Introduction to Data Communications
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17d. Subsets of Signals for Certain Applications

Data Signals

2 TXD Transmit Data Data generated by DTE BA
3 RXD Receive Data Data generated by DCE BB

Control Signals

4 RTS Ready to Send DTE wishes to transmit
5 CTS Clear to Send DCE ready to receive
6 DSR Data Set Ready (DCE Ready) DCE powered on & ready to go
20 DTR Data Terminal Ready (DTE Ready) DTE powereded on & ready to go
22 RI Ring Indicator Phones ringing

Test Modes

18 LL Local Loopback Initiate Local Loopback Self-Test
21 SQ/RL Signal Quality/Remote Loopback Initiate Remote Loopback Self-Test
25 TM Test Mode Initiate Test Mode

Synchronous Control Signals

21 SQ/RL Signal Quality/Remote Loopback Error in received data!
23 DSRS Data Signal Rate Selector DTE can dynamically select 1 of 2 data rates

Synchronous Timing Signals

15 TxSigC Transmitter Signal Element Timing - DCE DCE generated
17 RxSig Receive Signal Element Timing - DCE DCE generated
24 TxSigT Transmitter Signal Element Timing - DTE DTE generated

Ground/Shield

1 GND Chassis ground Shield DTE side only for noise protection.
Do NOT connect to signal ground!
7 SGND Signal ground Signal return path

Introduction to Data Communications
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