HI all, Sorry if this has been discussed already. But I couldn't find an answer.

I'm training with a S7-1200 1214C. I created a function block to control a VFD with common Start/Stop logic and also added a fail2Run logic and speed ramp up and down. To manage these 2 functionalities I created 2 timers (multi instance) but for some reason the 1 second timer used for ramping works but the 5 seconds timer for the fail2Run counts but never sets the Q.

Any idea on what I'm doing wrong?

I found the reason, timer input condition start is "related" to the fault as it is used as interlock.

the moment I got rid of the fault from the start the timer worked. 

So I guess the question now is, how can I still use the fault as interlock without having start and fault related? Could be also because start and fault are both declared as Output? 

Thanks