ROB LEE (Customer) asked a question.
CPU logic not responding correctly.
Version 3.80
C0-12dd2e-2-d cpu
multiple I/O cards
The program with the issue runs already on multiple equipment with no issues.
On a rung I have a NO input bit(X201) then several NC output bits(y101, Y102 etc) then a 5 second timer at the end. X201 closes, Y101 opens yet the timer will count up to the 5 second mark. This is happening on multiple lines of logic. I have factory reset the CPU, replaced the CPU and it still does this. I could not duplicate it in another rack with the same cpu. Could it be one of the IO cards in the rack? The equipment is off site, so I tested on a different set of IO cards and the program woks perfectly. Please advise. Y101 is tied to a C0-16td2 IO card.
I am not able to duplicate your problem.
You say you are not at the equipment. You are not able to actually monitor the "Y" values. So someone on site is telling you the machine is not operating correctly, correct?
Could the logic that turns on the "Y" outputs, which opens the N.C. "Y" contacts, not actually be turning on? For example, a limit switch which provides a permissive for the output to turn on is malfunctioning, and not providing the proper input, so the "Y" contacts stay closed, and the timer continues to run? This seems the most likely.
Is the timer setpoint set by an HMI?
Could the operator have entered the wrong setpoint? For example, the machine is expecting a 5-sec time limit, but the setpoint was set to 50?
Could the HMI programming have gotten changed? For example, HMI scaling is turned on, or the HMI scaling is wrong? Or the tag assignments are incorrect?
Could the PLC programming have gotten changed? For example, changed timer tags, or timer units, or delay setting, or retentive setting?
Everything is correct in the program, the customer "thought" it was doing the same thing but he had a controls tech look and it actually was not malfunctioning anymore. The issue WAS the CPU then. Thanks for looking into it.
No problem. I found the C-more provided very helpful alarm notifications for identifying any faults in the operation. Most times, programming the faults, and the actions to take due to the faults, was more involved than the actual machine control programming. Glad to hear it is now working.