Eia-232-D Connections - Motorola MVME2700 Series Installation And Use Manual

EIA-232-D Connections

C
EIA-232-D Connections
C-2
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.
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 (such as 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.
Notes 1. A high EIA-232-D signal level is +3 to +15 volts. A low level
is 3 to 15 volts. Connecting units in parallel may produce out-
of-range voltages and is contrary to specifications.
2. The EIA-232-D interface is intended to connect a terminal to a
modem. When computers are connected without modems, one
computer must be configured as a modem and the other as a
terminal.
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