# ID 270053

Watchdog: CNC monitors PLC - No sign of life of PLC. |
Description | The CNC monitors the PLC to see whether it gives a cyclic life sign. The monitor responds and reports that the PLC gave no life sign within the agreed time interval. One possible cause may be an unfavourable parameterisation of task priorities. When the watchdog mechanism is used, the PLC task must have a high priority.

See also:

[HLI// Section: Watchdog mechanism] for CNC Version < 2800
[HLI// Section: Watchdog mechanism] for CNC Version > 2800

Response | Class | 3 | Abort current job. |
Solution | Class | 6 | The PLC activated the monitor via the HLI. The PLC also specified the time interval within which it gives a life sign via the HLI. Therefore, check the PLC cycle time and compare it with the time interval within which the PLC is to give a cyclic life sign. The time interval must have a greater value than the PLC cycle time.

Then restart the controller.

Parameter | %1: | Error value [-]
Last state of the cycle counter with valid sign of life of the PLC
%2: | Current value [-]
Current state of the cycle counter
%3: | Current value [µs]
CNC cycle time
%4: | Current value [µs]
Parameterised time of the watchdog (see control unit)
Error type | - |