Pico 1760 help

I have basic unserstanding of PLCs in general and I got one of these PICO controllers for a project I am working on. What I can't figure out is how to get the thing to count a value up and down. I am creating an application that I need to count products in at one input and back out at the other. The counters in the PICO don't seem to work the way I need them to. Any help would be appreciated.

Jeremy

Can you post the code you already have?

I work with larger AB PLCs and we send the upstream sensor to a CTU, then the downstream counter to a CTD with the same address as the CTU:

I:1/0 CTU C5:0 Upstream counted value

I:1/1 CTD C5:0 Downstream counted value

We rejected bad bottles, with a sensor on either side of the rejector, and if the Counter value (.ACC) ever got above a set value, we shut the filler down since we were rejecting too many bottles; indicating a problem. We set up a counter reset every so often so that high .ACC values over long periods of time would not shut the filler down.

I don't have any code really written yet. All I have been doing is some testing. The problem I am having is everytime I change the set value for a certain counter it changer all of the other values for the same counter. For instance, The counter coil on the PICO is set for 5. That means that every other instance for counter 1 is set to 5 as well. What I don't get is how it get the direction function to work. In the manual it says to set DC1 to 1 for forward and 0 to count down. But the value comes up as 5.

I may not be familiar enough with the PICO but I thought you used RSLogix to program the PICO.

The counted value (.ACC) WILL be the same for every instance the address for the counter is used. If you count up 10 items and the same 10 items pass a sensor controlling the CTD version of the same counter, the net value is zero, which is what the .ACC value will be.

Let me know what software you're using, and that might help me help you.

Picosoft. You can download it form ABs website.

Wow!

I just downloaded the Picosoft program and found out how misinformed I was; someone told me PICOS used RSLogix.

I'm gonna look through the software and see if I can help. I bet someone with experience will step up first, tho. There's some sharp tacks on this board!

Sorry I couldn't help.

I think I figured it out. I was thinking value for the direction coil. the instruction say 1 or zero but they mean on or off. Now I just got to get the counting with the pulses figured out and I should be set. I need to get a one shot at the counter not a count every pulse the input is on.

Another question for you. I am working on this counting of products in and out and I am having a hard time getting my head to think right about how to turn on nad off these outputs based on the value of a counter.

Let me expain what I am trying to do.
I am working with two label applicators on a production line. There is a signal in the applicator I can get when the first one runs out of labels. What I am trying to do is control these so that the second labeler will start labeling products when the first labeler runs out of formats. Because product spacing is inconsistant I want to count the products in at the first labeler and count them out at the second one. That way the second labeler wont start labeling products until the counter reaches 0. I also need this to go the other way as well so that when the first labeler gets more formats loaded into it I need it to start labeling them and count to let the second labeler when to quit labeling.

I hope this makes sense. Thanks for any help you can give.

You could use a counter, but in this application it might make more sense to use a shift register. The Pico doesn't have 'shifting' instructions, but you can build a shift register in ladder quite easily... :nodi:

Start reading on page 4-43 of the Pico's user manual (available HERE if you don't have it). Also see Phil's explanation of shift registers HERE...

Once you have a grasp of shift registers, come back with any questions you have... :site:

beerchug

-Eric