SLC500 fault

[gromit 4]

Continue to get the following Major Fault on a SCL500 PLC. "A "stuck" runtime error is detected on I/O module. Exact slot cannot be determined." Major Error S:6 = 1F51h Clearing the fault and turning the key to Program and then Run clears the fault for a while, but then the fault reappears. Any ideas? Thanks!

[Mickey 71]

Have you tried to reseat the modules? You may have to remove them and replace one at a time to find the bad one. Do you have surge protection on all inductive loads?

[gromit 4]

Thanks Mickey. I am not sure about the surge protection, but will look into it. I have not tried to reseat the cards/modules, but will convey this to the technicians, as the fault usually occurs after hours.

[gromit 4]

Mickey, Regarding your questions, please see the responses below: q1: Have you tried to reseat the modules? You may have to remove them and replace one at a time to find the bad one? a1: We will reseat all modules the next time the fault occurs. q2: Do you have surge protection on all inductive loads? a2: Don't have any known surge protection; however, the panel and PLC is UPS powered.

[plcdp 11]

Unless your UPS has built in surge suppression, you are not protected from inrush spikes on any inductive loads. Edited 23 Apr 2014 by plcdp

[Mickey 71]

The surge protection I'm referring to is across each inductive load (e.g solonoid(s), contactors ) not the panels power source. Although its good you have the UPS. Edited 23 Apr 2014 by Mickey

[gromit 4]

So, are your talking about suppression diodes on 24 VDC circuits?

[Mickey 71]

Yes, but don't forget AC circuits also need it. See PDF surgeprotection.pdf

[gromit 4]

Thanks Mickey. Very good information..

[mhowasso 5]

38420 - SLC Processor: Error code 1F51H Question I have an SLC 500 series processor that has error code 1F51H in S:6. What does this mean and how do I troubleshoot this problem? Answer The processor has determined a major hardware error within the system. If the problems persists and recycling power does not clear the error code, the user should: Go offline, go to the I/O Configuration, and perform a Read I/O Config. If any slots change to unknown, get that module or possibly the chassis replaced. Pull all of the I/O modules Download a blank program to just the processor and power supply. Continue to add one module at a time until the hardware problem is discovered.