ABB ETL600 - Network Protocol

ABB Switzerland Ltd 1KHW001489-EN ETL600
RS232-
connection
Substation A
Substation B
EOC of
PLC link
ETL600 ETL600
HMI600
Fig. 4-6 Embedded operation channel
In the common situation, where several links are connected in tandem
(chain of links), all terminals can be reached from either side of the
chain by connecting the management ports of the terminals together
via RS485 bus as shown in Fig. 4-7.
RS232-
connection
ETL600
ETL600ETL600
Substation A
Substation B
ETL600ETL600
Substation C
ETL600
Substation D
EOC of
PLC link
EOC of
PLC link
EOC of
PLC link
RS485-
bus
RS485-
bus
RS485-
bus
HMI600
Fig. 4-7 Chain of ETL600 links
T-offs in substations can be handled by connecting the management
ports of the involved terminals via RS-232/RS-485 converters as
shown in Fig. 4-5.
4.5.3. Network protocol
The network protocol used by the ETL600 terminals is connectionless.
This means that all messages circulating in the network are routed to
all terminals attached to the network. Only the addressed terminal will
execute the commands contained in the message and generate an
answer. Closed loops are not allowed in the network. In the example of
Fig. 4-8, a closed loop exists between substations A and C. All
messages exchanged between substations A and C will be transmitted
over a data channel of 9’600 bps as well as over the 100 bps EOC
channel of the PLC link between terminals A3 and C3. Unless the
EOC of the PLC link A3-C3 is disabled for network management by
proper configuration via HMI600 (by not checking the box Network
management: EOC enabled in the HMI600 dialog box Configuration
/ System / Channel settings), the network will not operate properly.
Thus the EOC must be disabled for network management in this case.
4-12 November 2005 User Interface Program