Technical Specifications

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PID Output and Valve Position
PID Block and Trending
PID Output and Valve Position
Use this frame (Figure 98) to adjust the PID Output and see its response against the
valve position.
Figure 98 PID Output Slider
Trending Overview
The trend service can be used to observe the dynamic behavior of both the control
valve and its associated process variable. It is particularly useful for tuning the PID
process loop and can be used to alter the response of the positioner control algorithm
after Auto Tune. Each device is provided with one trend window. ValVue supports up to
30 trend windows.
The Trend window displays selected historical data for up to 12 hours. The selected
parameters can be actual valve position, target valve position, PID process variable and
PID process Set Point. Select Start to start trending and select Stop to stop trend. While
the trend is stopped the time axis continues to increase.
Figure 99 Trend Screen with Pressure Loop
When trend is restarted, the time that it had been stopped appears as a blank.