Alpha 2 - Counter / Flip Flop

[Lectrician]

Hi.

I don't do massive amounts with PLCs, but thought I could quickly knock up some logic, but am struggling a little for the best way.

I want to use a single input which when turned on, turns on an output 1.  When turned off, output 1 goes off.  When the same input comes on again, it should turn on output 2 instead, when it goes off, output 2 would go off.  I would usually achieve this without a PLC, using an impulse relay.  What I need though is THREE outputs to operate one after the other.

This is for 3 pumps, so when called, each pump takes its turn.  There is to be a timer which if exceeded brings the next pump on too, but that I can hopefully add, I just seem to be struggling with the best method of the sequential switching of the outputs.

I'm using an Alpha 2 as I have the programming lead and software, and have used them before for swimming pool pumps and fountain displays.  Thought I could do this too, but can't quite grasp the best method.  There is no counter I can see that you can "check" for it's value?

Any pointers would be great.

Thanks.

Edited February 24, 2021 by Lectrician

[JustinSmith]

you could do a comparison of an int that has a value that ranges 0-2. Just make sure the sequence isnt messed up on a power cycle. Never used alpha 2 controllers

[Lectrician]

Thanks.

Looking at it fresh this morning, I have it working.

I have taken the digital input to a counter.  I have used 3 compare functions to compare the counter to 1, 2, 3.  I have used a pulse function on count 3 to reset the counter.

So my next challenge is to use 3 new inputs to enable each pump.  This seems simple, take an input to an and gate so the pump only comes on during the cycle if its input is on, but I need to force the next output to come on if the preceeding input is not allowed to come on.

Hope that makes sense!  Basically, if there are 3 pumps doing the same job, input 1 cycles through these pumps, giving them all a turn at doing their job, but if a pump is switched off for maintenance, the logic needs to jump that output and turn on the next. If two pumps are turned off for maintenance, input 1 should just turn on/off the single remaining output each time.  It seems so simple in my head, but not on paper :-/

Edited February 24, 2021 by Lectrician

[Lectrician]

If Siemens Logo is a better option, I’d look into that, but don’t have software or a programming lead.  Id offer a commission to do a program if interested, but would need to be a little clearer on the needs