Use temperature sensor to trigger RR command
I have the four-input temperature sensor connected my comm port. Since I only use two of the sensors, I came up with the idea of using one of the others to monitor the IGN wire of my car so that I can do things in software when the ignition goes on or off.
A simple way of rigging this would be to put a relay on a temperature sensor so that it is only connected when the IGN is on, so RR will only receive data from this sensor when the IGN is on.
But I have no idea how to monitor this sensor with RR. I do not understand how this "tmr" or "timer" function works. "tempX" is going to be either a number or null, I guess. I'd need to execute a command both when this changes from a number to null and vice versa.
(My goal with this is to trigger a preexisting phidgets relay to keep the RMS wire of my power supply high, so that it doesn't turn off when I turn off the ignition. Instead it will turn off the screen, pause the music, and wait a half hour before hibernating. If the RMS goes high again before that time, it will turn on the screen and resume the music. Right now I run a command to turn on the relay manually when I have run in a store or whatever.)