KRC1 - Sudden Drive Enable problems

Hi folks - maaron here again, unfortunately I bear questions and a problem. Please note that software and build versions are forthcoming, I need to get back out to the floor to get them, however I suspect this is not a software-related problem.

To give some context, I'm running a set of GM Kuka KRC1 K150 frame robots on a production line. One is for occasional R&D, the other is (or rather was) in full production. It has been running without major issue for quite some time now, almost a year at this point.

According to the fault log on the controller, the robot came to an emergency stop toward the end of the second shift yesterday evening, and I have been unable to get it to move since. drives are not able to be enabled in EXT as they once were, and the deadman switch does not work in T1 or T2 to manually move the arm either.

Jumpers for the CC1 plug have not been changed, but I have tightened them to ensure a good connection. No errors occur that would suggest this as my main problem, only the "active commands inhibited" message.

A look in the cabinet shows a set of the LEDs on the main safety board (FE207?) are not lit. The picture attached shows what I'm looking at without any buttons pressed in T1/T2. In EXT pushing the drives on button on the KCP only toggles one small relay (V56) and does not lock in any other of the larger relays. I have gone so far as to swap the safety cards (both 207 and 208) with our parts robot and I am still experiencing the same symptoms.

TLDR:
KRC1 isn't enabling drives. The configuration has been working flawlessly to this point. Looking at the picture attached can someone verify that one or more of the LEDS that are not lit indeed should be lit? I'm perusing the wiring diagrams that came with the cabinet, and I'm having trouble pinpointing where I should be checking for power/continuity/etc. to determine if it's relays or wiring or something else entirely that is causing my problem. Any clues or leads are greatly appreciated.

Hi Panic - thanks for the reply.

Are there any fuses to check besides the ones on the PM600? All corresponding LEDs on that are lit, but I will go physically verify the fuses with an ohmmeter today.

My X11 plug (Safety plug, correct?) is wired to a breakout board I've built with some DIN rail terminal blocks and is jumpered there to make the necessary connections.

I also had a safety scanner / safety relay combo wired across pins 17-18, and 19-20, but that has been removed to eliminate it as the cause for the time being as I troubleshoot the issue. No E-stops are engaged.

Unfortunately the second R&D controller has been raided for some of its parts previously and it is questionable at this point whether I could get it to boot, so I'm hoping to not to have to go that route.

Well, I've had a resolution to this problem for a number of days, just figured I'd update the thread.

All fuses were fine, as were cables and connectors. Checked and re-checked jumpers and wiring to safety equipment. Went as far as powering off the cabinet to do a cold restart and even after that the robot would not move. So I called it a day and decided that it would be best if I came back the next morning to get back at the problem.

Did just that and as a Hail Mary decided to poke at the buttons to make sure it was still locked up and wouldn't you know it the drives powered up.

Long story short - the problem appears to have resolved itself and the robot has been working fine since (so far ). I suspect a pretty stubborn version of a single channel fault (LEDs not lighting, the nature of the system integration of this cell itself, and a couple of other threads I perused lead me to believe this is the most likely scenario).

Thanks again for your help - wish I had a better solution for future folks troubleshooting their own issues.