Rockwell Automation 1746-NI8 SLC 500 Analog Input Modules User Manual - Manual (Page 47)

5–6 Channel Configuration, Data, and Status
Publication 1746Ć6.8 - April 1997
Channel Data Word Values for Scaled Data
Input Type Signal Range ScaledĆforĆPID Proportional Counts (default) NI4 Data Format
± 10V dc -10.00V to +10.00V 0 to 16383 -32768 to 32767 -32768 to 32767
0-5V dc 0.0V to +5.00V 0 to 16383 -32768 to 32767 0 to 16384
1-5V dc +1.00V to +5.00V 0 to 16383 -32768 to 32767 3277 to 16384
0-10V dc 0.0V to +10.00V 0 to 16383 -32768 to 32767 0 to 32767
0-20 mA 0.0 mA to 20.0 mA 0 to 16383 -32768 to 32767 0 to 16384
4-20 mA 4.0 mA to 20.0 mA 0 to 16383 -32768 to 32767 3277 to 16384
± 20 mA -20.0 mA to 20.0 mA 0 to 16383 -32768 to 32767 -16384 to 16384
0-1 mA 0.0 mA to 1.00 mA 0 to 16383 -32768 to 32767 0 to 1000
➀
➀
This data format is not supported by the 1746ĆNI4 module, but is available for the 1746ĆNI8 module.
This section provides descriptions of how the data types are
expressed in the channel data word and examples of how to
mathematically convert the data.
Data Type Descriptions
The engineering units are 1 mV/step for voltage input types, and
1.0
µ
A/step for current input types.
The scaled-for-PID value is a 14-bit unsigned integer, with 0
representing the low scale value and 16,383 representing the full
scale value minus 1 lsb. The input signal range is proportional to
your selected input type and scaled into a 0–16,383 range, which is
standard to the SLC PID algorithm.
The proportional count value is a 16-bit signed integer. The input
signal range is proportional to your selected input and scaled into a
–32,768 to 32,767 range.
The 1746-NI4 data format converts the current and voltage signals
into 16-bit 2’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.
Voltage/Current Range Decimal
Representation
Number of
Significant Bits
Resolution
per LSB
-10V dc to +10V dc - 1LSB -32,768 to +32,767 16 bits
0 to 5V dc 0 to 16,384 14 bits
305 176 V
1 to 5V dc 3,277 to 16,384 13.67 bits
305.176 uV
0 to 10V dc - 1LSB 0 to 32,767 15 bits
Scaling the
Channel Data Word