ComGSM update

After writing back in April about my ideas of using an off-the-shelf mobile phone module as a ComGSM I’ve not made much progress since. I did order a suitable unit from ebay direct from China, and after a few weeks it arrived.

I eventually got one of these:


I took a few photos myself but the light is a bit odd and it looks exactly the same. Predictably, there are no useful instructions with it at all, so I’ve had to make a few guesses.

It has a standard pin header on the side, which is labelled on the board from left to right as VCC, Tx, Rx and GND. There is also a power supply connector block with two screw terminals labelld + and -. This is on the left of the picture. I did find reference in the brief information I could find to its standard settings being 9600baud, 8 bits, no parity and one stop bit. This is a pretty standard configuration and the same as I used for my tests described in earlier posts.

So in the end I thought the best thing to do was take the plunge and connect it up, and see what happened. I made a link cable up out of another old motherboard cable, and wired the power into the Aux 12v supply available on the main board. This isn’t a great picture but shows everything lashed up. The antenna is out of shot but just dangling on the antenna wire at the moment.

gsm2Here I learned some more important lessons which unfortunately cost me some time. After wiring it in I tried to connect using Wintex but I couldn’t make it work. I was really worried that I’d blown something up by connecting the GSM unit and after a lot of fiddling around I finally realised that I had simply got Wintex configured for the wrong type of panel (Premier 48 rather than Elite 48)!

Once I’d got this working, I then found that all of my sensors were dead and thus I once again worried that I’d broken something. Looking closely at the board I saw a new red light beneath one of the PCB fuses for the Aux 12v supply. I had obviously shorted out the supply when wiring the GSM board at some point. I was quite impressed with the attention to detail in the design, as having a red light under the fuse immediately showed me what was wrong. After replacing the fuse all was well again. There are several very bright red lights on the GSM board itself as well.

I’ve not been able to do much more testing as I’ve not yet put a SIM with credit into it. However, I did configure COM2 for the GSM module and on running Wintex saw the following:


So it does appear that the unit is recognising the GSM unit – hence GSM status ‘Online’ in the bottom right. The signal strength is effectively non-existent but that’s not surprising given that there is no working SIM in it. Also I’m not getting any errors that the COM port won’t initialise, which you do you get if you try to configure the module with nothing actually present.

So this all looks good… next thing is to get some credit on the SIM and try sending some messages!

11 thoughts on “ComGSM update”

  1. Hi, did you make any more progress with this?

    In addition can I ask where you got the texecom software from, I can’t seem to find it for download from texecom site any more, says I need installation login?

    I have just purchased a texecom alarm system for my house and would like to set it up myself so this software would be very useful.

    Also thinking of adding the GSM module you mentioned to allow the alarm to send txt if triggered.


  2. Sorry I’ve been rubbish at updating things!

    I have hit a problem in that I am not getting any communication with the GSM unit. The ‘online’ bit is a red herring, it says that whether the unit is connected or not. I have bought a small USB serial adapter to see if I can talk to the unit directly just in case there is a problem with baud rate or something. I’ve not had time to do this yet, but when I have I will post about it.

    You do need an installation login on the Texecom website – however you can get one of these easily and for free just by registering on the site. They don’t seem to mind who does this, and anyway given that I’ve installed an alarm I feel that I qualify as an installer! I’d thoroughly recommend getting it, it has made setting up and doing troubleshooting loads easier.

    I still think the GSM module will work, it might be that the one I have is faulty or something. I’d encourage you to have a go, and please let me know how you get on. I’ll post on this shortly.

  3. Ok, well I’ve taken the plunge and ordered one of these, seems to have the UART required, and supports the standard AT command set that you discovered coming from the serial port when enabled for GSMCom, however this one run’s off of 5v and they say it needs 1.5-2 amps so I can’t pull that power from the 5v line on the serial port, so I also ordered one of these that I can connect to the 12v Aux Port on the alarm, which allows up to 1A draw, and step the voltage down to 5v for the module.

    So when it all arrives I’ll hook it up and see if I can get it to work 🙂


  4. Looks great, and in fact seems a much simpler and more compact unit than the one I got. I must say I was slightly worried about the current draw from the Aux port, as it if gets anywhere near 1 Amp it might blow the fuse again. So far in my tests it has worked fine although I’ve not had it doing anything much.

    Still not had the chance to troubleshoot my module – please let me know how you get on with yours, if it works well I’ll give up on this and get one of those instead.

  5. Hi,

    Well I got my 12v – 5v Buck converter installed and my SIM800L module, buck converter adjusted to 5.04v (closest I could get to 5v).

    Wired it all in, hooked it up to COM1 on my board, and it appears to be working, although I now have to figure out how to get the alarm configured, when I look in Wintex, I now get the GSM Status (Green) online, the GSM signal Green @-77db and the GSM Bit Error Rate : 000 Green

  6. And I’ve just completed remote arm / disarm via txt message, just need to top up the PAYG sim card in the unit to test the SMS send function. As a slight foot note I purchased the ComWifi module as this was only £35 in the UK, which means I no longer need to stand next to the panel with my laptop, much easy to configure now !

  7. And finally got the panel sending messages to my mobile for alarm and status, once I topped up the SIM, so I conclude the module I brought works 100% with the panel, I’m only using it in SMS mode rather the GPRS IP, as I have ComWifi for the IP side.

    So all in probably cost me about £15 to enable the SMS functionality, way cheaper than buying an official COM GSM module, I’m happy !

    Thanks for your initial discovery that enabled all this.

  8. That’s great Andy!

    I’m delighted that the concept is proven. I think the module I have is either faulty or has the pins mislabelled, so I’ll investigate further. However if I don’t get anywhere I’ll get the one you have. By the looks of it things have moved on even in the time since I bought mine.

  9. I’ve now ordered the same as you, on the basis that even if my module does work the one you have is smaller and neater all round. I’ll still test the old one as well, may even find a use for it!

  10. Hi, don’t forget the buck converter, with the one I ordered and had to wind the pot a lot of times to get the voltage down to 5v, it seemed initially to be stuck with the same output as the input, so I thought it was broken, but 30-60 turns later the output voltage started to drop on my meter and I managed to get it stable around 5.04v once loaded up. I did the initial setup for the buck converter out of the alarm panel on my desk using a 12v lead acid battery as a power source, this allowed me to set the buck converter up, with only minor tweaking once installed in the alarm box, I drilled a hole in the top left of my alarm box to mount the GSM ariel and the used a couple of mounting posts and some hot glue to hold the extra circuit boards in place behind the main alarm board as in my alarm box in has about 6-7cm of clearance between the back of the main board and the back of the alarm box, if you want me to send you some pictures of my install happy to do.


  11. Thanks – yes I’ve ordered one of those as well. Thanks for the advice, will await delivery and post my experiences.

    I’d be interested to see your pics as well, I was going to do something similar but not sure it will fit behind the main board. Still there is plenty of space either side, not sure why Texecom supply theirs as a separate boxed unit.

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