R-30iB, Version 8.22. Ethernet/IP with DCS CIP-Safety.
This one's puzzling. I'm adding some new Ethernet/IP I/O adapters to this robot. There's plenty of unassigned I/O, and I made sure that I mapped the new adapters into DI/DO ranges that were not already assigned to anything.
The new I/O works, except that there's one DO that is "stuck" On -- if I try turning it Off, it just goes back to being on. I went back to the backup I made before I started making changes, and this particular DO was never assigned to anything. I also haven't been able to find any background programs or UOP assignments that make use of that DO, or in fact any DO within +/- 100 locations.
Even more odd, the cell PLC began reporting that the DCS signature had changed. Which was news to me, since I had made certain not to go anywhere the DCS configuration. Along with this, the robot began throwing an error message (but only on reboots) SYST-144 that $DCS_SGN.$CR had a "Bad DO assignment". I've gone looking for this variable in the System Variables menu on the robot, but $DCS_SGN has no sub-variable called $CR. And I haven't been able to find $DCS_SGN in my manuals, either.
I'm guessing that somehow, my mapping of previously unassigned DOs conflicted with the DCS Signature outputs to the PLC, but I've got no idea how that happened -- the CIP signals and the normal DOs should be completely segregated, shouldn't they? On top of that, the robot's DCS menu shows that the last time the DCS signature was changed was in 2018
Also, while DO 706 is "jammed" On, I don't see how it can be part of the DCS Signature -- if it were, going by the signature's current value, a lot of DOs in the lower 700s or upper 600s should be On, but only 706 is.
For lack of any better ideas, I tried deleting all the new DI/DO assignments I had made, putting the I/O mapping back to what it was before I started, but that didn't fix the error messages. In fact, the PLC threw a new message saying that the DCS signature had changed again.
In my RoboGuide, the virtual robot built from the original backup shows the DCS Signature Change Anunicator as RO[0], which would seem to
So, I have three questions, which may or may not be related:
1. How did the DCS signature change just by mapping some DIs and DOs that were previously unassigned?
2. How can DO 706 be stuck On when it's not assigned to any Rack/Slot? Whatever is "jamming" that DO had to have been present in the robot before I mapped that DO range, but there were none of the system faults I would have expected from something trying to set an unassigned DO.
3. If my added DI/DO mapping was somehow to blame for the PLC receiving a false indication that the DCS signature had changed, why didn't reverting to the original mapping fix it?