Pid Tuning Control Panel - Siemens SIMATIC S7-200 System Manual

S7-200 Programmable Controller System Manual

PID Tuning Control Panel

STEP 7--Micro/WIN includes a PID
Tuning Control Panel that allows you to
graphically monitor the behavior of your
PID loops. In addition, the control panel
allows you to initiate the auto-tune
sequence, abort the sequence, and
apply the suggested tuning values or
your own tuning values.
To use the control panel, you must be
communicating with an S7-200 PLC and
a wizard-generated configuration for a
PID loop must exist in the PLC. The PLC
must be in RUN mode for the control
panel to display the operation of a PID
l loop. Figure 15-2 shows the default Fi 15 2 h
screen for the control panel.
The control panel displays the station address (Remote Address) of the target PLC at the top
left-hand side of the screen. At the top right-hand side of the screen, the PLC type and version
number are displayed. Underneath the Remote Address field is a bar chart representation of the
process variable value along with both it's scaled and unscaled values. Just to the right of the PV
bar chart is a Current Values region.
In the Current Values region, the values of the Setpoint, Sample Time, Gain, Integral time, and
Derivative time are displayed. The value of the Output is displayed in a horizontal bar chart along
with its numerical value. To the right of the Current Values region is a graphical display.
The graphical display shows color coded plots of the PV, SP, and Output as a function of time.
The PV and SP share the same vertical scale which is located at the left hand side of the graph
while the vertical scale for the output is located on the right hand side of the graph.
At the bottom left hand side of the screen is the Tuning Parameters (Minutes) region. Inside this
region, the Gain, Integral Time and Derivative Time values are displayed. Radio buttons indicate
whether the Current, Suggested or Manual values for Gain, Integral Time and Derivative Time are
being displayed. You may click on the radio button to display any one of the three sources for
these values. To modify the tuning parameters, click the manual radio button.
You can use the Update PLC button to transfer the displayed Gain, Integral Time and Derivative
Time values to the PLC for the PID loop that is being monitored. You can use the Start Auto Tune
button to initiate an auto-tuning sequence. Once an auto-tuning sequence has started, the Start
Auto Tune button becomes a Stop Auto Tune button.
Directly underneath the graphical display is a Current PID selection region with a pull down menu
that allows you to select the PID loop that you wish to monitor with the control panel.
In the Sampling Rate region you can select the graphical display sampling rate from 1 to 480
seconds per sample. You can edit the sampling rate, then use the Set Time button to apply the
change. The time scale of the graph is automatically adjusted to best display the data at the new
rate.
You can freeze the graph by pressing the Pause button. Press the Resume button to resume
sampling data at the selected rate. To clear the graph, select Clear from the right-mouse button
within the graph.
388
th d f lt
Figure 15-2 PID Tuning Control Panel