model 2704 controller installation and operation handbook - Soliton

2704 Controller Tuning
8.6. GAIN SCHEDULING
Gain scheduling is the automatic transfer of control between one set of PID values and
another. In the case of the 2704 controller, this is done at a presettable value of SP, PV Error
or OP. This is determined in configuration level. Gain scheduling is used for the more
difficult to control processes which exhibit large changes in their response time or sensitivity
at, for example, high and low PVs, or when heating or cooling.
The 2704 controller has three sets of PID values. You can select the active set from either a
digital input, or from a parameter in the Loop Setup(PID) page, see Chapter 9, or you can
transfer automatically in gain scheduling mode. The transfer is bumpless and will not disturb
the process being controlled .
8.6.1. To Use Gain Scheduling
If gain scheduling has been enabled in configuration level:-
Do This
1. From any display press
as many times as necessary
to access the page header
menu
2. Press or to select
‘LP1 SETUP’
This Is The Display You
Should See
Additional Notes
Alternatives are LP 2 and
LP 3. These only appear
in the list if the loops are
configured
LPx SETUP page is at
Level 3 by default but may
have been promoted to L1
or L2.
3. Press to display subheaders
4. Press or to select
‘PID’
5. Press to show the
parameter list.
6. Press again to select
‘Active PID Set’.
7. Press or to select
the PID set to use for gain
scheduling
The choices are PID Sets
1 to 3.
To change the active PID
set, press to select,
then press or to
change.
You must now set up the three sets of PID values. The values can be manually set, or
automatically tuned as described earlier in this chapter. When tuning automatically you must
tune three times, once below the switching point ‘1/2 Boundary’ once between 1/2 Boundary’
and ‘2/3 Boundary’ ‘ and finally above ‘2/3 Boundary’.
Installation and Operation Handbook. Part No HA026502 Issue 1.0 Apr-00 8-11