Ademco alarm report format
Hi polarized,
Sorry for the delay, took some days off.
Unfortunately my poor knowledge of the English language makes me often misunderstood. Actually, if you look through my posts you'll see that it already gave me very unpleasant situations.
Unlike for me, it seems to be your birth language so I'll do my best to make myself clear. Here it goes:
An "Alarm dialer" (Industry terminology) has several input trigger channels, usually dry contact inputs but can be voltage actuated on some models. Please note that this "dialer" can be integrated in the alarm control panel, even driven by the same microcontroller.
It also has an input for the outside telephone line (PSTN) that, after crossing the double contacts of the line deviating relay, exits through the terminal block to the in-house phone network.
Upon an alarm, the outside phone line is then deviated from the house network to the dialer. This also cuts any ongoing conversation. After a short pause another relay, the line seize relay or an electronic current steering network, seize the line and listen for a dial tone. This is usually programable to "blind" dial.
The Alarm Monitoring Station telephone number is then dialed, DTMF or decadic (pulse) and the dialer listens for a handshake tone coming from the alarm receiver, 1400 Hz for Ademco slow format and 2300 Hz for other fast formats (DTMF, FSK...), if my memory is still good (As I said before, I can check these values if it is really important for you).
After receiving the handshake, the dialer starts sending out rounds of the alarm report consisting either 3 digits for customer number and 1 digit for channel code (alarm code... burglary, fire, medical ...) which is format 3/1, or then a similar 4/2 format. These digits are transmitted as a number of bursts of 1900Hz, the number corresponding to the meant digit where "0" is ten bursts. The timing is the same of a decadic (pulse dialing) where the "space" (open loop) is replaced by the burst and the "mark" (closed loop) is silence. Both these formats can be transmitted at 10 bps or 20 bps assuming that the receiver is capable of receiving both.
After receiving three equal rounds of information in a sequence, the receiver sends a kiss-of tone, which again I believe is 1400 Hz but I'm not sure. Then the dialer disconnects. If it couldn't obtain a kiss-off tone after a given time, it redials a maximum of 15 times, which is the maximum allowed by TBR21.
Hope this helped, if not, you can always "redial"
Keep well
JSS