Hi @Ssparky (Customer)​ 

Can you tell us what PLC you are using?

You are correct in thinking about using the comparison instructions in the program.

Thanks,

Garry

https://accautomation.ca/series/click-plc/

https://accautomation.ca/series/brx-do-more-plc/

https://accautomation.ca/series/productivity-1000-plc/

Here is a Click example. In my case, the tank is a remote PLC but the principle is the same. I have separate subroutine where I map the C15 bit to the actual output. I use SET and RESET instructions so that the state of the fill operation is retained in the event of a power cycle or program download. I use debounce timers to make sure the tank level truly is at or beyond the setpoint and not just a blip of the transmitter signal caused by noise or someone briefly opening a sample port. I also have a separate alarm subroutine that checks the health of my 4 to 20mA sensor and sets the alarm T48 if that signal is out of range for a couple of seconds. That alarm will also stop the fill cycle.