Rockwell Automation 1746-NI16V SLC 500 Analog Input Modules User Manual - Manual (Page 59)

Publication 1746-UM001A-US-P
Channel Configuration, Data, and Status 5-11
The 1746-NI4 data format converts the current and voltage signals
into 16-bit two’s complement binary values. The table below identifies
the current and voltage input ranges for the input channels, the
number of significant bits, and the resolution.
User-defined scaling count (Class 3 operation only) allows the
output image data words 16 and 17, 18 and 19, 20 and 21, or 22 and
23 to be selected to represent low-scale and high-scale limits. The
module uses these limits and scales proportionately between them.
For example, if words 16 and 17 are selected to represent low and
high scaling ranges, and word 16 contains 0 (decimal), and word 17
contains 20000 (decimal), this would represent the range of values to
which the voltage or current readings would be scaled. The lowest
voltage or current reading would be scaled to 0, and the highest
voltage or current reading would be scaled to 20000, with other
readings scaled proportionately between them.
If the module is in Class 1 mode, and you attempt to configure for
user-defined proportional counting, a configuration error is generated.
Using Scaled-for-PID and Proportional Counts
The scaled-for-PID and proportional count selections provide the
highest display resolution, but also require you to manually convert
the channel data to “real” units.
Voltage/Current Range Decimal Representation Number of Significant Bits Resolution per LSB
-10V dc to +10V dc - 1LSB -32768 to +32,767 16 bits 305.176 µV
0 to 5V dc 0 to 16,384 14 bits
1 to 5V dc 3,277 to 16,383 13.67 bits
0 to 10V dc - 1LSB 0 to 32,767 15 bits
0 to 20 mA 0 to 16,384 14 bits 1.22070 µA
4 to 20 mA 3,277 to 16,384 13.67 bits
-20 mA to +20 mA -16,384 to +16,384 15 bits
0 to 1 mA 0 to 1000 10 bits
1 µA
(1)
(1) This data format is not supported by the 1746-NI4 module, but is available for the 1746-NI8 and 21746-NI16 modules.