Siemens S7 200, no timers or counters allowed in subroutine

Rudolph · Mar 18, 2009

I'm new to PLC'S and I was given the task to program a valve with a HL and LL. If HIGH LIMIT isn't reached within 15s you must have a FAIL_TO_OPEN and if LOW LIMIT isn't reached in 15 seconds you must have a FAIL_TO_CLOSE. In the same breath i also had to program a MANUAL_OPEN, AUTO_OPEN, AUTO_MANUAL_OPEN, MANUAL_CLOSE, AUTO_CLOSE and an AUTO_MANUAL_CLOSE for the valve, but this is not my problem. My problem is to get the logic process working for the 15second count without using a TIMER or COUNTER in my subroutine(boss's rules). I know i must use a ADD_I(interger) along with some sort of pulse but i'm stuck and don't know where to go with this. Can anyone give me some guidence or help??

bkottaras · Mar 18, 2009

Rudolph said:
I'm new to PLC'S and I was given the task to program a valve with a HL and LL. If HIGH LIMIT isn't reached within 15s you must have a FAIL_TO_OPEN and if LOW LIMIT isn't reached in 15 seconds you must have a FAIL_TO_CLOSE. In the same breath i also had to program a MANUAL_OPEN, AUTO_OPEN, AUTO_MANUAL_OPEN, MANUAL_CLOSE, AUTO_CLOSE and an AUTO_MANUAL_CLOSE for the valve, but this is not my problem. My problem is to get the logic process working for the 15second count without using a TIMER or COUNTER in my subroutine(boss's rules). I know i must use a ADD_I(interger) along with some sort of pulse but i'm stuck and don't know where to go with this. Can anyone give me some guidence or help??

Using the Real Time Clock is an option.
Or, use an interrupt to generate a pulse every 15 seconds.

Siemens S7 200, no timers or counters allowed in subroutine

Rudolph

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bkottaras

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