NEWPORT iDRA Controller - Manual (Page 40)

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START AUTO TUNE PID:
Press d 27) Display flashes ENBL or DSBL.
Press b 28) Scroll through the available selections: “Enable” or “Disable”.
Press d 29) Display shows STRD stored message momentarily and then
advances to CYCL only, if it was changed, otherwise press a to
advance to CYCL Cycle Time Submenu.
If “Enabled”, the controller is ready to calculate P, PI or PID parameters.
The instrument performs this by activating the output and observing the
delay and rate at which the Process Value changes. The setpoints must
be at least 18°F or 10°C above the (PV) Process Value in order to
perform Auto Tune, otherwise an error message will be displayed.
To start Auto Tune PlD select PID, enable Auto PID and enable Start PID.
Sometimes Auto PID parameter needs fine tuning i.e. for each 5°F over
shoot increase the Proportional Band (PB) by 15% and for each ±1°F
fluctuation at the Setpoint (SP) increase reset by 20%.
Once started, display shows A.TUN with letters blinking in the rotating
pattern. When auto tune stops, display will show process value. Do not
perform any operations or settings before first stopping Auto Tune. Any
alarms or other output is disabled during Auto Tune.
If “AUTO PID” was “DISABLED”, the display will show the following
three submenus. This allows the user to manually enter values for
Proportional, Reset and Rate terms corresponding to P, I, and D. It also
can be used for Auto PID for disabling unwanted parameter i.e. PI enter
0000 for Rate.
PROPORTIONAL BAND SUBMENU:
Press d 30) Display flashes 1 st digit of the previous P PRoP Proportional
band value.
Press b & c 31) Press b and c buttons to enter a new “Proportional Band”
value.
Press d 32) Display shows STRD stored message momentarily and then
advances to REST only, if it was changed, otherwise press a to
advance to REST Reset Setup Submenu.
Proportional Band is in degrees of temperature or counts of process. Proportional
Band is defined, as the change in the instrument input to cause a 100% change
in the controller output.