Rockwell Automation 1769-OF4VI Compact I/O Isolated Analog Modules - Manual (Page 47)

Publication 1769-UM014B-EN-P - May 2010
Module Data, Status, and Channel Configuration for the Input Module 3-9
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 controller. For the 1769-IF4I, each input
channel is continuously sampled at an independent rate determined by the
filter setting selected for each channel. The module’s Input Data file is updated
on a channel-by-channel basis at a rate corresponding to the sample rate for
each enabled channel.
The Filter Frequency and Update Times table shows the channel update times
associated with each input channel filter setting. Selecting a filter setting for a
channel will set the indicated update time for that channel in the Input Data
file.
The Real Time Sampling function can be used to set a pre-determined module
update time. When a valid Real Time Sample rate is set by the user, the module
will update the Input Data file with the most recently sampled value from each
input channel at the interval (module update time) set by the Real Time Sample
rate. The Input Data file values are left unchanged between update times, but
the input channels continue to be sampled at the fastest rate allowed by each
channel’s filter setting.
Input Type/Range Selection
This selection along with proper input wiring lets you configure each channel
individually for current or voltage ranges and provides the ability to read the
configured range selections.
Table 3.6 Filter Frequency and Update Times
Filter Frequency Update Time per Channel Update Time per
Module (1)
(1) If you use real-time sampling, the user-configured sample rate is used as the module update time.
28.5 Hz 108 ms Not applicable
50 Hz 62 ms Not applicable
60 Hz 52 ms Not applicable
300 Hz 12 ms Not applicable
360 Hz 10 ms Not applicable