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National Instruments Corporation
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GPIB-120B User Manual
1
Introduction
This chapter contains a description of the GPIB-120B, lists what you need
to get started and optional equipment you can order, and explains how to
unpack the GPIB-120B.
Description of the GPIB-120B
The GPIB-120B is a high-speed bus isolator/expander with the following
features:
•
It is transparent to user software.
•
It electrically isolates two GPIB systems from each other and from the
power supply.
•
It expands the GPIB to interface up to 28 devices.
•
It extends the GPIB by effectively doubling the 20 m cable limit.
•
It has optional rack or din-rail mount hardware accessories.
The high-speed GPIB-120B bus isolator/expander connects two GPIB
(IEEE 488) bus systems in a functionally transparent manner.
The two bus systems are electrically isolated from each other. The two bus
systems are also isolated from the power supply. Isolation is maintained
up to 2500 VDC (withstand 5 s). Isolating an instrument or group of
instruments from an IEEE 488 bus Controller can eliminate ground loop
noise and induced common-mode noise, which may cause measurement
problems in both analog and digital systems. The two isolated bus systems
are physically separate, as shown in Figure 1-1; however, the devices
logically appear to be located on the same bus, as shown in Figure 1-2.