Rockwell Automation 1746-NT8 SLC 500 Thermocouple/mV Analog Input Module User Manual - Manual (Page 38)

Publication 1746-UM022B-EN-P - January 2005
3-8 Considerations Before Using Your Module
Update Time Calculation Example
The following example shows how to calculate the module update
time for the given configuration:
Channel 0 configured for 250 Hz filter frequency, enabled
Channel 1 configured for 250 Hz filter frequency, enabled
Channel 2 configured for 50 Hz filter frequency, enabled
Channel 3 through 7 disabled
Using the values from the table on page 3-7, add the sum of all
enabled channel sample times, plus one CJC update time.
Channel Turn-On, Turn-Off,
and Reconfiguration Times The time required for the module to recognize a new configuration
for a channel is generally one module update time plus 890 µs per
newly configured channel. If the filter frequency selected for the
newly enabled, configured channel is new to the module, then
auto-calibration is performed following configuration recognition.
Turn-off time requires up to one module update time.
Reconfiguration time is the same as turn-on time.
Auto-calibration Auto-calibration is performed by the module to correct for drift errors
over temperature. Auto-calibration occurs immediately following
configuration of a previously unselected filter frequency, and
generally every two minutes for all selected filter frequencies of the
system. The time required to perform auto-calibration is defined as
follows:
Channel 0 sampling time = 66 ms
Channel 1 sampling time = 66 ms
Channel 2 sampling time = 140 ms
CJC update time = 290 ms
Module update time = 562 ms
Auto-calibration Time
250 Hz Filter 60 Hz Filter 50 Hz Filter 10 Hz Filter
325 ms 525 ms 585 ms 1.975 s