Greetings everyone, I am seeking insights into a recent issue I encountered with my system. The setup includes 4 CompactLogix 5069-L310ER CPUs - one Supervisory and three remote units connected via their own 4G ethernet router. Communication is established through CIP reads in both directions, with the Supervisory reading the remote sites and vice versa. Despite functioning smoothly for years, a firmware upgrade from V29 to V34 on the Supervisory PLC caused a loss of communication with the remote PLCs. Surprisingly, the Supervisory could still read the remote PLCs, but the reverse was not possible. After troubleshooting and experimentation, I discovered that unchecking the "Connected" option within the message instructions of the remote sites resolved the issue. This raised questions about the significance of this setting change, especially since it worked fine with firmware V29. The error received was a "Connection Failure #0000_0125" without any clear explanation. While my understanding of the "Connected" option is limited, I typically leave it enabled as recommended. This unique issue post-firmware upgrade has led me to consider the impact of slower 4G communication on the system. Any insights or advice on this matter would be greatly appreciated. Thank you.
Due to the previous connection and caching of the MSG instruction, it was skipping the unconnected message buffer upon initial connection. This led to an error once the processor was changed. In order to resolve this issue, you must untick the connected box to establish a new connection through an unconnected buffer. Once this is done, you should be able to confirm that the connection is both connected and cached.
Robertmee noted that the MSG instruction was causing errors because it was connected and cached, bypassing the unconnected message buffer. To resolve this issue, the connection needed to be broken by unticking the connected box and establishing a new connection through an unconnected buffer. Despite re-establishing the connection, attempting to re-tick the "Connected" box resulted in immediate errors. This problem had not occurred with other message instructions until now, despite power cycles and firmware updates on the PLCs. The cause of this sudden issue remains unclear.
Hi there, it seems like your issue lies within the firmware upgrade and how it might be interacting with your existing communication protocol. The "Connected" setting in your Logix designer establishes CIP class 3 messaging which creates a connection-oriented communication. Upon upgrading your firmware from V29 to V34, it's plausible that some underlying alterations might have affected the efficiency of class 3 messaging in your setup, probably due to bandwidth issues with 4G. Unchecking the "Connected" box switches your communication to class 1 or class 0 (default for CompactLogix) which are connectionless, and likely why your communication was re-established. I recommend checking for any known issues with firmware V34 in relation with class 3 messaging and 4G communication.
It seems like you've narrowed down your issue to the "Connected" option in the message instructions. From my understanding, the "Connected" option implies that the data path is kept open for that communication with the other PLC. Keeping it open can be beneficial for faster updates and regular communications. However, with the upgrade to V34 from V29, there may have been changes in how these connections are managed and handled. These changes could potentially impact the performance with slower 4G networks as you've suspected. My advice would be to investigate the firmware notes or technical guides for potential changes in "Connected" setting behavior in V34. Additionally, reaching out to the vendor's technical support might provide further insight into this issue and if it's a bug that needs to be patched. It's always tricky when upgrades cause unforeseen issues, but the vendor's support team should be able to help guide you.
It sounds like you've gone through quite the troubleshooting journey! The "Connected" option typically establishes a continuous connection which can be sensitive to delays, especially with 4G networks. With your upgrade to V34, there may have been changes in how the firmware handles these connections or interprets communication timeouts, leading to the “Connection Failure #0000_0125” you experienced. By unchecking "Connected," you essentially switched to a request/response model rather than a continuous communication model, which could be more resilient over the variable latency of a 4G network. It might be worth reviewing the release notes for V34 to see if there were any documented changes to communication protocols that could explain this behavior. If everything stabilizes now, it sounds like a solid workaround while keeping an eye on future updates!
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Answer: - The firmware upgrade may have introduced changes that affected the communication settings or protocols between the Supervisory and remote PLCs.
Answer: - The "Connected" option in message instructions determines whether the PLC should establish and maintain a connection with the remote devices for communication. Unchecking this option may have resolved the communication issue post-firmware upgrade.
Answer: - Disabling the "Connected" option may have helped bypass a potential issue in the communication setup that arose due to the firmware upgrade, allowing the Supervisory PLC to read the remote PLCs successfully.
Answer: - Slower 4G communication speed may have contributed to communication failures or delays in data exchange between the Supervisory and remote PLCs after the firmware upgrade. It could be a factor to consider when troubleshooting communication issues in the system.
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