MultiSensor Question

Can anyone help with programming a multi sensor to achieve the following philosophy??

Below is an extract from a spec on a job, talking about the control philosophy for some open office type areas:

All On after first person enters room for the day (motion sensor in room to sense) until building secured. All Off when building Secured. Room to be dimmed to 320 lux at all times based on light level sensor control.

The Installation - Basically I have a multi sensor and 2 gang switch in the room. Lights are DSI dimmed via DSI controller at Distribution Board. I have bad memories from the C-Bus training that these multisensors can be a real pain.

I have set up the daytime, nightime movement to be the same, On, Re-Trigger, Re-Trigger, Idle. I want the switch to turn on the lights to 100% when the person first enters the room (PIR disabled at this point). I then want the switch to be timer for say 1hr. PIR is to then be "enabled" and act as re-trig timer for the lights - but I also want it to carry out light level maintenance. Can anyone help ?

 

"light level maintenance"

G'day Macka
Unfortunately I'm not much help! But I can confirm your doubts. I believe the Mulitsensor has the ability to provide the dimmed output that you have been asked for however in reality it's not likely to work (and I believe it puts lots of traffic on the C-Bus network). The room is to be dimmed to 320 lux, where? on the desk one assumes, but the light level sensor is on the ceiling. If it is 320 lux on the ceiling, it will be less at the desk ~2m below.
For energy efficient controls, Manual on & Auto off, with ability of manual off is what you want to achieve. Also keep the timer period down (1hr is way too long) otherwise the lights won't go off and the energy savings will be missed, so there will be little point having an occupancy detector. This is for an individual room/ office, an open area or large room will have different requirements. You always have to consider the usage of the area to achieve appropriate control.
Sorry I can't be more help. Cheers
Matthew

 

It's not really clear here whether you want the PIR to turn the lights on or you want to have a manual switch to turn them on.

I agree with Matthew, the Manual On with Auto Off or Manual Off idea is the best way to go.

It should be fairly straigthforward to make the switch turn on the room light and enable the PIR from the first button on your key unit. Just assign the key to 2 blocks in the key unit for the 2 group addresses you want to control. Set the key function to On.

For the second button I'd set it to an Off command on both the room light group and the PIR Enable group. This will turn off the light and disable the PIR.

I wouldn't use timers in the key unit, I'd use the timer in the PIR. These are set up on the Blocks Tab.

If you're using Manual On/Auto Off and Light Level Maintenance then I'd set it up the Multisensor in the following way. Set both Virtual Key 1 & 2 to Day Move. On the Occupancy Tab make sure you've got the 4 checkboxes for "Light & Movement" and "Dark & Movement" for keys 1 & 2 ticked. If you're not using the Sunset function then un-check the box for it on the occupancy tab. For as long as the unit detects movement the timer won't expire and the light will remain On. This will also minimise the network traffic.

If you want the multisensor to turn on other lights that are in the building when it's triggered then the most straightforward way to do it is to put a PAC on the network and write some code for it using the PICED software.

For the light level regulation use the Multisensor's Light Level Maintenance feature on the Light Level tab. Set the checkbox to Active and, once the group address that's selected in the Block drop-down box is turned on (by movement or from a switch) the unit will try and keep the light level it's measuring at the Target set on the Light Level tab. How tight the light level regulation is set by the Margin parameter on the same tab.

The unit won't flood the network with traffic. It uses a very slow ramp rate to do the regulation and messages are only sent when necessary. The feature can also be turned on/off by a group address if desired.

Remember that the best the unit can do is respond to the light level that it receives on the ceiling. That means that there will always be a difference between what you see on the desk below and what you read on the unit, so don't expect a reading of 320 lux at the unit to give you 320 lux on the work surfaces below. Take a lux meter and hold it on the ceiling, facing downwards. You might get quite a suprise.

There's some good general info on the Multisensor and measuring light levels available in a few old posts:
http://www.cbusforums.com/forums/showthread.php?t=2400
http://www.cbusforums.com/forums/showthread.php?t=2056
http://www.cbusforums.com/forums/showthread.php?t=2546

 

Matthew - this is a simplistic approach - using a meter you can measure the light level at the desk (320 lux) and then measure the light level at the sensor. Using an offset you can compensate for the poor location. It will also depend on the flooring below and how reflective it is.

While it may not be perfect, it never will with only one light level meter in a large room, there will always be darker spots and brighter spots, but you should be able to compensate and create an "average" light level.

Mick

 

OOps

Gents,
Got that the wrong way around, Sorry Macka for the bum steer . A value on the ceiling will depend on the luminaire type, reflection from the walls, floor & even furniture. It will be much less than on the desk.
Regards
Matthew