User manual

IEC61131 User and Reference Manual
April 22, 2008
514
The Event Reporting Method selection specifies how binary input events are reported. A Change
Of State event is an event object, without time, that is generated when the point changes state. Only
one event is retained in the buffer for each point. If a subsequent event occurs for a point, the
previous event object will be overwritten. The main purpose of this mode is to allow a master station
to efficiently poll for changed data. A Log All Events is event object with absolute time will be
generated when the point changes state. All events will be retained. The main purpose of this mode is
to allow a master station to obtain a complete historical data log. The selections are:
 Change of State
 Log All Events
The Event Buffer Size parameter specifies the maximum number of binary input change events
buffered by the RTU. The buffer holds all binary input change events, regardless of the class to
which they are assigned. If the buffer is completely full the RTU will lose the oldest events and
retain the newest; the ‘Event Buffer Overflowed’ IIN flag will also be set to indicate that the buffer
has overflowed. The Event Buffer size should be at least equivalent to the number of binary inputs
defined as Change of State type. This will allow all binary inputs to change simultaneously without
losing any events. The value of this parameter depends on how often binary input change events
occur and the rate at which the events are reported to the master station. The valid values for this
parameter are 0 - 65535. Default value is 16.
The Allow Duplicate Modbus Addresses checkbox determines if the Modbus I/O database
addresses assigned to the DNP data points must be unique. Check this box if you want to allow more
than one point to use the same Modbus address.