User Manual Owner's manual

Publication 1746-UM022B-EN-P - January 2005

Considerations Before Using Your Module 3-7

Update Time

The thermocouple 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 make the resulting data values available to the SLC

processor. It can be calculated by adding the sum of all enabled

sample times, plus a CJC update time.

The following table shows the channel sampling time for each filter

frequency. It also gives the CJC update time.

Channel Sampling Time

The times above include a settling time necessary between input

channel readings. The sampling times for filter frequencies listed do

not include a 45 ms open-circuit detection time utilized when the

channel is configured for open-circuit detection. CJC open-circuit

detection does not require the additional 45 ms settling time.

The fastest module update time occurs when only one channel with a

250 Hz filter frequency is enabled.

Module update time = 290 ms + 66 ms = 356 ms

The slowest module update time occurs when eight channels, each

using a 10 Hz filter frequency, are enabled.

Module update time = 290 ms + 470 ms + 470 ms + 470 ms + 470

ms + 470 ms + 470 ms + 470 ms + 470 ms = 4.05 s

Enabled

Enabled Enabled Enabled

Calculate

Sample

Channel 0

Update CJC

Sample

Channel 1

Sample

Channel 2

Sample

Channel 7

Sample

CJC

Channel

Channel 0 Disabled Channel 1 Disabled

Channel 2 Disabled Channel 7 Disabled

Channel Sampling Time for Each Filter Frequency (all values ±1 ms)

CJC Update Time 250 Hz Filter 60 Hz Filter 50 Hz Filter 10 Hz Filter

290 ms 66 ms 125 ms 140 ms 470 ms