C H A P T E R  4

Connecting Peripherals

This chapter discusses various methods of connecting peripheral devices to the SunSAI/P adapter and provides sample cable diagrams to aid in constructing the correct cable for your application, including:

Note - The cables shown in this section are for information only and are not supplied by Sun Microsystems.

Connecting to a Modem

To connect the SunSAI/P board to a modem, use a standard "straight-through" cable (FIGURE 4-1) to connect the modem to one of the DB-25 connectors on the connector box.

Note - Shielded cable must be used to remain in compliance with Part 15 of FCC rules.

Note - If you use modems for dial-in purposes, you may experience a problem where a modem will not hang up the phone line connection after all processes running on the port exit. As a workaround, configure the modem to be a bi-directional modem. Please refer to the Sun bug report number 4178202 for more information.

FIGURE 4-1 Modem Cable

Illustration shows a modem cable.

Connecting to a DTE Device

Terminals, serial printers, or another computer's serial port are examples of DTE devices. To connect the SunSAI/P board (which is also a DTE device) to another DTE device, you need a null modem cable or adapter.

Software Handshaking (XON/XOFF)

In most cases, serial terminals and printers need only a "three-wire" connection to the SunSAI/P board. The Solaris device driver supports XON/XOFF (software) handshaking, so the only signal lines necessary are Transmitted Data (TxD), Received Data (RxD) and Signal Ground (SG). Cables must be shielded to remain in compliance with FCC certification requirements, and the shield should be connected to Chassis Ground (GND) at both ends of the cable run.

A simple cable for connecting a terminal or a printer to a DB-25 equipped SunSAI/P board is shown in FIGURE 4-2.

FIGURE 4-2 Simple Terminal/Printer Cable

Note - Shielded cable must be used to remain in compliance with Part 15 of FCC rules.

The cable shown in FIGURE 4-2 is a three-wire null modem cable--that is, Transmitted Data on one end of the cable is connected to Received Data at the other end, and vice versa.

The male DB-25 end can be plugged directly into most serial terminals and printers without any adapters. The female DB-25 end plugs directly into one of the DB-25 connectors on the connector box assembly.

Hardware Handshaking (Ready/Busy)

Most terminals and printers use Data Terminal Ready (DTR) for Ready/Busy hardware handshaking. The cable shown in FIGURE 4-3 supports this method.

FIGURE 4-3 Terminal/Printer Cable with DTR Handshaking

Note - Shielded cable must be used to remain in compliance with Part 15 of FCC rules.

Note - Some Okidata printers use a control signal on pin 11, called Supervisory Send Data (SSD) instead of DTR. In this case, simply connect CTS on the female DB-25 side to pin 11 of the male DB-25, instead of pin 20. Other printer manufacturers may use different methods of flow control. Consult your printer's documentation for specific wiring requirements.

Using Hardware Flow Control

To use clear to send (CTS)/request to send (RTS) hardware flow control with devices such as modems, we recommend using the options provided by the
/opt/SUNWconn/bin/sitty utility. Use the sitty rtspace and ctspace options instead of the following Solaris stty command options: crtscts, crtsxoff, rtsxoff and/or ctsxon. Refer to the sitty(1m) man page and Chapter 7 of the SunSAI/P User's Guide for more information about the sitty utility.