ProSoft Technology MVI56-101S - Manual (Page 140)

Reference MVI56-101S ♦ ControlLogix Platform
User Manual IEC 60870-5-101 Slave Communication Module
Page 140 of 193 ProSoft Technology, Inc.
August 2, 2011
5.3.6 Events
In order to improve the communication efficiency, most applications will require
the Master to periodically poll for data changes with a higher priority than polling
for monitor data. Every time data change occurs, the slave should send this
information, typically with the date and time information on when the data change
occurred.
The following illustration shows the event communication between the Master
and the module during unbalanced mode:
The module can queue up to 99 events per data type. When the queue is full, the
oldest event will be deleted each time a new event is added to the queue. You
must configure the Master to poll the event queue frequently enough to avoid
losing events.
The events can be returned for Class 1 or Class 2 requests according to the data
type as follows:
Data Type Class Request
M_SP_NA Class 1
M_DP_NA Class 1
M_ST_NA Class 1
M_BO_NA Class 1
M_ME_NA Class 2
M_ME_NB Class 2
M_ME_NC Class 2
M_IT_NA Class 1
Note: In response to a Class 2 poll the module may respond with Class 1 data when there is no
Class 2 data available. So eventually the events for M_SP_NA, M_DP_NA and M_ST_NA points
may also be sent during a Class 2 response.