Rockwell Automation 1746-NI16V SLC 500 Analog Input Modules User Manual - Manual (Page 70)

Publication 1746-UM001A-US-P
5-22 Channel Configuration, Data, and Status
Input Type (Bits 3 and 2)
The input type bit field indicates what type of input signal the channel
is configured for, based on the configuration word. The input type
field is cleared when the channel is disabled.
Class 1 Data or Status Configuration (Bits 1 and 0)
When bits 1 and 0 are set to (0 0) or (0 1) in the configuration word,
data is being requested from channels 0
to 7 or 8 to 15 in Class 1 to be
reflected in the 8 input words. The module returns a 16-bit value for
the channel data which can be used directly. However, the resolution
of data in Class 1 is only 14 bits. Bits (1 and 0) are overwritten with
the data or status configuration information. Therefore, Class 1
operation reports a 16-bit data value with an error within ±3 LSB of
the actual value.
In Class 3, the input word reports 16 words of data and 16 words of
status information. When data is being reported in Class 3, the data
value is a 16-bit integer, whereby all 16 bits are real data, depending
on the data type.