Appendix B Specifications
Datacom specifications
SmartClass E1 Tester User’s Guide 123
Signal Lead Names
The signal leads for the supported interfaces use a variety of names. The
names describe the circuits between DTE and DCE, for example TXD is the
transmit data circuit, an output at the DTE and an input at the DCE. As the role
of the test instrument changes, the direction of this signal in the connector
changes. Table 51 provides a cross reference of signal lead names, including
signal direction.
Table 51 Signal lead cross reference
Signal Lead
(Direction)
Unified Name CCITT
RS-232
V.24
X.21 EIA-530 V.35
RS-449
V.36
Receive Data
(From DCE)
RXD 104 RD R RD RD RD
Transmit Data
(To DCE)
TXD 103 TD T TD SD SD
Clear To Send
(From DCE)
CTS 106 CTS I CTS CTS CS
Request To Send
(To DCE)
RTS 107 RTS C RTS RTS RS
Data Terminal (DTE) Ready
(To DCE)
DTR 108.2 DTR - DTR DTR TR
Data Set (DCE) Ready
(From DCE)
DSR 107 DSR - DSR DSR DM
Receiver Line Signal Detect
(From DCE)
DCD 109 RLSD - RLSD RLSD RR
Ring Indicator
(From DCE)
RNG
(not supported)
125 RI - RI CI IC
Local Loopback
(To DCE)
LLB 141 LL - LL LL LL
Remote Loopback
(To DCE)
RLB 140 RL - RL RL RL
Test Mode
(From DCE)
TMA 142 TM - TM TM TM
Transmitter Signal Element
Timing
(From DCE)
STC 114 ST - TC SCT ST
Transmitter Signal Element
Timing
(To DCE)
TXC 113 TT X XTC SCTE TT
Receiver Signal Element
Timing
(From DCE)
RXC 115 RT S RC SCR RT
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