Alpha Microsystems AM-6000 Owner's Manual download pdf (Page 87)

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A-2

Appendix A

AM-6000 Computer Owner's Manual, Rev. 00

You enable these specific signals by attaching cable wires to certain connector pins.

If a terminal or printer manufacturer says their device is RS-232 or RS-232C compatible, it will probably

be easy for you to connect it to your Alpha Micro computer system.

Before constructing the cable to connect a printer or terminal to your Alpha Micro computer system, you

need to consult the manufacturer's manual accompanying the device. It will tell you how to wire the

connector on the device end. Few devices use all of the defined signals. In most cases, you need to

connect only three or four pins. Although printer cables are sometimes a little more complicated on the

printer end, terminal cables are often the same on both computer and terminal ends.

Alpha Micro uses RJ-45 connectors for RS-232 device connection. The maximum length of RS-232

cables is

50 feet

between devices.

WHAT IS RS-422?

RS-422 is supported by the AM-355 and AM-358 boards only.

The AM-359 serial I/O board, as well as the AM-6000's four on-board serial ports do NOT

support RS-422.

IMPORTANT NOTE

The Federal Communications Commission (FCC) has established rules regarding allowable emission

levels of Class A computing devices (ref: Subpart J of Part 15 of FCC Rules). The Alpha Micro systems

to which this manual applies have been determined to be in compliance with the FCC rules. However,

you should be aware that if other devices, such as terminals and printers, are attached to these systems,

even if the devices are attached in accordance with the instructions contained in this manual, the

resulting configuration may not be in compliance with the referenced FCC rules. Corrective measures, if

any are required, are the responsibility of the user. Information on emission levels of peripheral devices

should be obtained from the manufacturer of the device.

CABLE CONSTRUCTION GUIDELINES

If you want to construct your own cables, there are a few things you should keep in mind before

soldering the cable connectors:

Cable Length

We strongly recommend that RS-232C cables be not more than fifty feet long. As you increase the cable

length beyond fifty feet, the reliability of the data signal decreases. This applies when using an untwisted

paired cable. These are some things you can do if the cables absolutely must be longer than fifty feet:

1. Alternatives to the RS-232 standard, namely RS-422, do allow communication over cables

longer than fifty feet. Since RS-422 is supported only by the AM-358 board, you will need some

special equipment to implement these standards.

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Alpha Microsystems AM-6000 Owner's Manual Page 87