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Valve outputs | Valve output - General
does not produce the desired heating reaction, on account of the sluggishness. With
sluggish underfloor heating systems, small constant command values (only short
switch-on phases of the PWM) frequently do not produce any significant level of
heating. With large constant command values, the short switch-off phases of a PWM
usually have no effect on underfloor heating systems or comparable heating sys-
tems. Here, two-point feedback control offers a simple, effective alternative. The
valves open or close completely. During activation, unnecessary constant valve posi-
tions are avoided using command value telegrams. In addition, the service life of the
electrothermal actuators is increased.
The conversion of the constant input signal into a switching command value takes
place internally in the device. During processing, the actuator evaluates the conver-
ted command value as if it were a received 1-bit command value. It forwards the
status directly to the appropriate output, taking the configured valve direction of ac-
tion into account. Thus, on a "Open valve" command (received command value >=
limiting value), the valve is opened completely. The output is then energised for ener-
gised closed valves and the output is deenergised for energised opened valve drives.
On a "Close valve" command (received command value < limiting value - hysteresis),
the valve is closed completely. The valve output is then not energised for deener-
gised closed valves and energised for deenergised opened valve drives.
As with a 1-bit input command value, in the functions and events listed below, valve
outputs configured to the command value data formats "Constant (1-byte) and activa-
tion with command value limiting value" are always activated by a constant command
value with pulse width modulation (PWM), provided that command values not equal
to 0% or 100% are to be set...
–
Active forced position,
–
Active emergency operation,
–
After bus voltage return,
–
After an ETS programming operation,
–
During a manual operation.
PWM keeps being executed until the named functions have been exited or, after the
named events, no more lower-level functions are active and a new command value
telegram is received via the bus, overriding the constant command value on the valve
output.
In the named cases, the constant command value is also included in the cal-
culation of the largest command value and that of the heat requirement and
pump control (optional functions).
Valve outputs which receive preset command values via the data format
"Switching (1-byte)" influence the heat requirement and pump control. Here,
the actuator evaluates the converted switching output signal in the same way
("OFF" is interpreted as "0%", "ON" is interpreted as "100%").
Heating actuator 6-gang with controller | Order no. 2139 00 | 21393100
Page 69 of 257
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