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Serial Interface Surge Suppression
Threshold Voltage
Response Time
Mechanical Requirements
Length
Width
Height
Weight
Cable Requirements and Specifications
This section specifies cable characteristics and requirements.
NOTE:
A gender changer may be required for DB-25 cabling if the AD278A/AD279A is being
used as a replacement or upgrade from a previous A6748A/A6749A PCI MUX installation. Also,
RJ-45 recabling is required if replacing or upgrading an A6748A/A6749A PCI MUX RJ-45
installation to an AD280A port module with RJ-45 connectors.
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.
13 V
< 10 nS
RJ-45 (AD280A) Model
12 inches (30.480 cm)
7 inches (17.780 cm)
2.25 inches (5.715 cm)
2 Pounds (907.20 gram)
DB-25 (AD281A) Model
12 inches (30.480 cm)
7 inches (17.780 cm)
4.2 inches (10.668 cm)
4 Pounds (1814.40 gram)
Cable Requirements and Specifications
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Troubleshooting
