Rockwell Automation 1756-IH16ISOE ControlLogix Sequence of Events Module - Manual (Page 59)

Publication 1756-UM528A-EN-P - April 2004
Using the Sequence of Events Module Features 5-7
Latch CST
Latch CST can be used to prevent the Sequence of Events module
from overwriting input data once it is timestamped.
• If Latch CST is enabled, the module only timestamps a
specific number of input transitions(e.g., the first transition in
CST Per Point mode) and ignores future input transitions (at
least until the controller clears the timestamp data already
received, as described on page 6-12 and page 7-20).
• If Latch CST is disabled, the module timestamps every input
transition and may overwrite previously recorded
timestamp data if the controller does not acknowledge the
data quickly enough.
This feature is set on a module-wide basis and is enabled
by default.
Use the Configuration tab in RSLogix 5000 to enable Latch CST, as
shown in the example below.
IMPORTANT
The bullets above provide a general description of
how Latch CST works. However, there are slight
differences between how the features affects
module behavior in each operational mode.
• For more information on how Latch CST is used
in CST Per Point mode, see page 6-7.
• For more information on how Latch CST is used
in FIFO mode, see page 7-9.
Click this box to enable the
Latch CST feature.
Unclick the box to disable
the feature.