Time of day based counter.

I am trying to make different counters active and inactive at certain times of the day. This is to collect data based on what shift it is. I want one counter to count during 1st shift, one for 2nd shift, and so on.

I am new to PLC's and I have no idea how to do this.

I'm using RSLogix5000.

Put your logic for each shift in a separate program file/function (That's what it is called in AB language right?) and call the according program/file function when the shift is active.

How long do you need to retain the shift count?

If it's just 24 hours, I would use one counter. Say it starts counting at the beginning of 1st shift at 6am. At 3:30 when the shift is changing, MOV the counter accumulator (ACC) into a first shift DINT, then reset the counter. You could do this with a single rung of logic with a few branches. Use LIM instructions so that when the time reaches a shift change, it will move the ACC into the correct shift register before it resets and is ready to count again.

The counts would stay in the PLC until the following day when that shift change occurs again and the count is overwritten.

I use Limit instructions to control several time of day events. I store the set points in integer files so I can change them without entering program mode or starting edits.

First thing first, use a GSV to get the current time. Then I typically use LIM like CaspianSage mentioned.

A GSV or the Clock AOI that rockwell provides.

I used a GSV and got it working. Thanks everyone.

I also use the sample code from AB called "
Time and Date Math Add-On Instructions"

Handy functions in there for time and date.