Sel 421 - Page 143

U.4.5
Date Code 20090715 User’s Guide SEL-421 Relay
Basic Relay Operations
Establishing Communication
need to communicate with the relay. Many off-the-shelf computer programs
provide terminal emulation. These programs are inexpensive and widely
available.
Use the cable connections appropriate for your terminal configuration. See
Section 4: Communications Interfaces in the Reference Manual for more
information on communications ports.
All ASCII commands you send to the relay must terminate with a carriage
return or carriage return/line feed; the terminal emulation program appends
the necessary carriage return when you press <Enter>.
You can truncate commands to the first three characters: EVENT 1 <Enter>
becomes EVE 1 <Enter>. Use upper- and lower-case characters without
distinction, except in passwords, which are case sensitive. For a list of ASCII
commands see Section 9: ASCII Command Reference in the Reference
Manual.
Help
When you are using a terminal, you can access built-in relay help for each
ASCII command. Relay help is access-level sensitive; you see only the ASCII
commands for the present access level when you type HELP <Enter>. For in-
depth information on a particular ASCII command, enter the command name
after typing HELP. For example, for help on the EVENT ASCII command,
type HELP EVE <Enter>.
When you are using
ACSELERATOR QuickSet, press <F1> to get help, or
select the Help menu from the
ACSELERATOR QuickSet toolbars. The help
information in
ACSELERATOR QuickSet gives detailed information and
sample screens in a GUI format.
Making an EIA-232
Serial Port
Connection
The following steps use any popular computer terminal emulation software
and SEL serial cables to connect to the SEL-421.
Use an SEL Cable C234A to connect a 9-pin computer serial port to the
SEL-421. Use an SEL Cable C227A to connect a 25-pin computer serial port
to the relay. See Section 4: Communications Interfaces in the Reference
Manual for further information on serial communications connections. These
and other cables are available from SEL. Contact the factory or your local
distributor for more information.
Step 1. Connect the computer and the SEL-421 using the serial
communications cable.
Use the 9-pin serial port labeled PORT F on the relay front panel.
Step 2. Apply power to both the computer and to the relay.
Step 3. Start the computer terminal emulation program.
Step 4. Set your computer terminal emulation program serial
communications parameters.
The default SEL-421 communications port settings are listed in
Table 4.2.
Also set the terminal program to emulate either VT100 or
VT52 terminals. These terminal emulations work best with
SEL relays.
Courtesy of NationalSwitchgear.com