•
Local Setpoint:
This is set to a constant value, which is manually adjustable, and is not read from
the input channel (and thus will not respond to signal changes from the DCS or other controller).
In local setpoint mode, the setpoint can be changed by local pushbutton or using HART
commands through ValVue.
•
Output:
This is the process controller output to SVI positioner. The output is characterized first
then is reversed if configured as an air-to-close valve to become the valve position setpoint. For a
linear and air-to-open valve, the controller output is equal to position setpoint.
•
Remote Automatic Mode:
In this mode, controller output is calculated based on the error
between process variable and remote setpoint.
•
Local Automatic Mode:
In this mode, controller output is calculated based on the error between
process variable and local setpoint that is adjustable manually.
•
Manual Mode:
In this mode, controller output is kept constant until manually adjusted. It is no
longer calculated by the PID algorithm.
In this illustration, the controller is in local automatic mode with local setpoint at 80.00 gpm, process
variable at 80.00 gpm, and output at 82.9%. Remote setpoint 97.63 gpm is also displayed in the
Remote Setpoint box and to alert the user of the setpoint change when the controller is transferred back
to the remote automatic mode.
Valve operation data, valve position and actuator pressure are also displayed on this window.
If the process controller is configured for ratio control application, both the measured setpoint and the
remote setpoint calculated are displayed in their corresponding engineering units.
93
Figure 57. Controller
Monitor Window
