How to use your external camera's motion detection with ZM
Background
Zone minder has an awesome 'trigger' architecture which allows any external event to trigger a recording on ZoneMinder. This section explains the basic architecture and then goes on to describe how you can use your own camera's HW motion detection to trigger a recording on ZM. You can replace this 'trigger' with any other event - such as, for example, triggering your ZM recording when say your Nest thermostat goes to Away mode. The options are limitless
Core Trigger Architecture
+-----------------+
| zmtrigger.pl | record on/off
|listening on port| directives over TCP
| 6802 |<------+
| | | polling or notification x
+-+---------------+ | - depends on device / \
| | capabilities / \
| | +---------------> |
| | | \ /
| | | \ /
+----------------+ | record | +---------+ |
| | | | | my own | | device
| Rest of Zone | | +-------| script |<--------------+
| Minder <------+ +---------+
| |
+----------------+
If you enable OPT_TRIGGERS in Options->System, then ZoneMinder starts a process called "zmtrigger.pl" (/usr/bin/zmtrigger.pl). This is a perl script that basically offers an easy to use interface for anyone to send it commands to its default TCP port (6802) to initiate/stop recordings. Note that zmtrigger also offers other means of IPC - I just found the TCP channel easy and reliable.
zmtrigger does not care what caused the event. All it is waiting for is a simple text instruction from anyone capable of sending a command to port 6802. So what that means is I can write any program that monitors anything, and when my program thinks something happened which warrants a recording, all I need to tell zmtrigger is "please record monitor 3" (and optionally specify more parameters)
Quick test
Lets assume you have a monitor id of 1. As a quick test (remember to enable OPT_TRIGGERS), just try this telnet zm_ip 6802 And when connected via telnet simply type in
<nowiki>
1|on+20|1|External Motion|External Motion <nowiki>
