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Interface Signals
Functional descriptions of the RS-449 interface signals are provided in
RS-449 Interface Signals
TABLE A-2
RS-449 Pin
No.
Signal Name
1
Shield Ground
19
Signal Ground (SG)
4/22
Transmit Data (TxD)
6/24
Receive Data (RxD)
5/23
Transmit Clock in (TxCI)
8/26
Receive Clock (RxC)
17/35
Transmit Clock (TxC)
7/25
Request to Send (RTS)
9/27
Clear to Send (CTS)
11/29
Data Set Ready (DSR)
12/30
Data Terminal Ready (DTR)
13/31
Data Carrier Detect (DCD)
Function
Enables tandem sections of shielded cable to retain continuity
through the connector.
Directly connects the DTE circuit ground to the DCE circuit
ground, providing a path for DTE and DCE signal commons.
Used by the DTE to pass binary data to the DCE for
transmission over the communications channel.
Used by the DCE to pass binary data received from the
communications channel to the DTE.
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.
Transitions on this lead enables the DTE to time data received
over circuit RxD.
Enables the DTE to provide transmit timing information to the
DCE so that the DTE can synchronize with data arriving over
the TxD lead.
Used by the DTE to advise the DCE it is ready to transmit data.
Used by the DCE to advise the DTE that the DCE is ready to
send data over the communications channel.
Used to advise the DTE of the Ready status on the DCE. In
most cases, this signal simply implies the unit is powered on.
Used by the DTE to advise the DCE it is ready to transmit or
receive.
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.
Appendix A
TABLE A-2
Cable Pin Assignments & Signals
.
27
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