Motorola VT2142 and Loop Current

Posts: 13 · Posted: Mon Jan 08, 2007 3:24 pm Post subject: Motorola VT2142 and Loop Current

I am having trouble with the Motorola VT2142 and ADT. I have a SafewatchPro and when it off hooks the voltage drops from 48V to 3.3V. It dials the phone, but does not sense the connection to Vonage.

I don't think there is enough current in the VT2142 to keep a constant 20 ma Loop. Anyone else using this adaptor? Anyone had any luck with another one (I'll go get something else if I can get one that works...)

Posts: 4777 · Vonage Forum **MVM** Joined: Aug 30, 2005 Posts: 4777

Rather than a current issue, you may have a reverse polarity issue. How did you connect the VT to the wiring? Also, did you get it connected to the correct terminals on the alarm panel?

Posts: 13 · Posted: Mon Jan 08, 2007 8:49 pm Post subject:

I am going to re-wire everything this weekend and try again. I'm also going to move the ATA closer to the alarm panel (right now it takes a convoluted path to get there) and wire it into the RJ31X jack that is on attached to the Alarm Panel. If that works then I have a good starting point that I can work off of.

I reversed the polarity once to test it, still did not work, however I'm not convinced I don't have a wiring problem someplace else. I am also looking for a 110 block to home run and re-wire.

On top of that I'm looking to build an OP-Amp current follower. I think this would be useful not only for me, but for others that have problems with shotty wiring and are using 'older' modems (Like Tivo and Alarms). It's become a minor project Very Happy

Posts: 4777 · Vonage Forum **MVM** Joined: Aug 30, 2005 Posts: 4777

Sounds like you have a good handle on this. I haven't heard any complaints about the Vonage adapters being able to supply enough loop current, so I sort of doubt that that's your issue.

Some of the issues that I have heard are mis-wiring, polarity, alarm type, and signalling protocol. You're taking care of the wiring and polarity issues. You might want to see if you can go to the lowest speed data protocol that your alarm supports. Also, temporarily plug a phone in at the Vonage adapter. Monitor the alarm while it's dialling out to make sure that it actually is making the attempt after seizing the line.

Posts: 13 · Posted: Mon Jan 08, 2007 10:35 pm Post subject:

Cool thanx.

I know it's seizing the line as I loose connection on the other side of the 31x. Also I can go on my Vonage account and see it has dialed the number. I think that it is not supplying enough current for the modem in the ADT alarm...

Thanx for your help!

Posts: 4777 · Vonage Forum **MVM** Joined: Aug 30, 2005 Posts: 4777

If it isn't supplying enough current for the ADT modem, how is the correct number being dialed, as verified on your Vonage account? Check that protocol. The last alarm issue that I worked in here came down to that after all the other problems were solved. The protocol that had been in use wouldn't work, but the lowest speed one did.

Posts: 13 · Posted: Wed Jan 10, 2007 8:23 am Post subject:

Steve48 wrote:

If it isn't supplying enough current for the ADT modem, how is the correct number being dialed, as verified on your Vonage account? Check that protocol. The last alarm issue that I worked in here came down to that after all the other problems were solved. The protocol that had been in use wouldn't work, but the lowest speed one did.

What should I be looking for vis-a-vis protocol? Are you talking baud rate?

Posts: 4777 · Vonage Forum **MVM** Joined: Aug 30, 2005 Posts: 4777

Yes, baud rate.

Posts: 13 · Posted: Wed Jan 10, 2007 9:00 pm Post subject:

Steve48 wrote:

Yes, baud rate.

Cool... I'll check out the document on the Ademco

Posts: 13 · Posted: Wed Jan 17, 2007 11:00 am Post subject:

Ha! I got it... After much ado.. sweat... and some tears...

Several problems...

1. ADT used a non-standard RJ31x and the wiring in the jack did not match the color code on the cable to the panel. I had to tone them out to find the right ones.

2. The wiring to the demarc outside was reversed (Tip-Ring) and I had to measure the voltages to determine the Ring (Battery) side of the line.

Once I got all that figured out and wired up correctly it worked fine. Of couse ADT was NO help... And now they know that I have Vonage... I may still switch to Alarm.com because it's cheaper...

Thank you everyone for your help. The moral of this story is that you can't just give up... and it will work.

As an addition: Sometimes the system has to call for 4 or 5 times to make a connection...