Unfortunately things haven’t gone quite as I had hoped, although I’m hoping this is more of a hiccup than anything else.
I have learned a few things about this GSM module:
Once you have installed a SIM you need to power cycle it before it will register
There are several LEDs on it – one of which is for power, and other for signal. This blinks very slowly before the SIM is registered, and then rapidly once it is registered.
I am not quite sure whether the pins are labelled properly
Having done a lot of fiddling around I have not been able to get any response out of the GSM unit by connecting it to the alarm panel. It should be showing a signal strength which it reads out from the module but it’s not showing. Similarly I can’t get it to send any kind of messages so there’s obviously something up.
My instinct is that it is not communicating at all, and there is something wrong with the interface between the panel and the module. The next thing to do is to try and interface with the module itself. I didn’t have anything suitable so looking on ebay I found this:
I liked this partly because it was cheap (£2.70) and also because it came with a short cable as shown to connect up the individual pins. It has arrived, and so the next thing to do is hook it up to the GSM module and see if I can get any communication going. This will let me confirm that the pinout is correct, and also what the baud rate etc should be because the alarm panel is expecting 9600 8-N-1.
I’ll post again once I’ve had a chance to test it.