104
Chapter 7
535-PROF User's Manual
Applications
Software Configurations
Pretune by Itself
1. Go to the
SELF TUNE
menu (press
MENU+FAST
)
2. Set the
TYPE
parameter to PRETUNE.
3. Set the
PRETUNE
type to the one that best matches the process (see above
section).
4. The next parameter,
TUNE PT.
, appears only for TYPE 1 pretune. This
parameter sets the PV point at which the output will switch off. In thermal
processes, this will help prevent overshoot. The default is AUTOMATIC.
5. If using TYPE 2 or TYPE 3 pretune, Set the value for
OUT STEP
. This
parameter defines the size of bump to be used. The resulting disturbance
must change the process variable by an amount that significantly exceeds
the peak-to-peak process noise, but does not travel beyond the “normal”
process variable range.
6. The next two parameters,
LOW LIMIT
and
HI LIMIT
, set the process variable
boundaries. If these boundaries are exceeded during the Pretune, the pretune
cycle will abort and return to manual control at the output level prior to the
initiation of pretune.
7. The next parameter,
TIMEOUT
, defines the maximum time in minutes within
which pretune must complete its calculations before it is aborted.
The first time a pretune is performed, set
TIMEOUT
to its maximum value.
Make note of the length of the pretune cycle. Then, adjust
TIMEOUT
to a
value about twice the pretune time.
The purpose of this parameter is to prevent a Pretune cycle from continuing
for an excessive time if a problem develops. The value has no impact on the
PID values being calculated.
8. Next is
MODE
. This defines what mode the controller will enter when pretune
is completed. Select MANUAL if there will be a need to review PID parameters
before attempting to control with them; the default is AUTOMATIC.
9. Place the controller under manual control.
10. Access the
TUNING
menu (press
MENU
).
11. Access the parameter
PRETUNE
(press
MENU
).
12. Press
and then ACK
to begin Pretuning.
The 3rd display will show the message EXECUTING.
13. When Pretune is complete, the 3rd display will show COMPLETED for two
seconds and then return to the current menu display.
Pretune TYPE 1 & Adaptive Tune
1. Go to the
SELF TUNE
menu.
2. Set
TYPE
to BOTH.
3. Set
PRETUNE
to TYPE 1.
4. Set a value for
TUNE PT
.
NOTE: TUNE PT.
= AUTOMATIC will work correctly only if the controller’s
setpiont is set up properly beforehand.
5. Set
NOISE BND
parameter.
6. Set the
RESP. TIME
parameter.
7. Make sure that the process is reasonably stable and place the controller
