A01699 — SI P1 (CU): Test stop for STO required

The manuals print this message as SI P1 (CU): Test stop for STO required. The Safety Integrated (SI) monitoring in the Control Unit (CU) has established that the time set in p9659 for the forced checking procedure (test stop) of the "STO" function (Safe Torque Off) has been exceeded, so a new forced checking procedure is required. The message does not result in a safety stop response — the drive keeps operating. Depending on the drive's configuration, the same condition can also be raised as a fault. On the G120C the instruction manual lists the message in its short table as Switch-off signal path test required.

• The time set in p9659 for the forced checking procedure (test stop) of the "STO" function has been exceeded; a new forced checking procedure is required.
• The test must be performed within the defined maximum time interval (p9659, maximum of 9000 hours) so that timely fault detection complies with the requirements laid down in the standards and the failure rates of the safety functions (PFH value) can be calculated.

1. Check the test interval configured in p9659 (SI forced checking procedure timer) and read the remaining time in r9660 (SI forced checking procedure remaining time).
2. Carry out the remedy: select STO and then deselect it again. After the next deselection of STO the message is withdrawn and the monitoring time is reset.
3. Operation beyond the maximum time period is permissible only if it can be ensured that the forced checking procedure is performed before persons enter the hazardous area who are depending on the safety functions correctly functioning.

• p9659 (SI forced checking procedure timer): sets the maximum time interval within which the forced checking procedure (test stop) for STO must be performed; the message appears once this time has been exceeded, with a maximum of 9000 hours.
• r9660 (SI forced checking procedure remaining time): shows how much time is still left before the forced checking procedure for STO becomes due — read it to see how soon the test stop has to be carried out.

The alarm needs no acknowledgement: after the next time the STO function is deselected, the message is withdrawn by itself and the monitoring time (p9659) is reset. If the drive has raised the condition as a fault instead, acknowledge it — the drive permits immediate acknowledgement (POWER ON) — and perform the STO select/deselect so the monitoring time restarts. Because no safety stop response has taken place, the drive itself does not need to be restarted.