Allen-Bradley 1771-OFE User Manual
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Allen-Bradley 1771-OFE User Manual

Allen-Bradley 1771-OFE User Manual

Analog output module
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Analog Output Module
Cat. No. 1771 OFE
User Manual
Allen-Bradley PLCs
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Summary of Contents for Allen-Bradley 1771-OFE

  • Page 1 Analog Output Module Cat. No. 1771 OFE User Manual Allen-Bradley PLCs...
  • Page 2 Allen-Bradley publication SGI-1.1, “Safety Guidelines For The Application, Installation and Maintenance of Solid State Control” (available from your local Allen-Bradley office) describes some important differences between solid-state equipment and electromechanical devices which should be taken into consideration when applying products such as those described in this publication.
  • Page 3 This manual has been revised and reformatted to make the manual more usable. To help you find new and updated information in this release of the publication, we have included change bars as shown to the right of this paragraph. Allen-Bradley PLCs...

  • Page 4: Table Of Contents

    Table of Contents Summary of Changes ......Preface ........Manual's Purpose .
  • Page 5 ......Two's Complement Binary ......Allen-Bradley PLCs...

  • Page 6: Preface

    Vocabulary In this manual we refer to the: Analog Output Module (cat. no. 1771-OFE) as the “output module” Programmable Controller as the “processor” or “controller.” Manual Organization The manual is divided into seven chapters. The following chart shows each chapter with its corresponding title and a brief overview of the topics covered in that chapter.

  • Page 7: Related Products

    Block Transfer with Mini PLC 2 and PLC 2/20 Processors Data Formats Related Products You can install your output module in any system that uses Allen-Bradley programmable controllers that have block transfer capabilities and the 1771 I/O structure. For more information on your programmable controllers, contact your nearest Allen-Bradley office.

  • Page 8: Overview Of The Analog Output Module

    Module Description The Analog Output Module (cat. no. 1771-OFE) is an intelligent block transfer module that converts binary or four-digit BCD values (supplied by your processor) to analog signals at its four module outputs. The module accomplishes the data transfer with block transfer programming.
  • Page 9 Figure 1.1 Communication Between Processor and Module To analog output devices – 12876 Programmable Analog Output Module Controller Cat. No. 1771 OFE The processor transfers your configuration and output data to the Allen-Bradley PLCs module via a block transfer write instruction.

  • Page 10: Accuracy

    Chapter 1 Overview of the Analog Output Module The module converts the data into proportional voltage or current outputs. These module outputs drive external analog devices. When instructed by your ladder program, the processor performs a read block transfer of output values and module status. The processor and module determine that the transfer was made without error.

  • Page 11: Module Installation

    I/O chassis backplane and/or power supply. Add this to the requirements of all other modules in the I/O chassis. Analog Module Power Requirement 1771 OFE1 1 5A @ 5V dc 1.5A @ 5V dc 1771 OFE2 1771 OFE3 2.5A @ 5V dc Allen-Bradley PLCs...

  • Page 12: Determine Module Location In The I/O Chassis

    Chapter 2 Module Installation ATTENTION: Do not insert or remove modules from the I/O chassis while system power is ON. Failure to observe this rule could result in damage to module circuitry. Determine Module Location You can place your module in any I/O module slot of the I/O chassis with in the I/O Chassis the following guidelines: Do not put the module in the same module group as a discrete...
  • Page 13 HOLD LAST VALUE setting. Figure 2.1 shows jumper positions for the 1771-OFE, Series B, Analog Output Module LAST STATE Configuration Jumpers. Important: Ignore the MAX, MIN, MID markings on the printed circuit board.
  • Page 14 Chapter 2 Module Installation Figure 2.1 LAST STATE Configuration Jumper Last State Output Level Front of Circuit Board Configuration Jumpers HOLD LAST STATE Table 2.A lists the output ranges and their minimum, maximum, and middle values. Table 2.A Output Last State Configuration Values Output Range Minimum Maximum...
  • Page 15 Locate the jumpers as shown in Figure 2.1. Carefully pull up on the jumpers to remove from the pins. Reposition as necessary to provide the value selected in Table 2.A. Allen-Bradley PLCs...
  • Page 16 Chapter 2 Module Installation Setting Voltage Range Configuration Jumpers (1771 OFE1 only) If you ordered the voltage output version, you must set several configuration jumpers located inside the module on the circuit board. To do this, follow these steps: Remove the covers from the module’s printed circuit board (Figure 2.2).
  • Page 17 Lift the locking latch holding the module into the chassis. (On chassis equipped with a chassis locking bar, pull the locking-bar pins to release the locking bar and swing it up.) front of chassis 12453 I Allen-Bradley PLCs...
  • Page 18 Chapter 2 Module Installation Position the keying bands (Figure 2.4) in the backplane connectors to correspond to the key slots on the module. This prevents you from inserting the wrong module in this slot. This analog module uses: between 10 and 12 between 26 and 28 ATTENTION: Observe the following precautions when inserting or removing keys:...

  • Page 19: Connecting Wiring

    Loop power must be supplied by the user. Field Wiring Arm Cat. No 1771 WC 12878 ATTENTION: To avoid injury to personnel and damage to equipment, disconnect and lockout ac power from the processor and system power supplies before wiring the module. Allen-Bradley PLCs...
  • Page 20 Chapter 2 Module Installation The module requires shielded cable for signal transmission to the analog devices. Use Belden 8761 or equivalent as described in the “Approved Vendor List,” publication ICCG-2.2. This cable consists of a single insulated, twisted-pair of conductors, covered along their entire length by a foil shield and encased in plastic.

  • Page 21: Interpreting The Indicator Lights

    Diagnostic Indicators ANALOG (12 BIT) 17948 Chapter Summary In this chapter, you learned how to set the module configuration jumpers, connect the field wiring to the field wiring arm, and install your module in the I/O chassis. Allen-Bradley PLCs 2-11...

  • Page 22: Module Configuration

    Chapter Module Configuration Chapter Objectives In this chapter, you will read how to configure your module using a block transfer write (BTW) instruction. Configuring Your Module Because of the many analog devices available and the wide variety of possible applications, you must configure the module to conform to the analog device and specific application that you have chosen.
  • Page 23 The remaining eight words (words 6 through 13) in the BTW are reserved for minimum and maximum scaling values. You enter these values if you wish to scale a particular channel. The following sections describe the module configuration word and the scaling words in greater detail. Allen-Bradley PLCs...

  • Page 24: Configuration Word

    Chapter 3 Module Configuration Configuration Word Word 5 of the block transfer write is the module configuration word (Figure 3.2). It contains information on: data polarity scaling polarity data format Figure 3.2 Configuration Block Transfer Write Word 5 Word/Dec. Bit Word/Octal Bit Word 5 1 = Channel 1...

  • Page 25: Default Configuration

    10 to +10 volts 4095 to +4095 10 to +10.00V +0.1% 4.88 mV/Bit 4 to 20 mA 0 to 4095 4 to 20.00 mA +0.1% 0.0039 mA/Bit 0 to 50 mA 0 to 4095 0 to 50.00 mA +0.1% 0.0122 mA/Bit Allen-Bradley PLCs...
  • Page 26 Chapter 3 Module Configuration Some examples of how to determine the value of the data word needed to produce the desired output voltage or current follow: Example 1 Output Range 4 20mA Data Format BCD (0 4095) Desired Output 9.5mA ∆...

  • Page 27: Scaling

    7 to Channel 1 scale maximum, word 8 to Channel 2 scale minimum, and so on (Figure 3.4). The maximum and minimum scaling values are the upper and lower limits for output data. The module’s microprocessor reads these values and Allen-Bradley PLCs automatically scales output data from the write block transfer.
  • Page 28 Chapter 3 Module Configuration The largest value that you can enter for a maximum scaling value is 9999. The smallest value you can enter for a minimum scaling value is -9999 (the minus sign is implemented by setting the appropriate bit in the configuration word).
  • Page 29 If the processor sends a data value to the module that corresponds to C, the value is scaled to the 100 C to 900 C range and the corresponding output voltage for that channel is 2.25 volts, which would position the scale accordingly at 31% of full scale. Allen-Bradley PLCs...

  • Page 30: Procedure For Configuring Your Module

    Chapter 3 Module Configuration Procedure for Configuring Now that we have explained the purpose and function of each word in the Your Module block transfer write block, you should be ready to enter configuration data. Consult your programming manuals for the proper techniques required to set up block transfer instructions with your programmable controller.

  • Page 31: Module Programming

    Refer to Appendix B for information on block transfer with the Mini-PLC-2 and the PLC-2/20. There are three types of block format instructions--one each for the PLC-2, PLC-3, and PLC-5 processors. Each is described in the paragraphs that follow. Allen-Bradley PLCs...

  • Page 32: Block Transfer Programming Plc 2 Family Processors Only 4

    Chapter 4 Module Programming Block Transfer Output data is transferred from the processor’s data table to the module Programming PLC 2 with a write block transfer. Diagnostic information is transferred from the module to the processor’s data table with a read block transfer. In order for Family Processors Only these transfers to take place, you must enter certain parameters into your block transfer instructions.
  • Page 33 BLOCK XFER WRITE Data Address: Module Address: Block Length: File: 200-277 BLOCK XFER READ Data Address: Module Address: Block Length: File: 300-377 FILE TO FILE MOVE Counter Address: Position: File Length: File A: 300-304 File R: 400-404 Rate per Scan: Allen-Bradley PLCs...
  • Page 34 Chapter 4 Module Programming Table 4.A Data Table Map Allen Bradley Programmable Controller PAGE Data Table MAP (128 word) ADDRESS PROJECT NAME OFE Data Table–Write Block PROCESSOR PLC-2 Family DESIGNER DATA TABLE SIZE STARTING WORD ADDRESS STARTING WORD ADDRESS BIT NUMBER BIT NUMBER DESCRIPTION DESCRIPTION...
  • Page 35 4095 and the maximum scaling value would be +4095. Since channel 3 has a negative minimum scaling value, you must set the polarity bit (bit 10) associated with channel 3's minimum scaling word in the configuration word (word 5 of the write block). 12891 Allen-Bradley PLCs...

  • Page 36: Block Transfer Programming Plc 3 Family Processors Only 4

    Chapter 4 Module Programming Figure 4.3 Binary Configuration Word Represented in BCD Channel 3 Minimum Scaling Factor Polarity Set (1) = Negative Reset (0) = Positive Word/Dec. Bit Word/Octal Bit Word 5 Binary 12892 Block Transfer Block transfer operation with the PLC-3 processor uses one binary file in a Programming PLC 3 data table section for module location and other related data.
  • Page 37 File R: xxxxx:xxxx read block transfer data file (buffer) is then Counter Address: xxxxx moved into a storage data file. This prevents Position/Length: Error the processor from transmitting invalid data Mode: All/Scan should a block transfer communication fault occur. Allen-Bradley PLCs...

  • Page 38: Block Transfer Programming Plc 5 Family Processors Only 4

    PLC-5 processor, extra programming will have to be added to the ladder program (i.e. a CPT or TOD instruction) to convert binary data to BCD data before it is transferred to the 1771-OFE module’s block transfer write data file. Also, when checking your program’s operation, remember to verify proper output voltage/current values based on the data values sent to the module.
  • Page 39 Rack 0, Group 0, Slot 0 File Configuration Control Array N11:0 Data File N11:5 Output Data Image N11:5 through N11:8 Status Word N11:9 Enable Bit N11:0/15 File Configuration Control Array N10:0 Data File N10:5 Allen-Bradley PLCs Configuration Word N10:9 Enable Bit N10:0/15...

  • Page 40: Other Programming Considerations

    Chapter 4 Module Programming Other Programming When writing your program, there are some additional programming Considerations techniques that you should consider. They are: block length and scaling considerations block transfer boundary word - PLC-2 family processors module update time buffering data - PLC-2 family processors only system expansion recommendations Block Length and Scaling Considerations There are three possible write block configurations that involve scaling:...
  • Page 41 035, the block transfer boundary word is addressed as 036. Figure 4.6 shows the data table structure and a sample GET/PUT instruction used to program a block transfer boundary word. Allen-Bradley PLCs 4-11...
  • Page 42 Chapter 4 Module Programming Figure 4.8 Data Table Structure and GET/PUT Instruction Example for Block Transfer Boundary Word 030 First Block Transfer Data Address 035 Last Block Transfer Data Address Timer/Counter 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 036 Address of Block Transfer Boundary Word Accumulated Values Area 037 Beginning Address for Timer/Counter Storag...

  • Page 43: Chapter Summary

    This eliminates the need to reconfigure your data table. Chapter Summary In this chapter you learned how to write data to the module, the data formats used for block transfer, special programming techniques, and were given sample program examples. Allen-Bradley PLCs 4-13...

  • Page 44: Module Status And Input Data

    Chapter Module Status and Input Data Chapter Objectives In this chapter, you will read about: reading data from the module block transfer read data format Reading Data from the Block transfer read (BTR) programming moves status and data from the Module module to the processor’s data table in one I/O scan.

  • Page 45: Chapter Summary

    The fifth word also indicates that I/O RESET has been established (when the processor is in the PROG/TEST or RUN mode). Chapter Summary In this chapter, you learned the meaning of the status data the module sends to the processor. Allen-Bradley PLCs...

  • Page 46: Calibrating Your Output Module

    Chapter Calibrating Your Output Module Chapter Objectives In this chapter, you will read how to calibrate your output module. Tools and Test Equipment Table 6.A lists tools and test equipment required for module calibration. Table 6.A Test Equipment Used On: Equipment Description 5 1/2 Digit Voltmeter...

  • Page 47: Voltage Output Version (1771 Ofe1)

    Step 2 (Figure 6.1). Place the LAST STATE configuration jumpers (Figure 6.2) in the MAX position (if they are not there already). Select the +10V output range by placing the four channel configuration jumpers in the position shown in Figure 6.3. Allen-Bradley PLCs...
  • Page 48 Chapter 6 Calibrating Your Output Module Connect the voltmeter leads across the top two screws on the field wiring arm (Channel 1). The top screw is positive, and the second (lower) screw is negative. Turn on the processor, I/O chassis, and the industrial terminal. Figure 6.1 Resistor Placement on Field Wiring Arm Field Wiring Arm...
  • Page 49 10. Adjust R29 until the reading is 10V +1mV. 11. Output -10V either with write block transfer data or by placing the LAST STATE configuration jumpers in the MIN position. 12. Adjust R28 until the reading is one-half the difference between -10V and the initial reading. Allen-Bradley PLCs...
  • Page 50 Chapter 6 Calibrating Your Output Module 13. Output full scale (+10V) again, either with write block transfer data or by placing the LAST STATE configuration jumpers in the MAX position. 14. Adjust R29 again until the reading is 10V +1mV. 15.

  • Page 51: Current Output Version (1771 Ofe2)

    Attach a resistor with a value of 250 ohms across Channel 1 (the top two screws) of the field wiring arm. Attach three more 250 ohm resistors across the remaining three channels on the field wiring arm just as you did in step 2 (Figure 6.4). Allen-Bradley PLCs...
  • Page 52 Chapter 6 Calibrating Your Output Module Figure 6.4 Resistor Placement on Field Wiring Arm Field Wiring Arm Channel 1 Channel 2 250 ohm resistors Channel 3 Channel 4 12991 Place the LAST STATE configuration jumpers (Figure 6.5) in the MAX position (if they are not there already). Figure 6.5 LAST STATE Configuration Jumpers in MAX Position LAST STATE...
  • Page 53 10. Output +4mA (1V - minimum scale) either with write block transfer data or by placing the LAST STATE configuration jumpers in the MIN position. 11. Adjust R28 until the reading is 3/4 the difference between 1V and the initial minimum scale reading. Allen-Bradley PLCs...
  • Page 54 Chapter 6 Calibrating Your Output Module Figure 6.6 Location of Resistor Pots LAST STATE Channel 1 Resistor Potentiometers Channel 2 Channel 3 Adjustment Screw Channel 4 12993 12. Output full scale (+20mA) again, either with write block transfer data or by placing the LAST STATE configuration jumpers in the MAX position.

  • Page 55: Current Output Version (1771 Ofe3)

    Important: If you have a spare or unused field wiring arm, you may want to temporarily switch it with the module’s present wiring arm. Use the spare wiring arm for test and calibration purposes to eliminate disconnecting your device wiring. Allen-Bradley PLCs 6-10...
  • Page 56 Chapter 6 Calibrating Your Output Module Important: The accuracy of this calibration procedure depends on the precision of the load resistors used. Use resistors with a tolerance of 0.01%. You should be able to obtain voltage readings to +5mV. (If you use resistors of a value different from 250 ohms, you should be able to obtain voltage readings of +0.05% of V out).

  • Page 57: Chapter Summary

    Your module is now properly calibrated and ready for use. Chapter Summary In this chapter, you learned how to calibrate your module using simple test equipment. Allen-Bradley PLCs 6-12...

  • Page 58: Diagnostics And Troubleshooting

    Chapter Diagnostics and Troubleshooting Chapter Objectives In this chapter, you will learn how to use the indicators on the front of the module and the diagnostic bits in the read block transfer status words to troubleshoot your module. Interpreting the Indicator The front panel of the module contains a green RUN and a red FLT (fault) Lights indicator (Figure 7.1).

  • Page 59: Read Block Transfer Status Words

    Reserved Data Valid used Reset Important: The user program that utilizes the read block transfer must make sure that bits 06 and 07 (the write enable and read enable request bits) of the MCB are not set simultaneously. Allen-Bradley PLCs...

  • Page 60: Chapter Summary

    Chapter 7 Diagnostics and Troubleshooting The first four words of the read block transfer show the actual 12 bits of data sent to the module’s digital-to-analog converters (DACs). The first four words in the read block transfer appear in 12-bit binary format regardless of the module’s mode of operation (BCD or 12-bit binary).

  • Page 61: Specifications

    C to +60 C (+32 F to +140 Storage Temperature: C to +85 C (-40 F to +185 Humidity Rating: 5% to 95% (Non-Condensing) Field Wiring Arm Catalog No. 1771 WC Allen-Bradley PLCs Field Wiring Arm Screw Torque 7 9 inch pounds...

  • Page 62: Multiple Get Instructions

    Appendix Block Transfer with Mini PLC 2 and PLC 2/20 Processors Multiple GET Instructions Programming multiple GET instructions is similar to block format instructions programmed for other PLC-2 family processors. The data table maps are identical, and the way information is addressed and stored in processor memory is the same.
  • Page 63 Accumulated Destination of Values Area Transferred Data Input Status Input Image Table Image Byte Status Byte Table Contains Done Bit Storage Location Contains File Timer/Counter Address in BCD Preset Values Area R = Read 07 = Bit 12994 Allen-Bradley PLCs...

  • Page 64: Setting The Block Length (Multiple Get Instructions Only)

    Appendix B Block Transfer with Mini-PLC-2 and PLC-2/20 Processors Setting the Block Length The output module is capable of transferring up to 13 words in one (Multiple GET Instructions program scan. The number of words transferred is determined by the block length entered in the output image table control byte.

  • Page 65: Data Table Formats

    0 X 2 0 X 2 1 X 2 0 X 2 0 X 2 0 X 2 1 X 2 1 X 2 1 X 2 0 X 2 0 X 2 1 X 2 12955 I Allen-Bradley PLCs...

  • Page 66: Signed Magnitude Binary

    Appendix C Data Formats Table C.A BCD Representation Place Value Decimal Equivalent Signed magnitude Binary Signed-magnitude binary is a means of communicating numbers to your processsor. It should be used with the PLC-2 family when performing computations in the processor. It cannot be used to manipulate binary 12-bit values or negative values.

  • Page 67: Two's Complement Binary

    All bits from right to left are inverted after the first “1” is detected. The two’s complement of 0 is not found, since no first “1” is ever encountered in the number. The two’s complement of 0 then is still 0. Allen-Bradley PLCs...
  • Page 68 Index Defaults, module, Description, Module, Block Length, Default, 4 10 Diagnostics, Block Length, Setting, 4 10 Block Transfer Boundary Word, 4 11 Multiple GET Instructions, Expansion Recommendations, 4 13 Programming Formats, Read, Write, block transfer, Fault Indicator LED, write, Features, block transfer read, Field Wiring Arm, 6 10...
  • Page 69 4 13 PLC-2 Family Processors, PLC-3 Family Processors, PLC-5 Family Processors, Programs, Sample, voltage output version, voltage range configuration plugs, RBT Status Words, Read Block Transfer, Word Related Products, Block Transfer Boundary, 4 11 Configuration, related publications, Scaling, Allen-Bradley PLCs...

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