Rockwell Automation 1746-NR8 SLC 500 RTD/Resistance Input Module User Manual - Manual (Page 51)

Publication 1746-UM003A-EN-P
Channel Configuration, Data, and Status 4-3
Module default settings for configuration words 0 through 7 are all zeros.
Scaling defaults are explained on page 4-9 under the explanation for the
User-set Scaling Select bits 13 and 14.
Channel Configuration
Procedure The channel configuration word consists of bit fields, the settings of which
determine how the channel operates. This procedure looks at each bit field
separately and helps you configure a channel for operation. Refer to the table
on page 4-5 and the bit field descriptions that follow for complete
configuration information. See page B-1 for a configuration worksheet that
can assist your channel configuration.
Configure Each Channel
1. 1. 1. 1. Determine the input device type (RTD type or resistance input) for a
channel and enter its respective 4-digit binary code in bit field 0-3 (Input
Type Selection) of the channel configuration word.
2. 2. 2. 2. Select a data format for the data word value. Your selection determines how
the analog input value from the A/D converter is expressed in the data
word. Enter your 2-digit binary code in bit field 4 and 5 (Data Format
Selection) of the channel configuration word. If you have chosen
proportional counts data format, you may define the scaling range. The
default valves for the limit registers are 0. If the lower limit and the upper
limit are both 0, the module uses -32,768 as the lower limit and +32,767 as
the upper limit. If the lower limit is equal to the upper limit, a
configuration error occurs. Otherwise, the module uses limit values in these
registers. Make sure to enter the lower and upper limits in the scale limit
registers for that channel, if you want user-defined scaling. An example on
page 4-9 (user-set scaling) explains how to do this.
3. 3. 3. 3. Determine the desired state for the channel data word if a broken input
condition is detected for that channel (open-circuit or short- circuit). Enter
the 2-digit binary code in bit field 6 and 7 (Broken Input Selection) of the
channel configuration word.
4. 4. 4. 4. If the channel is configured for RTD inputs and engineering units data
format, determine if you want the channel data word to read in degrees
Fahrenheit or degrees Celsius and enter a one or a zero in bit 8
(Temperature Units) of the configuration word. If the channel is configured
for a resistance input, this field is ignored.