KNX Blue IO 550 CV/551 CC

The KNX IO 550 CV /551 CC are compact RGB / RGBW / Tunable White dimming actuators with 4 outputs. The dimming actuators can be used e.g. for LED panels or stripes with RGB / RGBW / Tunable White configuration or as 4 independent dimmer channels. Every configuration allows controlling the channel by switching, rel. dimming and dimming value. Their new form factor allows an installation outside the cabinet e.g. in ceilings or furniture and thus closer to the LEDs.

Several comfort functions are integrated as well, including scenes, slumber fading, staircase light and sequencer. Two push buttons and several LEDs allow a local operation and a visualization of the device state. In addition to the output channels the device includes 16 independent functions for logic or timer control.

  KNX Blue IO 550 Constant Voltage (CV)

The KNX IO 550 CV features Constant Voltage (CV). The most important advantage of using constant voltage is its simplicity. Constant voltage dimming is based on PWM (pulse-width-modulation), the pulse width represents the brightness of the output. A wide range of LED lamps and LED stripes designed for constant voltage dimming is available on the market, this ensures a high level of compatibility. The devices can operate at a constant voltage of 12 V to 24 V. In constant voltage mode the current limitation which is essential for all LED components is realized within the lamps or stripes, typically just via simple resistors.

  KNX Blue IO 551 Constant Current (CC)

The KNX IO 551 CC features Constant Current (CC). LED lamps and stripes for constant current do not contain an internal current limitation. Instead these devices specify a nominal current which has to be provided by the connected power supply or dimming actuator. As a benefit the current limitation can be realized with high efficient electronic circuits instead of simple resistors. So the constant current mode leads to a significant lower power dissipation. In constant current mode the output current can be controlled for dimming. As there is no PWM on the output, the dimming behavior is flicker free. LED lamps for constant current are commercially available with typical values of e.g. 350 mA, 700 mA or 1000 mA.

  KNX Secure

For RF and IP communication secure communication is essential for the user acceptance. But also for twisted pair security helps to protect the infrastructure for example in public buildings or in hotels. All devices of the KNX Blue IO series are supporting KNX Data Security.

  Technical data

 Mechanical data

  • Housing: translucent plastic (ABS)
  • Dimensions: 132x46x20mm

Controls and indicators

  • 2 buttons and 3 LEDs, multicolor
  • KNX programming button with LED (red)


  • Device Model System B
  • Support of KNX Data Security
  • Compatible with ETS 5.5 (or higher)


  • Connector for KNX Bus (red / black)
  • Pluggable screw connector (3 poles) for dimming channel 1 and power supply
  • Pluggable screw connector (3 poles) for dimming channel 2/3/4

Output channel (Dimming)

  • KNX Blue IO 550 CV
    • PWM (frequency 480 / 600 Hz)
    • load current: 6 A total, freely distributable
  • KNX Blue IO 551 CC
    • XXX
    • XXX
  • Supply voltage: 12 .. 24 V⎓