Sensaphone SCADA 3000 Users manual - Manual (Page 209)

17-1
Chapter 17: PID Programming
Chapter 17: PID PROGRAmmING
The SCADA 3000 includes eight programmable PID (Proportional, Integral, Derivative) con-
trol algorithms which allow the unit to operate as a feedback controller. A feedback controller
is typically used to maintain a set point for a process. In a feedback control application you
would have one input (the feedback) and one output (the force or mechanism) that allows you
to maintain the setpoint.
To program a PID control algorithm, click on the PID button from the SCADA 3000 toolbar
or select PID from the Programming menu. The following screen will be displayed.
Figure 1: PID Form
Select the PID algorithm you wish to program by clicking on one of the buttons labeled PID 0
through PID 7. Listed below are the programming parameters associated with each PID algo-
rithm. Each parameter must have a value entered for that algorithm to calculate properly:
• Name: Type in a name to describe the process that the PID algorithm will be
controlling. Example: Water Pressure.
• Enable PID: Clicking this box will start the PID algorithm. Do not click it
until you have finished programming all of the parameters associated with
the PID form. Once enabled, the algorithm will execute automatically based on
the Reload Time. The Output UAF will change based on the results of the algo-
rithm.
• Input UAF: The input UAF is the feedback for the process. This must be an
analog signal. Select the input UAF by clicking the button next to the Input UAF
text box. A choice of all possible UAFs will be displayed. Select the input which
will provide the feedback for your process or enter the UAF manually by typing
the UAF directly into the text box.
• Output UAF: The Output UAF identifies the output device which will affect
the process. The output value will change as necessary to maintain the setpoint.
• Reload Time: The reload time determines how often the PID Algorithm is exe-
cuted. For example, if the reload time is set to 0.25 seconds, every quarter second
the PID algorithm will run.
• Target Set Point: This is the value that the PID algorithm is trying to main-
tain. The units of measure for the Target Set Point will be the same as for the
Input UAF. For example, if the Input UAF is measuring pressure in PSI, then the
Target Set Point must also be in PSI.