Microcontroller

[Franklin97355]

Are you checking for resistance? (Ohms)

[sk854016]

Yeah I checked for that

[Franklin97355]

Yeah I checked for that

And what did you get when you measured between COM and NO when the relay was activated and when it wasn't?

[sk854016]

When the relay is not active it read a 1 , when it is active it read a 0

[Franklin97355]

Then it is working.

[sk854016]

Why does no voltage appear when the relay is active

[Franklin97355]

Why does no voltage appear when the relay is active

It is a switch and connects COM to the NO pin when activated nothing more. Check out how a relay works

[sk854016]

I understand that, what I am saying is that I have a positive and negative power supply running to the DC+ and DC- ports. The NC NO and COM ports do not have any reading in regards to any voltage at all. They have ohm readings but the voltage is not reaching the output ports.

[Franklin97355]

but the voltage is not reaching the output ports.

It is not supposed to. Please read the manual for your thermostat so you will understand what should be happening.

[sk854016]

Shouldn't I be getting a reading of 12v from the Com and NC port when the relay is not activated?

[Franklin97355]

http://www.learningaboutelectronics.com ... witch-SPDT
http://www.learningaboutelectronics.com ... -a-circuit

[sk854016]

I think I understand now, I would connect my 12v power source to the DC+ and DC- ports. Also I would run a wire from my DC + port to my COM port so when the relay is active it connects to the NO port.

[sk854016]

So, my virginmobile phone sim card doesn't work with the sim900 shield for the arduino. I was suggested to use a Ting sim card through Aadfruit. This would work well with a sim900 shield? What would be the cost per sms?

[Franklin97355]

Which shield are you interested in?

[sk854016]

This is the shield
http://m.banggood.com/SIM900-Quad-band- ... aQodhgAGsQ