4. OPERATING MODES | English |
4.6 Closed Loop Control
4.6.1 General Description
The MICROMASTER provides a PI control function for closed loop control (see Figure 11). 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
Low Pass |
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Filter | Scaling |
| – |
P206 | P211, P212 |
Feedback
Sample
Rate
P205
P | Acceleration/ |
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|
|
|
| |
P202 | Deceleration |
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+ | Ramp | Motor | |
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| M | Process |
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| e.g. fan | |
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|
| |
| P002, P003 |
| Feedback |
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| (e.g. duct pressure) | |
I |
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| Transducer |
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| |
P203, P207
P208
Closed Loop Mode Disabled |
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P201 = 000 |
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Closed Loop Mode Enabled | Feedback | |
Monitor | ||
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P201 = 002 | P210 |
Figure 11: Closed Loop Control
4.6.2 Hardware Setup
Connect the outputs from the external feedback transducer to control terminals 3 and 4. This analogue input accepts a 0/2 - 10 V signal, has
15 V dc power for the feedback transducer can be supplied from terminals 8 and 9 on the control block.
4.6.3 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 11. 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 5. For further detailed information about PI operation refer to the Siemens DA 64 Catalogue.
© Siemens plc 1997G85139-H1750-U049-B
19 | 26/09/97 |
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