I have a three pump sequencer with some of the features you might want.
I am not proud of the logic I ended up with but would be glad to post it (tomorrow at the soonest).
It works
And, as required by the boss, allows the Micrologix to be completely bypassed by manual/off/auto selector switches.
The three pumps are given a maximum run time, minimum run time, and minimum off time.
My wastewater pit pump sequencer was born on a Tuesday when a Team Leader approached me with, "Hey, Paul, we're adding a third pit pump Sunday." [me, 'Oh really?'] "And we need it to be added to the controls so that it works with the other two, can you take care of that for me? Thanks..." "Oh, and we have to do this while it's running. We can maybe shut it down for about two hours at a time but only on a weekend....and there's no prints, but Bubba has some old books on the level probe..."
The pit level is measured by an antique level probe controller across the room from the motor panel. Demand is in the form of two digital inputs, one for one pump, two for two pumps, and we never run more than two pumps, so that might need to be edited for your purposes.
When a pump is turned off, it is skipped by the sequencer.
I added runtime totalizers too, but have not been back there to go online to see how well balanced they are.
It has been running for a couple months now. I need to go online and take a fresh look at that job soon, as I am sure I can do better with the logic now that I have freshly forgotten it...
Paul
