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instabus KNX/EIB System
Sensor
2.3.3
Actuating variable output
2.3.3.1
Actuating variable objects
The format of the actuating variable objects is determined depending on the control algorithm selected for heating
and / or cooling and, if applicable, also for the additional stages. 1-bit or 1-byte actuating variable objects can be
created. The control algorithm calculates and outputs the actuating variables in intervals of 30 seconds. With the
pulse-width modulated PI control (PWM), the actuating variable is updated, if required, only at the end of a time
cycle.
Possible object data formats for the actuating variables separately for both control options, for the basic and the
additional stage, are...
• the continuous PI control:
• the switching PI control:
• the switching 2-state control:
Depending on the selected control option, the controller is able to address heating and / or cooling systems, to
determine actuating variables and to output them via separate objects. One distinguishes between two cases for
the mixed mode "heating and cooling:
Case 1: Heating and cooling system are two separate systems.
In this case, the "Transmit actuating variable heating and cooling to a shared object" parameter should be
set to "no" (default) on the "Controller general" parameter page. Thus there are separate objects available
for each actuating variable which can be separately addressed via the individual systems. This setting
allows to define separate types of control for heating and cooling.
Case 2: Heating and cooling system are a combined system.
In this case the "Transmit actuating variable heating and cooling to a shared object" parameter may be
set, if required, to "yes" on the "Controller general" parameter page. This will transmit the actuating
variables for heating and cooling to the same object. In case of a two-stage control, another shared object
will be enabled for the additional stages for heating and cooling.
With this setting, it is only possible to define the same type of control for heating and for cooling as the
control and the data format must be identical. The ("Type of heating / cooling") control parameter for
cooling and heating still have to be defined separately.
A combined actuating variable object may be required, for example, if heating as well as cooling shall take
place via a single-duct system (combined heating and cooling system). For this purpose, the temperature
of the medium in the single-duct system must be changed beforehand by the system control. Afterwards
the control option is set via the object (often the single-duct system uses cold water for cooling during the
summer, hot water for heating during the winter).
Important:
Basically, it is not possible to heat and cool at the same time (actuating variables > "0")!
If required, the actuating variable can be inverted before the transmission. The actuating variable value will be
output in inverted form according to the object data format via the "Output of actuating variable heating" or "Output
of actuating variable cooling" parameters or via a combined "Output of actuating variable" object . The parameter
for inverting the additional stage(s) are additionally available in the two-stage controlled operation.
The following applies...
for continuous actuating variables: not inverted: Actuating variable 0 % ... 100 %,
for switching actuating variables:
44/82 Page 2100-xx/2101 xx
1 byte,
1 bit + additionally 1 byte (e.g. for status indication in visualization systems),
1 bit.
inverted:
Actuating variable 0 % ... 100 %,
not inverted: Actuating variable on / off,
inverted:
Actuating variable on / off,
Value 0 ... 255,
Value 255 ... 0,
Value 0 / 1,
Value 1 / 0.
07 /17
Subject to change without notice
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