Rockwell Automation 1762-IR4 RTD/Resistance Input Module - Manual (Page 47)

Publication 1762-UM003A-EN-P - February 2003
Module Data, Status, and Channel Configuration 3-13
Engineering Units x 1 Data Format
If you select engineering units x 1 as the data format for an RTD input,
the module scales input data to the actual temperature values for the
selected RTD type per RTD standard. It expresses temperatures in
0.1
°
C units. For resistance inputs, the module expresses resistance in
0.1
Ω
units, for all ranges except the 150
Ω
range. For the latter,
resistance is expressed in 0.01
Ω
units.
The resolution of the engineering units x 1 format is dependent on the
range selected and the filter selected. See Determining Effective
Resolution and Range on page 3-20.
Engineering Units x 10 Data Format
For the engineering units x 10 data format for an RTD input, the
module scales input data to the actual temperature values for the
selected RTD type per RTD standard. With this format, the module
expresses temperatures in 1
°
C units. For resistance inputs, the module
expresses resistance in 1
Ω
units, for all ranges except the 150
Ω
range.
For the latter, resistance is expressed in 0.1
Ω
units.
The resolution of the engineering units x 10 format is dependent on
the range selected and the filter selected. See Determining Effective
Resolution and Range on page 3-20.
Scaled-for-PID Data Format
If you select the scaled-for-PID data format, the module presents to
the controller a signed integer representing the input signal range
proportional to the selected input type. The integer value is the same
for RTD and resistance input types.
To obtain the value, the module scales the input signal range to a
linearized 0 to 16383 range, which is standard to the PID algorithm for
the MicroLogix, SLC, and PLC controllers. The 0 value corresponds to
the lowest temperature or resistance value, while 16383 corresponds
to the highest value. For example, if a 100
Ω
platinum 385 RTD is
selected, the lowest temperature for the RTD, -200
°
C, corresponds to
0. The highest temperature, 850
°
C, corresponds to 16383.
TIP
Use the engineering units x 10 setting to produce
temperature readings in whole degrees Celsius or
Fahrenheit. See Engineering Units x 10 Data Format
below.