You can read this post on LinkedIn as well. Introduction: Embarking on a journey through the intricate realm of Allen Bradley controllers can be both rewarding and bewildering. But fear not, fellow adventurers! Today, we delve into the enigma of Error Code 16#0204 , a puzzle that has left many scratching their heads. Prepare to unravel this perplexing riddle as we navigate the intricate web of local and remote I/Os. Grab your magnifying glass and join me on this thrilling escapade! If it is an all-or-none case, you can check ABB's article SLOGIX 5000 ERROR CODES WHEN USING ETHERNET IP AND ABB DRIVES . Section 1: Understanding the Issue When using a CompactLogix 5380 controller with two 1747-AENTR Ethernet communication modules and two 1746-A13 chassis, it was observed that only the last two modules (1746-IA16 and 1746-OW16) were not being recognized by the controller. Several assumptions were made initially, such as module failure or power consumption issues, but they turned...