Help on ladder logic

Describe your system and processes, and post your config file.
losco70
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Re: Help on ladder logic

Post by losco70 » Thu Nov 02, 2017 9:55 am

Hi JonW, on my panel I have a "push once" button and I would find a solution without changing my hardware...

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JonW
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Re: Help on ladder logic

Post by JonW » Thu Nov 02, 2017 10:12 am

It gets a bit more complicated, but it could still be done. I do something similar with my water fill process.

With a momentary switch, you would need to keep the process running all the time, but use the switch to jump states. By having state 0 of the process setup as something like "Wait for start", you can site idle at state 0, then upon press, jump to state 1. You can then still have multiple states in the process, but each state of the process should have an exit condition based on the DIN that would jump back to state 0 if the DIN were pressed.

Note that this isn't a ladder logic solution, but instead uses the exit conditions to jump through the process.

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Re: Help on ladder logic

Post by losco70 » Thu Nov 02, 2017 10:45 am

I will try this
thank you JonW

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oakbarn
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Re: Help on ladder logic

Post by oakbarn » Sat Nov 04, 2017 6:51 am

You can also set DIN 1 as an Exit Condition on Process 5 States then End Process. You would need top set that as one of the Exit Condition on ALL States of Process 5.

You would still use Ladder Logic to Start the Process.

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Re: Help on ladder logic

Post by oakbarn » Sat Nov 04, 2017 10:18 am

I tried to do this and run into a problem with logic. If you use one shot or a push button switch, the Process will come on and immediately Stop.

If you use a Toggle and have the DIN ON (and not one shot), the Process will stay on as long as the DIN is ON. Turn the DIN OFF and the Process Stops. The issue with this is that that is the only way to Stop the Process is to turn OFF the DIN. If the Din is still ON, and you Stop the Process on an Exit Condition or ALL STOP, the Process will immediately be ON at State 0.

You cannot use a Register to get around this as it Turns on on Exit of a State. If you had another Process State that proceeds Process 5 that has exited a State, you might be able to use it in Ladder Logic.


I actually use Four DINs with Toggle switches (One is a Push Button for the Alarm Cancel.) I use them to advance States (and can use them Stop Process as the Next State if I want to kill the Process) and use the Process Editor to Start a Process on Exit.

For Example, the Next to Last State of my Sparge Process (Process 3) is Obtain Boil. It Exists on Boil Temp reading 210 F (99c), I then have the Start Process 4 (Boil Process) Start and my Boil Timer Starts. I do not have to watch when the Wort Starts to Boil. I do sound an alarm so that I can adjust the flame on my Burner.

I do have 2 BCS 462s. One for Hot Side and then one for Fermentation. That way, I never mess with my Fermentation when brewing a new batch.

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