Rockwell Automation 1769-IF4FXOF2F Compact Combination Fast Analog I/O Module - Manual (Page 44)

44 Publication 1769-UM019A-EN-P - October 2008
Chapter 3 Module Data, Status, and Channel Configuration
Channel Step Response
The selected channel filter frequency determines the channel’s step
response. The step response is the time required for the analog input
signal to reach 100% of its expected final value. This means that if an
input signal changes faster than the channel step response, a portion
of that signal will be attenuated by the channel filter.
Module-update Time and Scanning Process
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 Data Input file.
In addition, if any output channels are enabled, a constant amount of
time must be added to the variable input update times to arrive at the
total module-update time. Module-update time can be calculated by
adding the sum of all enabled channel-update times. Channel update
times include channel scan time, channel switching time, and
converter configuration time. The module sequentially samples the
channels in a continuous loop, and then requires a constant amount
of time to write to any enabled output channels.
Module update time is calculated by adding up all of the input
channel update times and then adding a constant time if any of the
output channels are enabled. Each enabled input channel has one of
two channel-update times assigned. If No Filter is selected as the filter
setting for an input channel, its channel update time is 100 µs. If any
other filter setting is selected for an input channel, then its channel
update time is 200 µs. If one or both output channels are enabled, an
additional 100 µs must be added to the input-channel update time
total to arrive at the total module update time. The 100 µs added for
output channels being enabled is constant whether one or both
output channels are enabled.
Filter Selection Channel Step Response
5 Hz 802 ms
10 Hz 401 ms
50 Hz 81 ms
60 Hz 65 ms
100 Hz 42 ms
250 Hz 17 ms
500 Hz 10 ms
1000 Hz 5 ms