Operating Manual CMGZ 622
23
•
If the
Derivative D
is too high, the control loop will become unstable again.
•
If the control loop is running stable, the parameters
Proportional P
,
Integral I
and
Derivative D
should be noted for eventually re-setup.
Mathematic determination of the control parameters
•
If the behaviour of the control loop is known, the control parameters may be
calculated by the known mathematical procedures and saved in the parameters
Proportional P1...P4
,
Integral I1...I4
and
Derivative D1...D4
. (There is only the
parameter set active which is chosen by the BCD inputs; refer to „9.7 Switching the
control parameters“.)
•
If the control loop is oscillating, the control parameters will be fine-tuned as
described under „Experimental determination of control parameters“.
Note
There can be saved 4 different P, I, D and reference values (P1...P4; I1...I4;
D1...D4; Ref1...Ref4). This allows easy and flexible adjustment of the controller to
different materials. The instructions above is valid for all 4 sets of parameters. But
for better understanding, the instruction is written in common form. There is a
specific parameter set active, depending on Measuring Range and PID switched or
not! The reference values and control parameters for both Measuring Ranges must
be determinate (refer to „9.7 Switching the control parameters“.)
Note
Correct setting of the control loop can be difficult. To judge the adjustment of the
control parameters, an oscilloscope may be helpful to record the behaviour of the
feedback value. The oscilloscope shows if the control loop operates stable, and if
there is no more static error.
Note
The controller must be adjusted so that the feedback reaches the reference in the
shortest possible way but without overshooting. If the feedback overshoots, this is
seen on the display or with an oscilloscope.
9.6
Switching the control parameters
There can be saved 4 different P-, I- and D- values (P1...P4; I1...I4; D1...D4), as well
as 4 different tension reference values. Due to that, it is possible to adjust the control
loop flexibly to different material characteristics. However, switching to another set of
parameters is only possible if the controller is disabled.
