Serial Port Communications and Commands
10-5
SEL-300G Instruction Manual
Date Code 20060731
Table 10.4: Serial Communications Port Pin/Terminal Function Definitions
Pin Function
Definition
N/C No
Connection
+5 Vdc (0.5 A limit)
5 Vdc Power Connection
RXD, RX
Receive Data
TXD, TX
Transmit Data
IRIG-B IRIG-B
Time-Code
Input
GND Ground
SHIELD Shielded
Ground
RTS Request
To
Send
CTS Clear
To
Send
DCD
Data Carrier Detect
DTR Data
Terminal
Ready
DSR
Data Set Ready
For long-distance communications up to 500 meters and for electrical isolation of
communications ports, use the SEL-2800 family of Fiber-Optic Transceivers. Contact SEL for
more details on these devices.
C
OMMUNICATIONS
P
ROTOCOL
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 push) to set
RTSCTS = Y. Disable hardware handshaking by setting RTSCTS = N.
If RTSCTS = N,
the relay permanently asserts the RTS line until the buffer is full (for
SEL PROTO).
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.
If RTSCTS = H
the relay permanently asserts the RTS line (for MOD PROTO)
When PROTO = LMD
the RTSCTS setting is hidden and hardware handshaking is
disabled.
Summary of Contents for SEL-300G
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