buffer the different clients are reading at the moment. Clients are identified either by
the serial port from where the requests are issued or by the client's IP address in the
TCP/IP network. Up to 25 different IP addresses, belonging to both registered and
unregistered Modbus clients, can be memorized by the IED.
3.4.9.1
Single event record structure
The Modbus event record structure is located at addresses 49251...49262.
Table 26:
Event record structure
Address
Register
Values
Comment
49251
Event selection
1...4 and -1...-499
Write register
49252
Sequence Number
0...65535
49253
Unread records left
0...499
49254
TimeStamp
(Year,Month)
High byte:year, low byte:month
49255
TimeStamp (Day,
Hour)
High byte:day, low byte:hour
49256
TimeStamp (Min, Sec)
High byte:min, low byte:second
49257
TimeStamp
(Milliseconds)
Word: milliseconds (0...999)
49258
Event type
See separate description
49259
Data Object ID 1
0 or UID high word
See separate description
49260
Data Object ID 2
Modbus address or UID low
word
49261
Data Value
Modbus data value
Value into which object has
changed
49262
Data Value
Additional data
The event record can have two different data object identification alternatives. The
data object can be identified by the Modbus address on which the object resides or it
can be identified by a unique id which is platform dependent.
The identification alternative is selected with the Modbus parameter
Event ID
.
3.4.9.2
Single event record reading
As long as there are unread Modbus events available for the Modbus client in
question, bit 0 of Modbus SSR3 register remains "1".
Events are read in two steps. First, the client writes a selection code to the Event
selection register at location 49251. The selection code defines the type of read
operation that the client wants to perform. The selected event record is loaded by the
IED into the following 11 registers from 9252 to 9262. Second, the client reads out the
11 registers in one multiple register read operation.
1MRS757645 B
Section 3
Vendor-specific implementation
620 series
49
Communication Protocol Manual
