Rockwell Automation 1762-IR4 RTD/Resistance Input Module - Manual (Page 61)

Publication 1762-UM003A-EN-P - February 2003
Module Data, Status, and Channel Configuration 3-27
Determining Module
Update Time 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 processor. The
module sequentially samples the channels in a continuous loop as
shown below.
Module Update Sequence
Module update time is dependent on the number of input channels
enabled, input filter selection, and whether or not a calibration or lead
wire compensation sequence is in progress.
The fastest module update time occurs when only one channel is
enabled with a 1 kHz filter, with autocalibration and cyclic lead
compensation disabled. If more than one channel is enabled, the
update time is faster if all channels use the fastest filter, as shown in
example 1 below. The slowest module update time occurs when all
six channels are enabled with the 10Hz filter.
The following table shows the channel update times for all filter
frequencies assuming that no calibration or lead wire compensation is
in progress.
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 X Autocalibration or Lead Wire Compensation Disabled
Channel X Autocalibration or Lead Wire Compensation
Table 3.15 Channel Update Time vs. Filter Frequency
Filter Frequency
Maximum Channel Update Time
(1)
(1) Update times do not include cyclic calibration or lead wire compensation.
with 1 channel enabled with 4 channels enabled
10 Hz 303 ms 1212 ms
50 Hz 63 ms 252 ms
60 Hz 53 ms 212 ms
250 Hz 15 ms 60 ms
500 Hz 9 ms 36 ms
1 kHz 6 ms 24 ms