Configuration 
4/07  UDC2500 Universal Digital Controller Product Manual  43 
3.6  Accutune Set Up Group 
Introduction 
Accutune III automatically calculates GAIN, RATE, and RESET TIME (PID) tuning 
constants for your control loop. When initiated on demand, the Accutune algorithm 
measures a process step response and automatically generates the PID tuning constants 
needed for no overshoot on your process. 
Fuzzy, Fuzzy Overshoot Suppression: When enabled, this configuration will suppress or 
eliminate any overshoot that may occur as a result of the existing tuning parameters, as 
the PV approaches the setpoint. 
Tune, Demand Tuning: The tuning process is initiated through the operator interface keys 
or via a digital input (if configured). The algorithm then calculates new tuning parameters 
and enters them in the tuning group. Tune will operate with PIDA, PIDB, PD+MR and 
Three Position Step Control algorithms. 
 SP, SP Tuning: SP tuning continuously adjusts the PID parameters in response to 
setpoint changes. You can select tuning on minimum setpoint changes of  
5 % up to 15 % span. Perform SP tuning after you have configured the controller.  SP 
Tuning does not operate with the Three Position Step Control algorithm. 
Simplex Tuning is used when a Simplex Control Algorithm is configured and uses the 
current SP value and alters the output over the Output Limit Range. 
Duplex Tuning is used when a Duplex Control Algorithm is configured.  To perform a 
Duplex Tune, Two Local Setpoints must be configured per the Control Group in Section 
3.11.