10.6
SEL-351A Relay Instruction Manual Date Code 20080213
Serial Port Communications and Commands
Communications Protocol
Communications Protocol
Hardware Protocol
All EIA-232 serial ports support RTS/CTS hardware handshaking. RTS/CTS
handshaking is not supported on the EIA-485 serial PORT 1.
To enable hardware handshaking, use the SET P command (or front-panel
{SET} pushbutton) to set RTSCTS = Y. Disable hardware handshaking by
setting RTSCTS = N.
If RTSCTS = N, the relay permanently asserts the RTS line.
If RTSCTS = Y, the relay deasserts RTS when it is unable to receive
characters.
If RTSCTS = Y, the relay does not send characters until the CTS input is
asserted.
Software Protocols
The SEL-351A provides standard SEL protocols: SEL ASCII, SEL
Distributed Port Switch Protocol (LMD), SEL Fast Meter, SEL Compressed
ASCII, and SEL Fast SER. In addition, the relay provides Distributed
Network Protocol (DNP3) as an ordering option. The relay activates protocols
on a per-port basis. The SEL-351A is compatible with the SEL-DTA2
Display/Transducer Adapter. See setting sheets beginning with PORT 1
Settings (Serial Port Command SET P 1 and Front Panel) on page SET.28.
To select SEL ASCII protocol, set the port PROTO setting to SEL. To select
SEL Distributed Port Switch Protocol (LMD), set PROTO = LMD. To select
DNP protocol, set PROTO = DNP.
SEL Fast Meter and SEL Compressed ASCII commands are active when
PROTO is set to either SEL or LMD. The commands are not active when
PROTO is set to DNP.
SEL ASCII Protocol
SEL ASCII protocol is designed for manual and automatic communications.
1. All commands received by the relay must be of the form:
<command><CR> or <command><CRLF>
A command transmitted to the relay should consist of the
command followed by either a CR (carriage return) or a CRLF
(carriage return and line feed). You may truncate commands to
the first three characters. For example, EVENT 1 <Enter>
would become EVE 1 <Enter>. Upper- and lowercase
characters may be used without distinction, except in
passwords.
2. The relay transmits all messages in the following format:
<STX><MESSAGE LINE 1><CRLF>
<MESSAGE LINE 2><CRLF>
•
•
•
<LAST MESSAGE LINE><CRLF>< ETX>
Each message begins with the start-of-transmission character
(ASCII 02) and ends with the end-of-transmission character
NOTE: The <Enter> key on most
keyboards is configured to send the
ASCII character 13 (^M) for a carriage
return. This manual instructs you to
press the <Enter> key after commands,
which should send the proper ASCII
code to the relay.
Courtesy of NationalSwitchgear.com
To Next Page