68 Planning and use
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Building Automation
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Building Automation
Planning and use
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7.3.2 Continuous controller
A continuous controller has a continuously changing control value, which can take values between 0 and 100%.
With the KNX the control value signal is converted to a 1-byte value, i.e. the control value of 0% corresponds to the
value “0” and the control value 100% corresponds to the value “255”.
Devices such as electromotor actuators can be controlled by a continuous controller with a 1-byte control value.
They convert the received value directly to the valve position with an integrated motor. This enables optimum control.
The 1-byte control value of a continuous controller can also be sent to KNX heating actuators, which convert the
1-byte signal to a PWM value. This can be used to control electrothermal valves. It may be useful to restrict the
dynamic range, because electrothermal valves required a certain time to open and close (see also page 69, Section
7.3.3 PWM controller). This is done with the parameters “minimum control value” and “maximum control value”. For
example, if a maximum control value of 80% is preset, the controller always automatically sends the value 255 if a
control value of 204 is exceeded.
To prevent unnecessary bus loading the magnitude of the control value can be set to enable it to be sent on the bus.
The setting is a percentage value. The transmission of the control value is determined by a cycle time if it has not
changed. The cycle time should be set too small (e.g. every 10 min).