PIR Sensor Enable/Disable

Scenario:
A switch which turns on a Group Address: "Sensors" for an hour
"Sensors" is set to Enable 3 PIRs
Those 3 PIRs are set to turn different lights on for 2 hours.

What happens when the "Sensors" timer expires? Do the PIRs timers stop? or are they allowed to run their timer down? Are the lighting circuits left in whatever state they were when the "Sensors" timer expired? Or do they switch off?

 

Your PIRs would be disabled after an hour because of the switch timing out. When the PIR is disabled the timer would be cancelled, so if the lights were on they would continue stay on.

Enabling a PIR for 1 hour and the PIRs timer set to 2 hours does not seem productive. What are you trying to achieve?

I would be more inclined to disable the PIR when not used and have the PIR set to a 2 hour timer that is not a retrigger (I think it would be set to Start - but test this). This would then turn on the lights for 2 hours from first detected movement, only when the PIR is not disabled.

 

I used the times as an example. A customer actually wants the entry and hallway PIRs to enable, and turn circuits on for 3 minutes with any movement. But only when they activate a Welcome scene. so i'm trying to determine the best setup for this welcome scene.

 

How is this Welcome scene set and what determines that it's no longer valid? This is important to know if it's only during this window of time that the PIRs are allowed to be enabled.

How about the following:

• As part of the Welcome Home scene being set (by either user button press or some logical condition being met), enable the entry and hallway PIR. Give each PIR it's own enable/disable group.
• Once the entry or hallway group turns off, i.e. the 3 minute timer expires, disable that PIR.

This will mean that the entry and hall lights will turn on and remain on for as long as the PIR's in those areas continue to detect movement, but once the timer expires and the light turns off the PIR will be disabled. This will effectively give you a one-shot at those lights coming on automatically, they'll only turn on initially in response to movement but they'll remain on as long as they keep detecting movement. Once the timer expires and the lights turn off, the lights in those areas would revert to manual control only.

The only other thing to do would be to have something at a later time/condition go and disable the PIR's that didn't get triggered. This will prevent PIR's getting left in the enabled state indefinitely.

 

Thanks Newman, sounds perfect. So the welcome scene will trigger a timer for "Enable PIRs", which will be the enable group address for the PIRs, then in the blocks for the PIRs, this address will be triggered/retriggered along with the lighting group address?

 

Yep. Ideally you'd have a separate enable group for each PIR so they don't have any dependence on each other.

This won't work as the PIR will get left enabled. I'd have a few lines of logic running in a PAC or a C-Touch somewhere that simply turns the PIR Enable/Disable group off whenever it sees the corresponding lighting group for that PIR turn off.

 

how will they get left enabled? Is this caused by a circular reference?

We have installed a Wiser so i could put some logic in there

 

The PIR's have the ability to use the same lighting group for regular PIR functions AND the enable/disable group. This allows a single button on a network switch to toggle the state of the light AND enable/disable the PIR. As a consequence of this the PIR doesn't enable/disable itself even when sending a message onto C-bus on the same group as the Enable/Disable group. If it did so, the enable/disable state as set by the switch would get overridden every time the light turned off.

The proper way to do it is to use independent Groups for the light and the enable/disable. You then need to set the Enable/Disable state from another unit, not the PIR itself.