My project is to remotely control a set of side curtains on a greenhouse to help control temperature.
At present the curtains are controlled by a Delay timer, a thermostat, a relay, 24VDC power supply and 2X 24VDC motors. Every 15 minutes the delay timer turns on for 30 seconds and based on the thermostat setting, the relay is triggered and the motors open or close the curtains about a 1 foot. The motors have built in limit switches to prevent them from going too far up or down.
The system as is works well but there is no manual control to raise the curtains or lower the curtains. I would like to have the ability to manually control the motors up or down using an Arduino and relays.
I don’t have documentation on how things are wired currently but can see that it is a little messy between timer and relay and I don’t want to break something that works. I was planning to use relays to bypass the existing setup.
Relay set 2 would be used to control power to the existing circuit or the manual override
Relay set 3 would be used to control the direction of the motors when using manual override
Do I need a 4th relay set to stop power from going into the existing circuit when manually powering the motors?
Is there a better way to setup the relays?
*Updated Post to remove reference to PLC as it is just a timer and relay with no programmability other then off and on time.
