Posted 20 Aug 2018 Hello, Back in December 2017, we replaced a customer's PLC-5 control system with a CompactLogix. Everything was working fine until about a month ago, when they started having an I/O fault, Code 16 - I/O module connection failed on required module. At first it was showing up on multiple modules, and also the end cap. However, after a few more faults, it was only showing up on module 2. We replaced that module and the faults stopped for about a week and then returned. The module we replaced is a 1769-IA16. Any idea what may be causing this? The customer insists nothing was done to the panel since the initial installation. Share this post Link to post Share on other sites
Posted 20 Aug 2018 Unfortunately you are probably going to swap a lot of parts to find the culprit. How many I/O modules are there? One thing I ran into once that may be of help if module 2 continues to show the fault. I had a system that kept getting a fault on a specific module and it turned out to be the outgoing connector in the module to the left. Share this post Link to post Share on other sites