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AB Quality ALLEN-BRADLEY 1791, User Manual

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Configuring Your Block I/O for PLC

Family Programmable Controllers

Chapter 3

3-7

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.

Figure 3.4

Module Scan Time Relationships

Ch 0

Ch 1

Ch 2

Ch 3

Ch 0

Ch 1

Ch 2

Ch 3

Ch 0

Ch 1

100ms to 2s

1

Ch 0 & Ch 1

updated

BTW1

BTW2

Block Transfer

Read

Block Transfer

Write

Input Sample

Rate

Output Update

100ms to 2s

1

BTR1

BTR2

Ch 0 & Ch 1

updated

10ms

10ms

108ms

1

 Time depends on the remote I/O network configuration.

Module Scan Time

Summary of Contents for ALLEN-BRADLEY 1791

Page 1: ...1791 Analog Block I O Input Output Modules User Manual...

Page 2: ...lid 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 considerati...

Page 3: ...was not included in the previous release of this publication The modules are 1791 NDV 24V dc Analog Block I O voltage outputs 1791 NDC 24V dc Analog Block I O current outputs Updated Information Gener...

Page 4: ...O 2 3 Connecting Wiring 2 4 Termination Resistor 2 13 Remote I O Link 2 13 Extended Node Capability 2 14 Compatibility of 1771 I O Products with Extended Node Numbers 2 15 Selecting Remote I O Link S...

Page 5: ...Module 6 1 Chapter Objectives 6 1 Block Transfer Programming 6 1 PLC 3 Program Example 6 2 PLC 5 and PLC 5 250 Program Example 6 3 Sample Programs for Analog Block 6 4 PLC 3 Family Processors 6 4 PLC...

Page 6: ...rview of the topics covered in that chapter Chapter Title Topics Covered 1 Introducing Block I O Description of the modules including general and hardware features 2 Installing Block I O Module power...

Page 7: ...ac 4 2 analog 4 input 2 voltage output 1791 N4C2 120V ac 4 2 analog 4 input 2 current output 1791 NDV 24V dc 4 2 analog 4 input 2 voltage output 1791 NDC 24V dc 4 2 analog 4 input 2 current output Fo...

Page 8: ...02 or greater modular controllers Refer to the table below for information on using block I O with various Allen Bradley programmable controllers If You are Using You must use PLC 2 family programmabl...

Page 9: ...Terminal Strip for Input Output Remote I O and Power Connections Switch Assemblies POWER COMM FAULT 12631 I Terminal Strip Remote I O link power and input output connections are made to the removable...

Page 10: ...k and the programmable controller using either block transfer or discrete transfer When using block transfer Figure 1 2 the block looks like a 1 4 I O rack to the processor two words of input image ta...

Page 11: ...e daisy chained to a scanner 1747 SN Remote I O Scanner Module 10828 I 1 I O Rack Block I O each block is 1 2 I O rack 1 2 1 2 A simplified schematic of the input circuit of one input channel is shown...

Page 12: ...able operation will occur The figures below show examples of differential input mode and single ended input mode 10V GND in0 RET in0 inI0 inV0 10V inV0 RETin0 GNDin0 inI0 Differential Input Mode Singl...

Page 13: ...scale voltage NBS produces a count shown as input signal 4 For each range scale the input voltage which produces the ADC count of input signals 1 thru 5 in the above scale are shown below Input Signa...

Page 14: ...ary counts scaling mode activates when the module powers up This mode guarantees the maximum resolution The module sets the scalers as shown in the following table Scaler 10V 0 10V 5V 0 5V Smax 8191 1...

Page 15: ...ows how the five signals will be scaled using each of the three scaling methods In the user scaling column the Smax was set to represent 5000 and the Smin was set to represent 0 I t V l Scaling Method...

Page 16: ...small as 1k ohm 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 14 Bits 13 96 Bits Nominal Range Resol...

Page 17: ...nal Binary Counts Scaling Default Scaling User Scaling Approx 10 25V 8395 10250 5062 10V 8191 10000 5000 Smax 0 000V 0000 00000 2500 10 00V 8192 10000 0000 Smin Approx 10 25V 8396 10250 0062 Current O...

Page 18: ...ws this relationship Iout M x Module Data B where 20mA Smax Smin 20mA x Smax Smin M B Smax Smin You can choose one of three scaling methods binary counts default scaling user scaling User scaling is n...

Page 19: ...2 16 blocks channel 28 blocks scanner 57 6K 10 000 cable feet 1772 SD 1772 SD2 16 blocks channel 28 blocks scanner with 150 ohm terminator 115 2K 5 000 cable feet Any PLC 3 scanner module 16 blocks ch...

Page 20: ...terminator and extended node addressing 115 2K 5 000 cable feet PLC 5 family continued and extended node addressing 230 4K 2 500 cable feet 16 blocks channel 32 blocks per 57 6K 10 000 cable feet 16 b...

Page 21: ...erminator3 230 4K 2 500 cable feet 1 PLC 5 15 series A and PLC 5 15 series B prior to revision H B H can only address 3 blocks 2 PLC 5 25 revisions prior to A D can only address 7 blocks 3Analog block...

Page 22: ...7 5mm Block 12382 I Make wiring connections to the removable terminal block which plugs into the front of the block ATTENTION The terminal block is not keyed to prevent incorrect insertion If you rem...

Page 23: ...g Connections for the Analog Block with Voltage Inputs Figure 2 6 page 2 6 Table 2 C page 2 10 120V ac Wiring Connections for the Analog Block with Figure 2 7 page 2 7 Table 2 D page 2 11 24V dc Wirin...

Page 24: ...by connecting to user ground If an input channel floats outside of this range invalid input readings will result Figure 2 6 Wiring Connections for the 24V dc Analog Block with Voltage Input RIO 1 30 2...

Page 25: ...Current Input Output ATTENTION The 249 ohm input current shunt is rated at 0 25 Watts Do not exceed this rating Figure 2 8 Wiring Connections for the 24V dc Analog Block with Current Input and Custom...

Page 26: ...outside of this range invalid input readings will result 24V dc loop power supplied at terminal 25 on block Figure 2 10 Wiring Connections for the 24V dc Analog Block Module with Current Input and Bl...

Page 27: ...t Return 0 through 3 10 14 18 22 inI0 thru inI3 Current Input 0 through 3 11 15 19 23 Current Input RET in0 thru RET in3 Input Return 0 through 3 10 14 18 22 Input Ground GNDin0 GNDin3 Channels 0 3 gr...

Page 28: ...Input Return 0 through 3 10 14 18 22 inI0 thru inI3 Current Input 0 through 3 11 15 19 23 Current Input RET in0 thru RET in3 Input Return 0 through 3 10 14 18 22 Input Ground GNDin0 GNDin3 Channels 0...

Page 29: ...t Return 0 through 3 10 14 18 22 inI0 thru inI3 Current Input 0 through 3 11 15 19 23 Current Input RET in0 thru RET in3 Input Return 0 through 3 10 14 18 22 Input Ground GNDin0 GNDin3 Channels 0 3 gr...

Page 30: ...19 23 Current Input RET in0 thru RET in3 Input Return 0 through 3 10 14 18 22 Input Ground GNDin0 GNDin3 Channels 0 3 ground 12 16 20 243 Output out 0 RET out 0 Output 0 Return output 0 27 264 Output...

Page 31: ...ocks must be wired in series as shown in Figure 2 12 or Figure 2 13 Do not attempt to wire any block in parallel The number of blocks used depends not only on the user requirements but also on the sys...

Page 32: ...d and last block end The size of the terminator is determined by the system configuration Older system configurations must use a 150 ohm resistor at both ends With newer devices that can support it yo...

Page 33: ...nts distance required and the type of remote I O devices being used Throughput Requirements Block throughput using analog block is dependent on the controllers data transfer rate Analog block outputs...

Page 34: ...s addressing the block I O Each block I O module has two 8 position switches for setting starting I O group I O rack number communication rate last chassis last state block transfer discrete transfer...

Page 35: ...lers Chapter 3 3 2 Figure 3 1 Switch Settings for the Analog Block I O Modules SW2 8 Not used SW2 7 Not Used SW2 6 Last I O Group 0 Not last rack 1 Last rack SW2 5 Processor Restart Lockout PRL 0 Proc...

Page 36: ...1 0 0 1 Rack 12 Rack 12 Rack 12 0 0 1 0 1 0 Rack 13 Rack 13 Rack 13 0 0 1 0 1 1 Rack 14 Rack 14 Rack 14 0 0 1 1 0 0 Rack 15 Rack 15 Rack 15 0 0 1 1 0 1 Rack 16 Rack 16 Rack 16 0 0 1 1 1 0 Rack 17 Rack...

Page 37: ...1 1 0 1 1 1 Rack 70 1 1 1 0 0 0 Rack 71 1 1 1 0 0 1 Rack 72 1 1 1 0 1 0 Rack 73 1 1 1 0 1 1 Rack 74 1 1 1 1 0 0 Rack 75 1 1 1 1 0 1 Rack 76 1 1 1 1 1 0 Not Valid 1 1 1 1 1 1 Rack address 77 is an ille...

Page 38: ...with 4 blocks comprising 1 logical rack Image table usage for one assigned rack number is shown in Figure 3 3 Figure 3 2 I O Image Table for One Assigned Rack Number using Block Transfer Output Image...

Page 39: ...mage table usage for one assigned rack number is shown in Figure 3 3 Figure 3 3 I O Image Table for One Assigned Rack Number using Discrete Transfer Output Image Input Image 0 1 2 3 4 5 6 7 0 17 0 1 2...

Page 40: ...ler 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 Figure 3 4 Module Scan Time Relationships Ch 0 Ch 1...

Page 41: ...l status and input data from the module The maximum BTR data file length required is five words 0 thru 4 The block transfer read data format consists of input data and module status Word 0 contains th...

Page 42: ...scaling error 4 input channel 1 scaling error 5 input channel 2 scaling error 6 input channel 3 scaling error 7 channel 0 alarm error 8 channel 1 alarm error 9 channel 2 alarm error A channel 3 alarm...

Page 43: ...Data 2 Output Channel 1 Data 3 Output Channel 0 Minimum Scaling 4 Output Channel 0 Maximum Scaling 5 Output Channel 1 Minimum Scaling 6 Output Channel 1 Maximum Scaling 7 Input Channel 0 Minimum Scal...

Page 44: ...thru 6 for outputs and words 7 thru 14 for inputs Default Scaling Values are shown below Module Range Default Default Approximate Bits 10 11 12 13 Module Mode Bit 12 14 Bit 09 11 Bit 08 10 Default Mi...

Page 45: ...d the input signal must go above the low alarm limit or below the high alarm limit by an amount equal to the specified deadband Alarm deadband values must be less than or equal to one half the differe...

Page 46: ...an alarm condition to be removed the input signal must go above the low alarm limit or below the high alarm limit by an amount equal to the specified deadband Alarm deadband values must be less than...

Page 47: ...ansfer programming moves data from the module to the processor s data table in one I O scan The processor I O scan initiates the request to transfer data from the module to the processor The input ima...

Page 48: ...SLC configuration word is a subset of the PLC except an enable output bit is added alarms and user scaling are removed Words 1 and 2 contain output data Word 3 is reserved When using the analog block...

Page 49: ...providing maximum possible resolution Default Scaling When this bit is set to 1 default scaling is in effect 1 user Default Scaling When this bit is set to 1 default scaling is in effect Module Mode R...

Page 50: ...Time Bit Settings Filter Time Bit 03 Bit 02 Bit 01 Bit 00 Default no filter 0 0 0 0 Do not use 0 0 0 1 200ms 0 0 1 0 300ms 0 0 1 1 400ms 0 1 0 0 500ms 0 1 0 1 600ms 0 1 1 0 700ms 0 1 1 1 800ms 1 0 0 0...

Page 51: ...configuring BTW because it does not configure the module each time it is initiated the output update BTW The following example programs are minimum programs all rungs and conditioning must be include...

Page 52: ...used for both the read and write instructions for your module A different block transfer control file is required for every module A sample program segment with block transfer instructions is shown i...

Page 53: ...N10 0 5 N ER BTR Enable 15 1 EN BTW BLOCK XFER WRITE RACK GROUP MODULE CONTROL 1 0 0 N7 5 DN DATA FILE LENGTH CONTINUOUS N10 10 27 N ER 2 BTW Enable 15 N7 5 N7 0 EN BTW BLOCK XFER WRITE RACK GROUP MO...

Page 54: ...data and module status The following PLC 3 program can be altered to effectively address analog block modules Figure 6 3 PLC 3 Family Sample Program Structure EN BTR BLOCK XFER READ RACK GROUP MODULE...

Page 55: ...gram Structure EN BTR BLOCK XFER READ RACK GROUP MODULE CONTROL X X X XXX XX DN DATA FILE LENGTH CONTINUOUS XXX XX 00 N ER BTR Enable 1 EN BTW BLOCK XFER WRITE RACK GROUP MODULE CONTROL X X X XXX XX D...

Page 56: ...able to communicate with the processor and a programming terminal If the processor has block transfer capability you must enter ladder logic into the processor memory before calibrating the module You...

Page 57: ...IM Bit 08 10 0 Use for voltage inputs Input scaling in mV Bit 08 10 1 Use for current inputs Input scaling in A Bits 9 10 11 12 Not used Bit 11 13 EEPROM write bit OK When set 1 requests the current c...

Page 58: ...HL Indicates whether full scale or zero data point is being updated Bit 6 1 full scale Bit 6 0 zero data point Bit 07 Calibration Done bit DN When set 1 indicates calibration started and selected cha...

Page 59: ...ata for Channel 2 using most recent calibration data 3 Corrected Input Data for Channel 3 using most recent calibration data Calibrating Voltage Inputs Use the procedure below to calibrate the voltage...

Page 60: ...10 000V to the inputs you are calibrating 8 Set 1 the EX bit 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 9 Verify...

Page 61: ...you can calibrate them simultaneously Important To allow the module to stabilize energize the module for at least 30 minutes before calibrating To calibrate your module 1 Connect your test equipment f...

Page 62: ...minal is in decimal radix mode Important Input values are scaled in microamps Vary the input reference over the 0 to 20 milliamps range Make sure the module input indications in the appropriate BTR wo...

Page 63: ...ur test equipment for the output you want to calibrate This is shown in the figure below VO VRET Optional Load V 1791 N4V2 and 1791 NDV Important You can calibrate both outputs simultaneously 2 Verify...

Page 64: ...t Output values are scaled in millivolts Vary the output value in the appropriate BTW words over the 10V range Make sure the meter indicates the outputs are within acceptable limits Repeat steps 3 9 i...

Page 65: ...r the input you want to calibrate This is shown in the figure below IO IRET Optional Load A 1791 N4C2 and 1791 NDC Important You can calibrate both outputs simultaneously 2 Verify normal operation 3 S...

Page 66: ...ut values are scaled in microamps Vary the output value in the appropriate BTW words over the 0 to 20 milliamp range Make sure the meter indicates the outputs are within acceptable limits Repeat steps...

Page 67: ...and set BTW word 0 to C03Fh 4 Set the voltage source to 0 000V and set the terminal radix to decimal Enter the output meter reading in BTW words 1 and 2 5 Set the terminal radix to hexidecimal and se...

Page 68: ...dicates whether communication is occurring between processor or scanner and the block module FAULT Red 1 Indicates hardware or software error and if communication has failed POWER Green 1 When on indi...

Page 69: ...g received in Program mode FAULT OFF ON Flashing Normal Error hardware or software block power low COMM FAIL communication cable disconnected 100ms between valid frames no more than 255 valid frames b...

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Page 78: ...ting block I O in a PLC system 1 3 1 4 connecting wiring 1791 IOBA 2 5 2 6 2 7 2 8 D default configuration 6 1 description 1 1 differential input mode 1 5 discrete data tranfer word bit assignments 5...

Page 79: ...nges 1 4 series connections PLC 2 13 SLC 2 14 single ended input mode 1 5 specifications A 1 1791 N4C2 A 1 1791 N4V2 A 3 1791 NDC A 5 1791 NDV A 7 status indicators 1 2 8 1 switch assembly 1 2 T termi...

Page 80: ...The Netherlands Turkey United Arab Emirates United Kingdom United States Uruguay Venezuela Yugoslavia World Headquarters Allen Bradley 1201 South Second Street Milwaukee WI 53204 USA Tel 1 414 382 200...

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