Sun Microsystems Interface Adapter, Руководство пользователя

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Appendix A Cable Pin Assignments & Signals 27
Interface Signals
Functional descriptions of the RS-449 interface signals are provided in
TABLE A-2
.
TABLE A-2
RS-449 Interface Signals
RS-449 Pin
Number
Signal Name Function
1 Shield Ground Enables tandem sections of shielded cable to retain
continuity through the connector.
19 Signal Ground
(SG) Directly connects the DTE circuit ground to the DCE
circuit ground, providing a path for DTE and DCE
signal commons.
4/22 Transmit Data
(TxD) Used by the DTE to pass binary data to the DCE for
transmission over the communications channel.
6/24 Receive Data
(RxD) Used by the DCE to pass binary data received from the
communications channel to the DTE.
5/23 Transmit Clock in
(TxCI) Enables the DCE to transmit signal element timing to
the DTE. This enables the DTE Transmit Data signal on
circuit TxD to be in synchronization with On/Off
transitions on this lead.
8/26 Receive Clock
(RxC) Transitions on this lead enables the DTE to time data
received over circuit RxD.
17/35 Transmit Clock
(TxC) Enables the DTE to provide transmit timing
information to the DCE so that the DTE can
synchronize with data arriving over the TxD lead.
7/25 Request to Send
(RTS) Used by the DTE to advise the DCE it is ready to
transmit data.
9/27 Clear to Send
(CTS) Used by the DCE to advise the DTE that the DCE is
ready to send data over the communications channel.
11/29 Data Set Ready
(DSR) Used to advise the DTE of the Ready status on the
DCE. In most cases, this signal simply implies the unit
is powered on.
12/30 Data Terminal
Ready (DTR) Used by the DTE to advise the DCE it is ready to
transmit or receive.
13/31 Data Carrier Detect
(DCD) The DCE uses this lead to advise the DTE that an
incoming signal on the communications channel is
present. When first initialized this signal is an
indication to the DTE to expect data momentarily.