As a beginner in this field, I'm seeking assistance with a recurring issue. Could frequent memory loss indicate a faulty CPU? How reliable are SLC 500s? In the past week, we've had to reprogram our crusher van PLC three times. Currently, it's not connecting to the laptop at all. Initially, I thought the battery had died as it happens every two years. After replacing the battery and reprogramming, the memory was wiped clean again after three days. This cycle repeated a few times. I will try using a serial-to-serial cable instead of the USB to serial 1747-CP3 cable tonight to rule out any cable issues. Why does the memory keep getting erased? To prevent any power interruptions during generator switches and voltage spikes, I plan to install an APC battery backup (UPS) soon. The voltage and hertz levels appear consistent from the generator.
A faulty power supply within the chassis has the potential to erase stored memory data. This issue can lead to system malfunctions and data loss, emphasizing the critical role of a reliable power source in maintaining data integrity.
Robert, thank you for the recommendation. I recently purchased a new power supply and EEPROM to program it.
A problematic power supply is often the main reason behind memory loss issues. Other factors to consider are grounding problems, the chassis structure, i/o cards (especially analog cards), potential issues with the 24V power supply output, and even the processor itself. If you are dealing with memory loss problems, this discussion thread may pique your interest.
It is likely that a malfunctioning power supply is the culprit, however, there is a slight possibility that electrical noise may be causing the issue. Excessive electrical noise can result in the controller losing its program, possibly indicating a grounding issue as suggested by plvlce. When multiple hard contacts are opened simultaneously without any form of suppression, it can also lead to problems. For instance, a client faced a similar situation where turning off all outputs at once caused the PLC to lose its program. After adding suppressors to the relay coils, the issue was resolved. This highlights the importance of proper suppression techniques in ensuring the stability of PLC operations.
Experiencing a brownout or voltage surge can cause the program to be erased, which has happened to me multiple times. To resolve this issue, we installed a Corcom filter in the system for the 110 controls, effectively solving the problem. If the internal CPU capacitor charging system malfunctions, the CPU will lose the program during power flickers or brownouts. To address this, try reseating all cards, CPU, and power supply to the rack. Additionally, replacing the PLC battery may help. After performing the aforementioned steps, test the CPU by powering it off for 5 seconds and rebooting. If the system fails to retain the program when the power is restored, it's likely that the CPU needs to be replaced. For repairs on AB components, consider reaching out to companies such as MRO (Manufacturing Repair and Overstock) in Chattanooga. I have personally used Team Sesco multiple times without any issues. - James
It sounds really frustrating to deal with those memory issues, especially when you've already replaced the battery. Based on your description, it could be more than just the CPU since a faulty CPU typically doesn’t cause memory to erase constantly. It might be worth checking the PLC's power supply; unstable voltage can lead to memory loss. The UPS is a great idea, as protecting against power fluctuations can make a big difference. Also, ensure that all your connections are secure; intermittent cable issues can sometimes cause unexpected problems too. Keep us updated on how the serial-to-serial cable works out!
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Answer: Answer: Frequent memory loss can indeed be a sign of a faulty CPU in the SLC 500 5/03. It's worth investigating further to determine if the CPU needs replacement or if there are other underlying issues causing the memory loss.
Answer: Answer: SLC 500s are generally known for their reliability, but like any equipment, they can experience issues over time. Regular maintenance, proper programming, and troubleshooting can help ensure the continued reliability of SLC 500s.
Answer: Answer: The memory getting erased could be due to various reasons such as a faulty CPU, power interruptions, voltage spikes, or even issues with the programming. Investigating each of these aspects can help pinpoint the exact cause of the memory loss.
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