Basic Setup; Set Process Variable Units; Set Output (Transfer Function) - Emerson Rosemount 3051S Series Reference Manual

Configuration
October 2018
2.7

Basic setup

2.7.1

Set process variable units

The PV Unit command sets the process variable units to allow you to monitor your process using the
appropriate units of measure.
Field Communicator
Device Dashboard Fast Keys
HART 5 with Diagnostics Fast Keys
HART 7 Fast Keys
Enter the Fast Key sequence "Set Process Variable Units." Select from the following engineering units:
inH

inHg

ftH

mmH

mmHg

psi

AMS Device Manager
1. Right click on the device and select Configure from the menu.
2. Select Manual Setup from the left window pane.
3. Select the Process Variables tab.
4. Click the Unit drop down menu to select units.
2.7.2

Set output (transfer function)

The Rosemount 3051S has two output settings: linear and square root. Activate the square root output
option to make analog output proportional to flow. As input approaches zero, the pressure transmitter
automatically switches to linear output in order to ensure a more smooth, stable output near zero (see
Figure
From 0 to 0.6 percent of the ranged pressure input, the slope of the curve is unity (y = x). This allows
accurate calibration near zero. Greater slopes would cause large changes in output (for small changes at
input). From 0.6 to 0.8 percent , curve slope equals 42 (y = 42x) to achieve continuous transition from
linear to square root at the transition point.
Note
If low flow cutoff configuration is desired, use
square root and
If scaled variable is mapped as the primary variable and square root mode is selected, ensure transfer
function is set to linear. Do not set the transfer function to square root if square root mode is selected for
the primary variable as this would cause the square root function to be performed twice.
24
O

2

O

2
O

2


2-14).
"Re-mapping" on page 36
2, 2, 1, 2
2, 2, 1, 1, 2
2, 2, 1, 1, 2
bar

mbar

2
g/cm

2
kg/cm

Pa

kPa
"Scaled variable configuration" on page 33
to map scaled variable as the primary variable.
Reference Manual
00809-0100-801, Rev HA
torr
atm
MPa
inH O at 4 °C
2
mmH O at 4 °C
2
to configure
Configuration