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AB Quality ALLEN-BRADLEY 1791 User Manual

Analog block i/o input/output modules
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1791 Analog Block I/O
Input/Output Modules
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  • Page 1 1791 Analog Block I/O Input/Output Modules User Manual...
  • Page 2 Important User Information Because of the variety of uses for the products described in this publication, those responsible for the application and use of this control equipment must satisfy themselves that all necessary steps have been taken to assure that each application and use meets all performance and safety requirements, including any applicable laws, regulations, codes and standards.
  • Page 3 Summary of Changes Summary of Changes Summary of Changes This release of the publication contains new and updated information from the last release. New Information This release includes information on new block I/O modules now available. This information was not included in the previous release of this publication.

  • Page 4: Table Of Contents

    Table of Contents Summary of Changes ......Using This Manual ....... Purpose of Manual .
  • Page 5 Table of Contents Analog Block Applications Using Discrete Transfers ..Chapter Objectives ........Discrete Data Transfer .

  • Page 6: Using This Manual

    Preface Using This Manual Purpose of Manual This manual shows you how to use your block I/O with an Allen-Bradley programmable controller. It helps you: install your module program your module troubleshoot your module Audience You must be able to program and operate an Allen-Bradley programmable controller (PLC) to make efficient use of block I/O modules.

  • Page 7: Block I/O Products Covered By This Publication

    Preface Using This Manual Block I/O Products Covered This publication covers the following analog block I/O products: by this Publication Catalog Number Power Supply Voltage Inputs Outputs Description 1791 N4V2 120V ac analog - 4 input, 2 voltage output 1791 N4C2 120V ac analog - 4 input, 2 current output 1791 NDV...

  • Page 8: Introducing Block I/O

    Chapter Introducing Block I/O Chapter Objectives In this chapter, you will learn what analog block I/O is, its features, and how it functions. General Description Block I/O consists of small, self-contained remote I/O devices complete with power supply, programmable controller interface, input/output connections and signal conditioning circuitry.
  • Page 9 Chapter 1 Introducing Block I/O Analog block outputs are configured at the factory for either a current output or a voltage output. Outputs are not user-configurable. Figure 1.1 shows the physical features of the block I/O. Figure 1.1 Major Features of the Analog Block I/O Modules (1791 N4V2 shown) 1791 N4V2 ANALOG BLOCK Removable...
  • Page 10 Chapter 1 Introducing Block I/O How Block I/O Fits in a Block I/O is a complete I/O interface that includes the functionality of the PLC System I/O rack, adapter, power supply, and I/O module in a single unit. Connect sensors and actuators to the module and use the remote I/O cable to connect the block I/O to your programmable controller.

  • Page 11: Inputs

    Chapter 1 Introducing Block I/O Discrete transfer (Figure 1.3) is intended to be used with controllers which do not have block transfer capability. However, discrete transfer can be used with any PLC family controller. When using discrete transfer, the block looks like a 1/2 I/O rack to the controller (four words of input image table memory and four words of output image table memory).
  • Page 12 Chapter 1 Introducing Block I/O Voltage Input Voltage inputs can be either single-ended or differential. In the voltage mode, a signal applied between inV0 and the combination of RET in0 shorted to GND in0 provides a single-ended input mode. A signal applied between inV0 and RET in0 provides a differential input mode.

  • Page 13: Scaling

    Chapter 1 Introducing Block I/O This is illustrated using the +10V scale below: 14 Bits Resolution 13.96 Bits Input Signal Nominal Range In the above scale, input signals 1 thru 5 produce corresponding internal analog to digital converter (ADC) binary counts. A full scale (FS) voltage input produces an internal count of 16383 (input signal 1), while a bottom scale (BS) voltage input produces an internal count of 0000 (input 5).
  • Page 14 Chapter 1 Introducing Block I/O The following equation shows how the module interprets the input data: Module data = M x V where: – S – V ) – (S – V You can choose one of three scaling methods: binary counts (module sets scalers) default scaling (module sets scalers) user scaling (you set scalers)

  • Page 15: Outputs

    Chapter 1 Introducing Block I/O User Scaling User scaling is available only when using the block transfer mode. This mode allows you to define S and S in engineering units in the block transfer write data table. The integer range is 32,767 to –32,768. Important: If the range of user scaling values is set less than the range of binary counts scaling values, input resolution is sacrificed.
  • Page 16 Chapter 1 Introducing Block I/O Voltage Outputs - 1791 N4V2 and 1791 NDV A simplified schematic of a +10V output channel is shown below. Precision Operational OUTS Amplifier Opto Digital Isolation Output Isolated Analog Output Common Isolated Analog Isolated Analog Output Common Output Common 12501-I...
  • Page 17 Chapter 1 Introducing Block I/O You can choose one of three scaling methods: binary counts default scaling user scaling User scaling is not available when you select discrete transfer mode. The following table shows the output signals produced by various module data values entered in each of the three scaling methods.
  • Page 18 Chapter 1 Introducing Block I/O The output sacrifices a small amount of the resolution to provide a margin of 2.5% to allow for system or calibration inaccuracies as shown below. 13 Bits Resolution 12.9 Bits 20.5 Input Signal 0.0 –0.5 Nominal Range Scaling The digital data sent to the output is always scaled by the values set in the...

  • Page 19: Installing Block I/O

    Chapter Installing Block I/O Chapter Objectives In this chapter, you will learn how to mount the block, connect the remote I/O link, connect the input and output wiring to the block, and terminate the remote I/O link. Pre installation Before installation, you must determine the: Considerations scanner/processor to use number of blocks on your network...
  • Page 20 Chapter 2 Installing Block I/O Baud Rate Maximum When using Maximum Capacity Used Network Distance PLC 5/15 12 blocks with 150 ohm terminator 57.6K 10,000 cable feet 57.6K 10,000 cable feet 12 blocks with 82 ohm or 150 ohm PLC 5/20 115.2K 5,000 cable feet terminator...

  • Page 21: Installing The Block I/O

    Chapter 2 Installing Block I/O Baud Rate Maximum When using Maximum Capacity Used Network Distance 57.6K 10,000 cable feet 16 blocks/channel, 32 blocks/scanner (128 blocks with 4 blocks/scanner, (128 blocks with 4 115.2K 5,000 cable feet scanners) with 150 ohm terminator PLC 5/250 PLC 5/250 requires PLC 5 family (continued)

  • Page 22: Connecting Wiring

    Chapter 2 Installing Block I/O Figure 2.2 Mounting on a DIN Rail Block 1. Hook top of slot over DIN rail. 2. While pressing block against rail, pull down on locking lever. DIN Rail 3. When block is flush against rail, A B pt.
  • Page 23 Chapter 2 Installing Block I/O Figure 2.4 Terminal Block Pin Numbering Refer to the following table for wiring schematics and connecting wiring lists for the analog block modules. Power Supply Voltage Input For Schematic refer to: For wiring refer to: 120V ac Figure 2.5, page 2 6 Table 2.B, page 2 9...
  • Page 24 Chapter 2 Installing Block I/O Figure 2.5 Wiring Connections for the 120V ac Analog Block with Voltage Inputs L2/N USED Voltage Input USED in V0 Analog signals must be within the 10V User Analog in I0 common mode voltage range which is Input Device referenced to the analog input common in V1...
  • Page 25 Chapter 2 Installing Block I/O Figure 2.7 Wiring Connections for the 120V ac Analog Block with Current Input and Customer Supplied Loop Power L2/N USED USED Current Input Analog signals must be within the 10V common mode voltage range in V0 which is referenced to the analog User Analog input common (GND).
  • Page 26 Chapter 2 Installing Block I/O Figure 2.9 Wiring Connections for the 120V ac Analog Block with Current Input and Block Supplied Loop Power L2/N USED USED in V0 Loop Powered Analog signals must be within the in I0 Current Input 10V common mode voltage range in V1 which is referenced to the analog...
  • Page 27 Chapter 2 Installing Block I/O Table 2.B Wiring Block Designations for Cat. No. 1791 N4V2 1791-N4V2 Connections Connections Designation Description Terminal No. ac hot Power Power Connections ac neutral Chassis ground Transducer +24V For current input only Power Blue wire - RIO Remote I/O Remote I/O Connections...
  • Page 28 Chapter 2 Installing Block I/O Table 2.C Wiring Block Designations for Cat. No. 1791 NDV 1791-NDV Connections Connections Designation Description Terminal No. +24V dc Power Power Power Connections RET +24 dc Return Chassis ground Transducer +24V For current input only Power Blue wire - RIO Remote I/O...
  • Page 29 Chapter 2 Installing Block I/O Table 2.D Wiring Block Designations for Cat. No. 1791 N4C2 1791-N4C2 Connections Connections Designation Description Terminal No. ac hot Power Power Connections ac neutral Chassis ground Transducer +24V For current input only Power Blue wire - RIO Remote I/O Remote I/O Connections...
  • Page 30 Chapter 2 Installing Block I/O Table 2.E Wiring Block Designationsfor Cat. No. 1791 NDC 1791-NDC Connections Connections Designation Description Terminal No. +24V dc Power Power Connections Power Connections RET +24 dc Return Chassis ground Transducer Power +24V For current input only Blue wire - RIO Remote I/O Remote I/O...

  • Page 31: Termination Resistor

    Chapter 2 Installing Block I/O Termination Resistor A termination resistor must be installed on the last block in a series. Connect the resistor as shown in Figure 2.11. Figure 2.11 Installing the Termination Resistor Connect termination resistor across terminals 6 (BLU) and 8 (CLR). Refer to Table 2.A for proper terminator for your application.

  • Page 32: Extended Node Capability

    Chapter 2 Installing Block I/O Figure 2.13 Series Configurations for Block I/O Using the SLC Programmable Controller To 1747 SN Scanner Module Up to 8 blocks with SLC 5/02 Install terminating resistor 10834 I on last block. Extended Node Capability If this is the last remote I/O adapter on the remote I/O link in a PLC system, you must use a terminating resistor to terminate both ends of the remote I/O link (scanner end and last block end).

  • Page 33: Compatibility Of 1771 I/O Products With Extended Node Numbers

    Chapter 2 Installing Block I/O Compatibility of 1771 I/O Certain products are not compatible with extended node capabilities Products with Extended obtained with the use of 82 ohm terminators. Table 2.G lists those products Node Numbers that are not compatible. Table 2.G Non compatible Products Device...

  • Page 34: Configuring Your Block I/O For Plc Family Programmable Controllers

    Chapter Configuring Your Block I/O for PLC Family Programmable Controllers Chapter Objectives In this chapter, you will learn how to configure your block I/O when used with PLC family programmable controllers. This includes the following: setting the configuration switches addressing the block I/O Setting the Configuration Each block I/O module has two 8-position switches for setting: Switches...
  • Page 35 Chapter 3 Configuring Your Block I/O for PLC Family Programmable Controllers Figure 3.1 Switch Settings for the Analog Block I/O Modules SW2-8 1791 N4V2 Not used ANALOG BLOCK SW2-7 Not Used SW2-6 Last I/O Group POWER Not last rack COMM Last rack FAULT Processor...
  • Page 36 Chapter 3 Configuring Your Block I/O for PLC Family Programmable Controllers 1747 SN 1771 SN PLC 2 PLC 5 PLC 5/250 PLC 3 SW1 Switch Position Rack Rack Rack Rack Rack Rack Rack Rack Rack Rack Rack Rack Number Number Number Number Number...
  • Page 37 Chapter 3 Configuring Your Block I/O for PLC Family Programmable Controllers 1747 SN 1747 SN 1771 SN 1771 SN PLC 2 PLC 2 PLC 5 PLC 5 PLC 5/250 PLC 5/250 PLC 3 PLC 3 SW1 Switch Position Rack Rack Rack Rack Rack...
  • Page 38 Chapter 3 Configuring Your Block I/O for PLC Family Programmable Controllers When using block transfer, each analog block I/O module uses 2 words of output image table memory and 2 words of input image table memory. Each block occupies 1/4 rack of data table, with 4 blocks comprising 1 logical rack.
  • Page 39 Chapter 3 Configuring Your Block I/O for PLC Family Programmable Controllers When using discrete transfer, each analog block I/O module uses 4 words of output image table memory and 4 words of input image table memory. Each block occupies 1/2 rack of data table, with 2 blocks comprising 1 logical rack.

  • Page 40: Module Scan Time

    Chapter 3 Configuring Your Block I/O for PLC Family Programmable Controllers Module Scan Time Scan time depends on the block transfer rate over the remote I/O network, which is asynchronous to the module input sample rate and output update rate. The block transfer rate is dependent on the controller, program length, the amount of communication traffic to other modules on the remote I/O network and the speed (baud rate) of the remote I/O network.

  • Page 41: Analog Block Applications Using Block Transfers

    Chapter Analog Block Applications Using Block Transfers Chapter Objectives In this chapter, you will read about: reading data and status from the module block transfer read data format configuring the module and setting outputs with block transfer write instructions Reading Data and Status Block transfer instructions are used when the analog block is used with from the Module PLC programmable controllers with block transfer capability.
  • Page 42 Chapter 4 Analog Block Applications Using Block Transfers Table 4.A Bit/Word Descriptions for Block Transfer Read Instruction Decimal Bit Word Description (Octal Bit) Bits 15 (17) Power up (PU) status bit. This bit is set (1) if the module has not been configured since the last power up.

  • Page 43: Configuring The Module And Setting Outputs With Block Transfer Write Instructions

    Chapter 4 Analog Block Applications Using Block Transfers Configuring the Module and You must configure your block module by performing a block transfer Setting Outputs with Block write (BTW) instruction from the programmable controller to the module. Transfer Write Instructions Each input can be independently configured in one BTW.
  • Page 44 Chapter 4 Analog Block Applications Using Block Transfers The bit/word descriptions are shown in Table 4.B. Table 4.B Bit/Word Descriptions for the Block Transfer Write Instruction Decimal Bit Word Description (Octal Bit) Module Mode. Bits 12 15 (14 17) determine the operation of the block module. 15 (17) 14 (16) 13 (15)
  • Page 45 Chapter 4 Analog Block Applications Using Block Transfers Decimal Bit Word Description (Octal Bit) Word 1 Bits 00 15 (00 17) Output data for channel 0. Word 2 Bits 00 15 (00 17) Output data for channel 1. Word 3 Bits 00 15 (00 17) Minimum engineering scale factors for output channel 0 data.
  • Page 46 Chapter 4 Analog Block Applications Using Block Transfers Decimal Bit Word Description (Octal Bit) High alarm level for input channel 3. When the input value for this channel is greater than the Word 25 Bits 00 15 (00 17) high value, the corresponding high alarm bit is set in the BTR. Alarm deadband for input channel 3.

  • Page 47: Analog Block Applications Using Discrete Transfers

    Chapter Analog Block Applications Using Discrete Transfers Chapter Objectives In this chapter you will read about: discrete data transfer input data format output data format Discrete Data Transfer When used with SLC controllers, analog block data is transferred as discrete data using the 1747-SN remote I/O scanner module. The analog block uses 1/2 rack of memory in the I/O data table.

  • Page 48: Output Data Format

    Chapter 5 Analog Block Applications Using Discrete Transfers Table 5.A Input Image Table Bit - Decimal Word Description (Bit - Octal) Bits 00-15 Word 0 Input data for channel 0. (00-17) Bits 00-15 Word 1 Input data for channel 1. (00-17) Bits 00-15 Word 2...
  • Page 49 Chapter 5 Analog Block Applications Using Discrete Transfers Table 5.B Bit/Word Descriptions for Discrete Data Transfer - Output Table 1/2 Rack Decimal Bit Word Description (Octal Bit) Output Enable Bit OE Bit 15 (17) Bit 15 (17) Bit 15 (17) Outputs are held at 0.
  • Page 50 Chapter 5 Analog Block Applications Using Discrete Transfers Table 5.C Filter Time Selection Bit Settings Filter Time Filter Time Bit 03 Bit 02 Bit 01 Bit 00 Default - no filter Do not use. 200ms 300ms 400ms 500ms 600ms 700ms 800ms 900ms 1000ms...

  • Page 51: Programming Your Analog Block I/O Module

    Chapter Programming Your Analog Block I/O Module Chapter Objectives In this chapter, we describe block transfer programming sample programs in the PLC-3 and PLC-5 processors module scan time issues Block Transfer Your module communicates with the processor through bidirectional block Programming transfers.

  • Page 52: Plc 3 Program Example

    Chapter 6 Programming Your Analog Module PLC 3 Program Example Block transfer instructions with the PLC-3 processor use one binary file in a data table section for module location and other related data. This is the block transfer control file. The block transfer data file stores data that you want transferred to the module (when programming a block transfer write) or from the module (when programming a block transfer read).
  • Page 53 Chapter 6 Programming Your Analog Module PLC 5 and PLC-5/250 This program is very similar to the PLC-3 program with the following Program Example exceptions: Use enable bits instead of done bits as the conditions on each rung. Use separate control files for each block transfer instruction. Refer to Appendix B.

  • Page 54: Sample Programs For Analog Block

    Chapter 6 Programming Your Analog Module Sample Programs for The following are sample programs for using your modules more Analog Block efficiently when operating with the PLC-3 or PLC-5 family processors. These programs show you how to: configure the module read data from the module update the output channels Refer to the proper PLC-3 or PLC-5 documentation for additional...

  • Page 55: Plc 5 Family Processors

    Chapter 6 Programming Your Analog Module PLC 5 Family Processors The following PLC-5 program is very similar to the PLC-3 program with the following exceptions: You must use enable bits instead of done bits as the conditions on each rung. Rungs 2 and 3 have been replaced with 1 rung.

  • Page 56: Module Calibration

    Chapter Module Calibration Chapter Objective In this chapter we tell you how to calibrate your module. Tools and Equipment To calibrate your analog module, you will need the following tools and equipment: Tool or Equipment Description µ Precision Voltage Source 0-10V, 1 V resolution µ...
  • Page 57 Chapter 7 Module Calibration Table 7.B Calibration Block Transfer Write or Discrete Output Bit/Word Descriptions Decimal Bit Word Description (Octal Bit) Bit 00 Input select bit. Indicates input channel 0 being calibrated. Bit 01 Input select bit. Indicates input channel 1 being calibrated. Bit 02 Input select bit.
  • Page 58 Chapter 7 Module Calibration Table 7.D Calibration Block Transfer Read or Discrete Input Bit/Word Descriptions Word Decimal Bit Description (Octal Bit) Input calibration error bit. When set, indicates input channel 0 Bit 00 calibration error. Input calibration error bit. When set, indicates input channel 1 Bit 01 calibration error.
  • Page 59 Chapter 7 Module Calibration Table 7.E Discrete Transfer Input Data File Word/Bit Description Corrected Input Channel 0 Data Corrected Input Channel 1 Data Corrected Input Channel 2 Data Corrected Input Channel 3 Data Table 7.F Discrete Transfer Input Bit/Word Descriptions Word/Bit Description Corrected Input Data for Channel 0 using most recent calibration data.
  • Page 60 Chapter 7 Module Calibration Important: You can calibrate all four inputs simultaneously by wiring them in parallel. Verify normal operation. Select calibration mode, voltage input mode and the input channels you want to calibrate. For example, to calibrate input channel 0, set bits 15 (17), 14 (16) and 01 of BTW word 0 (C001h).
  • Page 61 Chapter 7 Module Calibration 10. Set (1) the WR bit 11 (13) in BTW word 0. For PLC systems: Monitor the OK bit 11 (13) in BTR word 0 until it is set (1). For SLC systems: Allow at least 5 seconds before continuing. 11.
  • Page 62 Chapter 7 Module Calibration Set the EX bit (bit 07 of BTW word 0). For PLC systems: Monitor the DN bit (BTR word 0, bit 07) until it is set (1). For SLC systems: Allow at least 5 seconds before continuing. Reset (0) the EX bit (BTW word 0, bit 07) and set (1) the HL bit (BTW word 0, bit 06).
  • Page 63 Chapter 7 Module Calibration Calibrating Voltage Outputs (1791 N4V2 and 1791 NDV) Use the procedure below to calibrate voltage outputs of the analog block I/O module. The procedure can be used for either PLC or SLC systems. The most accurate results are obtained by installing an optional load resistor which approximates the output load for the intended application.
  • Page 64 Chapter 7 Module Calibration Reset (0) the EX bit (BTW word 0, bit 07) and set (1) the HL bit (BTW word 0, bit 06). Measure the full scale point with a precision meter. Enter the measured voltage in millivolts into the BTW word (word 1 for channel 0, word 2 for channel 1).
  • Page 65 Chapter 7 Module Calibration Calibrating Current Outputs (1791 N4C2 and 1791 NDC) Use the procedure below to calibrate current outputs of the analog block I/O module. The procedure can be used for either PLC or SLC systems. You can calibrate any single input or output individually or, you can calibrate them simultaneously.
  • Page 66 Chapter 7 Module Calibration Reset (0) the EX bit (BTW word 0, bit 07) and set (1) the HL bit (BTW word 0, bit 06). Measure the full scale point with a precision meter. Enter the measured current in milliamps into the BTW word (word 1 for channel 0, word 2 for channel 1).
  • Page 67 Chapter 7 Module Calibration Calibration Example for the 1791 N4V2 Block I/O Module The following example shows you how to calibrate the inputs and outputs for the 1791-N4V2 block I/O module. For inputs – short all RET and GND together and short V 0 thru V together.

  • Page 68: Troubleshooting

    Chapter Troubleshooting Chapter Objectives In this chapter you will learn about the indicators on the block I/O module, and how to use them to troubleshoot the unit. Module Indicators Each block I/O module has indicators (Figure 8.1) which provide indication of module status. Each module has the following: Indicator Color Quantity...
  • Page 69 Chapter 8 Troubleshooting Table 8.A Troubleshooting Chart Indication Description Power No power Power okay COMM Communications not established Communication established Flashing Reset commands being received in Program mode FAULT Normal Error (hardware or software), block power low Flashing COMM FAIL - communication cable disconnected, 100ms between valid frames, no more than 255 valid frames between valid frames addressed to block, 20ms idle time exceeded.
  • Page 78 Index block compatibility, extended node capability, 2 14 block I/O, installing, pre-installation, features, block transfer, block transfer instructions, block transfer programming, block transfer read, image table usage, bit/word descriptions, one assigned rack number, block transfer write, input channel, bit/word descriptions, input data format, filter time selections, inputs,...
  • Page 79 Index I–2 remote I/O link wiring, 2 13 1791-N4V2, 1791-NDC, 1791-NDV, status indicators, sample programs switch assembly, analog block, PLC-3, PLC-5, scaling, terminal strip, scaling methods, termination resistor, 2 13 binary counts, throughput requirements, 2 15 default scaling, troubleshooting chart, user scaling, types of block I/O, scan time,...

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