cdrum543
Member
Hi, I have a customer that we did an upgrade for about 6 months ago, replaced a SLC503 w/ 5 IA16 and 5 OX8 IO cards, with a CompactLogix L33ER w/ 5 IA16 and 5 OW8I IO cards. 120vac power supply (1769-PA4). SLC503 was in service for many years with minimal issues.
About 4 months after being in service without any problems, on 2 separate occasions the program was wiped from the processor and loaded from the SD card. 3rd time the processor was dead (solid red OK indicator).
Replaced the PLC, 2 weeks later, again something happens and the PLC lost its program, loaded from the SD card. At this point we are trying to figure out what could be happening. Customer has an entire building surge protector, PLC is fed from a APC UPS. We decided to try powering the PLC via 24vdc using a 1769-PB4 and a new phoenix contact quint power supply, fed from the APC UPS, thinking this would provide some isolation. Checked for proper grounding and shielded all ethernet cables. Couple days after making these changes, same thing happens again.
I upgraded the firmware from version 24 to 30. Thinking maybe an input could be causing this I started tracing out wires and found 120vac inputs coming from multiple sources, some from within the same control panel as the PLC, others from outside the control panel. For instance there are 9 different breakers coming from a 120/240v breaker panel that feeds power into this panel. 1 of those provides the 120vac control power for this panel, this is where most of the inputs get their power from.
I am really at a loss for what is causing the processor to loose the program. My next thought is a surge coming in on one of the inputs, but all of the inputs still function.
About 4 months after being in service without any problems, on 2 separate occasions the program was wiped from the processor and loaded from the SD card. 3rd time the processor was dead (solid red OK indicator).
Replaced the PLC, 2 weeks later, again something happens and the PLC lost its program, loaded from the SD card. At this point we are trying to figure out what could be happening. Customer has an entire building surge protector, PLC is fed from a APC UPS. We decided to try powering the PLC via 24vdc using a 1769-PB4 and a new phoenix contact quint power supply, fed from the APC UPS, thinking this would provide some isolation. Checked for proper grounding and shielded all ethernet cables. Couple days after making these changes, same thing happens again.
I upgraded the firmware from version 24 to 30. Thinking maybe an input could be causing this I started tracing out wires and found 120vac inputs coming from multiple sources, some from within the same control panel as the PLC, others from outside the control panel. For instance there are 9 different breakers coming from a 120/240v breaker panel that feeds power into this panel. 1 of those provides the 120vac control power for this panel, this is where most of the inputs get their power from.
I am really at a loss for what is causing the processor to loose the program. My next thought is a surge coming in on one of the inputs, but all of the inputs still function.