Making Your Own Cables; A Note On Standards - HP A4500A - VMEbus Single Board Computer 744 Motherboard Manual

Making your own cables

This chapter includes advice which you may find useful when making your own
cables to connect devices to ports on the Modem Distribution Panel, the Direct
Distribution Panel, and the 24-port RJ45 Direct Distribution Panel.
You will also find some background information concerning the RS-232, RS-422,
and RS-423 standards.

A note on standards

As demand grows for terminal-to-system connections supporting higher baud rates
over greater distances, the use of RS-422 and RS-423 is becoming more prevalent.
This section gives an overview of these standards.
The RS-422 and RS-423 standards are electrical standards. They specify the
electrical characteristics of the digitial interface circuit.
The RS-232 standard specifies the electrical, physical, and logical characteristics of
the interface circuit.
Consequently, a comparison of RS-232 with RS-422 and RS-423 can only be a
comparison of electrical standards.
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