MVME162/D2A-1
A
SERIAL
INTERCONNECTIONS
Introduction
As described in previous chapters of this manual, one of the MVME162’s two
serial ports (port A internally,
SERIAL PORT 1/CONSOLE on the front panel) is
an EIA-232-D DCE port exclusively. The second port (port B internally,
SERIAL
PORT 2
on the front panel) can be configured via serial interface modules as an
EIA-232-D DCE/DTE or EIA-530 DCE/DTE port.
The MVME162 uses a Zilog Z85230 serial port controller to implement the two
serial communications interfaces. Each interface supports CTS, DCD, RTS,
and DTR control signals as well as the TxD and RxD transmit/receive data
signals, and TxC/RxC synchronous clock signals. The Z85230 supports
synchronous (SDLC/HDLC) and asynchronous protocols. The MVME162
hardware supports asynchronous serial baud rates of 110B/sec to 38.4KB/sec.
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 A-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.
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