Start timer and kill timer with one button

[OkiePC]

Sorry, could not help myself.

Click software is a free download, and the hardware is almost free.

https://support.automationdirect.com/products/clickplcs.html

Actually all of the A/D software except for DirectSoft is free and fully functional. The latest version of Do-More even has a built in simulator that works like a real PLC and can communicate using your PC ports (I used it to test a serial radio network!) I have not tried to use PSuite simulator for real world comms, but it might also be possible.

So drbitboy, get you some more 'o that free stuff!

 

[OkiePC]

I personally don't think a Flip-Flop is the best solution, unless it has the interlocks needed, but if the solution has the interlocks, do you need to remember ?

He needs one button to start and stop a process. This is all but the definition of a flip-flop. I don't dispute the need for proper interlocks.

 

[daba]

He needs one button to start and stop a process. This is all but the definition of a flip-flop. I don't dispute the need for proper interlocks.

flip-flop, set-reset, latch-unlatch, many implementations of similar functionality. (managed to get some long words in there!).

Many processor don't have J-K flip-flops, or any other variants I have forgotten (just remembered D-Type). I don't use them, I code to what is needed in any situation.

The point I was making was that he needs to consider the outcomes of power reset etc., and to act on them accordingly. Sometimes the inbuilt instructions don't "behave" in your favour, and you should code accordingly. Perhaps one of your 18 flip-flop methods might suit his needs.

 

[drbitboy]

Alternative, very similar to my previous flip-flop approach.

Pump should go off on power failure and stay off when power is restored (no Set/Reset), for both approaches.

########################################################################
### Detect rising edge (one-shot; ons) of Pushbutton input X001
### N.B. X001 may need a debounce

   X001              PBons
---]^[---------------(OUT)--------

########################################################################
### Timer driven by pump being 1

  Y001/Y002                            B<T1>
-----] [-------[Timer(On delay)  T1]-----o
               [...                ] 

########################################################################
### Pump output Y001/Y002 is State Coil/Fault coil circuit cf.
### http://www.contactandcoil.com/patterns-of-ladder-logic-programming/
### - {Trigger} is Pushbutton one-shot when pump is not running
### - {Break condition} is {T1 timing complete OR PB rising edge}

      Y001/Y002   PBons            Y001/Y002
---+-----]/[-------] [----------+----(OUT)-----
   |                            |
   |  Y001/Y002   B<T1>  PBons  |
   +-----] [-------]/[----]/[---+

Caveats

* Assumes synchronous, sequential (non-overlapping) I/O and program scans
* The {NOT PBons} of the break condition on the last rung could be moved to the second rung