Schweitzer Engineering Laboratories SEL-751 - Table 7.6 Serial Port Automatic Messages

7.17
Date Code 20170927 Instruction Manual SEL-751 Relay
Communications
Communications Protocols
transmission sources should monitor for the XOFF character to avoid overwriting
the buffer. Transmission should terminate at the end of the message in progress
when the relay receives XOFF. It can resume when the relay sends XON.
The CAN character (ASCII hex 18) aborts a pending transmission. This is
useful for terminating an unwanted transmission. You can send control
characters from most keyboards with the following keystrokes:
➤ XOFF: <Ctrl+S> (hold down the <Ctrl> key and press S)
➤ XON: <Ctrl+Q> (hold down the <Ctrl> key and press Q)
➤ CAN: <Ctrl+X> (hold down the <Ctrl> key and press X)
Automatic Messages
When the serial port AUTO setting is Y, the relay sends automatic messages to
indicate specific conditions. Table 7.6 lists these messages.
Access Levels
You can issue commands to the SEL-751 via the serial port or Telnet session to
view metering values, change relay settings, etc. The available serial port commands
are listed in the SEL-751 Relay Command Summary at the end of this manual.
You can access these commands only from the corresponding access level, as
shown in the SEL-751 Relay Command Summary. The access levels are:
➤ Access Level 0 (the lowest access level)
➤ Access Level 1
➤ Access Level 2 (the highest access level)
➤ Access Level C (restricted access level, should be used under
direction of SEL only)
The EPORT and MAXACC settings provide users with access controls for the
corresponding port. Setting EPORT to N disables the port and hides the
remaining port settings. The MAXACC setting selects the highest access level
for the port.
Access Level 0
Once serial port communication is established with the SEL-751, the relay
sends the following prompt:
Table 7.6 Serial Port Automatic Messages
Condition Description
Power Up The relay sends a message containing the present date and
time, relay and terminal identifiers, and the Access Level 0
prompt when the relay is turned on.
Event Trigger The relay sends an event summary each time an event report
is triggered. See Section 10: Analyzing Events.
Self-Test Warning or
Failure
The SEL-751 sends a status report each time it detects a self-
test warning or failure condition. See STATUS Command
(Relay Self-Test Status) on page 7.51.
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