DC motor polarity reversal with a twist
I have an idea to enable the use of an Estopp electric parking brake actuator via the keypad instead of the button and control module that comes with it. The actuator only has two wires so I am assuming that the parking brake control module reverses polarity to the actuator. There is no limit switch or anything that would break the circuit so I assume module turns off the power to the actuator based on amp draw or based on time. My thought is that I can wire up two relays with each one providing ground to each wire to the actuator in the normally closed position. Each relay would be on a separate output in the PDM. Then when I activate one output or the other to apply or release the parking brake, it will provide power to one of the relays and energize the relay at the same time. Then I will have one relay providing ground and one providing power and the actuator will start moving. I can experiment with the configuration and turn off each output based on time or amp draw. I have two questions. If I did this based on time, how do I do that. I have not done that yet, if it can be done. If I do it based on amp draw, can it trip and reset but not retry?
I'd hook the actuator direct to power and verify it really does not have a limt switch in it, as a small actuator I use for a different application does, even though it doesn't appear to.
If you need to use time based, I believe you can use the Timer feature in Duration mode. George had given me advice on setting up a Counter that was time based, but it was a loop because it needed to reset when the duration expired.
I think your output would then refernce 1) the button is on, and 2) the timer is true.