Texecom Premier 24 Burglar Alarm GSM
I recently switched broadband providers from Sky to Virgin Media, one of the side effects of this is that I no longer need a landline phone line. A downside of this was that my burglar alarm could no longer talk to the outside world. (I was using a Texecom Com2400 PSTN telephony module)
Since it was a pretty safe bet that the communications ports on the control panel motherboard were standard RS232 serial, I did a bit of googling to confirm that theory.. and quickly discovered that was a correct assumption. I hooked up a Chinese knock-off FTDI RS232-> USB adapter (99p), connected it up following the pinout I found online, and drilled a hole to allow me to mount the usb connector on the side of the panel.
I can now program the panel using Texecom's Wintex software simply by connecting up a USB to the side of the panel. This is a simpler and cheaper option than the official Texecom USB-COM (£36)
Hot off the heels of that success I thought I might be able to build a replacement for the official Texecom device designed to allow control and reporting via GSM (The ComGSM - Priced at £165), so I configured the second COM port to be a ComGSM.. fired up the Logic Analyser and had a look.
It turns out the system pretty much talks standard GSM AT commands. I pulled out a SIM800L EVB (£7) module (I've used these at work), and wired it up with 5V from a regulator attached to the 12V output of the control panel, then plugged its TX and RX into the panel, rebooted it and to my surprise it just works. I can now send SMS messages to the alarm to arm/disarm the alarm, as well as checking status. The alarm will also text me if it is activated.
All in all a great success.