vo eee aeu as 75 Technical Specifications DSCUSBH
60. ght click the device and select Properties from the pop up menu USB DSC Port COM7 Properties Genera Port Settings Driver Detais Bts per second z gt Stop bits 1 X Bue E Advanced Restore Defaults Please Note The BAUD rate of 9600 is displayed in the dialog box but is not the actual BAUD rate of the device and does not need changing at this point Mantracourt Electronics Limited DSCUSB User Manual 14 Select the Port Settings Tab from the window that appears Click the Advanced button r Advanced Settings for COM7 COM Port Number USB Transfer Sizes Select lower settings to correct performance problems at low baud rates Select higher settings for faster performance Defaults Receive Bytes 4096 Transmit Bytes 4096 v BM Options Miscellaneous Options Select lower settings to correct response problems Serial Enumerator iv Serial Printer 1 Latency Timer msec 1 Cancel If Power Off Timeouts Event On Surprise Removal 1 Set RTS On Close Li Minimum Read Timeout msec 0 Disable Modem Cid At Statup I Minimum Write Timeout msec 0 X You can now select a new Port Number from the dropdown list at the top of this dialog When you drop the list you may find that next to some of the listed COM ports there is an
61. han ASCII Communications Software for the Different Protocols To access a DSCUSB you will need a communications application running on your PC or PLC in addition to the appropriate hardware connections The simplest approach for initial experiments is to use the Instrument Explorer evaluation application Instrument Explorer can provide a window into intended parameters and variables This is supplied on a CD with the DSCUSB Evaluation kit or can be downloaded from our website http www mantracourt co uk software Instrument Explorer A full version of Mantracourt s VisualLink SCADA toolkit can be used for much more complex control and monitoring applications Contact our sales office for details Other simple ways of using the different protocols are as follows 1 The ASCII protocol only uses basic printable characters and so can be accessed with a simple terminal program like Windows HyperTerminal 51 Mantracourt Electronics Limited DSCUSB User Manual 2 The MODBUS protocol be accessed via a proprietary generic MODBUS application For evaluation purposes we suggest the free shareware demo of ModScan32 from Win Tech software visit www win tech com 3 MANTRABUS needs a purpose designed program to handle full 8 bit data bytes and the proprietary checksum calculations Instrument Explorer and VisualLink provide this Common Features of All Protocols The communications protocols are all of the
62. hanging or step input occurs and the difference between the new input value and the current filtered value MVV is greater than the value set in FFLV then the output of the filter will be made equal to the new input reading i e the fractional amount of the new reading added to the current reading is reset to 1 This allows the Filter to respond rapidly to fast moving input signals When a step change occurs which does not exceed FFLV the new filtered value is calculated as follows New Filter Output value Current Filter Output Value Input Value Current Filter Output Value FFST The time taken to reach 63 of a step change input which is less than FFLV is the frequency at which values are passed to the dynamic filter set in RATE multiplied by FFST The table below gives an indication of the response to a step input which is less than FFLV Update Rate 1 RATE see Output Rate Control above Of Final Value Time To settle 63 Update Rate FFST 99 Update Rate FFST 5 99 9 Update Rate FFST 7 For example If RATE is set to 7 100Hz 0 01s and FFST is set to 30 then the time taken to reach a of step change value is as follows Of Final Value Time To settle 63 0 01 x 30 0 3 seconds 99 0 01 x 30 x 5 1 5 seconds 99 9 0 01 x 30 x 7 2 1 seconds The following table shows the number of updates x FFST and the Error that the Filtered Ou
63. hen i 1 When gt CLXp 1 then i n 1 Otherwise i is chosen so that CLXj lt x lt CLXj 4 The resulting interpolated adjustment value is then calculated as ofs CLKj x x CLXi CLXi The compensated cell value is then calculated as CELL CRAW ofs 47 Mantracourt Electronics Limited DSCUSB User Manual How to Set Up Linearity Compensation A linearity correction can be set up either from sensor specification calibration data or more commonly from in system testing results Assuming we do not have any prior information on linearity errors the usual approach is to do a series of controlled tests with accurately known test loads Just as with temperature compensation it is possible to obtain a detailed graph of linearity error and then choose a best fit piecewise linear curve for the compensation table However it is generally good enough and much simpler to simply test at several different points and then apply an exact correction at those points If the error curve is reasonably smooth this should give exact results at the test points and reasonably accurate values in between NOTES Linearisation tests should only be done after the cell calibration is set because the correction values are dependent on the cell calibration Similarly linearisation testing should only be done at the calibration reference temperature or after temperature compensation is instal
64. hen notes whether the error then either remains i e couldn t be cancelled or if it disappears or if it re occurs within a short time and will take action accordingly The warning flags are latched indicators of transient error events By resetting the register the host both signals that it has seen the warning and readies the system to detect any re occurrence i e it resets the latch What the host should actually do with warnings depends on the type and the application Sometimes a complete log is kept sometimes no checking at all is needed Often some warnings can be ignored unless they recur within a short time Warning flags survive power down i e they are backed up in non volatile EEPROM storage Though useful this means that repeatedly cancelling errors which then shortly re occur can wear out the device s non volatile storage see WARNING Finite Non Volatile Memory Life in chapter 3 Diagnostics LEDs 2 EEA Blo 3 BER OOOOn as Nee 9 12 o Di E 20 oR o R23 oo iy lo of 9898 d 13 Hap RE lol oo ri meer eg Ble pig USB Tx Data E33 L5 o 2 Tio JEg tii
65. her hardware or software related Software 1 Check the MVV reading first and ensure it is correct This figure is the RAW input and is not affected by the user configurable calibration settings 2 If MVV looks correct check the calibration settings step by step Consider resetting all the calibration controls to default values see Chapter 4 The Reading Process This should make SOUT MVV at all times Hardware 1 Load Cell problem should be indicated by flags in STAT LCINTEG 2 Genuine hardware problems usually show up as total failure i e unchanging fixed readings usually either near zero or permanently at full scale Check wiring take voltage level readings and again if possible use a known good device and set up 3 Check the sensor is connected properly and has some resistance across the excitation leads output leads and across each arm of the bridge For a 350 Ohm gauge these readings should be approximately 350 Ohms 350 Ohms and 262 Ohms respectively when disconnected from the device 4 Check for a damaged DSCUSB device by replacement Unexpected Warning Flags Remember that all warning flags in FLAG must be explicitly reset they do not clear themselves when a problem is resolved If a flag cannot be cleared the cause must be persistent i e it keeps occurring This can be immediate regular every few seconds or irregular occasional See the Flags section chapter 3 for precise details of how the individua
66. hould be taken on how often SZ is written to see WARNING Finite Non Volatile Memory Life later in this chapter System Outputs SYS SOUT SYS is considered to be the main output value and it is this value that would be mainly used by the master SOUT is for backwards compatibility with Version 2 Reading Snapshot SNAP SYSN The action command SNAP samples the selected output by copying SYS to the special result parameter SYSN The main use of this is where a number of different inputs need to be sampled at the same instant 33 Mantracourt Electronics Limited DSCUSB User Manual Normally multiple readings are staggered in time because of the need to read back results from separate devices in sequence By broadcasting a SNAP command at the required time all devices on the bus will sample their inputs within a few milliseconds The resulting values can then be read back in the normal way from all the devices SYSN parameters Note Instrument Explorer provides wizards for easy calibration of the System stage There are two wizards Sys Calibration Auto and Sys Calibration Table these can be found under the menu item Wizards Control Shunt Calibration Commands SCON and SCOF The Device is fitted with a Shunt calibration resistor whose value is 100K This can be switched across the bridge using SCON giving an approximate change of 0 8mV V at nominal 2 5mV V The command SCOF removes the resistor from acro
67. ice Manager Click the Start button and select Run Type devmgmt msc into the box and click OK r 27 Run Type the name of a program folder document or Internet resource Windows will open it for you Open W Thistask will be created with administrative privileges Browse This will open the Device Manager window 13 Mantracourt Electronics Limited DSCUSB User Manual Device Manager g Device Manager File Action View m E Network adapters Bluetooth PAN Network Adapter 5 Broadcom 802 119 Network Adapter Er Intel R 82562V 2 10 100 Network Connect Pg VMware Virtual Ethernet Adapter for VMware Virtual Ethernet Adapter for VMnt H E Portable Devices H F Ports COM amp LPT USB DSC Port COM7 8 Processors 8 44 Sound video and game controllers 5 6 Storage controllers mg System devices Universal Serial Bus controllers WSD Print Provider Select the Ports COM amp LPT item and expand it If the DSC USB device has been installed correctly you should see an item named USB DSC Port COMx where the COM port assigned is shown in brackets If this COM port is between 1 and 8 then note the number as it will be needed when Instrument Explorer is used to connect to the device If the COM port is greater than 8 then it must be changed as follows Ri
68. if space allows OEM Field Connector Module the DSJ2 provides field terminals and a USB Type B connector Cased supplied in a desk mounting case approx 86 x 57 x 25mm with 1 4m of USB cable terminating in a type A plug and a 9 way D Type socket for the strain gauge connections High Stability 25 basic accuracy equates to 16 bit resolution Adjustable sensitivity Supplied pre configured for standard 2 5mV V full scale strain gauges A single additional resistor re configures the input between 0 5 and 100 mV V full scale Temperature sensing and compensation optional An optional temperature sensor module DTEMP is available which will enable an advanced 5 point temperature compensation of measurements Linearity compensation Advanced 7 point linearity compensation available as standard USB Uses a simple Virtual Communications Port as its connection method to a PC Device addressing allows up to 127 devices ASCII version allows for continuous output stream Low current Functions as Low Power Device i e draws less than 100mA one unit load when connected to 350 Ohm Bridge Digital calibration Completely drift free adjustable in system and or in situ via standard communications link Two independent calibration stages for load cell and system specific adjustments Programmable compensation for non linearity and temperature corrections Calibration data is transferable between devices for in
69. imiting or fusing NOT PROTECTED AGAINST REVERSE POLARITY OF SUPPLY Moisture Protection The DSCUSB must only be operated in a dry environment as moisture can dramatically degrade the measurement performance Any simple box or enclosure can be used however in extreme conditions an enclosure with the appropriate IP rating should be chosen If a metal enclosure is used it should be grounded to the SH connection Soldering Methods Take care when soldering cables to the pads Use a temperature controlled soldering iron set to a maximum 330 C for no longer than 2 seconds per pad Excessive heat or increased soldering time may result in damage to the PCB NOTES 1 Solder with water soluble flux should not be used even low residue as this can leave a surface film which attracts atmospheric moisture degrading measurement performance AN Power Supply Requirements The DSCUSB is a low power device lt 100mA and normally derives its power from the host machine It will operate over the worst case voltage range stated in the USB rev 2 0 specification i e 4 35 5 25V The OEM Module version as supplied with the Evaluation kit can be operated in Self powered mode i e powered by a separate supply 4 25V to 5 5V connected to pins 1 and 4 of J3 follow the screen printed legend on the PCB for the polarity Care should be taken to assure that this supply is not also connected to the host by the USB cable A single device
70. inal mV V level NMVV sic deese etnia ey se ceo e ees delve dee ew 28 mV V Output In Percentage Terms eee eene e ehh ehh heme enhn enhn 28 Temperature Valles TEMP cerro retorno e rede Ree eese da pete 28 Output Rate Control is 5 2 ree E len Mise tla be Ghee tle se Dex 28 Dynamic Filtering FFST and FELV era ra nea Fe Re E VASE FR dy 28 Cell sine xd sessi dese due dette sede beoe ede dee ebetesetea ee qevedevesese sedet ee ve desi dese ese eoe ieu deut R eas teer deren 30 Temperature Compensation in eect 30 Gell Sealing CGAI COES er re naa esr eR E ong ERROR Res Ya ee RE ER Ree eene REO 30 Two Point Calibration Calculations and 30 Calibration Methods EE a n 31 Gell Limits CMN CMAX ssc iis 31 Linearisation In ney donee Cesta ence ee 32 r ge crie ed edo o dui wehe T e ia 32 System Scaling SGA SOES sev eee ror EET obs oe eene EEA SA OE ERAS 32 Example of ca
71. iption Name o 1 unused reserved used Temperature under range TEMP TEMPUR 3 8 Temperature over range TEMP TEMPOR Strain gauge input under range ECOMUR Strain gauge input over range ECOMOR 64 Cell under range CRAW CRAWUR 128 Cell over range CRAW CRAWOR 256 SYSUR 512 SYSOR 1024 Unused 2048 LCINTEG 4096 Watchdog Reset WDRST 8192 unused reserved Unused 16384 BRWNOUT 32768 Reboot warning Normal Power up REBOOT NOTE The mnemonic names are used by convenience properties in Instrument Explorer but are otherwise for reference only the flags can only be accessed via the FLAG parameter Ol RJ WIN gt AJN 6 7 o ajA The various warning flags have the following meanings TEMPUR and TEMPOR indicate temperature under and over range The temperature minimum and maximum settings are part of the temperature calibration fixed at 50 0 and 90 0 C These flags are only active when the optional temperature module DTEMP is fitted ECOMUR and ECOMOR are the basic electrical output range warnings These are tripped when the electrical reading goes outside fixed 120 limits This indicates a possible overload of the input circuitry i e the input is too big to measure The tested value ECOM is an un filtered precursor of ELEC CRAWUR and CRAWOR are the cell output range warnings These are tripped when the cell value goes outside programma
72. ired mV V x 40 Example for 10mV V R49 10 x 40 400 Ohms Increasing Sensitivity When the full scale output is less than 2 5 mV V it may be desired to increase the sensitivity However it is often possible instead to compensate partly or entirely in software by increasing either or both of the software gain controls CGAI or SGAI Mantracourt Electronics Limited DSCUSB User Manual 70 To increase the sensitivity R20 is left in place by leaving the PCB track intact and R19 fitted in parallel R19 is calculated as R19 1 0 025 reqd mV V 0 01 Example for 1 5mV V Rig 1 0 025 1 5 0 01 150 Ohms Two effects should be noted 1 The purpose of increasing the hardware gain is to reduce reading noise which governs the effective resolution This gives better performance than increasing the gain in software 2 The sensitivity should however not be set greater than typically 1mV V Beyond this figure input noise usually dominates and no extra benefit can be achieved 71 Mantracourt Electronics Limited DSCUSB User Manual Chapter 11 Troubleshooting This chapter gives a quick guide to problem solving for DSCUSB devices Bear in mind that the quickest way to pin down problems is to usually replace items with known good alternatives This also applies to cables power supplies devices etc LED Indicator The LED is used to indicate the protocol selection the device is powered and the Device is
73. istinction between different access types is also protocol dependent in that some use a dummy read or write command to execute access Slave Addressing and Broadcast Every slave device on the bus is identified by a unique address value known variously as its station number node id etc depending on the protocol Each command message contains an address specifying to which slave device it is directed A slave will ignore all communications that are not addressed to it All the protocols also define a special address value normally 0 which is reserved for broadcast commands which all slaves act on No response is allowed to broadcast commands as multiple replies would collide with one another Parameters Parameters are the values used for all control settings and output values They have an associated storage type byte integer or real value and may be either read write read only or write only Output or result values are mostly read only Configurable parameters are held in non volatile storage so control settings are retained permanently even when power is removed Mantracourt Electronics Limited DSCUSB User Manual 52 Data Type Conversions and Rounding Type Conversion Depending on the protocol an integer byte parameter may need to be converted to or from a floating point representation for reading or writing The rules are as follows For reading integer and byte parameters are treated as unsigned
74. itivity Parameter Min Typical Max Units Ree ta Offset Temperature Stability cain Temperature Stability Gain Stability with Time Non Linearity before Linearization ppm of FR Internal Resolution 16 a counts divs Signal Filter Dynamic recursive type user Optional Temperature Resolution DTEMP Temperature Measurement Resolution 0 0625 0 0625 I Deg C Temperature Measurement Accuracy 10 to 85 05 Temperature Measurement Accuracy 55 to 125 gt Deg Temperature update Speed Seconds Electrical o S S S Power Supply voltage Lm Power Supply current 350 Ohm Bridge Data transmission transmission e 24 Output cable length speed dependant 5 m Environmental esti tl temperature range Storage temperature pumi amo oe 07 8 PCB Dimensions DSCUSB OEM PCB 43 x 28 x 4mm 1 6929 x 1 1024 x 0 472 PCB Dimensions DSCUSB OEM Module 82 x 60 x 20mm 3 2283 x 2 3622 x 0 7874 OEM PCB mounted on DSJ2 Cased version 86 x 57 x 26 5mm 3 3465 x 2 2492 x 1 087 excluding connector 95mm 3 740 including 9 way D type connector with 136 cm 94 462 feet USB cable Notes 1 From original offset at any time 2 1st Year 75 Mantracourt Electronics Limited DSCUSB User Manual Technical Specifications DSCUSBH Set for 2 5mV V sensitivity Parameter Min Typical Max Un
75. its Strain Gauge Excitation System 4 Wire Strain Gauge Drive Capability 5000 Ohms mV V 10 ppm C Offset Stability with Time 35 160 ppm of FR 1 300 a NNI ppm of FR Em pee E ud 2 _ Internal Resolution 16 Million Counts divs Resolution 1Hz readings Noise stable over 100s 200 000 Counts divs Resolution 10Hz readings Noise stable over 100s R esolution 100Hz readings Noise stable over 100s 50 000 Counts divs Resolution 500Hz readings Noise stable over 100s 18 000 Counts divs Signal Filter Dynamic recursive type user programmable Optional Temperature Resolution DTEMP Temperature Measurement Resolution 0 0625 Temperature Measurement Accuracy 10to85 05 f Temperature Measurement Accuracy 55 to 125 20 f Non Linearity before Linearization 5 ppm of FR 120 000 Counts divs Electrical Power Supply current 350 Ohm Bridge 6 75 m HEMDEN kbps m Data transmission Data transmission rate 2 4 460 8 ___ 5 su Output cable length speed dependant ee ee a nvironmental PE ee eel Operating temperature range C Storage temperature 40 85 C Humidity 0 95 RH CB Dimensions DSCUSB OEM PCB 43 x 28 x 4mm 1 6929 x 1 1024 x 0 472 PCB Dimensions DSCUSB OEM Module 82 x 60 x 20mm 3 2283 x 2 3622 x 0 7874 OEM PCB mounted on DSJ2 C
76. ived from the current measured temperature T as follows n number of points used as set by CTN When T CT1 then i 1 When T gt CTn 1 then i n 1 Otherwise i is chosen so that Ti lt T lt Ti 1 Once an index into the table has been established the gain value to be used is extrapolated between the index value and the value above If the temperature is above CT CTN or below CT1 then the calculated temperature gain value is extrapolated from CT CTN 1 to CT CTN or CT1 to CT2 respectively This can be represented mathematically as follows CALC CTG CTGi CTGi 1 CTGi x T CTi CTi 1 CTi The actual gain value used is 1 CALC CTGO x 10 6 and is multiplied by the uncompensated value The offset correction is then applied using the same temperature index i as found for the GAIN index above The Offset value is extrapolated between the same two temperature points This can be represented mathematically as follows CALC CTOj 4 x T CTi CTi The actual offset value used is CALC_CTO x 10 and is subtracted from the above gain adjusted value The output from the temperature compensation CMVV is then calculated as CMVV x 1 CALC_CTGO x 10 CALC_CTO x 10 The Temperature Measurement The temperature sensor used is a Dallas MAXIM 0518520 Digital Thermometer using the 1 Wire bus technology This gives a temperature measurement a
77. l warnings operate Bear in mind the following possible problems 1 REBOOT or an increasing CFCT may indicate intermittent connections 2 Where ECOMUR OR or EXCUR EXCOR are triggered suspect input wiring 3 Various range errors CRAWUR OR SRAWUR OR are also likely to be set if the excitation was interrupted EXCUR OR For range errors check the associated limit parameters CMIN MAX SMIN MAX 5 Problems are likely if any calibration MIN MAX parameters are set the wrong side of zero i e MIN 0 or lt 0 IN 73 Mantracourt Electronics Limited DSCUSB User Manual Problems with Bus Baud Rate There are a number of special difficulties to be considered here e Systems with very long cabling may not work with higher baud rates e Always remember devices need to be rebooted before certain changes take effect Recovering a lost DSCUSB For baud rate problems see previous section If the protocol is unknown e g the label has been removed or the diagnostic LED is not visible then try all three protocols ASCII MODBUS and MANTRABUS II until a response is obtained If a station number is unknown it can be reset via broadcast command STN 0 Always remember that a reboot power off or RST command is needed to change STN and BAUD settings Mantracourt Electronics Limited DSCUSB User Manual 74 Chapter 12 Specifications Technical Specifications DSCUSBS The DSCUSB is factory set for 2 5mV V sens
78. lculations for SGAI and 50 5 ehe nhe hee hse ernst 32 System Limits eed dee A user oreste abcde Whe donet eed eer 33 System AM 33 1 Mantracourt Electronics Limited DSCUSB User Manual SYS SRAW 5 em 33 System Outputs SYS SOUT eet eo clesvru scan echo 33 Reading Snapshot SNAP SYSN 33 ence pue 34 Shunt Calibration Commands SCON and SCOP 34 bij tile 34 1 34 Digital Output and OPOF 34 Digital 1 0 connection Details 34 OEM PCB d nc 34 35 Cased version Digital Output 35 Br meme 36 Diagnostics Flags FLAG And STAT O PEE 36 Latched Warning Flags FLAG 5 1 eee ee gue 36 Meaning and Operation of
79. le Ell 9 99154 l 1 a SERO DESI d Ica 1 1 c Rae Bia 598 A mo O o nr OEM PCB 6 wire load cell RL BON 8 ASR i 00000 as 9 12 Load Cell Connections 6 wire J E eaea SE Ma A o 7 1 a B23 IN p N m 1C4 Eliho o 29898 a sl ESP 1 1 B gei co P E N S g eet ee Cidjo ex OOOO Jes 04 T end coa HL coal Mantracourt Electronics Limited DSCUSB User Manual 66 OEM Module 4 wire load cell WAASN 5 Q Q Q m USB SOCKET Load Cell Connections 9X3 NI NI Oxa HS 292200 GND TEMP DIN DOUT OEM Module 6 wire load cell Load Cell Connections 6 wire NASN aN9 Q USB SOCKET NI NI HS 292000 GND TEMP DIN DOUT 67 Mantracourt Electronics Limited DSCUSB User Manual Cased Version 4 wire load cell Load Cell Connections Mantracourt Electronics Limited DSCUSB User Manual 68 Strain Gauge Cabling and Grounding Requi
80. led to avoid temperature effects from distorting the results The linearisation tests should not reveal any significant remaining linear trend in the errors If errors do appear to lie on a definite line this could drastically reduce the accuracy of the correction If this does happen it shows that the cell calibration is wrong and should be redone The table points must always cover more or less the whole range of output values to be used because corrections are extrapolated outward beyond the first and last points It is always worthwhile including more test points than will be used in the correction table because this gives confidence that no regions of rapidly changing error have been missed Tests should be done both with steadily increasing and decreasing load values as hysteresis effects for load cells are often of a similar size to non linearities Parameter Calculations and Example Based on the simple method outlined above we suppose that we have obtained test results for a series of precisely known load values test loads Xj give readings of CRAW Ci for i 1 n Then calculate the errors that need to be removed at these points Ej Xi Cj Now just enter these values into the correction table remembering to scale the errors CLN n CLX X CLKj 1000 Example Suppose we have a load cell and Cell calibration giving a result in the range 0 500 kgF The following test results were obtained using a
81. master slave type A central host device normally a PC or PLC acts as a bus master in control of all communications Communications consist of the master transmitting command messages addressed to particular DSCUSB slave devices The target slave may then transmit a response message back to the master Because there is only one bus master and slaves never initiate communications the master is in control of all communications This enables multi drop operation i e a single master can control any number of slave devices at a time In practice the master usually polls the attached slaves interrogating them in a fixed rotation Command Types A single command sent to a device can instruct it to read from or write to an internal parameter value or to execute a Control Action The device responds by returning data for a parameter read or a simple acknowledge for write or action Precise details depend on the protocol in use Each Command Message Contains the Following Information 1 The intended slave address or broadcast 2 The command to access 3 The access type one of read write execute 4 For write accesses only the write value The Command Response will then be one of the following three types 1 An error indication 2 Asimple acknowledge 3 A read data value implicit acknowledge The various protocols differ quite a lot in the available types of error and acknowledgements The d
82. ng point value Action Commands are implemented as dummy parameters Writing activates the command and reading returns a dummy value with no action Only two valid Message Function Codes are supported Function 03 Read Holding Registers to read a register pair Function 16 Preset Multiple Registers to write a register pair The start address must always be a valid parameter address which is always an odd number see the following The only permitted data length is two registers i e 4 bytes Registers cannot be read or written singularly in larger groups or using other addresses i e even numbered registers cannot be addressed directly Parameter Addresses All MODBUS parameter addresses are derived from the equivalent MANTRABUS register number by a simple times 2 plus 1 calculation For example the FLAG parameter is Mantrabus register 14 so this occupies MODBUS holding registers 29 and 30 i e 2 14 1 29 See the command table in Chapter 9 for the starting register numbers Parameter Values All exchanged values read and write parameters are in the standard IEEE 4 byte floating point format The 32 Bits of the number are distributed as follows MSB 31 Sign bit 1 negate 30 23 Exponent 7 bit excess 127 LSB 22 0 Mantissa 23 bit fraction with implicit 1 The value of the number is thus 1 yis 2 Exponent 127 1 Mantissa 57 Mantracourt Electronics Limited DSCUSB User Manual No
83. o be in force units which can be used by System to convert to units of weight Temperature compensation and Linearisation are covered in detail in their own chapters Temperature Compensation in brief When the optional temperature hardware module DTEMP is connected temperature compensation is available This facility can remove the need for fitting compensation resistors to strain gauges The compensation can apply for both gain and offset with up to 5 temperature points The input for the temperature compensation is MVV and the output from the process is CMVV If no temperature compensation is invoked CMVV is equal to MVV A detailed explanation is given in chapter 5 Cell Scaling CGAI COFS The temperature compensated value CMVV is scaled with gain and offset using CGAI and COFS respectively The gain is applied first and the offset then subtracted This would be used to produce a force output in the chosen units this output being termed CRAW CRAW CMVV X CGAI COFS Two Point Calibration Calculations and Examples Examples are given here for two point calibration as this is by far the most common method Cell Calibration The scaling parameters are CGAI and COFS CGAI is in cell units per mV V COFS is in cell units The cell output calculation is in the absence of temperature and linearity corrections CRAW CMVV x CGAI COFS If we have two electrical output MVV readings for two known force loads fA and fB
84. offset Also taken into account is any variation in the test weights at different temperatures This is a complex mathematical procedure which is best solved by a PC programme such as the wizard Mantracourt Electronics Limited DSCUSB User Manual 46 Chapter 6 Linearity Compensation This chapter describes the Linearity Compensation features and how to use them Purpose and Method of Linearisation Load cell sensor outputs are never precisely proportional to the input applied load If the graph of the measurement output against the true value shows slight deviations from the ideal straight line then slight errors remain even when the basic calibration offset and gain is as good as possible Linearity compensation adjusts the raw measurement by a small amount that is calculated as a function of the raw measurement value itself Ideally this will adjust the output response for any given input load by exactly the right amount to place the final result onto the ideal straight line The DSCUSB non linearity compensation uses a single lookup table similar to those used for temperature compensation see previous chapter This provides a linearly interpolated compensating value with up to 7 control points which is then added to the output result Generally linearisation is a finer level of compensation than temperature compensation It should only be applied after the basic Cell calibration and temperature compensation if any have
85. on Board Sensor Connections Waassn ddssn B USB SOCKET DSCSUSB MOTHERBOARD GND TEMP DIN DOUT Load Cell Connections OX3 NI NI OX3 HOS Optional temperature sensor Temp for temperature compensation Next we will set Instrument Explorer to automatically update dynamic parameters from the device so that we can see values such as SYS changing on the screen To do this either click the button on the mp aed toolbar or click on the Parameters menu and select the Auto Sync item Note that these options toggle 2l So be sure to leave your selection in the active state gt Mantracourt Electronics Limited DSCUSB User Manual 20 From the Parameter List click the amp next to the System heading to expand this level The Parameter List should look as follows This now exposes more levels that can be expanded as required by clicking the amp next to the heading name 1 0 0 0 100 0 100 0 0 0 Dynamic values such as SYS and SRAW will now be updating in real time from the device Once you have connected the load cell the SYS parameter should display realistic values in the parameter list pane These values should correspond to mV V assuming the device is in its factory default state For diagnostics the device has two sets of flags one being latched and
86. orer Do e Save and restore customisable user workspace e Read and Write individual instrument parameters e Save and restore parameter configurations e Log data to a window or file e Perform calibration and compensation Installing Instrument Explorer Install the Instrument Explorer software by inserting the CD in the CD ROM drive This should start the AutoRun process unless this is disabled on your computer If the install program does not start of its own accord run SETUP EXE on the CD by selecting Run from the Start Menu and then entering D SETUP where D is the drive letter of your CD ROM drive The install program provides step by step instructions The software will install into a folder called InstrumentExplorer inside the Program Files folder You may change this destination if required Shortcut icons can be created on your desktop and shortcut bar After installation you may be asked to restart the computer This should be done before proceeding with communications This section deals with using Instrument Explorer to communicate with the DSCUSB device and the drivers are installed during Instrument Explorer setup If you are planning to communicate with the DSC with your own software contact Mantracourt for information on where to get a stand alone set of drivers Installation Install Instrument Explorer Version 1 build 6 4 or higher ensuring that the option for installing the DSC USB drivers is s
87. r provides wizards for easy calibration of the Cell stage There are two wizards Cell Calibration Auto and Cell Calibration Table these can be found under the menu item Wizards 31 Mantracourt Electronics Limited DSCUSB User Manual Cell Limits CMIN CMAX These are used to indicate that the desired maximum and minimum value of CRAW have been exceeded They are set in Force units If CRAW exceeds the value set in CMAX the CRAWOR flag is set in both FLAG and STAT the value of CRAW is also clamped to this value If CRAW is less than the value set in CMIN the CRAWUR flag is set in both FLAG and STAT the value of CRAW is also clamped to this value Linearisation In Brief Linearisation allows for any non linearity in the strain gauge measurement to be removed Up to 7 points can be set using CLN The principle of operation is that the table holds a value at which an offset is added The point in the table that refer to CRAW are named CLX1 CLX7 The offsets added at these point are named CLK1 CLK7 and are set in thousandths of a cell unit The output from the Linearisation function is CELL If no Linearisation is used CLN lt 2 the CELL is equal to CRAW A Detailed explanation is given in chapter 6 System System is where the Force output CELL is converted to weight when installed into a system see Chapter 4 for more details Other features such as SZ offers a means of zeroing the system output SYS Peak
88. r this reason any communications application should always check command responses and flag a problem when these responses are not activated Possible problems can be categorised according to where in the chain of communication the problem may be The typical chain runs as follows e PC software port connection baud rate station number protocol e PC serial port working e USB lead to DSCUSB e Bus wiring e DSCUSB device wiring station number baud rate protocol working Mantracourt Electronics Limited DSCUSB User Manual 72 A quick checklist elaborates on these areas if you are using the Instrument Explorer evaluation software other software may have different requirements at the PC end Check as follows PC End 1 PC software settings correct serial port baud rate and protocol standard data setup is 1 start bit 1 stop bit no flow control 2 PC serial port okay check with another serial device e g wire two PCs together with Hyper Terminal running on both Evaluation Board or Device 1 Power reaches the device with correct polarity 2 USB Connections correct 3 Device settings correct station number baud rate How do you know these are correct A substitute device is very useful here 4 Device protocol double check product label 5 Device running okay LED is flashing 6 Devices take 45 55mA supply current without sensor attached 65 75mA with 350 Ohm gauge Bad Readings The cause can be eit
89. ractice SRAW and SYS can be used to represent something like gross and net values Cell and System Scaling Both the Cell and System calibrations are simply linear rescaling calculations i e they apply a gain and offset In both cases four parameters define the scaling offset and min and max limit values These calculations are applied in the following way Output Input x GAI OFS Output min output MAX Output max output MIN In addition if the value exceeds either limit one of two dedicated error flags is set The control parameters thus have the following characteristics e GAl is the multiplying factor set in output units per input unit e OFS is the value that gives zero output set in output units e MAX and MIN are output limit values set in output units The units and functions of the main scaling controls can thus be summarised as Cell Calibration CGAI Force mV V mV V gain factor COFS Force CELL Offset Value CMIN Force Minimum value for CRAW CMAX Force Maximum value for CRAW System Calibration SGAI Eng Force SYS CELL gain factor SOFS Eng SRAW value offset SMIN Eng Minimum value for SRAW SMAX Eng Maximum value for SRAW SZ Eng SYS value offset MVV is mV V Force is force units and Eng is engineering units 41 Mantracourt Electronics Limited DSCUSB User Manual Calibration Parameters Summary and Defaults The various control parameters are listed for each
90. rements To achieve full performance specifications and conform to environmental approvals it is important to follow the wiring procedures outlined in this section DSC Strain Gauge Cabling Arrangement Key Requirements If the OEM PCB is fitted within the body of a load cell the strain gauge wires should be kept as short as possible at most 20cm The EXC wires should be twisted together also the SIG pair and the two pairs kept apart It is also recommended to secure the wires from moving due to shock or vibration The shield connection SH should be connected to the body of the load cell via a very short length of wire 20mm max Load cell body SH ro ACoA 8 958 0000 _ z B 3 REg u u load cell body ls Di ms Ics 9 O OF 5 0 0000 B Ground load cell body If the DCell is mounted outside the body of the load cell then for optimal performance twin twisted cable should be used although standard 4 core shielded cable can be used in low noise environments EMC Gland Shield Exc Exc In N B Shield terminated at EMC gland using 360 termination N B White core shown as yellow in above diagram Shield tail length must be kept to a minimum 69 Mantracourt Electronics Limited DSCUSB User Manual Strain Gauge Sensitivi
91. rite only execute Datatype float int byte 4 byte real two byte integer 1 byte integer none MB reg register number for MANTRABUS protocol MD reg start register address always odd for MODBUS protocol NOTES All Modbus accesses are in register pairs Modbus addresses are 2 MANTRABUS 1 Mantracourt Electronics Limited DSCUSB User Manual 62 Chapter 10 Installation This chapter gives detailed information on integrating the DSCUSB into a production system including mounting protection adjustments wiring and electrical requirements Before Installation Carefully remove the DSCUSB device from its shipment box Check that the device is complete and undamaged Check the Product Type Code on the product label is that which you ordered The DSCUSB can operate in any industrial environment providing the following limits are not exceeded Operating Temperature 40 C to 85 C Humidity 95 non condensing Storage temperature 40 C to 85 C For precise details of Environmental Approvals see chapter 15 It is advisable to follow the following installation practices where possible e Minimise vibration e Do not mount next to strong electrical or magnetic fields transformers power cables e Install electrical protection device as the unit is not internally fused e Always ensure the package is secure and protected
92. rror checking on the data received by the device Example A command to set the BAUD parameter to 3 on station 1 could look like this 1001 BAUD 3 CR assuming a device with STN 1 is present it will respond with CR Read Command Returns the requested value specified by the command The returned value is formatted according to the DP and DPB values The response consists of a sign character DPB decimal digits before a decimal point DP digits after the point and a terminating CR The length of the response is thus fixed at DP DPB 3 characters Example command to read the SOUT output could look like this 1001 SOUT CR if the value 32 1 and format settings are DP 3 and DPB 5 the response string will be 00032 100 lt CR gt Action Command If the device accepts the command then a CR is transmitted Example A command to reset device 14 would look like 1014 RST lt CR gt Mantracourt Electronics Limited DSCUSB User Manual 54 the response string will be solely lt CR gt Broadcast Commands If the station address in a command message is 000 this means a broadcast command All slaves act as normal on a broadcast command but do not respond Example A command to all devices on the bus to sample their inputs would look like this 1000 SNAP CR no response Bad Commands If any command is not understood by the device then a is transmitted followed by a CR Example
93. s ll is FEh this being different from the older Mantrabus l FFh to allow the two protocols to be mixed on one bus Checksum Both Host amp Device send their EXOR checksum of all data sent excluding framing character in nibble format with the MS nibble being first e g EXOR Checksum of data is A7h Checksum characters sent OAh 07h Data Transfer Data is both sent and received as 4 bytes split into 8 nibbles following the station number plus two nibbles of checksum Floating Point Data Format All data sent amp received in Mantrabus ll is in the IEEE floating point format this being a 4 byte floating point number The byte containing the sign amp exponent is sent first with the LS byte of the mantissa being last The memory layout of the 4 byte floating point numbers is MSB 31 Sign bit 1 negate 30 23 Exponent 7 bit excess 127 LSB 22 0 Mantissa 23 bit fraction with implicit 1 The value of the number is thus 1 sien 2 Exponent 127 1 Mantissa Note the assumed 1 before the mantissa exception to this is the special value 0 0 which is represented as 4 zeroes e g a floating point number of 12345 678 is represented as hex C6 40 E6 6 This is transmitted in nibble format as hex OC 06 04 00 OE 06 OB 06 End of Data Identifier As the protocol has no fixed length or length identifiers the last nibble of data sent to the device has its MS nibble set This indicates to the device
94. s written CO 50 checksum hi lo Read Command Example Read a value from registers 13 14 on slave 52 by sending hex 34 station address 03 function code read 00 OC start reg hi lo 00 02 quantity 2 registers 01 AD checksum hi lo A correct response with a value of 55 2317 Hex C25CED51 would then be hex 34 station response 03 function code read 04 byte count ED 51 C2 5C data AA D4 checksum hi lo Execute Command Example Execute command 101 on slave 17 by sending hex 11 station address 10 function code write 00 64 start addr h64 100 register 101 00 02 quantity 2 registers Mantracourt Electronics Limited DSCUSB User Manual 58 04 byte count 00 00 00 00 data value irrelevant AO B4 checksum hi lo The Acknowledge response is then hex 11 station response 10 function code write 0064 the Data Address of the first register 0002 the number of registers written 02 87 checksum hi lo The Mantrabus Il Protocol Mantrabus ll is a two wire system where data is transmitted amp received over a common pair of wires Comms traffic is synchronised by using a unique 8 bit framing character For this reason the framing character must not appear as data in a command or reply from the responding DSCUSB The protocol ensures this does not occur by splitting data bytes into 4 bit nibbles while the framing character amp station number remain as 8 bits Framing Character The framing character for Mantrabu
95. series of known test loads For test load of x1 Okg 8 CELL reading 1 0 0010 For test load of 2 100 13kg CELL reading c2 100 44 For test load of x3 199 72kg CELL reading c3 200 57 For test load of x4 349 97kg CELL reading c4 349 75 For test load of x5 450 03kg CELL reading c5 449 98 We choose these precise test points as our linearisation reference points so CLN 5 CLX1 0 0010 CLX2 100 44 CLX3 200 57 CLX4 349 75 Mantracourt Electronics Limited DSCUSB User Manual 48 Note on the example If you graph the errors from the above example the results look like this 0 4 0 2 0 0 2 0 4 This doesn t show any very definite linear trend so the calibration is okay However there is a big jump between points 3 and 4 which might be worth a more detailed investigation Some important features of the error curve could have been missed by the test 49 Mantracourt Electronics Limited DSCUSB User Manual Chapter 7 Self Diagnostics Diagnostics Flags The main diagnostics facilities are by means of the flags See Flags in chapter 3 for a full description of the flags and their meaning The flags are normally used in the following way FLAG is read at regular intervals by the host like the main output value but generally at longer intervals If some warnings are active i e FLAG is non zero then the host tries to cancel the warnings found by writing FLAG 0 The host t
96. service replacement Self diagnostics Continuous monitoring for faults such as strain overload over under temperature broken sensors or unexpected power failure All fault warnings are retained on power fail Multiple output options Choice of three different protocols for ease of integration ASCII MODBUS or MANTRABUS All variants provide identical features and performance 5 Mantracourt Electronics Limited DSCUSB User Manual Special Facilities Output Capture Synchronisation A single command instructs all devices on a bus to sample their inputs simultaneously for synchronised data capture Output Tare Value An internal control allows the removal of an arbitrary output offset enabling independent readings of net and gross measurement values Dynamic Filtering Gives higher accuracy on stable inputs without increasing settling time Programmable Output Modes Output rate control enables speed accuracy trade off ASCII output version provides a decimal format control and continuous output mode for dumb terminal output Unique Device Identifier Every unit carries a unique serial number tag readable over the communications link External Temperature Sensing optional An external temperature module is available for improved accuracy especially tracking changing temperature conditions Software Reset A special communications command forces a device reboot as a failsafe to ensure correct operation Mantracourt
97. ss the bridge It is important for the user to remember to switch out the shunt calibration resistor after calibration has been confirmed Digital I O Digital input The state of the digital input pin is interrogated via bit 1 IPSTAT of the Dynamic Status Flags STAT The digital input is a volt free contact type 10k pull up resistor to 5V and will accept switch or relay contacts etc Digital Output OPON and OPOF The OEM PCB and OEM Module versions feature a digital input and a digital output As supplied the cased version only provides a digital output due to the insufficient number of spare pins on the 9 way D type connector This can be changed to a digital input instead by removing and fitting 0603 surface mount resistors see below for details The digital output is an open collector transistor rated at 100mA 30V maximum Care must be taken to limit the current to this value The output can be switched on and off using the commands OPON and OPOF respectively Digital I O connection Details OEM PCB ey Bee 0000 L2 pz 898 e om Dio R23 oo e AL 0 sl lo of RE Jele E BP Be 522 9 o ooo et
98. sssssssssosssossssssesesesssececeseeeceeeeeesesees 19 Connecting a Load deux eaae ve desee EN 20 DSJ2 Evaluation Board Sensor 20 Performing System Calibration sess secos esee rre 22 Sys Calibration Table 22 Sys Calibration Auto Method e Nhanh ndn ese ino n nean 25 Chapter 3 Explanation of Category Items oE ori iaiia sse esee eee enne 27 enne C 27 Output Format Controls DP and DPB ASCII ONLY 27 Informatioh 2 5 5 I eL eie e Dee 27 Software Version si 2 as cesa eee narinaa e eR ERA Ee debate ERES RESCUE UR so cee arl APR nie 27 Serial Number SERL and 5 essere tenerse 27 Strain Gauges fc icc coeds E D 27 mV X output o etes Seatac ewe ert Exe ER Nae Yee PU cene xo NOE cus ROI etes ree Se Ee Uae sens coe bane ee de 28 Nom
99. stage This also includes the compensation parameters not covered in this chapter but shown in the flow diagram The Default values shown set the device back to its nominal default calibration mV V Cell Control Defaults Command Action Default Values FFLV Filter dynamic level 0 001 FFST Filter Steps max 100 NMMV Nominal 2 5mV V 2 5 RATE Rate 10Hz 3 CGAI basic cell gain 1 0 COFS basic cell offset 0 0 CTN number of temp points 0 CT1 5 temp points Deg C 0 0 0 0 0 0 CTO1 5 offset adjusts 0 0 0 0 0 0 CTG1 5 gain adjusts 1 0 1 0 1 0 1 0 CMIN CRAW min limit 3 0 CMAX CRAW max limit 3 0 CLN number of linearity points 0 CLX1 7 linearity raw value points 0 0 0 0 0 0 CLK1 7 linearity adjusts 0 0 0 0 0 0 System Control Defaults Command Action Default Values SGAI basic gain 1 0 SOFS basic offset 0 0 SMIN SRAW min limit 100 0 SMAX SRAW max limit 100 0 SZ output zero offset 0 0 Mantracourt Electronics Limited DSCUSB User Manual 42 Chapter 5 Temperature Compensation This chapter explains how to use the Temperature Compensation facilities to compensate for changes in the measurement with ambient temperature Temperature compensation is only provided when an optional module DTEMP comprising a digital temperature sensor is wired to the DSCUSB Purpose and Method of Temperature Compensation Most measurement methods are affected by changes in temperature
100. t may sometimes be necessary to alter the formatting for best accuracy in reading writing values eg if DP 5 and DPB 2 the value 1 257 is output as 01 25700 The new value of DP and DPB does not take effect until the RST command is issued or the device is power cycled Information The Information heading in the parameter list reports the current version of the device s software and the device s unique serial number Note that VERSION is the readable item derived from the device s internal value of VER and SerialNumber is derived from SERL and SERH Software Version VER The VER parameter read only byte returns a value identifying the software release number coded as 256 major release minor release eg current version 3 1 returns VER 769 Serial Number SERL and SERH SERL and SERH are read only integer parameters returning the device s serial number This is decoded as 65536 SERH SERL The VisualLink Instrument Explorer drivers include a convenience Serial Number property that automatically calculates this Strain Gauge This is where the measurement process starts If the optional temperature module is fitted then TEMP will display actual temperature in C Otherwise TEMP will display 125 C RATE is the parameter that selects the measurement cycle update rate 27 Mantracourt Electronics Limited DSCUSB User Manual mV V output MVV MVV is the factory calibrated m
101. ta could be calibration time and date operator number customer number etc This data is not used in any way by the DSCUSB Mantracourt Electronics Limited DSCUSB User Manual Reset The Reset command RST This command is used to reset the device This command MUST be issued if the following parameters are changed before the change will take effect RATE STN BAUD DP amp DPB Alternatively the power maybe cycled The reset action may take up to about a second to take effect followed by the normal start up pause of 1 second WARNING Finite Non Volatile Memory Life The DSCUSB uses EEPROM type memory as the storage for non volatile controls i e all the settings that are retained even when powered down The device EEPROM itself is specified for 100 000 write cycles for any one storage location although typically this is 1 000 000 Therefore When automatic procedures may write to stored control parameters it is important to make sure this does not happen too frequently So you should not for example on a regular basis adjust an offset calibration parameter to zero the output value However it is reasonable to use this if the zeroing process is initiated by the operator and won t normally be used repeatedly For the same reason automatically cancelling warning flags must also be implemented with caution It is okay as long as you are not getting an error recurring repeatedly and resetting it every few seconds 39
102. te the assumed 1 before the mantissa The exception to this is the special value 0 0 which is represented as 4 zeroes e g a floating point number of 12345 678 is represented as hex C6 40 E6 6 These 32 bits are mapped onto a register pair in the following way The lower register holds bits 15 0 and the upper register bits 31 16 These values are coded according to normal Modbus conventions so the actual byte sequence in a read write message is thus R2t6 Which in terms of bits is 15 8 7 0 31 24 23 16 Error Codes Only three Modbus Error Codes are supported which are used as follows 01 Illegal Function request for function other than 3 or 16 02 Illegal Data Address attempt to read an unsupported register address 03 Illegal Data Value attempt to write a read only parameter or message too long for buffer valid messages have a known maximum length Write Command Example Write value 1 23 represents as hex 3F9D70A4 to registers 57 58 on slave 4 by sending hex 04 station address 10 function code write 00 38 start reg hi lo N B h38 56 addresses register 57 00 02 quantity 2 registers 04 byte count 4 70 A4 first lower register 17 value hi lo 9D second upper register 18 value hi lo 6B AB checksum hi lo A correct response would then be hex 04 station address 10 function code write 0038 the Data Address of the first register 0002 the number of register
103. tected on the following virtual serial ports COM3 Select the serial port to which the device is connected from the drop down list and click the OK button Mantracourt Electronics Limited DSCUSB User Manual 18 Viewing Device Data The following main parameter list should now appear in the central pane Instrument Explorer Parameter List W Instrument Explorer i Comms Traffic x p cet OPER 15 09 06 01 03 04 00 00 00 00 FA 3 15 09 0 01 03 00 B2 00 02 64 2C 15 09 06 USRS ADP15 15 09 06 01 03 04 00 00 00 00 FA 3 standard 15 09 06 01 03 00 B0 00 02 C5 EC ADW15 15 08 06 USR8 standard 15 09 06 01 03 04 00 00 00 00 3 ga LC 15 Strain Gauge 150306 01 03 00 AE 0002 5 EA standard Cell lano m2 15 09 06 01 03 04 00 00 00 00 FA 3 way 15 System 15 09 05 01 03 00 AC 00 02 04 2A Control standard 5 15 09 06 USR6 ES 15 09 06 01 03 04 00 00 00 00 FA 3 Flags E 15 09 06 01 03 00 AA 00 02 E4 2B MantraASCII 2 User Storage 15 09 05 USRS Reset 01 03 04 00 00 00 00 FA 3 dg onn 15 01 03 00 A8 00 02 45 USR4 DSC v3 01 03 04 00 00 00 00 FA 3 06 01 03 00 A6 00 02 24 28 eq PSC USB 15 09 06 USR3 15 09 06 01 03 04 00 00 00 00 FA 3 01 03 00 A4 00 02 85 ES 03 06 USR2 Mantrabus 2 010304 00 00 00 00 FA 3 06 01 03 0042 00 02 65 E9 15 USR1 15 09 06 DSCALON 15 08 06 DSGINTEG 15 09 06 DOLDVAL 15 09 06 DSY
104. tegories to which parameters and generated variables belong This provides a convenient method for describing the functionality and purpose of each The categories can be seen from Instrument Explorer s Parameter List pane and are as follows Communications For the ASCII protocol there are DP and DPB controls which set the format of the ASCII string returned by the device see Chapter 12 Care should be taken when changing the station number or baud rate as communications can be lost with the host Also note that some commands require the reset RST command to be sent or a power cycle before the new values take effect STN BAUD DP and DPB are such commands When using Instrument Explorer to change either the STN or BAUD parameter communications with the device will be lost after the RST command has been issued as the software will be using the previous settings In this case you need to change the device settings in Instrument Explorer by selecting Change Settings from the Communications menu Output Format Controls DP and DPB ASCII ONLY The parameters DP and DPB are used to control the formatting of floating point values in the ASCII protocol DP controls the number of decimal places after the point and DPB controls the number of decimal places before the point Values of 1 8 are appropriate in both cases All output values are then transmitted in this same format As values are limited to a normal 4 byte accuracy about 7 digits i
105. the standard DSCUSB OEM Evaluation Kit which contains everything needed to communicate with a PC It is advised that first time users wishing to familiarise themselves with the product use the Mantracourt Evaluation Kit This provides a low cost easy way to get started If you do not have an Evaluation Kit the instructions in this chapter mostly still apply but you will need to wire up the device and have some means of communicating with it e The OEM Evaluation Kit A 6 way screw connector for the strain gauge A 4 way screw connector for a temperature sensor and the digital I O A 4 way USB screw connector A type B USB connector to interface to a computer An Evaluation DSCUSB with the Comms protocol of your choice e ACD ROM containing Instrument Explorer software and USB drivers e A USB lead e A DTEMP temperature sensor Other Things you will need e APC running Windows or above with a spare USB port and 45Mb free disk space and ideally e A strain gauge load cell or simulator typically 350 5000 ohms impedance Refer to specifications Chapter 12 Communications Interface Information DSCUSB devices can connect to a PC by plugging into a USB port and do not require an external power supply as they appear as a single unit load i e they draw lt 100mA Appropriate drivers must be installed which are bundled with Instrument Explorer and DSC Toolkit These create a virtual serial port allowing the DSCUSB to appear to the
106. tput value will differ from the constant Input Value x FFST Error 1 36 78794412 2 13 53352832 3 4 97870684 4 1 83156389 5 0 67379470 6 0 24787522 7 0 09118820 8 0 03354626 9 0 01234098 10 0 00453999 11 0 00167017 12 0 00061442 13 0 00022603 14 0 00008315 15 0 00003059 16 0 00001 125 17 0 00000414 18 0 00000152 19 0 00000056 20 0 00000021 29 Mantracourt Electronics Limited DSCUSB User Manual Remember if the step change in mV V is greater than the value set in FFLV then New Filter Output value New Input Value i e the output jumps to the new input value and the internal working value of FFST is reset to 1 This is then incremented each update set by RATE until it reaches the user set value of FFST Cell This is the level where integration between the DSCUSB and the strain gauge bridge takes place see Chapter 4 for more details Features include 5 point compensation to produce a temperature compensated value CMVV when the optional temperature module D Temp is fitted Scaling using a gain and offset CGAI and COFS respectively producing the value CRAW Linearisation using up to 7 points producing the final output from this section known as CELL Over load and under load values can be set in CMIN amp CMAX to alert the user to forces outside the intended or safe operating area These features allow the output CELL t
107. ty Maximum length should not exceed 20m Normal 4 core shielded cable can be used in areas of low electromagnetic noise Power and Communication Standard good quality USB cables should be used In the case of the self powered OEM Module described above use a USB type A to wire tails cable or cut off the type connector of a standard cable and strip back the outer sheath and connect the GND USBDP and USBDM cores to the 4 way screw connector J3 Leave the Vcc core unconnected Connect the external 5V supply to GND and VCC Ensure that the 5V supply stays within the limits 4 25V to 5 5V 65 Mantracourt Electronics Limited DSCUSB User Manual Temperature Sensor A shielded twisted pair is recommended with a maximum length of 10m the shield being connected to the load cell body or SH if DSC For short lengths lt 2m in a low noise environment inside load cell body for example then normal cable can be used Identifying Strain Gauge Connections OEM PCB 4 wire load cell rer B B BEE RUE 858000060 o Load Cell Connections ud S 12 ____ 5 n L ExctA of ajo H H n dol
108. ty Adjustment The DSCUSB is factory optimised for 2 5mV V If your strain gauge does not deliver a 2 5mV V full scale output you may want to adjust the sensitivity of the electronics hardware and or the software gain controls If an input mV V setting of more than 2 5mV V is required the hardware sensitivity must be adjusted to avoid saturating the input If the setting is less than 2 5mV V you can correct in software alone but increasing the hardware sensitivity will generally improve accuracy There is provision on the DSCUSB PCB for changing the mV V setting R20 can be changed an extra resistor R19 added and or a track cut as shown below D4 rn Bal coal The PCB track can be cut as shown above to disconnect the 100 Ohm gain resistor R20 and a suitable value resistor fitted as R19 to change the sensitivity A high quality 0805 surface mount resistor 25ppm C or better should be used to maintain performance Reducing Sensitivity To accommodate a sensor output larger than 2 5mV V it is necessary to reduce the electrical sensitivity of the input circuitry To decrease the sensitivity the track should be cut to remove R20 from the circuit and resistor R19 fitted as calculated by the following formula R19 requ
109. ue at table point N CTO1 CTO5 mV V MV V x10 Offset adjustment at Offset table point CTG1 CTG5 ppm Gain x109 at Gain table point N Mantracourt Electronics Limited DSCUSB User Manual 44 CTN sets the number of points in the gain amp offset tables A CTN value of less than two effectively switches off temperature compensation The maximum number of point is 5 values greater than 5 reset to 0 switching off temperature compensation CT1 to CT5 sets the temperature in of the correction points The table must be filled from CT1 up to amp including CT CTN and must be entered in order of increasing temperature value CTO1 to CTO5 provide the offset adjustment in mV V x10 The reason for the multiplication is due to the limitation set by the ASCII protocol of only being able to enter up to 6 decimal places The CTOx value is subtracted from the uncompensated value CTG1 to CTG5 provide the gain adjustment in ppm terms The actual gain value used is calculated as 1 CTGn x 10 Internal Calculation The temperature compensation calculation is described as follows The GAIN correction is applied first The current measured temperature is checked against the table values CT1 to CT CTN to establish an index value if the measured temperature is below that of CT1 then CT1 is used as the index If the temperature is above CT CTN 1 then CT CTN 1 is used This can be represented as follows A working table index i is der

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