Apply watchdog timer in the circuit

[jcp]

Hi experts;
How can apply a watchdog timer in the circuit (Ladder+ hardware) what type of timer is requried physicaly ?
PLease guide me with details and i need a circuit diagram?
Regards

 

[showshocka]

this is a good one. can't wait for the replies!

 

[jkerekes]

A watchdog timer is usually built into the PLC. It trips if one scan of the program takes too long to finish. What are you trying to accomplish?

 

[jcp]

Hi;
I want to do if programme takes too much time the master electromabnetic relay de-enerzie which control the critical output devices like fuel and some valve.
How can i fix this task?
regards

 

[bernie_carlton]

Here is an example from Brentek when the pulses stop the contacts can be used to break the control latch.

They also have two articles on the right side of their main page discussing the application.