7.2
SEL-749M Relay Instruction Manual Date Code 20080918
Communications
Communications Interfaces
Serial Port
To connect a PC serial port to the relay front-panel serial port and enter relay
commands, you will need the following:
➤ A personal computer equipped with one available EIA-232
serial port.
➤ A communications cable to connect the computer serial port to
the relay serial ports.
➤ Terminal emulation software to control the computer serial
port.
➤ An SEL-749M Relay.
Some of the SEL devices available for integration or communication system
robustness are included in the following list:
➤ SEL Communications Processors (SEL-2032, SEL-2030,
SEL-2020)
➤ SEL-2800 Fiber-Optic Transceiver
➤ SEL-2890 Ethernet Transceiver
A variety of terminal emulation programs on personal computers can
communicate with the relay. For the best display, use VT-100 terminal
emulation or the closest variation.
The default settings for all EIA-232 serial ports are listed below:
Baud Rate = 9600
Data Bits = 8
Parity = N
Stop Bits = 1
To change the port settings, use the SET P command (see Section 6: Settings)
or the front-panel. Section 8: Front-Panel Operations provides details on
making settings with the front panel.
IRIG-B
Two physical interfaces are provided for the demodulated IRIG-B time-code
input. One physical interface is via terminals (B01 and B02) and the other is
part of the serial Port 3 physical interface. Only one interface can be used at a
time. When using serial Port 3, connect to an SEL communications processor
with Cable C273A (see the cable diagrams that follow in this section or SEL-
5801 Cable Selector software.
+5 Vdc Power Supply
Port power can provide as much as 0.5 A total from all of the +5 Vdc pins.
Some SEL communications devices require the +5 Vdc power supply.
Connect Your
PC to the Relay
The front port of the SEL-749M is a standard female 9-pin connector with pin
numbering shown in Figure 7.1. The pinout assignments for this port are
shown in Figure 7.6. You can connect to a standard 9-pin computer port with
SEL Cable C234A; wiring for this cable is shown in SEL-749M Cable
Connections to Communications Devices on page U.7.3. SEL Cable C234A
and other cables are available from SEL. Use the SEL-5801 Cable SEL
ECTOR
software to select an appropriate cable for another application. This software
is available for free download from the SEL website at www.selinc.com.
For best performance, SEL Cable C234A should not be more than 15 meters
(50 feet) long. For long-distance communications and for electrical isolation
of communications ports, use the SEL family of fiber-optic transceivers.
Contact SEL for more details on these devices.
Courtesy of NationalSwitchgear.com
To Next Page
Loading...
