Rockwell Automation 1769-IR6 Compact I/O 1769-IR6 RTD/Resistance Input Module - Manual (Page 55)

Rockwell Automation Publication 1769-UM005B-EN-P - March 2012 55
Module Data, Status, and Channel Configuration Chapter 4
Raw/Proportional Data Format
The raw/proportional data format provides the greatest resolution of all the
data formats. For this format, the value presented to the controller is
proportional to the selected input. It is also scaled to the maximum data range
allowed by the bit resolution of the A/D converter and selected filter
frequency.
If you select the raw/proportional data format for a channel, the data word
will be a linearized number between -32768…32767. The value -32768
corresponds to the lowest temperature value for an RTD or the lowest
resistance value for a resistance device.
Linear Relationship Between Temperature and Proportional Counts
The value +32767 corresponds to the highest value for the device. For
example, if a 100
Ω platinum 385 RTD is selected, the lowest temperature of -
200
°C corresponds to -32768 counts. The highest temperature of 850 °C
corresponds to +32767 counts. See Determining Effective Resolution and
Range on page 65.
+ 32,767
-32,768
850 ˚C
±200 ˚C
Counts
°C