AD278A/AD279A PCI MUX Support Guide, June 2006

Technical Specifications

Cable Requirements and Specifications

Appendix A

Cable Requirements and Specifications

This section specifies cable characteristics and requirements.

Physical Characteristics

RS-232 serial interface cables must have the following characteristics:

• Must be shielded

• Must have low capacitance

• Designed specifically for serial data transmission

Grounding Requirements

RS-232 interface cables must have shield grounded at both ends of the cable. HP recommends Chassis ground

available on the shell of RoHS DB-25 connectors and pin 4 of a 10-pin RJ-45 connector.

Environmental Requirements

Good shielding provides reasonable protection against noise (electromagnetic interference, or EMI). However,

cables must still be routed away from noise sources wherever possible. Avoid laying cables in close proximity

to transformers, generators, motors, fluorescent lights, and so on.

Data Rate Information

The maximum data rate that can be used for RS-232 connections is determined by the quality and length of

the interconnecting cable. The quality of the cable (for transmission purposes) is determined by the

capacitance per foot rating of the cable.

Table A-4 lists the recommended maximum cable length for a given data rate. Longer cables may be

implemented at your discretion.

NOTE Not all RoHS products support all of the data rates listed below.

Table A-4 Data Rate Versus Cable Length

Data Rate (bps)

Maximum Cable

Length

57,600 or less 100 feet (3048.000 cm)

115,200 80 feet (2438.400 cm)

230,400 40 feet (1219.200 cm)

460,800 20 feet (609.600 cm)

921,600 10 feet (304.800 cm)