COMBIMASTER & MICROMASTER Integrated
REFERENCE MANUAL
©
Siemens plc. 1999
| G85139-H1731-U300-D2
20
5.8 Closed Loop Control
Closed loop control is only possible when an
OPm2 or a serial link is connected to the
COMBIMASTER.
5.8.1 General Description
The COMBIMASTER provides a
Proportional/Integral (PI) control function for
closed loop control
(see Figure 8)
. PI control is
ideal for temperature or pressure control, or
other applications where the controlled variable
changes slowly or where transient errors are
not critical. This control loop is
not
suitable for
use in systems where fast response times are
required.
Note:
The closed loop function is not
designed for speed control, but can be
used for this provided that fast
response times are not required.
When closed loop PI control is enabled (P201
= 002), all setpoints are calibrated between
zero and 100%, i.e. a setpoint of 50.0 = 50%.
This allows general purpose control of any
process variable that is actuated by motor
speed and for which a suitable transducer is
available.
S etpoint
S caling
P 211, P 212
Feedbac
k
S am ple
R
P 205
Low
P ass
P 206
P
P 202
I
P 203, P 207
A cceleration
/
D eceleration
R
P 002, P 003
M otor
M
P rocess
e.g. fan
T ransduce
P 20
+
P 201 =
Feedback
(e.g. duct
pressure)
P 201 =
C losed Loop M ode
C losed Loop M ode
P 21
Feedbac
k
Figure 8: Closed Loop Control
5.8.2 Hardware Setup
Connect the signal wire from the external
feedback transducer to control terminal 10. Set
jumper JP303 if voltage input type is required
(default) or set JP302 if current input type is
required.
15 V dc power for the feedback transducer
can be supplied from control terminal 8.
5.8.2 Parameter Settings
Closed loop control cannot be used unless
P201 is first set to 002. Most of the
parameters associated with closed loop
control are shown in Figure 8. Other
parameters which are also associated with
closed loop control are as follows:
P001
(value = 007)
P061
(value = 012 or 013)
P210
P220.
