LGT_CORR: Lighting correction, brightness and illuminance
Function
The LGT_CORR [FC 446] calculates the actual effective illuminance and effective brightness value. The effective values are calculated from the delivered sensor value which is adjusted by correction factors.
The correction factors are determined by doing a measurement using a lux meter and dividing this hand measured value by the sensor value. Two correction factors are determined, one for daylight and one for artificial light.
The effective illuminance value is calculated based on the actual light progress value and the maximum illuminance of the illuminator.
The effective brightness value is determined by calculating first the effective daylight value and adding the effective illuminance value. The effective daylight value is calculated based on the input parameters Brgt, CorrFactDlgt, CorrFactAlgt and the already determined ImncEff.
Functionality
ImncEff and BrgtEff are calculated according to formulas. The FC checks the inputs for meaningful values.
For ImncEff calculation:
If LgtCmdPrgsVal < 0.0, then ImncEff will be set to 0.0
If Imnc < 0.0, then ImncEff will be set to 0.0
For BrgtEff calculation:
If CorrFacDlgt <= 0.0, then BrgtEff will be set to 0.0
If CorrFacAlgt <= 0.0, then BrgtEff will be set to 0.0
Only if the input parameters are within the meaningful range, ImncEff and BrgtEff will be calculated. ImncEff and BrgtEff can only have 0.0 or a positive value. In case of a positive overflow the values will be limited to REAL_MAX (3.402822e38).
Pin description (inputs)
Pin | E | O | Description |
Brgt | pa |
| Brightness. |
Imnc | pa |
| Illuminance. |
LgtCmdPrgsVal | pa |
| Lighting command progress value. |
CorrFacDigt | pa |
| Correction factor daylight. |
CorrFacAlgt | pa |
| Correction factor artificial light. |
Pin description (outputs)
Pin | E | O | Description |
BrgtEff | a |
| Effective brightness. |
ImncEff | a |
| Effective illuminance. |
Pin data
Pin | Description | Data type | Default value | E.g. Engineering unit or Text group | Min. | Max. | Pin type |
Brgt | Brightness | REAL | 0.0 | lx | 0.0 | 3.402822e38 | In |
Imnc | Illuminance | REAL | 0.0 | lx | 0.0 | 3.402822e38 | In |
LgtCmdPrgsVal | Lighting Command progresss value | REAL | 1.0 | % | 0.0 | 3.402822e38 | In |
CorrFacDlgt | Correction factor daylight | REAL | 1.0 | – | 0.0 | 3.402822e38 | In |
CorrFacAlgt | Correction factor artificial light | REAL | 1.0 | – | 0.0 | 3.402822e38 | In |
BrgtEff | Effective Brightness | REAL | 0.0 | lx | 0.0 | 3.402822e38 | Out |
ImncEff | Effective illuminance | REAL |
| lx | 0.0 | 3.402822e38 | Out |
Engineering and commissioning
Configure brightness sensor correction function
Calibration is required because the sensor is mounted on the ceiling and brightness must be controlled for the table/desk level.
A calibrated lux-meter is required to achieve solid results for configuration.
Consider the measurement range of the internal light sensor. (e.g. UP258 20…1000 lx)
Proceed as follows:
- Measure first in a dark room, preferably without daylight.
- Measure the illuminance of the lamp at 100% output with a lux-meter on the table.
- Enter this value under parameter Inmc.
- Calculate CorrFacAlgt = Inmc / Brgt (value measured by the brightness sensor)
- Enter the value under parameter CorrFacAlgt.
- Now measure under normal daylight conditions in the room. In other words, lighting is switched off. Room brightness should be approximately 500 lx.
- Calculate CorrFacDlgt = brightness as measured with lux-meter / Brgt (value measured by the brightness sensor)
- Enter the value under parameter CorrFacDlgt.