Alarm system terminal with a known protocol?
Posted: Wed Sep 10, 2008 11:59 am
Hi guys,
My house came with an alarm system. It's made by an unknown Belgian brand called 'Eurotec', which seems to have gone out of business. I had a failing battery and now the names of my detector loops are gone. Those settings can only be restored by a proprietary computer program, using a proprietary cable (which is probably just a TTL-RS232 level shifter), costing over 600 Euro. So that's not going to happen.
On the other hand, I've been looking voor affordable wall-mounted terminals to control my domotica system. A full color touch-screen version is what springs to mind, but a simple 2x16 character LCD with a 3x4 keyboard would do the trick too. And that's exactly what my alarm system terminals are!
So I have been poking around these terminals. Using an oscilloscope I quickly found out that it uses a 2-wire multi-drop protocol wil RS485 signalling levels. The bit rate was a bit odd: 16.667bit/s, but using Linux I was able to manually set the bit rate devisor. So I have bought myself an Advantech Adam 4520 RS232-RS485 converter and watched the traffic. The past three evening I have spent counting bits on the oscilloscope, but nothing makes sense. I strongly suspect these critters are deviating from the standard UART transmission. I see a lot of break conditions, and it seems they are transmitting over 12 bit symbols. I have even considered the 9 data bit Philips variety, but that doesn't compute either. Now I am considering to write my own firmware for their internal PIC processor, but that's a lot of work.
<b>So my question is:</b> Does anybody know about alarm system terminals with an LCD and a keyboard and a known protocol, currently on the market? Preferably not wireless and with a price lower than 100 Euro.
My house came with an alarm system. It's made by an unknown Belgian brand called 'Eurotec', which seems to have gone out of business. I had a failing battery and now the names of my detector loops are gone. Those settings can only be restored by a proprietary computer program, using a proprietary cable (which is probably just a TTL-RS232 level shifter), costing over 600 Euro. So that's not going to happen.
On the other hand, I've been looking voor affordable wall-mounted terminals to control my domotica system. A full color touch-screen version is what springs to mind, but a simple 2x16 character LCD with a 3x4 keyboard would do the trick too. And that's exactly what my alarm system terminals are!
So I have been poking around these terminals. Using an oscilloscope I quickly found out that it uses a 2-wire multi-drop protocol wil RS485 signalling levels. The bit rate was a bit odd: 16.667bit/s, but using Linux I was able to manually set the bit rate devisor. So I have bought myself an Advantech Adam 4520 RS232-RS485 converter and watched the traffic. The past three evening I have spent counting bits on the oscilloscope, but nothing makes sense. I strongly suspect these critters are deviating from the standard UART transmission. I see a lot of break conditions, and it seems they are transmitting over 12 bit symbols. I have even considered the 9 data bit Philips variety, but that doesn't compute either. Now I am considering to write my own firmware for their internal PIC processor, but that's a lot of work.
<b>So my question is:</b> Does anybody know about alarm system terminals with an LCD and a keyboard and a known protocol, currently on the market? Preferably not wireless and with a price lower than 100 Euro.