Gira KNX 2139 00 Product Documentation page 65

Valve outputs | Valve output - General
Valve outputs, which receive preset command values via the data format
"Switching (1-bit)", influence the heat requirement and pump control. Here, an
"OFF" command value is interpreted as "0%" and an "ON" command value as
"100%".
Data format of the command value input "Constant (1-byte) and activation with
pulse width modulation (PWM)"
Command values corresponding to the data format "Constant (1-byte)" are imple-
mented by the actuator with an equivalent pulse-width-modulated switch signal at the
valve outputs. Taking the cycle time settable in the actuator for each output into ac-
count, the average output signal resulting from this modulation is a measure of the
centred valve position of the control valve and thus a reference for the set room tem-
perature. A shift of the mean value, and thus a change in the heating capacity, can
be obtained by changing the duty factor of the switch-on and switch-off pulses of the
output signal (see figure 7). The duty factor is adapted constantly by the actuator, de-
pending on the command value received (normal operation) or by active device func-
tions (e.g. manual operation, forced position, emergency operation).
Image 7: Resulting mean value through variable duty factor with pulse width modula-
In accordance with the configured valve direction of action, the appropriate outputs
are either energised or deenergised, depending on the valve position to be ap-
proached. In so doing, the duty factor is inverted automatically for a deenergised
opened drive. Thus, depending on the valve type used, there is no unintended mean
value shift.
Example: Command value: 60% ->
– Duty factor, deenergised closed: 60% ON, 40% OFF,
– Duty factor, deenergised opened: 40% ON, 60% OFF.
Example: Command value: 100% ->
– Duty factor, deenergised closed: Permanently ON,
– Duty factor, deenergised opened: Permanently OFF.
Heating actuator 6-gang with controller | Order no. 2139 00 | 21393100
tion
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