Hello, I am experiencing a 57h fault where the Specialty I/O module is not responding to a lock shared memory command within the required timeframe. This fault occurs randomly and, while it can be reset and run fine temporarily, it keeps reoccurring. We have already replaced the scanner card, but the issue persists. Upon reviewing an old printout detailing the connections, I discovered that the faulty module is connected to (3) 1791 I/O modules, (2) 1771 PLCs, and a PV600. The scanner card is housed in a 1746. Although I have not located all the devices in the facility yet, I have verified the functionality of (2) 1791 modules, (1) 1771 PLC, and the PV600. They all appear to be functioning properly with no faults. Can anyone offer any suggestions? I have also checked the connections of the devices I have found so far.
Thank you for providing those details! Since the issue is related to backplane communication, it is unlikely that the problem lies with the RIO network or RIO devices. If replacing the 1747-SN RIO Scanner did not resolve the problem, the root cause may be a failing backplane or power supply. There is a small chance that mis-addressed Block Transfer buffers could be causing the xx57h fault, especially if the same buffers are used in multiple block transfer functions. However, this issue is more commonly associated with the redundant 1747-BSN rather than the standard -SN. If the program has not been recently modified, this is an unlikely cause. If there is an available slot in the chassis with the SLC-500 CPU, you may want to consider moving the 1747-SN and updating all related logic in that slot.
Thank you for responding! I have not noticed any changes in the program. After speaking with a tech expert from Allen Bradley, I learned that certain backplane dates are known to have issues. Unfortunately, I could not find a date on mine to verify this information. The tech also suggested checking the grounds, which appeared to be in good condition. However, due to the extensive size of the shop where this system is located, some connections may have been undone and I am unsure of their exact locations to inspect. Ultimately, we have decided to proceed with installing a new backplane.
From my experience with similar faults, you may want to inspect the integrity of the communication cables connecting the Specialty I/O module to the scanner card. The intermittent nature of the fault may suggest that there's a physical problem with the cable or connectors causing a break in the communication sporadically. Also, consider checking your system’s overall grounding; improper grounding can sometimes lead to weird system behavior. Remember to verify the data transmission rate for compatibility as well - all devices need to communicate at the same rate, a mismatch could be the reason for your fault.
It sounds like you've already done a great deal of troubleshooting, which can be a taxing process. I've encountered similar issues in the past where the problem wasn't actually with the module or the scanner card, but rather the communication between the two. Given that you've already replaced the scanner card, this could be a potential issue. You said that you've checked the connections, but have you also examined the integrity of your cabling? Sometimes, wear and tear on the cables, or even electromagnetic interference, can cause sporadic communication issues. Even if everything seems okay at first glance, it may be worth checking this out in greater depth or even replacing the cables as a process of elimination.
It sounds like you’ve already done a thorough investigation! Given the intermittent nature of the fault, it might be worth looking into the communication timing and the load on the I/O modules, as sometimes they can become overloaded if too many devices are communicating at once. Additionally, check the ground connections and ensure that there are no cross-talk issues due to nearby machinery or other electrical interference. Sometimes, even a loose connection that seems fine can cause these kinds of sporadic issues, so double-checking all connections, including the ones you haven’t yet located, could reveal something. Good luck!
It sounds like you’ve done a great job methodically checking the connections and verifying the functionality of some components. Since the 57h fault is intermittent, it could also be related to signal integrity or grounding issues, especially with multiple devices in the mix. I’d recommend examining the power supply to the Specialty I/O module and ensuring it’s stable and within specs. You might also want to look at the communication cables between the modules; sometimes a damaged or poorly shielded cable can cause sporadic faults. If you haven’t already, check the configuration settings as well to ensure they align with your system's requirements. Good luck, and I hope you find the culprit soon!
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Answer: - A 57h fault indicates that the Specialty I/O module is not responding to a lock shared memory command within the required timeframe.
Answer: - The scanner card has been replaced, and the connections of the devices have been checked.
Answer: - The faulty module is connected to (3) 1791 I/O modules, (2) 1771 PLCs, and a PV600.
Answer: - The fault occurs randomly and can be reset temporarily, but it keeps reoccurring.
Answer: - (2) 1791 modules, (1) 1771 PLC, and the PV600 have been verified to be functioning properly with no faults.
Answer: - The thread does not provide specific suggestions for resolving the fault, so further troubleshooting or expert advice may be needed.
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