SmartVue Operator’s Manual
10-0004-R13
23
5.0 Setting Up a Control Process
Like a process, a
control process incorporates the continuous acquisition of a measurable
signal. In this case, however, an output value (called the
modified variable) is required so
that changes to the process being controlled can be measured via a
feedback sensor and
an error value (the difference between the user specified setpoint and the measured input
value being fed back) can be computed. The result is subsequently supplied to a PID
control algorithm so that the error value can be minimized over time. The block diagram
below shows how the various aspects of a control process work together.
Figure 5-1 Block diagram of a closed-loop control process
In addition to the modified variable, various other parameters for a control process can be
assigned to a meter so it can be displayed on the
Meter screen including: the feedback
variable, the error value, and the setpoint value. The control process input value can, of
course, also be chosen for display.
You also have the choice of using either a manually entered setpoint or an external
setpoint that is governed by the signal connected to one of the SmartVue’s inputs.
Setting up a control process is similar to setting up the basic process explained earlier.
The instructions below describe the procedure for setting up the control process while the
output setup is described in Section 7.0
Setting Up an Output.
•
Label
•
Units
•
Scale
•
Setpoint (manual)
•
PID parameters
Sensor Input
Meter
Scale
Output
Sensor
Feedback
Process
being
controlled
SmartVue
Modified
Variable
External Setpoint
