Analog Input Function Block - Emerson Rosemount 644 FOUNDATION Reference Manual

Configuration
September 2018
2.4.3

Analog Input function block

Configure the AI block
A minimum of four parameters are required to configure the AI block. the parameters are described
below with example configurations shown at the end of this section.
CHANNEL
Select the channel that corresponds to the desired sensor measurement. The Rosemount 644 measures
both sensor temperature (channel 1) and terminal temperature (channel 2).
L_TYPE
The L_TYPE parameter defines the relationship of the sensor measurement (sensor temperature) to the
desired output temperature of the AI Block. The relationship can be direct or indirect.
Direct
Select direct when the desired output will be the same as the sensor measurement (sensor
temperature).
Indirect
Select indirect when the desired output is a calculated measurement based on the sensor measurement
(e.g. ohm or mV). The relationship between the sensor measurement and the calculated measurement
will be linear.
XD_SCALE and OUT_SCALE
The XD_SCALE and OUT_SCALE each include four parameters: 0%, 100%, engineering units, and
precision (decimal point). Set these based on the L_TYPE:
L_TYPE is Direct
When the desired output is the measured variable, set the XD_SCALE to represent the operating range of
the process. Set OUT_SCALE to match XD_SCALE.
L_TYPE is Indirect
When an inferred measurement is made based on the sensor measurement, set the XD_SCALE to
represent the operating range that the sensor will see in the process. Determine the inferred
measurement values that correspond to the XD_SCALE 0 and 100% points and set these for the
OUT_SCALE.
Note
To avoid configuration errors, only select Engineering Units for XD_SCALE and OUT_SCALE that are
supported by the device. The supported units are:
Pressure (channel 1)
14
Temperature (channel 2)
C
°
F
°
K
R
W
mV
C
°
F
°
K
R
W
mV
Reference Manual
00809-0400-4728, Rev CA
Configuration