Getting light level from SENLL

Hi,

I am doing some low level stuff to interface C-Bus to Johnson Controls. It's all going OK so far, but I need to know how to read a light level.

I can use \0603002A0E02<chksum> to get the temperature out of unit number 3, what parameter do I read to get light level?

Also, how do I do the same thing for a multi sensor?

Thanks

Kevin

 

The temperature sensor cannot read light level. I assume you're talking about the basic 5031PE light level sensor? I'm not sure about how to do it in that one.

For the Multisensor you can use the LL Broadcasting feature in the unit. It will transmit the current LL onto a Group Address as a 0 - 100% value of the unit's full-scale light level sensing range. For example, if the sensor works up to 4700 lux and it sees 2350 lux then it will broadcast a level of 50%. It's best to keep the broadcasting rate down to avoid too much network traffic. About 1 minute is a good start (set on the blocks tab).

 

Err - trying this

Yeap, am actually talking about getting light levels out of a light level sensor.

Am currently trying this:

\0603002A9901
(for sensor addressed as 3).

which gives me 1 byte back, i.e.
82999B4A, the reading is 9B

and am using lux = reading * ( 1.15 + ( 10 * ( ( reading / 255 )^3 ) ) )

which means 9B => 526 lux.

Not sure if the conversion formula is right but seems to match what we have measured here.

 

Your formula is not quite right. It should be:

Lux = 25 * 2.718 ^ (Reading / 52)

In this case, a reading of 9B will give a result of 492 lux.