Motorola MVME2600 manual EIA-232-D Connections

B

Serial Interconnections

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-Dstandard defines the electrical and mechanical aspects of this serial interface. The interface employs unbalanced (single-ended) signaling and is generally used with DB-25 connectors, although other connector styles (for example, DB-9 and RJ-45) are sometimes used as well.

Table B-1lists 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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