Service manual

Appendix B Signal Description B-3
FIGURE B-2 Serial Port A and B Connectors Pin Configuration
TABLE B-2 Serial Port A and B Connectors Pin Assignments
Pin Signal Name I/O Description
1 Not connected none None.
2 TXD O Transmit data. Used by the data
terminal equipment (DTE) to transmit
data to the data circuit 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 I Receive data. Used by the DCE in
response to received data from the
DTE.
4 RTS O 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 I 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.
6 DSR I Data set ready. Used by the DCE to
indicate if it is ready to operate. When
DSR is ON, the DCE is connected to
the line and ready to exchange further
control signals to start data transfer.
113
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113
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Serial port A
Serial port B