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92 UDA2182 Universal Dual Analyzer Product Manual January 2009
6.14 PID Control Configuration
Overview
PID (Option) - Proportional (P), Integral (I) and Derivative (D), (3-mode) control action
based on the deviation or error signal created by the difference between the setpoint (SP)
and the Process variable analog input value (PV). PID Tuning parameters are available.
Automatic tuning with Fuzzy Logic Overshoot Suppression can be configured.
Other parameters listed in this group deal with how the analyzer will control the process
including: PV High and Low, Setpoint High and Low limits, the Control Algorithm and
Action, PID Tracking (TRV and TRC), Number of Tuning Parameter Sets and associated
parameters, Setpoint Rate, Power-up Recall, Output Limits, Failsafe Output Value,
Alarm setpoint type and value, and Alarm Hysteresis.
PID Tracking
PID tracking is a means to control a PID’s output without the PID loop winding up.
It is accomplished by the use of two inputs.
TRC (tracking control) – selects the tracking mode (See Table 6-13)
TRV (tracking value) – is the commanded output value in percentage
(PID Output = TRV Input when TRC = ON) (See Table 6-13)
When TRC is active, the front-panel display will indicate TRV for the PID loop.
Remote PID Tracking
Variables can be connected to TRC and TRV to allow remote control of the PID output.
TRC can be connected to a digital variable
TRV can be connected to an analog variable
PID Tracking versus Manual Mode
Tracking is not the same as manual mode.
• Tracking value cannot be adjusted from the front-panel. Manual output value can.
• Manual output cannot be adjusted remotely. Tracking value can.
• Manual has priority over tracking. If operating in the tracking mode, the output
can be adjusted from the front-panel by selecting manual and adjusting the output.
When manual is terminated, the active mode will be TRC and the output will go
to TRV.
Using Auto/Manual Switch
It may be desirable to use a discrete input to place a PID into manual momentarily to
freeze the output. With tracking, this can be done.
1. Connect the TRV to PID output
2. Connect the TRC to a discrete input
When the discrete input is active, the output is frozen – MANUAL select.
When the discrete input is inactive, the PID runs in the auto mode – AUTO select.