4.111
Date Code 20100129 Instruction Manual SEL-751A Relay
Protection and Logic Functions
Front-Panel Settings (SET F Command)
Set PROTO := SEL (standard SEL ASCII protocol), MOD (Modbus RTU
protocol), or one of the M
IRRORED BITS protocols, as needed for your
application. For detailed information, refer to Appendix C: SEL
Communications Processors, Appendix E: Modbus RTU Communications,
and Appendix I: M
IRRORED BITS Communications.
Use the MBT option if you are using a Pulsar MBT9600 baud modem (see
Appendix I: M
IRRORED BITS Communications for more information). With this
option set, the relay transmits a message every second processing interval and
the device deasserts the RTS signal on the EIA-232 connector. Also, the
device monitors the CTS signal on the EIA-232 connector, which the modem
deasserts if the channel has too many errors. The modem uses the device RTS
signal to determine whether the MB or MB8 M
IRRORED BITS protocol is in
use.
Set the AUTO := Y to allow automatic messages at a serial port.
The relay EIA-232 serial ports support software (XON/XOFF) flow control. If
you want to enable support for hardware (RTS/CTS) flow control, set the
RTSCTS setting equal to Y.
Set FASTOP := Y to enable binary Fast Operate messages at the serial port.
Set FASTOP := N to block binary Fast Operate messages. Refer to
Appendix C: SEL Communications Processors for the description of the
SEL-751A Fast Operate commands.
Set PROTO := DNET to establish communications when the DeviceNet card
is used. Table 4.57 shows the additional settings, which can be set only at the
rear on the DeviceNet card. Once the relay detects the DeviceNet card, all
Port 4 settings are hidden. Refer to Appendix G: DeviceNet Communications
for details on DeviceNet.
Front-Panel Settings (SET F Command)
General Settings
Local bits provide control from the front panel (local bits), and display points
display selected information on the LCD display. However, you need to first
enable the appropriate number of local bits and display points necessary for
your application. When your SEL-751A arrives, four display points are
already enabled, but no local bits are enabled. If more display points are
necessary for your application, use the EDP setting to enable up to 32 display
points. Use the ELB setting to enable up to 32 local bits.
Table 4.57 Rear-Panel DeviceNet Port Settings
Setting Name Setting Range
MAC_ID 0–63
ASA 8 Hex characters assigned by factory
DN_Rate 125, 250, 500 kbps
Table 4.58 Display Point and Local Bit Default Settings
Setting Setting Prompt Range Default
EDP DISPLAY PTS ENABL N, 1–32 4
ELB LOCAL BITS ENABL N, 1–32 N
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