Motorola MVME2603-1121A, Инструкция по установке и эксплуатации

Страница: 180 / 210

EIA-232-D Connections
C-2
C
handles both synchronous (SDLC/HDLC) and asynchronous
protocols. The hardware supports asynchronous serial baud rates
of 110B/s to 38.4KB/s and synchronous baud rates of up to
2.5MB/s.
Each port supports the CTS, DCD, RTS, and DTR control signals, as
well as the TxD and RxD transmit/receive data signals and
TxC/RxC synchronous clock signals. Since not all modem control
lines are available in the Z85230, a Z8536 CIO device is used to
provide the missing modem lines.
EIA-232-D Connections
The EIA-232-D standard defines the electrical and mechanical
aspects of this serial interface. The interface employs unbalanced
(single-ended) signaling and is generally used with DB25
connectors, although other connector styles (e.g., DB9 and RJ45) are
sometimes used as well.
Table C-1 lists the standard EIA-232-D interconnections. Not all
pins listed in the table are necessary in every application.
To interpret the information correctly, remember that the EIA-232-
D serial interface was developed to connect a terminal to a modem.
Serial data leaves the sending device on a Transmit Data (TxD) line
and arrives at the receiving device on a Receive Data (RxD) line.
When computing equipment is interconnected without modems,
one of the units must be configured as a terminal (data terminal
equipment: DTE) and the other as a modem (data circuit-
terminating equipment: DCE). Since computers are normally
configured to work with terminals, they are said to be configured
as a modem in most cases.