ZMTrigger
About
/usr/bin/zmtrigger.pl (debian location) is an optional program for Zoneminder that listens on the network for commands. Read the script for a brief description.
One way it can be used is to overlay text information from an external source (e.g. temperature sensor) onto the video feed. It can also be used as an external trigger source for cameras. By using an external trigger source, you can avoid some of the problems inherent in ZM - that of false alarms. False alarms are commonly caused when the video feed has a change come across it, such as a weather events, bugs, or the transition from daylight filter to night ir filter. An external trigger source might be one or more of a PIR, Microwave, or Ultrasonic sensor.
Configuration
Enable it first, by going into options, config, and checking Enable Triggers.
Then
# service restart zoneminder
Verify it is running with
ps auxw | grep zmtrigger
Usage
Overlaying Text Data onto a Video Feed
After you have verified the script is running, test it is working.
Choose a monitor by monitor ID, say monitor 1, then add %Q to the monitors timestamp section.
The monitor must be in either modect, mocord, or nodect mode.
Open the video feed for monitor 1.
Then type in another terminal
telnet ipaddress 6802
in the telnet session type the following
1|show||||testingOSD
then press return.
Refer to Documentation for what this command means. A brief explanation for this is:
MonitorID # | Show text mode |||| text to put in.
You should immediately see testingOSD in place of the %Q you put in the timestamps section.
For more examples and scripts of ZMTrigger search the forums.
Example Script
Here is a script of connecting to an ipaddress that serves a value from a sensor. Wget is not as fast as possible, but this is simple and works quickly as a test.
#!/bin/bash counter=1 while [$counter -le 10] do PRESSURE=`wget ipaddress -q -O -` echo "1|show||||$PRESSURE" | telnet ipaddress 6802 sleep 4 #((counter++)) done
As an External Trigger
It is possible, with some minor effort, to configure a device to communicate to ZMTrigger.pl at the Zoneminder Server IP Address, using a microcontroller and a device that does the actual triggering. Some common microcontroller options would be 8-bit microcontrollers such as the Arduino Uno, the ESP8266, or potentially an ARM based SBC such as the Raspberry Pi, Beaglebone, and others.
Types of Sensors
You will need to decide which sensors to use. There are many options, and in fact it is limited by your imagination. I'll start with the common options, the ones most likely to be used by a weekend linux hacker, and then discuss future expansion potential. The first available options for Arduino solutions would be a PIR sensor, a Microwave sensor, or an Ultrasonic sensor.
PIR Sensors
PIR stands for Passive Infrared. These devices can be obtained from prices of $4 and up online. Across auction sites from China for the cheapest, to hobbyist electronics stores like Sparkfun (OpenPIR) for middle level, and then for brand name sensors from electronics distributors like Digikey, Mouser, and Farnell. These sensors are useful, but have limitations.
- Range is limited to about 20 Feet.
- Sunlight will cause false triggers. Direct OR indirect.
- Works good in a hallway, or room where no outdoor sunlight will penetrate.
Overall, the PIR Sensors are good if you have the right environment. They are not feasible outside.
Microwave Sensors
Microwave sensors operate in the 10-24GHz radio bands. The 10 GHz sensors have a range of about 30-40 feet for a person, more for large vehicles (reflective metal objects). The 24GHz sensors have shorter range. There are a variety of these, from brand name, to cheap. HB100 is a common 10GHz model, though it requires an external amplifier to read the uV signal. This can be as simple as an lm386 arduino module. Other sensors have circuitry built in to output a high or low signal depending on the motion, and how sensitive you make it. These sensors are a step above the PIR in some ways, but have their own limitations.
- Relatively short range for radio. Typically 10M, but some claim 15M. Depends on how conductive the item in motion is.
- Can't use multiple of these, as they may interfere with each other. (need to test)
- Items are detected greater when moving towards or away the sensor, not as much when moving across its field of sight.
Troubleshooting
tail -f /var/log/zm/zmtrigger.log
Enable debug on it in the logs and set to 9. The logs that contain the /var/log/zm/ logs are the component logs in options.
MySQL server has gone away error
After following forum recommendations to use mysqltuner (see MySQL), mysqltuner told me to add wait_timeout=300 to my.cnf.
Unfortunately, ZMTrigger will disconnect every five minutes, if this is enabled. It appears that ZMTrigger will "Loading monitors" every five minutes, so you can't have a wait_timeout equal or lower than that. Otherwise the MySQL server will go away. If the wait timeout is higher, then ZMTrigger will "Loading monitors" without error.
This timeout error doesn't seem to adversely affect any other features of ZM so, a low wait_timeout may be acceptable if you don't use ZMTrigger.
The default wait timeout is 8 hours for MySQL. The solution seems to be add a wait_timeout >300, or use the default. Reference:[1]
