Rockwell Automation 1746-NT4 Series B,D17466.6.1 SLC 500 4-Channel Thermocouple/mV Input Module User Manual - Manual (Page 54)

Publication 1746-UM007C-EN-P - July 2004
5-2 Channel Configuration, Data, and Status
Channel Configuration
Procedure The channel configuration word consists of bit fields, the settings of
which determine how the channel will operate. This procedure looks
at each bit field separately and helps you configure a channel for
operation. Refer to the chart on page 5-4 and the bit field descriptions
that follow for complete configuration information. Appendix B
contains a configuration worksheet that can assist your channel
configuration.
1. Determine the input device type (J, K, etc. thermocouple) (or
mV) for a channel and enter its respective 4-digit binary code in
bit field 0-3 of the channel configuration word.
2. 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 2-digit binary
code in bit field 4-5 of the channel configuration word.
3. 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.
4. If the channel is configured for thermocouple inputs or the CJC
sensor, 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 of the configuration word. If the channel is configured
for a mV analog sensor, enter a zero in bit 8.
5. Determine the desired input filter frequency for the channel and
enter the 2-digit binary code in bit field 9-10 of the channel
configuration word. A lower filter frequency increases the
channel update time, but also increases the noise rejection and
channel resolution. A higher filter frequency decreases the
channel update time, but also decreases the noise rejection and
effective resolution.
6. Determine which channels are used in your program and enable
them. Place a one in bit 11 if the channel is to be enabled. Place
a zero in bit 11 if the channel is to be disabled.
7. Ensure that bits 12-15 contain zeros.
TIP
When using RSLogix 500 version 6.10 or higher, you
can use the software’s I/O wizard to configure the
NT4 channels. Refer to Appendix E for more
information.