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General => Technical support => Topic started by: gillecaluim on June 22, 2018, 11:03:38 AM

Title: HVAC controller
Post by: gillecaluim on June 22, 2018, 11:03:38 AM

I'm new to programming the PLC
I'm trying to design a zoned HVAC system controller for a dual stage heat pump.
Most of the ladder logic is working but I'm trying to get a few extra features
After a heating/cooling call is finished, I'd like to keep the fan running and damper open for a set period of time to flush the conditioned air out of the system.
so, what is the most efficient way to create a limited time pulse width on the falling edge of a relay coil so that when the heating/cooling call is finished the fan runs a little longer?

Title: Re:HVAC controller
Post by: gillecaluim on June 22, 2018, 02:54:49 PM

never mind, found a demo that solved the situation.
using a latch & timer circuit  :)

Title: Re:HVAC controller
Post by: garysdickinson on June 22, 2018, 03:51:02 PM

I know that you found an answer.  

I'd already worked up an example of how I handle this issue.  So I thought that I might as well post it.

Best regards,

Gary D*ckinson