Timers or Counters?

[AutoNub]

I'm using PC Worx and am trying to program something to keep track of the time a particular product is operational using years, months, days, hours, minutes, seconds format. I want to assign these time units or integer values to a variable to in turn display them on my HMI. It has been a while since I last worked with timers or counter though and my attempts today have failed. I suspect this is a pretty simple task for experienced programmers, so I wonder if someone would show me? I have been using LogicPro as my simulator...

Just use a simple normally open contact to simulate the on condition. I'm primarily interested in knowing how to increment and retain the time units to be stored so they can be used on my HMI. Any assistance will be appreciated! Thanks!

 

[dbh6]

I have not used PC Worx neither am i sure what that is, but ill try and explain how i would do it theoretically using ladder logic. Generally in Allen bradley, GE and other brands of PLC's, their are memory address specifically assigned to serve as your free running clock, which you can use to represent your year, month, days, hours, minutes, seconds and even microseconds in some PLC's.

Based on your example when the NO contact goes High or On you can move (MOV)these memory locations to another memory locations that each time the NO contact goes high a new set of data can be moved from your free running clock.

As for the Counter you can use it in this manner when the NO open contact goes high have the counter increment, this counter will tell you how many times the particular has activated from an "off" or inactive conditions.

For your timer, if i understood you correctly you want to be able to time each that "On" condition occurred and accumulate that time so you will have the ability to tell how long the particular product was on so that once a specific time is reached you can take the necessary action.

If you have a RTO (Retentive Timer) this can be easily done. When you have the "On" condition put it in series with an RTO timer the timer will increment based on your time base, and the best part about this timer is, if your "On" condition goes away the accumulated time won't be reset. Hope this helps