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+--- Thread: PIR TTL Open Collector (/thread-4028.html)
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- rodime - 10-29-2014
Hello,
We have a motion detector that has a TTL Open Collector Alarm Output. Is this able to work with comfort and if so what should be the zone type/config settings?
Thanks
- slychiu - 10-29-2014
You can connect the open collector output to Comfort zone input. Connect the Zone Common to the ground/0V of the detector
Zone type is the same as a normal PIR ie PIR Night/away or PIR away
- rodime - 10-29-2014
Hi Chiu,
I did that, however the movement triggers a zone trouble alarm (using pirnightaway with security off). Is the fact that it is TTL output significant?
- slychiu - 10-29-2014
A zone trouble alarm is due to End of line resistors or lack of EOL resistors
If the zone shunt is in the double EOL position then you must connect the EOL resistors
If you do not want EOL resistors then move the shunts to the No EOL position
- rodime - 10-29-2014
The shunt is in no EOL, we\'ve not use EOL before and this is a new type of PIR. Could this be something built into the PIR requiring EOL? PIR documentation is non existent.
When testing the circuit, the movement triggers a pulsed output as opposed to a continuous close. Not sure if that is relevant.
- slychiu - 10-29-2014
Are you sure it is an Open Collector output? There may be a voltage connected to the output causing the zone trouble. A zone trouble is caused by external voltage at the zone input
Disconnect the detector from Comfort and measure the voltage between Open collector and common. When there is no movement, there should be no voltage, when there is movement the voltage should be close to 0
- rodime - 10-29-2014
The documentation states it is a TTL alarm output and open collector 30ma max. Using a multimeter I get a reading of 3.4v when the movement triggers
- slychiu - 10-29-2014
3.4 Volts is not an open collector voltage when the transistor is on
anyway there seems to be a contradiction as a TTL output is not an open collector output.
TTL is a digital output > 3.4 volts high and < 2.0 volts low (but TTL logic should have gone extinct together with the dinosaurs)
An open collector output is a transistor output which is open circuit when off and pulled to 0V when on
- rodime - 10-29-2014
ok, so assuming it is in fact a TTL digital output, can this be used with Comfort?
- slychiu - 10-29-2014
Try a digital n/c zone type
See if it can detect on and off
If so you can change the alarm type to make it trigger alarm