F01773 — SI Motion P1 (CU): Test stop fail-safe digital output error

F01773 is raised when processor 1 (P1) of the Control Unit (CU) finds a fault during the test stop — the forced checking procedure of the failsafe digital output (F-DO). During a test stop the two processors switch the F-DO channels between ON and OFF and compare, via readback, whether each channel actually reaches the required state. When this comparison fails, the drive stores a diagnostic word in r0949 that names the affected channel, the test stop state in which it happened and the reason.

The fault always arises on processor 1 during the F-DO test stop; the reason code Y in the fault value distinguishes the cases:

• Y = 1: processor 2 was in an incorrect test stop state — an internal fault.
• Y = 2: the expected states of the DOs were not fulfilled; the readback runs via DI 22 on a CU305 and via DI 5 on a CU240.
• Y = 3: an incorrect timer state on processor 1 — an internal fault.
• Y = 4: the expected states of the diag DOs were not fulfilled (CU305: internal readback on processor 2).
• Y = 5: the expected states of the second diag DOs were not fulfilled (CU305: internal readback on processor 1).

If several test stop faults have occurred, the first one that occurred is the one shown.

1. Check the wiring of the failsafe digital output (F-DO).
2. Restart the test stop.
3. If the restarted test stop is completed successfully, the fault withdraws itself; if further test stop faults are queued, the next one is then signaled.

The drive writes the diagnostic word of this fault into r0949, to be interpreted hexadecimal. It is structured RRRVWXYZ, one nibble per function:

• R: reserved.
• V: the actual state of the affected DO channel on processor 1 — what was read back from the hardware (bit 0 = DO 0, bit 1 = DO 1, etc.).
• W: the state required for this channel.
• X: the DO channels involved, bit 0 = DO 0, bit 1 = DO 1, etc.
• Y: the reason for the test stop fault, as listed under causes.
• Z: the test stop state in which the fault occurred. States 0 to 3 form the synchronization phase between the two processors without any switching operations; states 4 to 13 alternate switching and checking — both channels OFF, check, DO + ON and DO - ON, check, DO + OFF and DO - ON, check, DO + ON and DO - OFF, check, both channels OFF again, final check; state 14 is the end of the test stop.

For the reasons 2, 4 and 5, the fields X and V carry the DI or diag DO state instead of the DO state. In the manual's example, F01773 is signaled with 0001_0127 while the paired processor-2 fault F30773 shows 0000_0127: after DO-0 was switched ON, the check in state Z = 7 did not confirm the external readback (Y = 2) — 0 was expected (W = 0) but 1 (V = 1) was read back from the hardware, whereas processor 2 saw the states as expected.

• r0949 — fault value: read the diagnostic word of this test stop fault here and interpret it hexadecimal, as described under fault value.

This fault is acknowledged by a POWER ON — switch the drive off and on again. Afterwards restart the test stop; once it runs through without a discrepancy the fault disappears, and any further queued test stop fault is then displayed in the same way.