Rockwell Automation 1756-IH16ISOE ControlLogix Sequence of Events Module - Manual (Page 126)

Publication 1756-UM528A-EN-P - April 2004
B-8 Integrating The HiProm GPS Module (1756HP-GPS) into a ControlLogix Sequence of Events Module System
Converting Timestamps
from CST Format to
Universal Coordinated
Time Format By default, the Sequence of Events module uses the CST to timestamp
input transitions in CST Per Point mode. You can configure the
module to convert CST timestamps to UCT timestamps before sending
the data to the owner-controller.
To configure the Sequence of Events module to convert timestamps to
UCT in CST Per Point mode, you copy a pair of timestamps (one in
CST format and one in UCT format) from the 1756HGPS module to
the following tags in the Sequence of Events module’s output word:
• O.UCTTime
• O.CSTTime
Figure B.4 shows an example of a ladder logic rung that copies the
timestamp pair from the 1756HP-GPS module to the Sequence of
Events module’s output tags. You need to do this for every Sequence
of Events module in your system if you want the module to send
timestamps in UTC format.
Figure B.4
In this example, the synchronous copy begins at the GPS.UTC tag on
the 1756HP-GPS module and copies 4 DINTs (because the Length = 4)
worth of data; included in the 4 DINTs is not only the GPS.UTC tag
but also the GPS.CST tag. The timestamps are copied to the
O.UCTTime and O.CSTTime tags in the Sequence of Events module’s
output tags.
The GPS.PPS (pulse per second) bit is used to send new pairs once a
second at the GPS satellite’s tone.
IMPORTANT
If the O.UCTTime and O.CSTTime tags = 0, the
Sequence of Events module sends timestamp data to
the controller in CST format.
If the O.UCTTime and O.CSTTime tags = a nonzero
number, the Sequence of Events module sends
timestamp data to the controller in UCT format.