[Logix] resetting TOT total and oldtotal

Hi all,

I've been using the TOT instruction for totalizing flows wherever I've not had flowmeters with totalizer pulses. It works great and I have it set up to reset each night at midnight to provide daily flows; I then use OldTotal to display "yesterday's flow".

One thing I can't quite figure out, though, is how you'd go about resetting both the Total and OldTotal values simultaneously. The client wants to be able to reset the flow totalizers with a button in the HMI. To reset the Total is easy I just one-shot the ProgResetReq input; but how would I go about resetting the OldTotal? The only thing I can think of is sending two pulses to ProgResetReq, but that may be a bit of a pain. I tried overwriting the OldTotal value but the TOT block repopulates the tag, so it won't be that easy. I'm going to mess with this a bit, but was wondering if you guys had any suggestions.

XIC HMI_ResetTotals ONS BST OTE Total.ProgResetReq NXB OTE OldTotal.ProgResetReq BND

... ostensibly. You can break that across two rungs.

Hi JeremyM,

Thanks for the reply.

I'm a bit confused about what exactly you're suggesting, maybe because I'm not as familiar with the FBD TOT instruction. I don't see any reference to being able to reset the Total and OldTotal separately in the 1756-RM006 instruction reference manual so I'm not sure how this would work; also, the TOT instruction is in a function block diagram routine and the totalizer is a local parameter; how would I access it in a ladder logic rung?

Am I totally missing something here?

My mistake, I thought you had two TOTALIZERS at once.

Would something like this (or the equivalent ST logic) suffice?

JeremyM said:

My mistake, I thought you had two TOTALIZERS at once.

Would something like this (or the equivalent ST logic) suffice?

Click to expand...

Indeed, just one totalizer. I can totally see your approach if you thought I had two.

As for your code example, that very well may work! Very clever with the second one shot. I'll give that a try. Thanks!!

How'd it go?

JeremyM said:

How'd it go?

Click to expand...

Haven't quite gotten to testing it, had a few things come up. Will report back when I give it a shot.