36
AUTOTUNING
Before initiating the autotune function, first decide if you would like
to autotune at setpoint or 10% of full scale below setpoint. Set the set-
point (SV), alarms (AL, AH) and the cycle time (TC). Bring your process
near setpoint before starting the autotune procedure. Autotuning works
best for heating processes in which the setpoint is 100°F (60°C) above
ambient temperature.
Set the parameter AT to either “1” (to auto-tune at setpoint) or “2” (to
auto-tune at 10% of full scale below setpoint) and press SEL key to start
auto-tuning. The point indicator at lower right will then start blinking.
When the auto-tuning is completed, the point indicator stops blinking
and the parameter AT will automatically be set to “0.”
Duration of the autotune process varies with every application. The
auto-tuning process may take between 1 and 30 minutes to complete.
If it fails to complete, an abnormality may be suspected. In this case,
recheck the wiring, control action, and input type code. Refer to
page 38 and Appendix A for additional details.
The PID parameters calculated by autotuning will be retained even if
the power is lost. However, if the power is turned off during the auto-
tuning process, you must restart Autotuning. To abort the autotune
procedure, set AT to “0.” Auto-tuning has to be repeated if there is a
significant change in SV, P-SL or P-SU, or in the controlled process.
Autotuning can also be performed while fuzzy control is selected.
Summary of Contents for CN4321
Page 33: ...32 SYSTEM WIRING DIAGRAMS Example 1 Example 2...
Page 45: ...44 Deadband Overlap...
Page 48: ...47 Table of Input Type Codes...
Page 50: ...49...
Page 53: ...52 Table of Alarm Action Type Codes CN4321...
Page 54: ...53 Table of Alarm Action Type Codes CN4431...
Page 59: ...58 Table of Output Type Codes...
