Emotron VS10 Operation Instructions Manual page 251

9. Diagnostics: Check current reference value and feedback of the variable:
• The current reference value (setpoint) is displayed in
• The current variable (actual value) is displayed in
After the basic setting of the process controller has been carried out, a fine adjustment of
the PID controller must be executed for an optimum control mode (see the following
section).
Fine adjustment of the PID controller
The dynamics of the PID controller is parameterised based on the gain of the P component
0x4048 (P601.00), the reset time for the I component
the D component 0x404A
as PI controller, the D component is deactivated.
Basics
• If only the P component is used and the system operates in a steady-state status
(reference value is constant and process variable is controlled to a fixed value), a
certain system deviation always continues to exist. This remaining system deviation is
also called "stationary deviation".
• The I component ensures that no permanent system deviation remains. Here, the reset
time 0x4049 (P602.00)determines how much the duration of the control deviation
influences the control. A high reset time means a lower influence of the I component
and vice versa.
• The D component does not respond to the height of the system deviation but to their
rate of change only. The D component acts as a "damper" for overshoots. Overshoots
may occur if the control tries to respond quickly to changes in the system deviation or
the reference value. Thus, the D component reduces the risk of instabilities due to
overshoots.
For most applications, the setting of the gain of the P component and the
reset time for the I component is sufficient for the fine adjustment. The
setting of the gain of the D component may by required for a further
stabilisation of the system especially if a quick response to system deviations
is to take place.
Execute fine adjustment:
1. Set the reset time for the I component to 6000 ms in
the I component.
• With this setting and the default setting of
operates as P controller.
2. Increase gain of the P component step by step in
gets instable.
3. Reduce gain again until the system is stable again.
4. Reduce gain by another 15 %.
5. Set reset time for the I component in
• With this setting it should be noted that a too low reset time may cause overshoots,
especially in case of high steps of the system deviation.
6. Set optional gain of D component in
• With this setting it should be noted that the D component responds very sensitively
to electrical disturbance on the feedback as well as digitisation errors.
(P603.00). In the default setting, the process controller operates
0x4049
0x404A (P603.00).
0x401F:001 (P121.01).
0x401F:002 (P121.02).
0x4049 (P602.00) and the gain of
0x4049 (P602.00)
0x404A (P603.00), the process controller
0x4048 (P601.00) unit the system
(P602.00).
to deactivate