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AssuredElectrical, Master Electrician
Category: Electrical
Satisfied Customers: 4241
Experience:  Contractor-42+ Years in the ElectricalTrade
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Im using Direct Logic PLC Unit DL105. Im using Direct Logic

Customer Question

Im using Direct Logic PLC Unit DL105.
Im using Direct Logic DL105 PLC
I cannot figure out a way to input an "alternating" relay in the ladder logic.
Example Every time x1 closes I want the relay to alternate between Y0 & Y1
I've been trying for hours and hours. I will pay very well for the answer!!
Submitted: 2 years ago.
Category: Electrical
Expert:  AssuredElectrical replied 2 years ago.

Welcome. My name is ***** ***** would be glad to assist.

When Y0 or Y1 coils are on, what are they controlling?

Is there feedback of any type from the items being turned on or off?

If you can give some details of the actual sequence taking place once Y0 or Y1 is turned on, it may help to determine best way to try and get the alternation.

Let me know and we can continue,


Customer: replied 2 years ago.
Whex x1 closes y1 signals a motor starter that runs a pump. The floats turn it on and off. But their are 2 pumps. I want the pumps to alternals from y0 and y1. Float 1 is x1 Float 2 is x2. If you can show me a basic way to do this i can out it in my ladder logic. Right now I have mechanical alternating relay doing this and I like to do it with the PLC. Hope that's enough info to your wanting
Expert:  AssuredElectrical replied 2 years ago.

Ok, thanks.

Please clarify the floats.

I am assuming, You have a low and high level float? X1 is low and X2 is high ?

Will look over the info and see can be worked out and post tomorrow..


Expert:  AssuredElectrical replied 2 years ago.

Ok, have a possibility below as seen in the picture.

ONLY need something to perform a Rest on the counter after the sequence is over, will be looking into that shortly.

Look it over and you can even try it, just no real world output connections.

You can force the inputs on and off to simulate the sequence and then force a contact for the reset and verify it working.

Hopefully will have the rest answer before long, still working on the situation.

This is based on standard pump level control with a low and high level floats.

Expert:  AssuredElectrical replied 2 years ago.

Do you have anything that takes place after the pump has shutdown, perhaps?

We just need something to trigger a Reset on the counter when the second run has taken place?

Might be able to use the low level float to trigger another counter and us it on the last run, to be the counters


I did not want to get into a logic read situation where it could get out of sink.

Let me know if you can do the simulation as posted and hand force what takes place for verification.

That is what we do on all programs, trigger and make them run off line to verify prior to going live.

Use dummy coils and then change them later.

Customer: replied 2 years ago.
I have this all pre built on my desk using limit switches and light bulbs for test run. How i do it before loading any software permentally. This is an 22 page ladder logic for what im designing. Just stuck on the alternating pumps. One NO float at top of pit and 1 NO float at bottom of pit.
X1 is top float x2 is bottom float. Just need YO = pump 1 and Y1 = pump 2 output alternater. If you just make any kind of alternating circuit silimar to my description will be good enough. Then i can see how its performed and incorporate it into my ladder logic. I cant think of any other ways to explain sorry. Hope this help. Ill look at your 2 attachments soon as i get home.
Thanks allot. I will compensate you for all your time. Just keep track of it please.
Thank you
Expert:  AssuredElectrical replied 2 years ago.

Ok, I just updated the ladder logic to match your float switches, have the X2 as low level and X1 as high level now.

It should work, still trying to determine the best way to Reset the counter, the rest should work in simulation.

Expert:  AssuredElectrical replied 2 years ago.

Sorry about the previous diagrams, wrote the low level like you would with standard wiring format and power flow, not the PLC.

Updated is below, the X2 will make on rise in water and actually be a NC but in the logic, it needs to be written as NO so the bit 1 will set the contact as closed and power flow.