PWM (Pulse Width Modulation) dimming with constant voltage is used to control LED strips, RGB lights and tunable white fixtures connected to a 12 V or 24 V power supply.
PWM frequency setting
LED dimming modules (LED/OC) support professional frequencies up to 25,000 Hz. In practice, due to cabling properties and the fixtures themselves, a suitable frequency may need to be found:
- Values below 400 Hz can be disruptive (stroboscopic effect)
- At some frequencies audible whining may occur
- At very high frequencies the signal may blend between cycles and dimming will not be linear
- Recommended value: a safe value is, for example, 587 Hz
Individual modules share PWM frequencies across multiple channels. For example, a 12-channel LED/OC module has two output groups, each with its own adjustable frequency.
Output types on the module
LED dimming modules (LED/OC) have outputs configurable as:
Universal outputs
One output = one device:
- Digital output - on/off without dimming
- LED Dimmer - adjustable frequency 1 - 25,000 Hz, suitable for constant-voltage dimming of LED strips
- Pulse-width modulation - slow PWM with a period of 0.5 s - 7,200 s, used for example for gradual opening of 24 V thermostatic valves
RGB / RGBW Lights
Multichannel devices using 3–4 outputs:
- RGB light - 3 outputs (Red, Green, Blue)
- RGBW - 4 outputs (Red, Green, Blue, White)
Each output is assigned to one channel of the module.
Tunable white light
Uses 2 outputs to mix color temperature:
- Output 1 - one of the module’s channels (usually warm white)
- Output 2 - one of the module’s channels (usually cool white)
Blinds, roller shutters, mix valves
On LED modules, this functionality is rarely used and is included only for completeness.
They use 2 outputs for 1 device:
- One output for opening (Force up )
- The second output for closing (Force down )
Both outputs must be on the same module, at any positions within the module.
Service settings devices
LED Dimmer values
- Min value - default: 0 %
- Max value - default: 100 %
- Use other value when output is turned off - default: off
- E.g. value 80% sets physical device to 20%.
Dimming curves
Relative luminance - default: enabled
- Based on CIE 1391 standard. Increase of light power leads to smaller increase of perceived luminance. If this setting is turned on, change of brightness e.g. between 50% - 100% will be more visible.
AC dimming - default: off
- The set brightness level is considered as a flat area under the sine curve
- Power linearization, most noticeable for values close to 0% and 100%
This setting makes sense mainly for 230 V dimmable bulbs. For constant-voltage PWM dimming of LED strips it does not make sense.
Additional settings
- Dimmer step time
- 0 - 2,000 ms (default: 200 ms)
- Defines how the module should gradually change output values to make transitions smooth
- For longer dimming actions (defined in actions) the controller will divide the dimming into shorter segments
- Gradual dimming reduces inrush currents
PWM
- PWM frequencies for the output group - 1 - 25,000 Hz
Tunable white light
The module blends the color temperature within the range defined by outputs 1 and 2.
Output 1
- Output - one of the module’s channels
- Color temperature - K (Kelvin, e.g. 2700 K for warm white)
- Intensity - lm (lumens)
Output 2
- Output - one of the module’s channels
- Color temperature - K (Kelvin, e.g. 6500 K for cool white)
- Intensity - lm (lumens)
Mixing type
Balanced
- The total light output does not change depending on the color temperature. For example: at 100% power and average color temperature, both channels (warm and cold) are running at 50% light output.
Max
- For each color temperature, the system calculates the maximum possible output for each channel. For example, at 100% power and average color temperature, both the warm and cool channels go to 100% power.
Values
- Min value - default: 0 %
- Max value - default: 100 %
- Use other value when output is turned off - default: off (0)
RGB / RGBW Lights
Output Red
- Output - module channel
- Intensity - lm (lumens)
Output Green
- Output - module channel
- Intensity - lm (lumens)
Output Blue
- Output - module channel
- Intensity - lm (lumens)
Output White
Displayed only for the RGBW version.
- Output - module channel
- Intensity - lm (lumens)
- Color temperature - K (Kelvin)
Mixing type
This setting makes sense only if the individual color components have a different intensity in lumens. Colors have different intensities in lumens.
Min
- Prioritizes color accuracy. Channels with higher light output may not be used at 100%
Max (default)
- Prioritizes maximum performance, at the expense of color accuracy. This setting is practical when the power of the white channel of RGBW light is significantly higher than the power of the R, G and B channels.
Values
- Min value - default: 0 %
- Max value - default: 100 %
- Use other value when output is turned off - default: off (0)