![background image](http://html.mh-extra.com/html/abb/controlmaster-cm30/controlmaster-cm30_user-manual_2344095.webp)
ControlMaster CM30, CM50 and CMF310
Universal process controllers,
1
/
4
,
1
/
2
DIN and fieldmount
8 Templates and Functionality
IM/CM/ED–EN Rev. X
93
8.3.3 Cascade with Feedforward
This template connects 2 PID loops together in order to enhance the control of a Master variable (loop) by
manipulation of a slave loop. The first (master) controller provides the set point for the second (slave)
Controller. The 2 controllers are linked internally.
To the Master output a feedforward signal is added. This signal is a disturbance variable which is weighted
by the feedforward ratio and bias values. When the auto/manual mode is changed via the front panel or by
a digital signal both the master and slave controllers change mode, the slave setpoint can then be adjusted
from the front panel, and this value is then tracked by the Master controller (taking account of the
feedforward signal) to ensure a bumpless transfer back into auto mode.
Note
. As part of the cascade template, logic equation 1 is preconfigured.
Changes to this equation will result in the cascade template not functioning correctly.
AIN 1
AIN 2
AIN 3
AIN 2
PV 1
Local
Set Point
x Ratio
+ Bias
(Slave)
Loop 2
PID
Control
PID
O/P
Manual
Output
Local
Set Point
x Ratio
+ Bias
Analog
Output
AO1
OP
Output Type
SPV
SSP
Motorized
Valve
Split
Output
RLY1
RLY2
RLY1
OP2
OP1
1
Cascade with Remote Setpoint Only
1
Time Prop
Output
(Master)
Loop 1
PID
Control
PID
O/P
MPV
MSP
FF
MSP
AIN 2
AIN 4
x Ratio
+ Bias
Local
Set Point
Local
Set Point
Loop 1
PID
Control
(Master)
PID
O/P
2
Time Prop
Output
Motorized
Valve
Split
Output
AO2
RLY1
RLY2
RLY1
OP2
OP1
Output Type
Analog
Output
Manual
Output
MPV
SSP
SPV
Loop 2
PID
Control
(Slave)
AIN 3
AIN 1*
*Source can be changed in
Control / FeedForward
configuration –
PID
O/P 1
x Ratio
+ Bias