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Component Interfacing, Module

Preparation, and Installation

Chapter 2

25

Figure 2.2

Example Encoder Diagram (250 Line)

Marker Pulse

at 360 o

Channel A

Channel B

X1

X2

X4

Quadrature
Multiplier

Single Encoder Line

250 Lines for
one rotation (360     )

o

Encoder
Output

Counts
Decoded
on the 
Module

10403

Figure 2.3

Burg Pin Jumper Selection

Jumper

Labels

JPR1

JPR2

Jumper Setting

for x1 Multiplier

Left 1

2

3

Right

JPR1

1 + 2 (left)

2 + 3 (right)

1 + 2 (left)

JPR2

2 + 3 (right)

1 + 2 (left)

1 + 2 (left)

Jumper

Positions

Encoder Count

Multiplier

x 1

x 2

x 4

10402

Summary of Contents for 1771-SF1

Page 1: ...User Manual Servo Interface Module Cat No 1771 SF1 Allen Bradley ...

Page 2: ...hield Connection 2 3 Module Preparation 2 4 Module Installation 2 6 Keying 2 7 Specifications 2 8 Programming and Operation 3 1 General 3 1 Data Transfers 3 1 DAC Data Servo Motor Speed 3 1 Control Byte Servo Motor Amplifier Inhibit 3 3 Encoder Counter Values Position Pulses 3 4 Target Values Position Interrupts 3 4 Special Servo Lines on the Backplane 3 4 Marker 3 5 A B 3 5 CCW CW 3 5 Target Valu...

Page 3: ...can be programmed to cycle through precise speed and position profiles Figure 1 1 Typical Microprocessor Based Servo Control System ÉÉ ÉÉ ÉÉ ÉÉ ÉÉ Single Motor User Program EPROM Plug in EPROM 1771 1771 Amplifier Inhibit Motor Current Inhibit Velocity Common Channels A B Channels Position Loop 50KHz Max 10399 Shaft Differential Tach Velocity Loop Servo Return Controlled Power Servo Drive User Appl...

Page 4: ...r 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 and software support associated with the micro controller servo interface module and intended application User Considerations ...

Page 5: ...haracteristics for monitoring the rotational direction and position of a drive shaft Full quadrature 90o 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 ...

Page 6: ...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 m...

Page 7: ... 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 c...

Page 8: ...t 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 ...

Page 9: ... X4 Quadrature Multiplier Single Encoder Line 250 Lines for one rotation 360 o Encoder Output Counts Decoded on the Module 10403 Figure 2 3 Burg Pin Jumper Selection Jumper Labels JPR1 JPR2 Jumper Setting for x1 Multiplier Left 1 2 3 Right JPR1 1 2 left 2 3 right 1 2 left JPR2 2 3 right 1 2 left 1 2 left Jumper Positions Encoder Count Multiplier x 1 x 2 x 4 10402 ...

Page 10: ...he same I O rack with any of the standard AC and DC 1771 I O modules However it 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...

Page 11: ...spond to the slots to allow insertion of the module so that only the servo interface module will fit in this slot Refer to Figure 2 4 Snap the keying bands on the upper backplane connectors between these numbers printed on the backplane 8 and 10 16 and 18 Needlenose pliers can be used to insert or remove keying bands Figure 2 4 Keying Diagram 2 4 6 8 1 0 1 2 1 4 1 6 1 8 2 0 2 2 2 4 2 6 2 8 3 0 3 2...

Page 12: ...ram 40 ft encoder input 40 ft TTL output 5 ft analog output Max Input Frequency Ambient Temperature Rating 50 KHz any channel Operational 0o to 60o C 32o to 140oF Storage 40o to 85oC 40o to 185oF TTL Input Output Voltage 0 6 V max low voltage Relative Humidity Rating 2 4 V min high voltage 5 to 9 without condensation TTL Input Current 15mA per line driver channel differential inputs only TTL Outpu...

Page 13: ...ne 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 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 ra...

Page 14: ...oltage can be determined as follows POSITIVE OUTPUT 1 Output voltage volts decimal equivalent of the binary number 4 883 x 10 3 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 3 volts bit 2 Convert the decimal equivalent to the binary number 3 Add 1 b...

Page 15: ... 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 memory 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 po...

Page 16: ...ion 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 ...

Page 17: ...ircuit 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 con...

Page 18: ...vo 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 25510 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 M...

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