Siemens Stober CombiDrive CM400/3 - Manual (Page 15)

3. Operating Information English
© STÖBER plc 1997
13 05.02.01
3.8 Closed Loop Control
Closed loop control is only possible when an OPm2 or a serial link is connected to the CombiDrive ® .
3.8.1 General Description
The CombiDrive ® provides a Proportional/Integral (PI) control function for closed loop control (see Figure 7). 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.
Setpoint
Scaling
P211, P212
Feedback
Sample
Rate
P205
Low Pass
Filter
P206
P
P202
I
P203, P207
Acceleration/
Deceleration
Ramp
P002, P003
Motor
M
Process
e.g. fan
Transducer
P208
+
–
P201 = 000
Feedback
(e.g. duct pressure)
P201 = 002
Closed Loop Mode Disabled
Closed Loop Mode Enabled
P210
Feedback
Monitor
Figure 7: Closed Loop Control
3.8.2 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.
3.8.3 Parameter Settings
Closed loop control cannot be used unless P201 is first set to 001. Most of the parameters associated with
closed loop control are shown in Figure 7. Other parameters which are also associated with closed loop
control are as follows:
P001 (value = 007)
P061 (value = 012 or 013)
P210
P220
Descriptions of all closed loop control parameters are provided in section 4. For further detailed information
about PI operation, refer to the Siemens DA 64 Catalogue.