Oddities with VMBPIRM behaviour

Hello there!

I have a Velbus installation with multiple VMBPIRM modules installed in the hallways/toilets/… to automate the lights. I have a combination of VMB4DC (connected to 0-10 Dimmers) and VMB4RYLD (connected directly to the lights) modules that are being switched on by the PIR-sensors.

I have switched around multiple configurations and read the official PIR-guide: https://www.velleman.eu/downloads/velbus/01_faq/faq_velbus_pir_basiskoppeling_en.pdf

I however keep running into the issue that no matter what, the lights turn off when I am still in the room and motion is being made.

An example:
VMBPIRM module mounted on the wall, Motion1 duration set to 3mins, Momentary (follow) action defined switching on a light (Relay) on the Motion-1 Channel.

What happens:
I am standing in the hallway near the frontdoor chatting with visitors, clearly in range/sight of the PIR-sensor. (I also confirmed in VelbusLink that the Motion-channels show “Pressed” confirming the sensor “sees me”?) After exactly 3 minutes, the light switches off, eventhough we are still standing there and moving/making hand gestures. I then have to wave my arms around a few times quite harshly to make the light come back on again. I have also tried waving my arms around like a madman during the initial 3 minute-interval but this does not seem to have any effect (apart from confusing my visitors). After the initial 3 minutes, the light would always switch off, and only come back on after like 2-3seconds minimum.

What I would expect:
The motion channel should keep getting pressed, extending the time the relay stays open by 3 minutes every time. This does not seem to be the case? I have also tried changing the action from Momentary (follow) to Restartable timer, this does not seem to change much in the behaviour however.

I’ve spent quite some time fiddling around but it seems I am not getting anywhere, any help or advice would be very helpful!

P.S.: I also have a setup with 2x VMBPIRM sensors controlling one light (relay output). What would be the correct VelbusLink-configuration to use here? I would like to have them both work the same (turn on the light for 3mins when movement is detected), I would think going with “Restartable Timer” is the correct approach here, as “Momentary follow” would allow for one sensor to turn off the light, whilst the timer on the second sensor was still running (in the situation that I would run past Sensor1 first, and 1min later run past Sensor2)?



Give this a try, you’ll be surprised by the result.

You can add multiple “follow” actions to a single output, but it works as an OR gate.

The output will only switch off, when all the triggers are off / released.



Thank you for your response, if the follow action works as “OR” that would indeed not be a concern.
Do you have any experience/input on the main situation I’ve created this post for by any chance?


I see your issue now that I read it again.

Dimming settings are slightly different

Try this

On motion - use an atmospheric dim action, with no time out as in, use Continuous.

Add an Off action or Zero atmospheric to the Absence channel.
Then configure your required “no motion” duration

Simple relays can just use the Follow action linked to motion, with whatever timeout you want

Or I use a Restartable timer on a motion event, where the Restartable timer is longer than the PIR duration.

I hope that helps you


Are you sure you are not using the motion output that is taking into account the lighting condition?

I had following issue:

VMBPIRM configured to switch the lights only when it’s dark.
Motion & dark → light on
VMBPIRM now detects light (the light which was switched on would shine onto the VMBPIRM just a little).
Conditions not valid any more. Still motion, but not dark anymore.
Timer expires → light off.
Now it’s dark & motion → light on again.

Same sort of stupid cycle.

Probably not yours, but never know.

Greetings Matthijs

Hey @Jondeb, were you able to figure this out? I realized I’m suffering from the same, and that it usually happens in a small area around the area under the sensor when the movements are minimal. I all the sensor is able to see is roughly my scalp only and thus the movement delta over time is less than one might expect.

Once it starts happening, it is particularly frustrating to have to wave my hand, or more often stand up and move around for the motion to trigger. I tried playing with motion sensitivity as well to no avail, unfortunately (in fact, motion sensitivity setting seems to do nothing from what I can tell…)