Stop Watch PLC

Hi team

A little new to this.

I want to create a PLC program that will start and stop a stopwatch.

I need one input (A0) to close the start/stop output to the stopwatch (QA0) and a second input (A1) to do exactly the same.

However, I don't want the stop watch to start if the first input (A0) is closed again whilst timing - only once the second input (A1) has closed can it stop.

Help?

Your logic is a bit unclear.

You need to define the relationship between the inputs and the output more clearly.

If the output is ON because a specific input started it and that affects the logic then you may need internal logic bits to retain that status.

Also, it isn't necessary but it may be helpful if you would identify the specific PLC you are targeting.

From the description it sounds like the stopwatch is external to the PLC and the PLC is just controlling its start/stop. It also sounds like you are trying to time two possibly near simultaneous events. You might expand on that.

Thanks Bernie.

Yes - external stopwatch.

It is a Array SR22MRDC.

It is used in competition scene where a beam start will start the stopwatch, and a second beam will stop it. But I don't want the watch to stop again if someone mistakingly walks through first beam.

So A0 - start, A0 - stop : both to same output QA0.

I am using SuperCAD.

It sounds like a simple latch circuit.

You have something like this:

   Input 1      Input 2         Output

------] [------+------]\[---------------( )

                 |

   Output  |

------] [------+

And - since I'm not familiar with that PL I'm assuming it uses basic ladder programming.