Hello everyone! My colleague and I have been troubleshooting a challenging issue with our Point I/O rack system. We have a setup consisting of a 1734-AENT Ethernet adapter, 5 1734-IB8S input cards, a 1734-EP24DC power supply, 3 1734-O8BS output cards, and an additional 1734-IB8S card. Recently, we have been experiencing dropped inputs from cards in slots 1, 2, 3, and 9 at unpredictable times. This issue is affecting various inputs, including crucial ones connected to a light curtain module. We have observed drops of about 15ms, occurring randomly. Despite our efforts to adjust the power source and configurations, the problem persists. After experimenting with different solutions, we found that connecting the problematic inputs directly to the +24V line of the rack somewhat resolved the issue. However, this workaround is not foolproof, as the light curtains also connect to the same +24V line and have their own outputs in the safe state. We have tried replacing the light curtains and rewiring them to the Point IO rack, but the problem persists. The dropped inputs are scattered throughout the machine and do not follow any specific wiring patterns. The common denominator appears to be the Point IO rack and power supply. Despite replacing parts and troubleshooting extensively, the issue remains unresolved. We are seeking suggestions for potential solutions to this persistent problem. Any advice would be greatly appreciated. Thank you!
Although I am unfamiliar with this topic, I came across a helpful tech note (available to everyone) that discusses resolving flickering issues at the end of a light curtain. The tech note, QA46751, emphasizes the importance of correctly configuring the IB8S input channels for OSSD or pulse testing. Did you remember to reconfigure the input channels each time you experimented with different wiring?
Do you know the date code for your IB8S module? There has been a reported issue with IB8S units causing unexpected drops of 1734 racks. You can find more information on this in the Rockwell Knowledge Base. From what I remember, the problematic modules were manufactured around 2021.
Issue resolved! By utilizing an oscilloscope, we identified a 1.4VAC @ 12KHz voltage between rack 0V and ground, with pulsing peaks reaching ±5V. This induced current was caused by two SEW Movidrives, where the ground wire was intertwined with the motor wires using a ferrite core. By separating the ground wires and re-routing them directly, the induced current decreased by 70%, resolving the problem. This solution required some mental effort, but the valuable information provided by others was greatly appreciated. Though it may not have been the exact fix this time, acquiring more knowledge is always beneficial!
I've worked with Point I/O systems for several years and intermittent faults like this can be particularly tricky to troubleshoot. A couple of things come to mind. Firstly, have you checked the grounding of your Point I/O rack system? Inadequate grounding may lead to unpredictable errors. It's also important to verify that the rack is receiving a consistent 24V power supply, as fluctuations can cause the issues you've mentioned. And lastly, do consider the possibility of EMC interference. This could be caused by things like VFDs or large motors close to your I/O or Ethernet cables. Hope this helps and best of luck solving this pesky problem!
It sounds like a tricky situation. Given that you've already tried some hardware replacements with no luck, it makes me wonder if there might be a problem with the I/O update times, or the network itself. The 1734-AENT adapter you're using does handle the I/O update very precisely, but keep in mind that it's also impacted by the overall network performance. Perhaps there are network issues that are causing the updates not to happen within the expected time frame. It could also be an issue with an RPI (Requested Packet Interval) setting that's too aggressive. Try increasing the RPI setting to see if it results in any improvement. You may also want to check for higher than normal network traffic that could be causing congestion and delays. If you are using managed switches, take a glance at your port statistics for unusual packet loss or error rates. It might not solve your problem completely, but it's something worth checking out.
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Answer: - The dropped inputs could be caused by various factors such as power supply issues, wiring problems, or potential hardware malfunctions within the Point I/O rack system.
Answer: - The users have tried adjusting the power source, reconfiguring settings, connecting inputs directly to the +24V line, replacing light curtains, and rewiring components to the Point I/O rack.
Answer: - The dropped inputs seem to be scattered throughout the machine without following specific wiring patterns, suggesting a potential issue related to the Point I/O rack system or power supply.
Answer: - Connecting the problematic inputs directly to the +24V line of the rack has somewhat resolved the issue temporarily, but it is not a foolproof solution due to conflicts with other connected devices.
Answer: - It is advisable to conduct a thorough inspection of the wiring, check for grounding issues, consider testing with different power supplies, and consult with technical support from the manufacturer for further assistance in resolving the problem.
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