Light Level Sensor Question

Could someone be kind enough to explain to me how Light Level Sensor operates (internally).

I have the following settings

Light Level ------------- West Light Level
Light On/Off ------------- West Light Level On/Off
Enable Group ------------- [Unused]


With the initial setup of the LLS, after connecting it up, it did not seem to influence the Gas. I ended up changing the enable group to a temporary GA that was on at the time, and the LLS started manipulating the Gas. I changed the enable group back to [Unused] and all worked okay. I changed the GAs manually and the LLS would change them back after a few seconds.

But after a month or so, the LLS stopped working and I and I repeated the above process and it started working again. Last night the same thing happened and I tried the process and nothing helped. The Last measurement on the unit showed correct LUX levels.I ended up setting the GA manually and disconnected my laptop. This morning the lights turned off as they should which means the LLS kicked in again.

I have no idea why this would be the case. My Global Setting for the Status report is 3 seconds. There is no other unit controlling the above mentioned GAs.

Any ideas.

 

Is this a 5031PE

or a 5753PEIRL?

There are some very subtle differences between these products with regard to enable / disable function, so I would like to know what we are dealing with.

In general, what you have described sounds like it should work, and the sensors should not be mis-behaving.

Don

 

It is a 5753PEIRL.

 

OK. here's how the enable / disble works in the 5753PEIRL:

At power-up, the internal enable flag is set (enabled)

If the group address for Light level sensor enable group is not (unused), then the last enable state found on the network prior to loss of power will be restored, otherwise the Light level sensor will be left enabled

So far so good. Power cycling should be a reliable way of getting the Light level sensor to work if it has been somehow disabled

The Light level sensor can be enabled / disabled via IR remote control (look under GLOBAL tab). Is there any chance that the remote control feature is enabled and that an IR signal has been received to toggle the enable state? The IR code used here is quite simple, but does incorporate a CRC, so it would be pretty unlikely that this would happen.

Don

 

The GLOBAL tab has

Timing Parameters Status Report (set to 3 seconds).

There is nothing else ....

Am I missing something here?

 

Josh

Then your unit is not a 5753PEIRL as you mentioned earlier. It sounds like a 5031PE. This is a much older product with less features and no IR enable/disable.

 

It is an outdoor unit, bought six months ago. How would this be an older product?

 

Josh

I was referring to older in terms of design, not manufacture.

To answer your original question, the 5031PE works like this:

Light On/Off
If the measured light level is below that set by the target (- margin) then the unit will turn the Light On/Off Group to On. If the measured light level goes above the target (+ margin) then the unit will turn the Light On/Off group to Off.

Light Level
The unit will ramp this group up and down to try and maintain the measured light level at the target value. A smaller margin means tighter control but more C-Bus traffic.

Enable Group
This simply enables/disables the sensor.

 

Does the unit send 1 ON command, or does it resend the command after a period?

If another unit changes the state of the GA, will the 5031PE send another ON command?

Both questions are based on the light level not changing as below ....

Will the same apply here?

 

Josh

The unit does not periodically re-send an On command if the group is already on.

If any other unit changes the on/off state of the Groups that are under the control of the 5031PE then the unit will re-issue the On or Ramp commands. The unit re-sends it's commands onto C-Bus if some other unit puts the group into a different state than what the 5031PE wants.

The unit does not do anything too fast. The Light Level control uses ramp rates of 1 minute to avoid rapid changes in LL that can be caused by things like passing car headlights, clouds etc. When the light level crosses the threshold then it will wait anywhere up to 8 seconds or so before issuing it's commands on the bus.

 

Thanks Newman, that answers my question(s).