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DR4300 Circular Chart Recorder
100 DR4300 Circular Chart Recorder Product Manual 12/03
4.3.12 Tuning Parameters Set Up Group
Introduction
Tuning consists of establishing the appropriate values for tuning constants so that your recorder responds
correctly to changes in process variable and setpoint. You can start with estimated values, but you will
have to watch the system to judge how to modify the values. The tuning group parameters described in this
subsection are available only if:
• your recorder supports control
and
• the control type specified in the control setup group using the “CTRALG” (control algorithm)
parameter is “PIDA” or “PDMR”.
Two sets of PID constants
Two sets of PID constants are provided for duplex control. When the recorder is used in a heat/cool
application, the first set (“PB” or “GAIN”, “RATE T”, and “I MIN” or “I RPM”) apply to heat control.
The second set (“PB2” or “GAIN 2”, “RATE2T”, and “I2 MIN” or “I2 RPM”) are used for cooling
control.
Accutune II
Accutune II provides foolproof, trouble-free on-demand tuning in the recorder. No knowledge of the
process is required at start-up. The operator simply enters the desired setpoint and initiates the tuning. The
recorder immediately starts controlling to the setpoint while it identifies the process, calculates the tuning
constants and enters them into the tuning set up group, and begins PID control with the correct tuning
parameters. This works with any process, including integrating type processes, and allows retuning at a
fixed setpoint. The tuning sequence will cycle the recorder’s output two full cycles between 0 % and 100
% (or low and high output limits) while allowing only a very small process variable change above and
below the setpoint during each cycle.
Detailed instructions for using Accutune are provided in Appendix D.
Fuzzy overshoot suppression
A parameter is provided to enable/disable fuzzy overshoot suppression. When enabled, fuzzy overshoot
suppression minimizes process variable overshoot following a setpoint change or a process disturbance.
This is especially useful in processes which experience load changes or where even a small overshoot
beyond the setpoint may result in damage or lost product.
The fuzzy logic observes the speed and direction of the PV signal as it approaches the setpoint and
temporarily modifies the internal controller response action as necessary to avoid an overshoot. There is
no change to the PID algorithm, and the fuzzy logic does not alter the PID tuning parameters.