Posted 24 Jul 2019 Hi Guys... I am facing the error in 1756-L74 Controller. Controller shows an error code, with following description. Error: T03: C16 IO Connection Failure. What are the possible causes for this? How to Hard reset the same controller? Share this post Link to post Share on other sites
Posted 24 Jul 2019 The user manual says to check: 1) ...the I/O module is in the chassis 2) ...the electronic keying requirements 3) ...the controller properties major faults tab and module properties connection tab Expand the I/O Configuration tree and look for a module with a yellow triangle icon: Open that module's properties dialog and go to the connection tab. There is a check-box there for "Major Fault on Controller If Connection Fails While in Run Mode". Evaluate whether or not that box needs to be checked. On the "General" tab, look at "Electronic Keying". For most applications, you're fine with "Compatible Keying". If it says "Exact Match" and that module has been replaced with one that's a different revision, you may get this fault. Again, evaluate your application to see which kind of keying is necessary. BEFORE changing EITHER of these settings, click the "Help" button to learn exactly what they do and evaluate the system in detail to see how changing that setting could affect your operations. Share this post Link to post Share on other sites