A KRC4 that operates in T1/T2 but reports operator safety open in automatic mode points to the automatic-mode operator-safety path, not a general motion or program fault. The evidence identifies X11 safety-door channels and operator-safety acknowledgement as the primary checks. It also shows a wiring list that may have been copied from a KRC2, so do not assume its pinout applies to a KRC4.
Why T1/T2 Works but Automatic Mode Does Not
The reported behavior is mode-dependent: the controller runs without an error in T1/T2, while the program cannot run in automatic mode. The safety-door circuits are used in AUT and EXT but not in T1/T2. Therefore, successful operation in a test mode does not prove that the automatic-mode safety inputs are complete.
MOVE_ENABLE was identified as relevant to EXT rather than AUT, although the source expresses uncertainty. If the failure occurs specifically in EXT, include move enable in the diagnostic scope; do not treat it as the confirmed cause of an AUT-only failure.
Check the KRC4 X11 Safety Circuits
| Function under investigation | Candidate X11 pairs from the evidence | Required decision |
|---|---|---|
| Safety-door channels |
3-4 and 21-22
|
Verify both pairs against the exact KRC4 X11 documentation and the machine safety design. |
| Operator-safety acknowledgement |
5-6 and 23-24
|
Verify whether an acknowledgement circuit is required and how the external safety system must drive it. |
| Move enable | No pin pair confirmed | Check only from the applicable KRC4 documentation, particularly for EXT operation. |
The pin pairs above were proposed as possible bridges, not established as a verified pinout for every KRC4 configuration. Do not install permanent bypass bridges around a safety door or protective device. Confirm the controller variant, connector pinout, risk assessment, and external safety-system wiring before changing X11.
Correct the Wiring and Safety Configuration
The reported X11 wiring included 108-106, 107-105, 32-31, 14-13, 29-30, 11-12, 27-28, 9-10, 25-26, 7-8, 19-55, 1-37, 2-38, and 20-56. The evidence questions whether this is a KRC2 X11 arrangement and states that KRC4 connections differ. Treat that list as unverified until it is checked against the documentation for the installed controller.
- Identify whether the requested operating mode is AUT or EXT and record the exact
operator safety openindication. - Compare every installed X11 connection with the pinout for the exact KRC4 controller; do not reuse a KRC2 pin list.
- Trace both safety-door channels through the external safety system and verify that each reaches its required safe state when the guard is closed.
- Check the operator-safety acknowledgement circuit if the safety design requires it.
- If acknowledgement is supplied externally, review the Safety Configuration setting and change
By ButtontoExternalonly when that matches the installed hardware and validated safety design. - After restoring all guards and protective devices, test T1/T2, AUT, and—if used—EXT separately. Confirm that opening the guard prevents automatic motion and that closing and acknowledging it clears the operator-safety indication as designed.
FAQ
Why does a KRC4 run in T1/T2 but show operator safety open in automatic mode?
The safety-door inputs are used in AUT and EXT but not in T1/T2. Test-mode operation therefore does not confirm that the automatic-mode X11 safety path is closed.
Which X11 pins should I check for KRC4 operator safety open?
The evidence identifies 3-4 and 21-22 as candidate safety-door pairs, with 5-6 and 23-24 as candidate acknowledgement pairs. Verify these pairs against the exact KRC4 X11 documentation before altering any safety wiring.
Should KRC4 Safety Configuration use By Button or External?
Use External only when the operator-safety acknowledgement is provided by the external safety system and the validated design requires it. Otherwise, retain the configuration specified for the installed acknowledgement hardware.