Queue on disk
If the centre does not answer or Nx restarts, alarms wait on the server disk and are sent in order once the centre answers, each one only once.
Guide · Nx Witness
Sending Nx Witness alarms to an alarm monitoring centre (SIA DC-09, Contact ID).
With the IA-N Analyse 1.4.0 plugin, the Nx Witness server itself sends its video analytics alarms to the receiver of an alarm monitoring centre, using the SIA DC-09 protocol, SIA-DCS or Contact ID format, over TCP or UDP. You set the server once (Site Administration › Integrations › IA-N Analyse › Alarm monitoring centre), then each camera to be transmitted; a schedule to the second decides what goes to the centre. Alarm monitoring is included in every licence, trial included.
Updated on 21 October 2026
Server settings
Once for the whole Nx server.
- 01 / Enable
Transmission
Site Administration › Integrations › “IA-N Analyse” › “Alarm monitoring centre”: tick “Send alarms to the monitoring centre”, choose the format (SIA-DCS or Contact ID) and enter the “Site account number” given by the centre.
- 02 / Connect
The primary centre
Receiver address and port given by the centre, link supervision (NULL messages) and periodic test agreed with it. Backup centre and encryption key if the centre provides them.
- 03 / Schedule
The transmission hours
“Transmission schedule” page: a ready-made schedule (always, at night, nights and weekend, outside office hours) or a custom one, to the second; “Dated exceptions” for a closure or works.
- 04 / Test
With the centre
“Send a test to the centre” button: the answer is shown (acknowledged, refused or no answer). “Current state” button: transmission active or suspended, and until when.
Settings of each camera
Then camera by camera.
- Camera Settings › Integrations › “IA-N Analyse” › “Alarm monitoring centre”: tick “Send this camera's alarms to the centre”.
- “Zone (camera) number for the centre”: the camera's rank is suggested; agree it with the centre, which sees for example “zone 007”.
- “Alarms sent”: tick the alarms to send (intrusion, line crossing, zone entry…).
- “Schedule per rule” if needed: for example intrusion only at night.
What is sent, and when
A transmission that loses no alarm.
Always sent
The periodic test, the link supervision and faults (video loss then video back, licence fault, analysis stopped) are sent even outside the schedule.
Outside the schedule
The alarm is not sent to the centre: it stays in Nx with the mention “outside monitoring schedule”.
Message content
What the centre receives.
- The site account number, the alarm code, the zone (camera), the partition and the time.
- If enabled: a short text (alarm type, camera, rule name) and a viewing link.
- No image, no license plate, no biometric data; ordinary plate reads are never sent.
The viewing link (camera and alarm time) lets the centre's operator open the video with their own Nx account; a link containing a user name or a password is refused. During the test, check with the centre how its software displays it.
GDPR
The centre is a recipient of the data.
When alarm monitoring is enabled, alarms also go to the centre chosen by the customer. The centre is a recipient: it must appear in the site's record of processing activities and in its data protection impact assessment (DPIA), with a data processing agreement. The transmission log, with no personal data, is deleted after 12 months. See the guide GDPR and video analytics in Nx Witness.
Frequently asked questions
Alarm monitoring from Nx Witness
Another question? Our sales team will answer.
Do you need an alarm transmitter in addition to the Nx server?
No. With the IA-N Analyse 1.4.0 plugin, the Nx server itself sends the alarms to the centre's receiver, over the network, via TCP or UDP.
Is alarm monitoring a paid option of the plugin?
No. It is included in every IA-N Analyse licence, full or trial.
Which formats must the alarm monitoring centre receive?
The SIA DC-09 protocol, in SIA-DCS or Contact ID format, over TCP or UDP, clear or encrypted, depending on what the centre uses.
What happens if the centre stops answering?
Alarms wait in a queue on the server disk, then are sent in order once the centre answers, each one only once. A backup centre can also be set.
Does the centre receive images?
No. It receives the account number, the alarm code, the zone, the partition, the time and, if enabled, a short text and a viewing link that it opens with its own Nx account.
Also worth reading
To find out more.
Nx Witness is a trademark of Network Optix, Inc.; DW Spectrum, of Digital Watchdog.
An alarm monitoring centre to connect to Nx Witness?
Alarm monitoring is included in the 30-day free trial.