Sun Microsystems Netra t 1120, Service Manual, Page: 132 / 148

C-2 Netra t 1120/1125 Service Manual • August 1998
C.2 Serial Ports A and B
The serial port A and B connectors are DB-25 connectors located on the system board
back panel.
FIGURE C-2
illustrates the serial ports A and B connector configuration,
and
TABLE C-1
lists the connector pin assignments.
FIGURE C-2
Serial Ports A and B Connector Pin Configuration
TABLE C-1
Serial Port Pinouts
Pin Mnemonic Signal Name Description
1 Not connected None
2 TxD Transmit Data Used by the data terminal equipment (DTE) to
transmit data to the data circuit terminating
equipment (DCE). Except when control data is being
sent, RTS, CTS, SYNC and DCD must be ON for this
line to be active.
3 RxD Receive Data Used by the DCE in response to received data from
the DTE.
4 RTS Ready To Send Used by the DTE to condition the DCE for data
transmission. The transition to ON directs the DCE
to go into transmit mode. The transition to OFF
directs the DCE to complete the transmission.
5 CTS Clear To Send Used by the DCE to indicate if it is ready to receive
data from the DTE. When CTS, DSR, RTS and DTR
are ON, the DCE is ready to transmit data received
from the DTE across the communications channel.
When only CTS is ON, the DCE is ready to accept
dialing or control signals only. When CTS is OFF, the
DTE should not transfer data across TxD.
1 13
25 14
1 13
25 14
Serial port B
Serial port A