Technical Manual
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Central Operation Unit Smart
MDT technologies GmbH •
51766 Engelskirchen • Papiermühle 1
Phone: +49-2263-
880 • Fax: +49-2263-4588 • [email protected] • www.mdt.de
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2 Pipe system:
In a common pipe system for the cooling and heating process, there is only one communication
object that controls the control value. The change from heating to cooling or from cooling to heating
is made by a changeover. This can also be used simultaneously for changing between heating and
cooling medium in the system. This ensures, for example, that warm water flows in a heating/cooling
ceiling during heating and cold water during cooling. In this case only one common controller (PI,
PWM or 2-point) can be selected for the control value. The direction of action can also only be
defined identically for both processes. However, the individual control parameters for the selected
controller can be parameterized independently of each other.
4 Pipe system:
If there is a separate pipe system for the heating and cooling process, both processes can also be
parameterized separately. Consequently, separate communication objects exist for both control
values. This makes it possible to control the heating process e.g. via a PI control and the cooling
process e.g. via a 2-step control, as both processes can be controlled by different devices. For each of
the two individual processes, completely individual settings for the control value and the
heating/cooling system are therefore possible:
Heating/Cooling switchover:
With the "Heating/cooling switch over" setting it is possible to set whether the controller
automatically switches between heating and cooling or whether this process should be carried out
manually via a communication object. In the case of automatic switchover, the controller evaluates
the setpoints and knows which mode it is currently in based on the set values and the current actual
temperature. If, for example, heating was previously carried out, the controller switches over as
soon as the setpoint for the cooling process is reached.As long as the controller is in the dead zone,
the controller remains set to heat, but does not heat as long as the heating setpoint is not undershot.
If the switchover "via object" is selected, an additional communication object is displayed, which can
be used to make the switchover. With this setting, the controller remains in the selected mode until
it receives a signal via the communication object. For example, as long as the controller is in heating
mode, only the setpoint for the heating process is considered, even if the controller is actually
already in cooling mode. The cooling process can therefore only be started when the controller
receives a signal via the communication object that it should switch over to the cooling process. If the
controller receives a 1 via the communication object, the heating process is switched on, and if a 0,
the cooling process is switched on.
The following table shows the associated communication object:
Number
Name
Length
Usage
163
Heating/Cooling switch over
1 Bit
Switchover between heating and cooling
0 = cooling; 1 = heating
Table 61: Communication object
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Heating/Cooling switch over
