I am attempting to create a connection between my One Link smoke alarm network and an arduino by using an old one link alarm as a bridge to the arduino. I have located two connectors on the one link board that say RS232 in and RS232 Out. However, they do not appear to have the standard 12v on them. When the alarm is sounding, the out pin reads about 6mV between itself and ground. I am trying to figure out a way to signal the arduino using this voltage. The other option would be to utilize the alarm speaker connection which I have disconnected from the speaker. That appears to send a pulse at a specific frequency to make the speaker alarm at a certain tone. Is there any chance of connecting that to the arduino and triggering an action. I don't want to experiment with connections as I don't want to fry my arduino. I have enough understanding of electricity and circuits to learn more, but not enough to know exactly how to make this work right now. Ultimately I would like to have the arduino send an email to me if the alarms sound. I just need to get the signaling part down and then I will start to investigate the code. Thanks for any help you can provide.