ABB i-bus KNX Product Manual page 144

®
ABB i-bus KNX
Commissioning
Four limitations are available. They can be used, for example, for the control of various operating modes,
e.g. frost/heat protection, comfort, night shut down and standby. In normal cases, the room thermostat
takes these operating modes into account in its control variable for the actuator.
Important
The parameterized start-up behavior which is a technical characteristic of the fan has a higher priority
than a limitation, i.e. if a limitation is activated in fan speed 2 and start-up behavior is parameterized with
fan speed 3, the following behavior will result: The fan is in the OFF state and receives a control signal
for fan speed 1. First it goes to speed 3 (start-up speed), then 2, which is specified via the limitation.
Due to the limitation, the actual required fan speed 1 will not be reached.

The sequence of the displayed parameters corresponds with their priorities, i.e. the parameter with the
highest priority has limitation 1 followed by limitations 2, 3 and 4.
Note
The fault operation, e.g. with a malfunction of the room thermostat, has a lower priority than the fan
limitation, i.e. if fan speed is limited during a thermostat malfunction, only the upper or the lower limit of
the fan limitation can be set at maximum.
When you exit automatic control, e.g. by a manual action, the limitations are inactive.
The set limitations are reactivated when automatic mode is reactivated.
The following points apply for limitations:

The fan speed and valve position can be parameterized independently.

The limitation need not necessarily apply to one fan speed only. It can also encompass another range
of the fan speeds, i.e. only certain fan speeds can be set if the limitation is active. In this way, a limited
control is also possible.

The limitation is activated if a telegram with the value 1 is received on the communication object
Limitation. The limitation is deactivated if a telegram with the value 0 is received on the
communication object Limitation. A manual action ends automatic operation.

If a limitation is activated, the product switches to the parameterized fan speed regardless of the
control value. If another fan speed or a speed outside the "limitation range" is set when the limitation is
activated, then the required speed or the limit speed of the range is set.

After switch off of the limitations, the fan speed and the communication objects for valve control are
recalculated and executed. This means that during limitation, the product operates normally in the
background, the outputs are not changed and implementation only occurs once limitation ends.
Each of the four limitations used to limit the fan speeds has the same parameters.
Important
They are prioritized according to the listed sequence. The highest priority is assigned to limitation 1, e.g.
Frost/Heat protection; the lowest priority is assigned to limitation 4, e.g. standby operation.
142 2CDC508134D0202 | FCA/S 1.x.x.1