Process Control
January 2023
•
Rev. 0
• Standard Devices User Manual
17
Process Control
Controllers
For a controller to regulate the flow or pressure, it needs to
have a setpoint established. The setpoint is the amount of
flow or the pressure that the controller attempts to achieve
in a process line.
Setpoint
SETPT
or
MENU
→
CONTROL
→
Setpt
The
setpoint selection screen
indicates the engineering
units and maximum allowable setpoint (e.g.,
SLPM: +1.000
Max
).
To establish a setpoint, enter the desired value and press
SET
, the device immediately begins to control the flow or
pressure. A zero setpoint can be established by selecting
CLEAR
and then
SET
.
Setpoint Options
The setpoint can be configured with a few options to better
control your process based on your needs. Below are various
setpoint options and functions.
Auto-tare and Zero Setpoint Options
MENU
→
CONTROL
→
Setpoint Setup
→
Zero Setpoint
A controller can automatically tare itself when it has a zero
setpoint. Once the setpoint is given, the device waits a
specified amount of time before taring.
Delay Before Tare
manages how much time the controller waits before taring.
Make sure the delay provides enough time for the process
to stop flow and settle.
!
Caution:
Auto-tare typically is not
recommended for pressure controllers.
Ramp
controls whether the device honors setpoint ramping
down (
) or immediately goes to the zero setpoint.
If set as
Honor ramp to 0
, the controller moves down to a
zero setpoint at the specified ramp rate. If set as
Instantly
to 0
, the controller immediately moves the process to zero
when a zero setpoint is given.
Setpoint Source
MENU
→
CONTROL
→
Setpoint Setup
→
Setpoint Source
Controllers with RS-232 or RS-485 communication accept
setpoints from the front panel and serial commands
(
). Alternatively, an analog source can be used
instead.
•
When the source is set to
Serial/Front Panel
, the
controller accepts input from either the front panel
or an RS-232/RS-485 connection. Neither source
is a slave of the other, and the controller accepts
the most recent command from either source.
•
When the source is set to
Analog
, the device
ignores serial setpoint commands and prevents
setpoint input from the front panel.
C
ontrol menu
.
Setpoint source menu
.
Zero setpoint
(auto-tare)
menu
.
Setpoint screen.
