26
Navigating and Customizing Your Flow Controller
Commanding a new setpoint
Press the SETPT button from either the Main Display or the Control Menu (MENU
> CONTROL) to choose a new setpoint. The setpoint selection screen indicates
the maximum allowable setpoint (e.g., SLPM 20.00 Max). To cancel a setpoint,
press CLEAR.
Changing the setpoint source
Unless your mass ow controller has been ordered with an industrial protocol,
it will accept setpoints from the front panel, a serial connection or an analog
signal. Change the setpoint source by selecting MENU > CONTROL > ADV CONTROL >
SETPT SOURCE.
» When the source is set to Serial/Front Panel, the controller will accept
input from either the front panel or an RS-232/RS-485 connection. Neither
source is a slave of the other, so the controller will accept the most recent
command from either source.
» When the source is set to Analog, the controller will ignore serial setpoint
commands and will prevent input from the front panel.
Adjusting the setpoint with the optional IPC (Integrated Potentiometer Control)
If your controller has been ordered with a potentiometer control knob (IPC),
the setpoint source must be set to Analog for the controller to accept setpoint
commands from the IPC.
When using an analog setpoint signal with a controller that has an IPC,
leave the IPC knob at the midpoint when it is not in use.
Changing the control loop variable
Your mass ow controller can control the ow rate or the pressure in your
process. Change the control loop variable by selecting MENU > CONTROL > ADV
CONTROL > LOOP SETUP > LOOP VAR. Loop variables include mass ow, volumetric
ow and absolute pressure. Devices with internal barometers also allow
control of gauge pressure.
Note: When pressure is selected as the control loop variable, ow
controllers with upstream valves will control the outlet pressure. Those
with downstream valves can control upstream backpressure, but these
must be congured for this type of control.
When changing the control loop from mass or volumetric ow to
absolute or gauge pressure, you may need to adjust the PID settings
for optimal stability and speed of response. (See PID on page 27.)
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