ProSoft Technology MVI56-104S - Manual (Page 69)

Ladder Logic MVI56-104S ♦ ControlLogix Platform
User Manual IEC 60870-5-104 Server Communication Module
ProSoft Technology, Inc.
Page 69 of 188
November 18, 2009
3.3.2 Event Messages (9958) Blocks
Block ID 9958 is reserved to send Event Messages from the processor to the
module. Each block can send up to 10 events to the module in each block
transfer.. If a value of 9958 is placed in the Write Block ID of the output image,
event messages are sent from the processor to the module. For more information
about IEC events, refer to Events (page 131).
The module supports a buffer queue of 99 events per data type. When the queue
is full for a particular data type is full, the module will delete the oldest event in
the queue if a new event is received.
This block should be used only to pass events with a predefined time-stamp (the
module will automatically send time-stamped events when monitor database
values change). While using block 9958, disable the events for those specific
points (refer to Group Codes (page 49)) to avoid multiple event generation
(caused by point value update through both the database and Block ID 9958).
The original firmware supported only Greenwich Mean Time (GMT) format time-
stamps. Beginning with firmware version 1.20 and later, a Coordinated Universal
Time (UTC) time-stamp option was made available. Now there are two versions
of Block ID 9958, one for GMT time-stamps and one for UTC time-stamps. Be
sure to use the correct one for your application.
If you follow the examples in the sample ladder logic, it is easy to select which
9958 block structure to use. Use the controller tag structures,
IEC870S.Control.EventBlock_GMT, for GMT time-stamped events. Use the
controller tag structures, IEC870S.Control.EventBlock_UTC for UTC time-
stamped events.
The following topics show the differences in block formats between these two
types of 9958 blocks and define the controller tag structures associated with
them.