7.13
Date Code 20170927 Instruction Manual SEL-751 Relay
Communications
Communications Protocols
Ethernet Protocols
As with other communications interfaces, you must choose a data exchange
protocol that operates over the Ethernet network link to exchange data. The
relay supports FTP, Telnet, Ping, Modbus/TCP, DNP3 LAN/WAN, C37.118,
and IEC 61850 protocols.
You should carefully design your Ethernet network to maximize reliability,
minimize system administration effort, and provide adequate security. Work
with a networking professional to design your substation Ethernet network.
File Transfer Protocol (FTP) and MMS File Transfer
FTP is a standard protocol for exchanging files between computers over a
TCP/IP network. The SEL-751 operates as an FTP server, presenting files to
FTP clients. To create an FTP session, you need the FTP username and
password. The default username and password are FTPUSER and TAIL,
respectively. The SEL-751 supports two FTP sessions at a time. Requests to
establish additional FTP sessions are denied.
Manufacturing Messaging Specification (MMS) is used in IEC 61850
applications and provides services for the transfer of real-time data, including
files, within a substation LAN.
File Structure
The file structure is organized as a directory and subdirectory tree similar to
that used by Windows and other common operating systems. See Virtual File
Interface on page 7.58 for information on available files.
File dates within the last 12 months are displayed with month, day, hour, and
minutes. Dates older than twelve months have the year, month, and day. The
times are UTC.
Access Control
To log in to the FTP server, enter the value of the Port 1 setting FTPUSER as
the user name in your FTP application. Enter the Port 1 setting FTPACC level
password as the password in your FTP application. Note that FTP does not
encrypt passwords before sending them to the server.
MMS is enabled when Port 1 setting E61850 is set to Y. No authentication is
required. MMS File Transfer is enabled when setting EMMSFS is set to Y. If
MMS Authentication is enabled via the CID file, then an authenticated
connection must be established via MMS for MMS file transfer to take place.
Using FTP and MMS
A free FTP application is included with most web browser software and PC
operating systems. You can also obtain free or inexpensive FTP applications
from the Internet. Once you have retrieved the necessary files, be sure to close
the FTP connection using the disconnect function of your FTP application or
completely closing the application. Failure to do so can cause the FTP
connection to remain open, which blocks subsequent connection attempts
until FTPIDLE time expires. See Appendix F: IEC 61850 Communications
for information about using MMS.
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