An Obvious and easy one? - Motor control with lvl switches (Ladder)

Hello,

I think this is obvious and basic, but I know you (readers) are more expert than I am new, so here goes...

I have a motor and a tank. The tank has three level switches, HIHI, HI and LO, all three are normally open.

I want to control the motor so that when the HI trips (closes) (LO is already closed) the motor pumps down the tank UNTIL LO is reset. The process repeats ONLY when HI trips (closes) again.

This seems easy, but I'm just second-guessing that it can easilly be coded without something other than an OR rung.

Any help appreciated! Thanks.

See Pic:

Thanks, Mickey.

I'll test this out tomorrow (but programming it now!)

Cheers,

Tim

Dear TimD
I think below logic can help you. altought i forgot to place a NOT gate in output!
All you want that motor start when LS-L and LS-H are active. then motor stay on this state until both of them changed to inactive.and The process repeats.

the output of this logic is(with an "NOT" gate):
(read up to down)
LS-L LS-H OUTPUT
0 00000000000
0 10000000000 (remain in pervious state)
0 10000100001 (toggle)
0 10000000001 (remain in pervious state)
0 00000000000 (toggle)
(repeat above)

Best regards.
J-P

I would put the HIHI switch in parallel with the HI switch, just in case the HI switch failed, you would still avoid over filling the tank. Also, use the HIHI switch to sound an alarm or stop filling or both.

Hi Ken, great idea, thanks, I'm going to use that LSHH as standard practice now.

John, thanks for the circuit explanation, also helpful as I am used to seeing gates obviously on schematics, this helps me visualize what I am supposed to be doing electronically, very useful!

Thanks to all!!

Cheers

Tim