Rockwell Automation 1746-NI8 SLC 500 Analog Input Modules User Manual - Manual (Page 44)

5–3 Channel Configuration, Data, and Status
Publication 1746Ć6.8 - April 1997
Select Input Type (Bits 0-2)
The input type bit field lets you configure the channel for the type of
input device you have connected to the module. Valid input is an
analog voltage or current that provides a signal within one of the
specified ranges.
Determine the input device type for a channel and enter its respective
3-digit binary code in bit field 0–2 of the channel configuration
word. You must also set the DIP switches of the module for voltage
or current.
Select Data Format (Bits 3-5)
Select a data format for the data word value. Your selection
determines how the analog input value from the A/D converter will
be expressed in the data word. Enter your 3-digit binary code in bit
field 3–5 of the channel configuration word.
The data types are engineering units, scaled-for-PID, proportional
counts, 1746-NI4 data format, and user defined scaling for Class 3
operation only. For all data types, the channel data word is
proportional to the analog input signal.
To have the data in “real” units, the channel data word must be
scaled mathematically. See Channel Data Word on page
5–5 for
the default scaling values and Scaling the Data Channel Word on
page
5–6 for data type descriptions and scaling examples.
Select Open Circuit State (Bits 6 and 7)
Determine the desired state for the channel data word if an open
circuit condition is detected for that channel. Enter the 2-digit binary
code in bit field 6–7 of the channel configuration word. Open circuit
errors are only detected for 4–20 mA input types (bits 6–7 are
ignored for other input types). The open circuit options are zero,
upscale, and downscale.
•
If zero is selected, the channel data word is forced to 0 during an
open-circuit condition.
•
Selecting upscale forces the channel data word value to its full
scale value during an open-circuit condition. The full scale value
is determined by the selected input type and data format.
•
Selecting downscale forces the channel data word value to its low
scale value during an open-circuit condition. The low scale value
is determined by the selected input type and data format.