Rockwell Automation 1746-NI8 SLC 500 Analog Input Modules User Manual - Manual (Page 36)

4–5 Preliminary Operating Considerations
Publication 1746Ć6.8 - April 1997
The module update time is defined as the time required for the
module to sample and convert the input signals of all enabled input
channels and provide the resulting data values to the SLC processor.
Module update time can be calculated by adding the the sum of all
enabled channel sample times (0.75 msec per channel).
The 1746-NI8 module sequentially samples the channels in a
continuous loop.
Channel 0 Disabled Channel 1 Disabled Channel 2 Disabled Channel 3 Disabled
Sample
Channel 0
Sample
Channel 1
Sample
Channel 2
Sample
Channel 3
Enabled Enabled Enabled Enabled
Channel 4 Disabled Channel 5 Disabled Channel 6 Disabled Channel 7 Disabled
Sample
Channel 4
Sample
Channel 5
Sample
Channel 6
Sample
Channel 7
Enabled Enabled Enabled Enabled
The following table shows the module update time. The module
update time is the same regardless of the filter frequency. The fastest
module update time occurs when only one channel is enabled. The
slowest module update time occurs when 8 channels are enabled.
Module Update Time
Number of Channels Enabled Update Time
1 0.75 msec
2 1.50 msec
3 2.25 msec
4 3.00 msec
5 3.75 msec
6 4.50 msec
7 5.25 msec
8 6.00 msec
Module Update Time