1771-6.5.14,Servo Interface Module User Manual
Contents
1. Module Field Wiring Arm O Channel A TTL on 1 C9 Een O Channel A wel Gg Driver O ER ChannelB p S 3 Channel B O lS N Marker m 5 Q Marker ls N su Drive Current Inhibit a al _ ACS Amplifier On Off S Servo 10 Amplifier Analog Control 10V F S ae Not Used 2 lS I Lo 10401 The cable distance between the servo interface module and the differential line drivers should not exceed 40 feet Use a twisted conductor pair within a shielded braid Belden 8761 or equivalent for connections to the line drivers Use a 14 gauge conductor for the analog output to the servo amplifier and make this connection as short as possible to minimize the voltage drop in the cable Belden 8761 or equivalent cable has a foil shield with a bare stranded drain wire The shield should be connected to earth ground at one end of the cable only This can be at the customer end of the cable or at an I O chassis mounting bolt or stud At the other end of the cable the shield should be cut short and taped back to insulate it from any electrical contact This is to guard against unwanted radiated electrical noise and ground current loops 2 3 Chapter 2 Component Interfacing Module Preparation and Installation The common terminal of the servo interface module should not be used for the shield connect2. program to perform the various functions of the servo interface module 3 6 N Rockwell Automation Allen Bradley a Rockwell Automation Business has been helping its customers improve pro a ductivity and quality for more than 90 years We design manufacture and support a broad range Allen Bradley of automation products worldwide They include logic processors power and motion control devices operator interfaces sensors and a variety of software Rockwell is one of the worlds leading technology companies Worldwide representation aee M Argentina e Australia e Austria e Bahrain e Belgium Brazil e Bulgaria e Canada Chile e China PRC e Colombia e Costa Rica Croatia e Cyprus e Czech Republic e Denmark e Ecuador e Egypt e El Salvador e Finland e France e Germany e Greece e Guatemala e Honduras e Hong Kong e Hungary e Iceland e India e Indonesia e Ireland e Israel Italy e Jamaica e Japan e Jordan e Korea e Kuwait e Lebanon e Malaysia e Mexico e Netherlands e New Zealand e Norway Pakistan e Peru e Philippines e Poland e Portugal e Puerto Rico e Qatar e Romania e Russia CIS e Saudi Arabia e Singapore e Slovakia e Slovenia e South Africa Republic e Spain e Sweden e Switzerland e Taiwan e Thailand e Turkey e United Arab Emirates e United Kingdom e United States e Uruguay e Venezuela e Yugoslavia Allen Bradley Headquarters 1201 South Second Street Milwaukee WI 53204 USA Tel 1 414 382 2000 Fax 1 414 382 4444 P
3. Allen Bradley Servo Interface Module User Cat No 1771 SF1 Man ual Table of Contents Introduction 0 0 0 cece eee ewe eee n n nnn n 1 1 Description reisen 1 1 User Considerations 000 cece eee eee ee aees 1 2 Component Interfacing Module Preparation and Installation 00 0s eee e eee 2 1 General ben 2 1 Component Interfacing lise 2 1 nna TP 2 1 Differential Line Drivers 1 2 0 0c ccc ee eee 2 1 Servo Drive Package 0 0 cece cece eee eee eee 2 1 cn zu mess teehee be baa Ean kone ren 2 2 WINING sa beta dbo te odd Br ara 2 2 Cable Recommendations 0000 cece nennen 2 3 Shield Connection zu 2 40 Rennen 2 3 Module Preparation 00 0 0 ccc cece eee eee aes 2 4 Module Installation 00 0 0 ccc cece eee eens 2 6 AO ern nee ee 2 7 Specifications seu xs erbRR A dear AR REG UREPERRFERE RFERE 2 8 Programming and Operation 3 1 Generals desidi s Aoi re Lan 3 1 Data WANSIONS ar see ee 31 DAC Data Servo Motor Speed 000 cee eaee 3 1 Control Byte Servo Motor Amplifier Inhibit 3 3 Encoder Counter Values Position Pulses 3 4 Target Values Position Interrupts 0000000ee 3 4 Special Servo Lines on the Backplane 3 4 rri u ee Oot meds Sale eee 3 5 AS Bi echo dn ae eee las nave dnte dali Petes 2 3 5 BEWIEW sera 3
4. In order to transfer the information described in Paragraph 3 1 from or to the servo interface module certain memory addresses have to be accessed in the micro controller Whenever a Z 80 instruction is written to or read from a control function address for the servo interface module the instruction will force low one of the corresponding special enable lines DSEN 10 17 This signal instructs the servo interface module to latch data received from the 8 bit bidirectional backplane data bus system write or to place data on the data bus system read The control functions their addresses and corresponding DSEN lines are tabulated in Table 3 B 3 5 Chapter 3 Programming and Operation Table 3 B Servo Control Features DAC Data MSBY 600EH Write 8 bit byte DAC Data LSBY 600DH Write 15 Upper 4 bits of byte Target Value Preset 600CH Write 14 0 255 9 in binary Control Byte 600FH Write 17 Bit 2 limits drive current Bit 3 turns OFF the servo amplifier Data Byte Reset Command 600BH Write 13 Resets DAC data Target Value Preset and Control Byte by loading zeros Also reset at power up Read Counter Accum Value 6008H Read 10 0 255410 in binary Counter Reset 6009H Write 11 Resets counters and decoder logic by loading zeros Also reset at power up Marker Latch Reset 600AH Write 12 Resets the Marker Latch Refer to the Micro Controller Users Manual Publication No 1771 6 5 5 for additional information on developing the
5. 40 ft encoder input e 40 ft TTL output e 5ft analog output Ambient Temperature Rating Operational 0 to 60 C 32 to 140 F e Storage 40 to 85 C 40 to 185 F Relative Humidity Rating e 5 to 9 without condensation General Data Transfers DAC Data Servo Motor Speed Programming and Operation The servo interface module controls the operation of a single motor servo drive package in accordance with commands received from the micro controller Outputs to the servo amplifier of the drive package include 10 000 to 9 995V analog output signal for proportional motor speed and direction control A TTL output to limit the drive current from the servo amplifier to the motor A TTL output signal to turn the servo amplifier ON or OFF The servo interface module also monitors motion by counting quadrature pulses from a shaft encoder The pulses represent the rotational position of the encoder shaft or servo motor drive shaft The servo interface module sends an interrupt signal to the micro controller every time the accumulated counts of quadrature pulses equal a preset target value This signal can be used to minimize the programming required to monitor and control the position of the drive shaft Differential line drivers convert the single ended encoder signal to differential pulses for Channels A B and Marker of the module The driver also transmits a complement set of pulses equal but logically
6. following control voltage and current levels TTL output to inhibit the motor current TTL output to turn OFF the servo drive amplifier TTL Output Voltage 2 4V min high 0 6V max low TTL Sink Current 12 mA max 2 1 Chapter 2 Component Interfacing Module Preparation and Installation Isolation Wiring 2 2 TTL Source Current 7 9mA 2 4V 10 to 10V DC analog output for forward or reverse proportional motor speed control None of the terminals of the servo interface module are protected against misapplication of AC DC or reverse DC CAUTION Do not apply voltage or current sources to the terminals of the servo interface module except those specified for the terminals Damage to the module may result If voltages are misapplied and damage is done to the terminal side of the module the system side including the data bus to the micro controller is protected to 500V DC maximum isolation from the terminal side of the module The line drivers and the servo amplifier of the motor drive package should be wired to the field wiring arm connector of the servo interface module as shown in Figure 2 1 Full Quadrature Encoder Cable Recommendations Shield Connection Chapter 2 Component Interfacing Module Preparation and Installation Figure 2 1 Typical Connection Diagram Servo Interface
7. must not be used in an I O rack containing microprocessor based I O modules The only exceptions to this are the following microprocessor based I O modules which do not interfere with the operation of the servo interface module 8 Bit Analog Input Module Cat No 1771 1E Encoder Counter Module Cat No 1771 IJ IK CAUTION The Servo Interface Module Cat No 1771 SF1 will operate only when paired with the Micro Controller Cat No 1771 UC1 WARNING Avoid placing microprocessor based 1771 VO modules except as noted in the same I O rack with the servo interface module Unpredictable operation could occur with resulting damage to equipment and or injury to personnel Allen Bradley Servo Interface Module User Cat No 1771 SF1 Man ual Chapter 2 Component Interfacing Module Preparation and Installation Specifications 2 8 Counter Input e Differential e Full quadrature encoder Counter Range 0 255410 e Marker input is latched and reset by user program Max Input Frequency e 50 KHz any channel TTL Input Output Voltage e 0 6 V max low voltage e 2 4V min high voltage TTL Input Current e 15mA per line driver channel differential inputs only TTL Output Current e 7 9mA 9 2 4V as source e 12mA max as sink Number of TTL Outputs e Two Analog Output Single Channel to Servo Amplifier e 10V to 9 995V e 5mA to 5mA max Max Cable Distance e
8. opposite to Channel A Channel B and Marker channel All data transfers between the micro controller and the servo interface module take place over the normal I O 8 bit data bus on the backplane of the 1771 I O rack The transfer of each one of the following data bytes is initiated by a separately addressed read or write instruction from the micro controller The enable commands are transmitted over the special DSEN lines described in the Micro Controller User s Manual Publication No 1771 6 5 5 The servo interface module contains a Digital to Analog Converter DAC that sends a 0 to 10V analog voltage to the servo amplifier of the motor drive package The voltage controls the speed and rotational direction of the servo motor The input to the DAC is a 12 bit binary number sent from the micro controller that allows the speed and rotational direction of the servo motor to be changed by user program The DAC converts the 3 1 Chapter 3 Programming and Operation 3 2 lower 11 bits to the 0 to 10V DC analog output Bit 12 designates the sign or for forward or reverse motion The resolution of the digital to analog conversion is 10V 2048 bits or approximately 4 883 mV bit Table 3 A shows the relationship between the input binary number from the micro controller and the analog output voltage from the servo interface module for sample values The binary number for any desired output voltage can be determined as follows POS
9. 5 Target Value Interrupt 0 0 ccc cee eee 35 Programming the Servo Control Functions 3 5 Introduction Description The Allen Bradley Servo Interface Module Cat No 1771 SF1 when used with the Micro Controller Cat No 1771 UC1 can control single axis positioning systems such as found in machine tool applications When combined with a single motor variable speed drive package and a full quadrature encoder this microprocessor controlled servo drive system Figure 1 1 can be programmed to cycle through precise speed and position profiles Figure 1 1 Typical Microprocessor Based Servo Control System User Program EPROM Programming Unit Plug in EPROM User Application Single Motor Drive Package Amplifier Inhibit SF1 sane a Rem we S ome y Controlled Power Shaft Encoder Channels A amp B ChannelsA amp B Marker Marker Differential Position Loop 50KHz Max Line Driver 10399 1 1 Chapter 1 Introduction User Considerations Operating features described in this manual must be totally programmed in the user software Z 80A opcodes of the accompanying micro controller The servo interface module has the capability to perform as described provided that the software of the micro controller has been completely developed The user must assume full responsibility for performing all systems engineering programming a
10. Control Functions Chapter 3 Programming and Operation A low TRUE signal is transmitted to status port bit 0 after the marker signal is latched by the servo interface module for each completed revolution of the encoder shaft A write instruction to 600AH will reset this latched output A low TRUE signal appears at status port bit 1 whenever the target value preset is greater than the accumulated value of the counters counting the encoder pulses The bit goes high when the accumulated value becomes equal to or greater than the target value Generally a low signal appears at status port bit 2 when the rotation of the encoder shaft is counterclockwise CCW A high signal will then indicate clockwise CW rotation This relationship depends on system hardware and or wiring polarity Whenever the accumulated value of the encoder counter becomes equal to the target value preset an interrupt signal is sent to the micro controller The vectored interrupt is generated by the counter timer circuit CTC Channel 2 in the micro controller The interrupt condition is automatically reset by the micro controller during execution of the return from interrupt instruction RETI The micro controller must be programmed to perform this function The servo interface module controls the drive package in accordance with commands received from the micro controller module All programming of the micro controller is written in the Z 80 instruction set
11. ITIVE OUTPUT 1 Output voltage volts decimal equivalent of the binary number 4 883 x 10 volts bit 2 Convert the decimal equivalent to the binary number 3 Take the complement of the binary number NEGATIVE OUTPUT 1 Output Voltage volts decimal equivalent of the binary number 4 883 x 10 volts bit 2 Convert the decimal equivalent to the binary number 3 Add 1 bit to the binary number Refer to the rpm voltage chart provided by the servo motor manufacturer to complete the relationship between the DAC input binary number and servo motor speed and to determine the direction of rotation which is indicated by the sign bit Chapter 3 Programming and Operation Table 3 A DAC Input Output Sign Bit Input Bit Pattern Analog Output Voltage 0 111 1111 1111 10 000V 0 111 1111 1110 9 995V 0 111 1111 1100 9 990V 0 000 0000 0011 19 5mV 0 000 0000 0010 14 6mV 0 000 0000 0001 9 7mV 0 000 0000 0000 4 9mV 1 111 1111 1111 0 1 111 1111 1110 4 9mV 1 111 1111 1101 9 7mV 1 111 1111 1100 14 6mV 1 1 000 0000 0011 9 985V 1 000 0000 0001 9 990V 1 000 0000 0000 9 995V 2 3 1 Low TRUE Bit Patterns 2 MSBY 3 LSBY The 12 bit binary input to the DAC is transferred to two bytes using two write instructions The Most Significant BYte MSBY is eight bits long It can be loaded into memory location 600EH DSEN Line 16 enables the transfer The Least Significant BYte LSBY can be loaded into memor
12. e printed circuit board and are identified by the labels JPR1 and JPR2 Position the jumpers according to Figure 2 3 2 4 Chapter 2 Component Interfacing Module Preparation and Installation Figure 2 2 Example Encoder Diagram 250 Line Channel A a c ec Encoder Output Channel B TN E EE E x1 Mr MR NEN Counts Marker Pulse Decoded at 3600 Quadrature gb TL on the Multiplier 2 Module X4 Single Encoder Line 250 Lines for one rotation 36 10403 Figure 2 3 Burg Pin Jumper Selection Jumper Jumper Setting Jumper Encoder Count Labels for x1 Multiplier Positlons Multiplier JPR1 JPR1 JPR2 1 2 left 2 3 right JPR2 2 3 right 1 2 left Left 2 3 Right gt 1 2 left 1 2 left 10402 2 5 Chapter 2 Component Interfacing Module Preparation and Installation Module Installation 2 6 The module should be located in the I O slot adjacent to the Micro Controller Cat No 1771 UC1 If located further down the rack propagation delays due to longer signal paths along the backplane could degrade performance High speed communication between the micro controller and servo interface module necessitates this location The servo interface module must be used with the micro controller It cannot operate with PC processors or adapters The servo interface module can be used in the same I O rack with any of the standard AC and DC 1771 I O modules However it
13. ion This terminal is a common with respect to the analog output TTL outputs and pull up resistors on the differential inputs WARNING Do not use the common terminal of the servo interface module field wiring arm for the shield connection Unpredictable operation could occur with resulting damage to equipment and or injury to personnel Module Preparation Prior to installation the multiplication factor for counting the encoder quadrature pulses must be set internally The quadrature pulses are transmitted through the differential line drivers to the terminals of Channels A and B An additional complementary set of equal but logically opposite pulses are transmitted by the drivers to the terminals of Channel A and Channel B The servo interface module can be set to count either 1 2 or 4 of the quadrature pulse edges for each quadrature set depending on the desired positioning precision Figure 2 2 The desired multiplier x1 x2 or x4 can be set manually by inserting the pair of Burg pin jumpers on selected pairs of terminals The jumpers are located on the printed circuit board inside the module They are accessible by removing the cover plates according to the following procedure Remove the four slotted screws from the label side of the module Remove the left and right cover plates Place the printed circuit board on a table solder side down The pair of Burg pin jumpers are located in the center of the component side of th
14. nd software support associated with the micro controller servo interface module and intended application General Component Interfacing Encoder Differential Line Drivers Servo Drive Package Component Interfacing Module Preparation and Installation This chapter describes the necessary characteristics of user provided components preparation and installation of the module and wiring considerations Refer to the Micro Controller Users Manual Publication No 1771 6 5 5 for installation of the micro controller module The servo interface module must be compatible with other components of the control system including the differential line drivers shaft encoder and servo drive package containing the servo motor control amplifier Required characteristics of these components are stated below An encoder should have the following characteristics for monitoring the rotational direction and position of a drive shaft Full quadrature 90 out of phase typical Maximum frequency to the servo interface module is 50 KHz for Channels A B and marker Line drivers with the following characteristics can be used to transmit encoder quadrature pulses to the servo interface module Differential outputs for Channel A Channel B and marker TTL Source and Sink Currents 15 mA max TTL Output Voltage 2 4V min high 0 6V max low Outputs available to the servo motor control amplifier must be compatible with the
15. ublication 1771 6 5 14 February 1983 PN 955089 98A Supersedes 1771 821 September 1983 Copyright 1986 Allen Bradley Company Inc Printed in USA
16. y location 600DH It contains data in the upper 4 bits The lower 4 bits are not used DSEN line 15 enables the transfer DAC data is reset at power up or by the data byte reset command write location 600BH Control Byte Servo Motor Bit 2 of the control byte is used to inhibit amplifier drive current to the Amplifier Inhibit servo motor Bit 3 is used to turn OFF the servo motor amplifier They are low TRUE optically isolated TTL outputs 3 3 Chapter 3 Programming and Operation Encoder Counter Values Position Pulses Target Values Position Interrupts Special Servo Lines on the Backplane 3 4 A write instruction to memory location 600FH latches these bits DSEN Line 17 enables the transfer from the servo interface module The control byte is reset at power up or whenever the data byte reset command is programmed The encoder line drivers generate pulses for each encoder line Assume that a 250 line encoder is used as in Figure 2 2 When the quadrature multiplier is x1 a counter increment of 1 means that the encoder shaft has turned through 1 44 This can be translated into the linear movement of a feed slide proportional to the number of drive shaft threads per inch When either the x2 or x4 quadrature multiplier is used one count is equivalent to a turn of 72 or 36 respectively The micro controller can be programmed to read the accumulated value of the encoder counters in the servo interface module b
17. y a read instruction from memory location 6008H A read from the encoder counters is usually performed when the encoder is halted or turning very slowly A read from this location does not halt counter operation DSEN Line 10 enables the transfer from the servo interface module The encoder accumulated value is set to zero at power up and after 255 counts It also can be set to zero by the counter reset command which is a write to location 6009H The target value determines at which count in the accumulated count of encoder pulses an interrupt will be sent to the micro controller The target value is an 8 bit comparator preset ranging from 0 255 Target value interrupts can be counted to monitor and control the rotational position of the drive shaft A write instruction to memory location 600CH latches the target value DSEN Line 14 enables the transfer from the micro controller to the servo interface module The target value preset is reset to zero at power up or by the data byte reset command write location 600BH Four special backplane lines are used to monitor servo signals at the micro controller The first three lines transmit the marker A gt B and CCW CW signals respectively to the status port of the micro controller They are read at memory address 7000H These signals are always on line The fourth line transmits the interrupts to the micro controller Marker A gt B CCWICW Target Value Interrupt Programming the Servo
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