How To: Rockwell Automation Allen-Bradley PLC-5 to ControlLogix Conversion

Electronic Drives and Controls, a nationwide recognized Rockwell Automation systems integrator showcases a real-life Allen-Bradley PLC-5 to ControlLogix conversion in the video below.  Using this space-saving kit allows the upgrade to exist in the same footprint and with minimal rewiring. Follow along with the directions below.

Equipment shown in this tutorial:

  • Conversion base plate
  • I/O conversion module
  • Pre-wired cables
  • Cover plate
  • ControlLogix rack


On the PLC-5, we mark the I/O modules, remove the serial cables, the AC power, and the tie wraps. We remove the PLC-5 I/O headers, letting them carefully drape below the PLC-5 rack. The screws of the PLC-5 rack are loosened and a helper is called in to lift the rack off its mounts. We give the back panel a nice cleaning to prepare for the conversion base plate. The mounting screws are installed in the same holes as the PLC-5 rack, then we add the base plate and bottom screws.

The I/O conversion modules are snapped into the base plate. These 25- or 37-pin modules transition the PLC-5 I/O wiring to ControlLogix using the PLC-5 headers we draped below earlier. The Rockwell Automation selection guide will help you determine these part numbers.

Next, we reinstall the PLC-5 headers in the order as they were marked. The pre-wired cables are installed on the I/O conversion modules. We make sure all 12 cables are nice and snug. We have mounted the new PLC I/O modules and the A-17 rack, and then to the conversion cover plate. This hooks on the conversion base plate, and then is secured with screws. The header ends of the pre-wired cables are snapped into the ControlLogix I/O modules, then the rack’s back power supply.

Notice the missing ControlLogix terminal module. Since an exact I/O conversion from PLC-5 to ControlLogix is not available, we simply wired the conductors to a 1756 terminal block on site and according to our wiring schematics.

Now, let’s reconnect the AC power, then the data highway connections for legacy components we will replace later. Finally, the Ethernet connection is snapped in and we are ready to start testing and troubleshooting our system in a fraction of the time had we not used this labor-saving conversion kit.

From PLC-5 to ControlLogix in the same space and minimal rewiring. Of course, that was the easy part. Need help programming, troubleshooting, and starting up your new ControlLogix system? Give Electronic Drives and Controls, the nationwide PLC and drives integration specialists, a call or click.