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Room temperature controller | Command value output and command
value limit
In addition to the command value output following a change, the current com-
mand value may be periodically transmitted. In addition to the times when
changes are to be expected, other command value telegrams will be output
according to the active value after a configurable cycle time. This ensures that,
during cyclical security monitoring of the command value in valve drive or in
the addressed switch actuator, telegrams are received within the monitoring
time. The time interval defined by the parameter "Cyclical (0 = inactive)"
should correspond to the monitoring time in the actuator (cycle time in the con-
troller is preferably to be configured smaller). The "0" setting will deactivate the
periodic transmission of the command value.
With continuous PI control it must be noted that if the cyclical and the auto-
matic transmission are both deactivated, no command value telegrams will be
transmitted in case of a change!
–
Switching PI control (PWM):
In case of a switching PI control (PWM), the room temperature controller cal-
culates a new command value internally every 30 seconds. The parameter
"PWM cycle time" defines the cycle time of the PWM command value signal.
If the command value is changed, the current PWM cycle is adapted as re-
quired so that the duty factor corresponds as directly as possible to the new
command value. This adaptation is carried out in the same way as during ac-
tivation of the valve outputs (see figure 8).
–
2-point feedback control:
In case of a 2-point feedback control, the room temperature and thus the hys-
teresis values are evaluated periodically every 30 seconds, so that the com-
mand values, if required, will change solely during these times. As, with this
control algorithm, no continuous command values are calculated, the para-
meter "On change by (0 = inactive)" has no effect with this control algorithm.
In addition to the command value output following a change, the current com-
mand value may be periodically transmitted on the bus. In addition to the times
when changes are to be expected, other command value telegrams will be
output according to the active value after a configurable cycle time. This en-
sures that, during cyclical security monitoring of the command value in valve
drive or in the addressed switch actuator, telegrams are received within the
monitoring time. The time interval defined by the parameter "Cyclical (0 = in-
active)" should correspond to the monitoring time in the actuator (cycle time in
the controller is preferably to be configured smaller). The "0" setting will deac-
tivate the periodic transmission of the command value.
Command value limit
Optionally a command value limit can configured in the ETS. The command value
limit allows the restriction of calculated command values to the range limits "Minimum
command value" and "Maximum command value". The limits are permanently set in
the ETS and, if command value limitation is active, can be neither undershot or ex-
ceeded during device operation. It is possible, if available, to specify various limiting
values for the basic and additional stages and for heating and cooling.
Heating actuator 6-gang with controller | Order no. 2139 00 | 21393100
Page 165 of 257
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