Rockwell Automation 1746-NR8 SLC 500 RTD/Resistance Input Module User Manual - Manual (Page 54)

Publication 1746-UM003A-EN-P
4-6 Channel Configuration, Data, and Status
Input Type Selection (Bits 0 through 3)
The input type bit field lets you configure the channel for the type of input
device you have connected to the module. Valid input devices are shown in the
previous table.
Data Format Selection (Bits 4 and 5)
The data format bit field lets you define the format for the channel data word
contained in the module input image. Valid data types are engineering units,
scaled-for-PID, and proportional counts. If you select proportional counts and
are operating in Class 3, you have the option of using user-defined scaling
(output registers O:8 through O:23). Unless you specify otherwise, the data is
scaled to the full scale range for that channel.
Table 4.2 Bit Descriptions for Data Format Select
Using Scaled-For-PID and Proportional Counts Formats
The RTD module provides eight options for displaying input channel data.
These are 0.1°F, 0.1°C, 1°F, 1°C, 0.1
Ω,
1
Ω
, Scaled-for-PID, and Proportional
Counts. The first six options represent real engineering units and do not
require explanation. The Scaled-for-PID selection allows you to directly
interface RTD Data into a PID instruction without intermediate scale
operations and Proportional Counts selection provides the highest display
resolution, but also require you to manually convert the channel data to real
Engineering Units.
(5) This bit is ignored when a resistance device is selected.
Binary
Value Select Description
00 engineering units x 1 Express values in 0.1 degree or 0.1
Ω
or 0.01
Ω
for 150
Ω
pot., only
01 engineering units x 10 Express values in 1 degree or 1
Ω
or 0.1
Ω
for150
Ω
pot.,
only.
10 scaled-for-PID The input signal range for the selected input type is its
full scale input range. The signal range is scaled into a 0
to 16383 range, which is what the SLC processor expects
in the PID function.
11 proportional counts The input signal range is proportional to your selected
input type and scaled into a -32768 to +32767 range
(default) or user-set range, based on the scale limit words
(O:e.8 to O:e.23)