Bulletin 1492 PLC I/O Wiring ConversionSystem for Allen-Bradley® 1771 to 1756ControlLogix™ I/OSelection GuideBulletin 1771 PLC to ControlLogix 1756 I/O Field WireConversion SystemField Wire Conversion SystemThe Bulletin 1492 PLC 1771 to ControlLogix 1756 I/O field wireconversion system provides a fast and efficient way to convert theexisting I/O field wires from a bulletin 1771 I/O system to a Bulletin1756 I/O system. The Bulletin 1492 conversion system enables thefield wiring on a particular Bulletin 1771 I/O module terminal block(swing-arm) to be maintained, so there is no or very limited rewiringrequired to convert to a compatible 1756 I/O module. Conversionsolutions are available for 22 of the most widely used 1771 I/Omodules.Time Saving FeaturesThe time to convert for example the field wiring for a 1771 8-slot I/O chassis without the conversion system can typically be between sevento nine hours.1This assumes time to:�Unscrew and remove each I/O wire from each I/O module terminal block�Remove the old I/O housing/rack from the control cabinet �Drill new holes in the control cabinet for the new 1756 I/O chassis�Mount the new I/O chassis�Install the new I/O modules in the new I/O chassis�Re-dress each I/O wire for each module�Re-label each I/O wire�Attach each wire to the I/O module terminal block�Confirm operation: Once the conversion of field wires is complete the integrity of each connection has to be verified to ensure a wiringerror wasn't made. This troubleshooting process may add 30 minutes or several hours to the conversion. The conversion system potentiallyreduces the 7 to 10 hours required to convert the field wiring for an 8-slot I/O housing/rack to one hour or less. In many applications,saving 6 to 8 hours of downtime can eliminate tens to hundreds of thousands of dollars of revenue. Multiply that savings by the number of8-slot housings in your factory and you can see the benefit of the I/O conversion system. Visit our website: www.ab.com/catalogsPublication 1492-SG121A-EN-P3Bulletin 1492Bulletin 1771 to 1756 I/O Field Wiring Conversion SystemTable of ContentsTime Saving Features....this pageConversion Modulesand Cables . . . . . . . . . . . .4Conversion of theBulletin 1771 I/OHousing...............................5Selection Table for1771-to-1756 DigitalI/O Swing-ArmConvertion Modulesand Pre-Wired Cables...6Typical Keys toConversion Success:1771-to-1756 FieldWire ConversionSystem ...............................7Conversion ModuleSpecifications...................8Conversion ModuleInstallation andApplicationConsiderations.................91492 Conversion System BASICSConversion Modules and CablesThe Bulletin 1492 conversion system virtually eliminates the rewiring process by using conversion modules. The conversion modules providethe mating connections to the specific 1771 I/O swing-arm with the attached field wires. It routes those field signals, via a 1492 wiring systemconnector and a 1492 pre-wired cable to the compatible terminals of the 1756 I/O module. Conversion ModulesPre-wired 1492 CablesConversion Assembly Cover-PlateThe conversion assembly cover-plate covers and protects theconversion modules, while providing the mounting platform forthe Bulletin 1756 I/O chassis and associated I/O modules.The cover-plate comes with pre-drilled and tapped holes,which allow mounting the 1756 chassis in several locations(left, center, or right).NOTE: The total depth of the conversion assembly andmounted Bulletin 1756 chassis is approximately 10.5 inches.Conversion Assembly Base-PlateThe conversion modules are housed in a conversion assemblybase-plate which uses the same mounting footprint and panelmounting holes as the 1771 I/O Chassis it replaces. Therefore,no new holes need be drilled in the control cabinet.Visit our website: www.ab.com/catalogsPublication 1492-SG121A-EN-P4Bulletin 1492Bulletin 1771 to 1756 I/O Field Wiring Conversion SystemConversion Systems Components - Exploded ViewBuleltin 1771 to Bulletin 1756 Chassis Conversion System Selection ProcessVisit our website: www.ab.com/catalogsPublication 1492-SG121A-EN-P5Bulletin 1492Bulletin 1771 to 1756 I/O Field Wiring Conversion SystemStep 1: Determine the number of 1771 I/O modules used in the 1771 I/O Chassis to be converted to 1756. NOTE: In some cases two 1756modules may be required for one 1771 module. Select the applicable 1492 conversion modules from the Digital and Analog ConversionSelection Table Matrix (Table 2 and 3).Step 2: Review the Max Slots for I/O and Chassis Width data from Table 1, and select a 1756 I/O Chassis which meets your conversionneeds from Step 1. Ensure the information from the I/O Conversion module tables 2 and 3 on page 4 and 5 are reviewed first.Step 3: Once the 1756 Chassis is selected, select the Conversion Assembly. The conversion assembly has the same dimensional foot-printas the 1771 chassis (without power supply) and can use the same mounting hardware. The assembly consists of a base-plate to hold theconversion modules and a cover-plate to protect the modules and to mount the selected 1756 chassis. The combined depth of theconversion assembly with the 1756 chassis mounted is 10.25 inches (Controller w/key) to 10.0 inches (controller w/o key).Conversion of the Bulletin 1771 I/O HousingTable 1 provides selection information for the conversion assembly base-plate and cover-plate. The selection process is based on thepreviously installed Bulletin1771 housing. These components function as a matched set and therefore ship as a single catalog number. The following illustration provides an overview of the conversion components.Table 1:Bulletin 1771 to 1756 Chassis Conversion System Selection ProcessChassisParameter1Bulletin 1771 ChassisBulletin 1756Equivalent ChassisBulletin 1771 ChassisBulletin 1756Equivalent ChassisBulletin1771ChassiswithoutPowerSupply �Equivalent1756ChassisBulletin1771ChassiswithoutPowerSupply �Equivalent1756Chassis-A1Bwithout PS-A1B withPS-A4‡-A7-A2Bwithout PS-A2B withPS-A7§-A10-A3B1-A13♣-A4B-A17®Max Slotsfor I/O4436886912121616ChassisWidth �9.0112.6110.3514.4914.0117.6114.4919.0219.0123.1524.0129.06MountingAssembly1492-MUA1B-A4-A71492-MUA2B-A7-A101492-MUA3-A10-A131492-MUA4-A13-A1711771-A3B is not listed as it is used for 19 inch wide instrumentation panels.�Two 1771 width dimensions are provided. The dimension without PS (power supply) is used when a 1771 chassis slot mounted power supply (e.g. 1771-P4S, -P6S, etc) is used. The dimension with PS includes a 1771 chassis left side mounted power supply (e.g. 1771-P1, -P2, etc.). Notice that in some cases the widthdimension of the 1756 chassis (including its power supply) exceeds the width of the 1771 chassis with or without the 1771 chassis left side mounted supply.For conversion flexibility the conversion cover plate has pre-drilled and taped holes to allow mounting several different 1756 chassis to account for differencesin I/O slot usage and width dimension. Cover plate hole locations allow the excess 1756 chassis width to be evenly distributed to both sides, or excess to rightor left. Carefully consider this when mounting.‡1756-A4 may work in a 1771-A1B application if four or less I/O slots were used. Conversion cover-plate is capable of mounting -A4 or -A7§1756-A7 may work in a 1771-A2B application if six or less I/O slots were used. Conversion cover-plate is capable of mounting -A7 or -A10♣1756-A10 may work in a 1771-A3B1 application if nine or less I/O slots were used. Conversion cover-plate is capable of mounting -A10 or -A13®1756-A13 may work in a 1771-A4B application if 12 or less I/O slots were used. Conversion cover-plate is capable of mounting -A13 or -A17�An external power supply (eg. 1771-P2) adds 3.6 inches to the width dimension.