I'm wanting to interface with my alarm dialler. Apparently
PROGRAMMABLE OUTPUT
The SD1+ has a single programmable output. When active the output
applies 0V to its terminal and is capable of sinking up to 100mA of current.
Forgive me, but what does this mean in terms of using it with an Arduino? Would I look for an I/O pin pulled low that is normally high? THANKS
it means nothing to us.
since the alarm dialer output has no use to the Arduino, output is information that is not needed.
what is needed is what the input would be.
since there seems to be almost no information and there is no description of what you want other than to 'interface' it might be a good idea to give a better description of what you have and what you want it to do.
then post links to the data sheets or instructions for the device.
we can take wild guesses and speculate that when INactive, the SD1+ OUTPUT (misnomer) is neither grounded nor providing any voltage on the output
with it is active, it brings said pin to ground, and will sink up to 100mA. that means you can easily light an LED, that means you can activate an opto-isolator and that means you can get a signal showing the thing is active.
we still have no clue what active means.
The manual for an SD1+ Speech Dialler, which I think is the device the OP is refering to, can be found here;
https://docs-emea.rs-online.com/webdocs/0638/0900766b806385bd.pdf
Pages 5 & 11 refer to the output.
"The SD1+ has a programmable transistor output capable of supplying 100mA of current. This output can be activated when the SD1+ is triggered, when an alarm has been successfully transmitted or acknowledged, or when the SD1+ detects a communication error".
"The SD1+ has a programmable transistor output (switched to0V when active) for various function assignments".
I guess the OP wants an Arduino to monitor the ouptut and do something when the SD1+ signals an alarm condition has happened. Note the OP said the ouptut could sink 100mA but this manual says it can supply 100mA.
Really sorry I haven't been back to reply (or even read) these replies since I posted my initial question! I didn't think I'd had any replies. I'd set the topic to send me an email if any replies came in and as I got no email, I presumed the topic had gone unanswered. So please don't take my tardy reply as a lack of gratitude.
It looks like annoyingly there is an error in the printing of the spec sheet I found (and which I meant to link to in my original post). Thanks for making me look even more of a buffoon, printing error!
Dave in NJ, to answer your question, I wish to do as ardly figured out: I want to use an Arduino to monitor the SD1+ for an alarm condition. I'm mainly struggling with what "switched to 0v" means. Switching something to 0v to me, an electronics noob, suggests turning something OFF! 
Thanks all
Dan_ce:
Really sorry I haven't been back to reply (or even read) these replies since I posted my initial question! I didn't think I'd had any replies. I'd set the topic to send me an email if any replies came in and as I got no email, I presumed the topic had gone unanswered. So please don't take my tardy reply as a lack of gratitude.It looks like annoyingly there is an error in the printing of the spec sheet I found (and which I meant to link to in my original post). Thanks for making me look even more of a buffoon, printing error!
Dave in NJ, to answer your question, I wish to do as ardly figured out: I want to use an Arduino to monitor the SD1+ for an alarm condition. I'm mainly struggling with what "switched to 0v" means. Switching something to 0v to me, an electronics noob, suggests turning something OFF!
Thanks all
Actually, it means the pin is connected to the device ground and can carry up to one amp. Sounds like a relay terminal. So it could activate a pretty good sized relay, or could set an Arduino pin to zero it if was defined as input with internal pullup resistor.
Why they wrote it that way, I don't know. Some beginning technical writer, I suppose.
Paul