R7426D UNIVERSAL INPUT CONTROLLER
Off Delay for On/Off Output (C.26)
The On/Off output is controlled by the Plant / System On/Off
input and provides an Off switching output with adjustable
delay time e.g. to operate the fan still for a certain time after
Output Y1 = 0%
The off time delay can be adjusted by the parameter
PARAMETER SETTINGS AND
Main Setpoint W1 (P.01)
The main setpoint is either set by the parameter W1
(CPATYP = 0 or 1) or by the external setpoint potentiometer
(CPATYP = 2).
High/Low Limit Setpoint W
For high or low limit control, the control parameter W
used as setpoint.
During limit control, the throttling range Xp2 and reset time
tr2 are active.
Limit control will be active only, if the X2 signal (X2ext = 0) is
available or alternatively the sensor X1 (X2ext = 1) is used
also for limit control.
For cascade control the limit setpoint W
control point at which the submaster setpoint (W
maintains the limit value and is not shifted anymore by the
master control loop.
High or low limit control is in accordance with the parameter
Submaster Setpoint W
The R7426D controller provides cascade control which uses
two control loops, master and submaster to maintain the
master setpoint CTRP1. Cascade control will be active, if
sensor X2 is connected and the control parameter W
to any value other than Off.
This adjustment sets the control point of the submaster
control loop, cascade input (X2), at zero deviation of the
master control loop. If the controlled input X1 deviates from
the master setpoint CTRP1, the submaster setpoint W
automatically altered (CTRP2
Cascade control is disabled, if the submaster setpoint W
set to Off.
Low limit of CTRP2 is performed if control parameter
LimTyp = 0 and high limit of CTRP2 is performed if control
parameter LimTyp = 1.
On/Off Output: Delay
Off → On: 0 min
On → Off: 0...60 min
Reset Span Adjustment R
The reset span adjustment R
%, the submaster setpoint W
(X1) deviates by 50% of the throttling range Xp1.
Throttling Range Xp1 / Xp2 (P.08 / P09)
Throttling range X
variable change, required at the main sensor (X1) and limit or
cascade sensor (X2) to operate the output device from full
open (100%) to full closed (0%) or vice versa.
Xp1 is the throttling range for the main control loop, Xp2 is
the throttling range for limitation or cascade control
(submaster control loop).
High or Low Limit Control
Table 6. Throttling Range, Reset and Derivative
Setting Guidelines for Proportional Band of
P, P+I and P+I+D Control
To estimate the proportional band (throttling range X
stable control under all different load conditions the control or
correcting range X
controlling element has to be known. This is the maximum
difference in the controlled variable between the fully closed
and fully open position of the final controlling element (e.g.
The proportional band X
calculated by using the following rule-of thumb formula:
For room control the following rule-of-thumb formula can be
In P+I or P+I+D control the same proportional band can be
used as for P control.
The following rule-of-thumb formula are used for P+I control:
Discharge air control
determines the reset effect in
is altered, if the main input
adjustment determines the controller
Sens. Xp1 Xp2 tr1 tr2 vd/td
of the controlled variable by the final
for discharge air control can be