AHowellPG (Customer) asked a question.
I have a couple of BRX PLC's driving a seed conditioning plant and we have a lot of motors/belts/etc. and I'm trying to get a PM schedule built into the PLC and HMI.
Essentially, I'm trying to figure out the best practice to create an uptimer so if Y1-57 are active (per output), accumulate on a timer to run a maintenance clock, after X hours perform X service. On the HMI display a bank of the timer's .acc value, and allow for a reset from the HMI once PM has been performed.
In my googling and video watching so far I'm not sure that a retentive timer alone will suit my needs because from what I can understand from the videos I've watched so far, anytime the PLC is switched to program mode for a programming change then back to run it will reset the timers which is good for troubleshooting but may be a problem in my case as we are in a constant state of tweaking and reprogramming to add features/fix problems I create :).
Am I understanding the retentive nature of accumulating timers incorrectly? If so, that may solve my problem entirely.
Thanks in advance!
See TMRAG - Global Timer.
I should have asked the duration of these. Millisecond resolution Timer is probably not necessary. The maximum range is around 2Billion milliseconds, which is slightly more than 24 days, or 596 hours. What is the max PM schedule?
If not, you will have to write some logic using ST4 (1 second on/off) differential countact and some INC boxes to count SECONDSs in a D (so 2 billion SECONDS), so 1000x or range of 596,000 hours or 24,000 days.
I had tried a few of them so far but hadn't gotten to that one. I wasn't sure since it doesn't have a reset bit if it would function for the required task, it makes more sense now that I read it better that you actually *need* to run a timer reset bit so that you can reset it.
The time limitation may suffice for bearing, belt, and cleanliness maintenance, I'll need to check with our maintenance lead on what timing they expect/pull manuals and read it myself to make sure. I suspect there may be a few that don't need checked as often, but I do like your idea of using an ST4(or an ST3 for longer term. With that in mind, I am already doing some similar time conversions to measure RPM with some prox sensors on conveyor shafts that has been working pretty reliably using up counters in conjunction with timers. Retention after programming changes was the key I was missing as I couldn't get it from that.
I'll give it a whirl and see what I come up with. Thank you for the suggestion!
To Reset those, use RSTT (Reset Timer) box. Just tie your specific HMI bit to the rung to reset the specific timer (and have the rung also RST the HMI bit). The HMI screen should see the time go from (say) 151 hours to 0 hours for that specific schedule bit/timer pair.
My thoughts exactly, I'll let you know how it goes, I think that was the missing link I was looking for.