I was experiencing a recurring issue with my 1769-L23-E PLC and its IO setup, including embedded inputs and outputs, 1769-IQ32, and 1769-OW16. Every 3-6 hours, a major fault for IO connection loss would occur. Despite replacing the end cap, IQ32, and OW-16, the problem persisted. Even after trying different end caps and confirming a stable 24.4V voltage, the OW-16 continued to fault. I then replaced the PLC with a L24ER-QB1B and installed a new end cap, but the issue remained. The fault seemed to only affect the OW-16, raising questions about the cause. With all components now new, I ensured a solid ground for the DIN rail and monitored voltage fluctuations while the system was operational. Additionally, buzzing from the 120v contactors connected to the OW-16 raised concerns about possible EMF interference. Any insights on resolving this perplexing issue would be greatly appreciated.
"Hello! I believe the answer you're looking for can be found in the post by Ken Roach. Check it out here: https://www.plctalk.net/qanda/showpost.php?p=509698&postcount=7"
I came across that information previously. It appears that the AENTR Ethernet module could be applicable in this scenario, as it features a webpage and customizable chassis size. However, it seems that my PLC does not have the functionality to configure chassis size. If I am mistaken, please feel free to correct me as I am feeling frustrated with this situation. Additionally, I discovered that entering the IP address into a web browser reveals a webpage with diagnostic data, but no other configuration options are available.
It is important to mention that the system will continue running normally for a period before experiencing a fault. When dealing with the L23E model, simply clearing the fault and switching it back to run mode will reset the system. However, with the L24ER model, the module remains faulted and requires a power cycle for it to reset. This discrepancy is believed to be caused by the different behaviors of V19 and V33.
Have you experimented with RSLinx software for Rockwell remote IO devices? When accessing the device properties in RSLinx, you may come across a property page with a specific tab where you are able to adjust the chassis size settings on some Rockwell remote IO modules.
The L24ER-QB1B does not require or support setting the chassis size, unlike the L19ER-BB1B. When creating a project for the L19, you are prompted to input the number of expansion modules, and the expansion I/O folder in the Controller Organizer allows for editing later. The L24, however, does not offer this feature. It is assumed that the chassis size is determined by the configured modules. The machine running for an extended period implies that the issue is not a simple configuration error. Ensure that all inductive loads from relay output modules are suppressed to prevent potential faults, especially on MicroLogix systems.
Sounds like an incredibly frustrating issue you're dealing with! One aspect that you haven't mentioned is the condition of your wiring and terminal blocks. Given you've replaced nearly every other component, faulty wiring could be a reason causing intermittent IO connection failures. If a wire is either loosely connected or fraying, it might cause sporadic faults. Also, regarding the buzzing from the 120v contactors, you could potentially be experiencing EMF interference as you mentioned. To isolate the issue, you could try rerouting these cables separately, possibly using shielded wiring for the buzzing contactors. A ferrite bead could also help decrease high frequency noise. If it's possible and safe to do so, consider disconnecting some devices one at a time to narrow down if a specific device is causing this. Best of luck with your troubleshooting!
Based on what you describe, it seems like both hardware and related wiring is not the issue since you've replaced practically every relevant component. Instead, this might be a software or EMF interference issue, as you suggested. Did you thoroughly check software settings or program logic? Sometimes, the trouble may lie in the IO address setup. As for the buzzing 120v contactors, it's absolutely possible that they might be causing EMF interference. You might want to consider using some kind of shielding on the wires or, if possible, relocate these contactors further away from the PLC and its IO modules.
You've certainly done a thorough job troubleshooting thus far! A few extra thoughts strike me. Sometimes, the routing of the cables can inadvertently expose your PLC to electrical noise; your mention of the buzzing contactors makes me wonder if this could be the case. If your signal cables are run near power cables, there could be some electromagnetic interference that only affects the OW-16 due to its location or the nature of its function. You may want to reroute your cables, or better yet, use shielded cable to help prevent any possible EMF interference. Alternatively, have you checked whether the OW-16's load condition might be exceeding its rating at any point? Overloads could potentially trigger recurrent faults. Keep us posted on your progress.
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Answer: - The issue could be related to possible EMF interference from the buzzing 120V contactors connected to the OW-16 module.
Answer: - The user has replaced various components including the end cap, IQ32, OW-16, and even the PLC itself. They have also ensured a stable 24.4V voltage, checked for voltage fluctuations, and monitored the grounding of the DIN rail.
Answer: - The fault persisting only with the OW-16 module could indicate a specific issue related to this particular module, possibly due to EMF interference or other underlying factors.
Answer: - Troubleshooting steps may involve checking for grounding issues, monitoring voltage stability, investigating potential sources of interference like EMF, and ensuring proper connections and configurations within the IO setup.
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