1756 L62S Losing Program v17

Hey guys,

Been having an issue with a AB CPU 1756 L62S (red safety) randomly losing the program while in run.
Things i have tried or replaced.

Replace backplane
Added more chasis grounds
Replace 24V source to backplane Ps
Replace L62S and slave
Replace all local I/O

Issue happens randomly machine could run for months without happening or sometimes will happen 2 days in a row

Faults present when downloading the program again

Type 14 safety task fault
Code 9 - a non recoverable fault has occurred in Safety Partner


If anyone can help will be highly appreciated.

Thanks in advance.

i have had this happen with several slc 500 and a plc 5.
the plc experiences a brownout (low voltage) condition and starts to shut down.
in the process, the voltage returns to normal and the plc tries to restart.

place a surge suppressor ahead of the plc ( i use corcom).
if that continues, use a constant voltage transformer.
pressed for time, a line went down.
james

I isolated the 24V feed to CpU with spare power supply with battery backup UPS for the supply. Program failed 2 weeks after. Will this power blip affect the safety guarlogix modules that monitor safety I/o. We use the ethernet safety modules to monitor multiple i/o.

Has the system been running fine until recently?

Maxkling said:

Has the system been running fine until recently?

Click to expand...

Yes issue started about a year ago. Ever since we been trying different things AB and machine manufacturer has recommended but still not find the root cause.

Different companies do different things, so have noticed when a constant voltage transformer has been used and the program does not get lost. But have noticed when cheap companies dont CVT the processor rack and power supply and other temperamental electronics and those same programs seem to just go poof.

Jim3846 said:

Different companies do different things, so have noticed when a constant voltage transformer has been used and the program does not get lost. But have noticed when cheap companies dont CVT the processor rack and power supply and other temperamental electronics and those same programs seem to just go poof.

Click to expand...

Its 24V rack feed not 120V

waterbottle said:

Faults present when downloading the program again

Type 14 safety task fault
Code 9 - a non recoverable fault has occurred in Safety Partner

Click to expand...

This safety task fault will delete the program and require that the program be downloaded again. That is by design.

The 'book' solution is to replace the safety partner. You've done that without success.

I was going to say replace the backplane, but it looks like you've tried that.

Have there been any program changes before this started? Safety signature still in place?

Timbert said:

This safety task fault will delete the program and require that the program be downloaded again. That is by design.

The 'book' solution is to replace the safety partner. You've done that without success.

I was going to say replace the backplane, but it looks like you've tried that.

Have there been any program changes before this started? Safety signature still in place?

Click to expand...

The program has had few changes mostly online changes to improve the process of the machine (timers added boolean tag here and there). No changes to the safety logic. Processor is safety locked and safety signature in place.

Just kicking this one out again. We have continued to experience this issue sporadically. Will go away for 6 months and them it will come back 3 times in a week. Still looking for any assistance on this.

https://rockwellautomation.custhelp.com/app/answers/answer_view/a_id/629126/loc/en_US#__highlight

Series B 1756-L6xS Controller may power up with no program and minor battery fault logged

ID: IN33491 | Access Levels: Everyone

Looks like it has a problem with losing power or some kind of fault clearing memory for these controllers v14-v19 firmware.


It appears there is a problem with the controller saving memory while in process. It requires power to complete data transfers internally, and if you lose power in the middle of a data transfer, capacitors (or a battery in this case) are supposed to save it from corruption and allow it to complete the transfers. When they don't complete you get corruption and a cleared program i'm thinking.

Same idea when it comes to flash drives and external harddrives being pulled from power before completing file transfers, OR, without being "ejected". you get the corruption of the drive due to writes/transfers not being completed.

Edit: I know you aren't yanking it out in the middle of operation, but it doesn't mean it can't happen under other conditions that can simulate a temporary power loss while being used.