KRC2 Motors will not engage in AUT, no error messages

Hey, all. Looking to quickly pick the hive mind again.

My saga upgrading these customer KRC2s continues. Just for the record, these KRC2s (KSS 5.5.15) had SafeOperation 2.1 installed from the factory, but always had it turned off, and the X40 jumper plug in place. The robots were operated by using AUT mode, hand-selecting the program, and using Drives On and Start from the pendant.

So far, we've replaced the old X11 circuit with a new panel, wired up the X40 (but not activated SafeOp yet), and added fresh ProfiBus I/O. All the X40 signals are now closed by either panel jumpers, or by our new safety relays, and I've confirmed that those are all wired correctly using the SafeOp Diagnostics screen.

Everything works at this point, except that I cannot get the motors to come on in AUT mode. T1&T2 are fine. I've checked against prior backups to ensure we haven't changed any system settings that would effect AUT mode -- $MOVE_ENABLE, $DRIVES_OFF, are still set to $OUT[1025].

The strangest part is that there are no error messages that would indicate why the motors won't come on. The only error messages are "27004 Brake Test Required" and "411 Safety Mode Not possible," which have been a constant on these robots for years, and didn't stop them from running in AUT.

411 is just a "nag" message to indicate that SafeOp has been disabled, according to the manual, and as far as I can tell, 27004 is just a side effect of that. As I said, the customer has been running these robots for years in AUT with those errors present. Of the two, 411 should vanish as soon as I activate SafeOp, and 27004 shouldn't stop the robot unless SafeOp is active.

My gut feeling is that there's something in the X11s doing this to use (on both robots!), but I can't recall running into this before. The closest I can recall was a weird X11 issue on pre-ed2005 KRC2s where having one particular enable line broken would allow the robot to run in AUT or EXT, but block the drives in T1 or T2, without an error message (that one took me two days to track down)

I'm going to be attacking this in the morning, but if anyone has ever seen this kind of thing as has a suggestion of what to check, I'm all ears.

So, it was utterly silly. But took a while to track down.

The new X11 circuit had (for some reason) tied X11.44 (External Drives On) to X11.43 (Test Output B). This basically prevented the KCP button from being able to generate the full pulse that the KRC needs to see in order to turn the motors on. That's why the robots worked perfectly in T1&T2, and threw no errors in AUT, but would not engage the servos.

I ended up working it out by plugging in a full-service X11 jumper plug (fortunately we had one), and finding that the drives would engage in AUT. After that, it was a matter of checking the production X11 circuit against the service jumper, one wire at a time.

Side note: the cross-tying of X11.44 to X11.43 appears to have created some false symptoms in the ESC Diagnostics that had KUKA Support thinking that the safety chips in the KPS600s (on both robots) had been damaged while the safety circuits were being rewired.