ControlMaster CM30, CM50 and CMF310
Universal process controllers,
1
/
4
,
1
/
2
DIN and fieldmount
7 Advanced Level
50
IM/CM/ED–EN Rev. X
…Control / …Loop 1 (2) Control
Control Action
If the required controller action is known it can be set using this parameter. Otherwise it can
be set to
Unknown
and
Autotune
(see page 29) determines and selects the correct action.
Direct
For applications where an increasing process variable requires an increasing output to
control it.
Reverse
For applications where an increasing process variable requires a decreasing output to
control it.
Unknown
For applications where the control action is not known (run Autotune to set the control
action automatically).
On/Off Hysteresis
Autotune
PID
Refer to
Basic
Level on page 28.
Gain
S
cheduling
Gain Scheduling
is used to improve the control of non-linear
processes where the non-linearity is not time dependent.
Processes with time-dependent non-linearity can be controlled
with adaptive control. The gain scheduler selects different
PID
parameters (see page 30) according to the value of a
user-selected reference signal.
3 Different settings for
PID
parameters can be used, within 3
ranges set by the user-defined parameters (
Limit 1
and
Limit 2
[see page 51]) that are expressed in the engineering range of the
Gain Scheduling
(GSRef) reference signal. When the value of the
reference signal passes one of the limits the next set of
PID
parameters is switched in.
How Gain Scheduling Works with
Autotune
When tuning is first performed, or after
Gain Scheduling
(or
Autotune
[see page 29]) is reset, the autotuner calculates
PID
parameters for the set selected by the GSRef signal and also copies those values into the other 2 sets of
PID
parameters.
If
Autotune
is then run with
Gain Scheduling
in one of the other 2 sets (see chart above), it calculates the
PID
values for
the set selected by GSRef and also copies these to the set that was not calculated before.
If the Autotune is run with GSRef in the third set, it calculates the
PID
values for that set and leaves the other 2 sets
untouched.
Any further running of the autotuner updates only the set that is selected at the time until
Gain Scheduling
(or
Autotune
) is reset. For example:
If
Autotune
is run with GSRef <
Limit 1
, it calculates values for the first set of
PID
parameters and also copies
these into the other 2 sets as well.
If
Autotune
is then run with GSRef >
Limit 2
, it calculates
PID
values for the third set of
PID
parameters and
also copies these to the second set.
If
Autotune
is then run with GSRef between
Limit 1
and
Limit 2
, it calculates values for the second set of
PID
parameters and leaves the other 2 sets untouched.
P
I
D
GsRef
PB
TI3
TD
PB
TI2 TD
PB
TI1 TD
TI
Gsref
Set 3
Set 2
Set 1
Limit
2
Limit
1