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GPIB-140A User Manual
The GPIB-140A and GPIB-140A/2 bus extenders comply with the specifications of the
ANSI/IEEE Standard 488.1-1987 and the ANSI/IEEE Standard 488.2-1992, including the Find
Listeners protocol. With the GPIB extenders, you can overcome the following two configuration
restrictions imposed by IEEE 488:
•
A cable length limit of 20 m total per contiguous bus or 2 m per each device on the bus,
whichever is smaller
•
An electrical loading limit of 15 devices per contiguous bus
Each GPIB-140A system extends the GPIB to a maximum distance of 1 km, and each
GPIB-140A/2 system extends the GPIB to a maximum distance of 2 km. Both systems extend
the loading limit to 28 devices (including the GPIB extenders), without sacrificing speed or
performance. You can connect these point-to-point extension systems in series for longer
distances or in star patterns for additional loading.
Using the HS488 protocol, the maximum data transfer rate over the extension is greater than
2.8 Mbytes/s. The GPIB extenders use a buffered transfer technique with a serial extension bus,
which maximizes performance and minimizes the cabling cost. Furthermore, the extender does
not affect the transfer rate between devices on the same side of the extension. The GPIB extender
can also check for errors to make sure that the data transmitted successfully over the fiber-optic
link.
Because the GPIB-140A and GPIB-140A/2 are functionally transparent extenders, the GPIB
communications and control programs that work with an unextended system also work with an
extended system. However, the
Parallel Poll Response Modes
section in Chapter 3,
Configuring
and Using Your Hardware
, describes one exception to this transparency in conducting parallel
polls.
Time-Saving Development Tools
Your kit includes the GPIB-140A or GPIB-140A/2 bus extender. In addition, you can order the
NI-488.2, LabWindows
™
/CVI
™
, or LabVIEW software from National Instruments to speed
your application development time and make it easier to communicate with your instruments.
The NI-488.2 software supports the concurrent use of multiple types of GPIB hardware. For
example, you can communicate with GPIB devices through a PCI-GPIB, a PCMCIA-GPIB, and
a GPIB-ENET/100 in the same system at the same time. The NI-488.2 software, along with the
GPIB hardware, transforms your computer into a GPIB Talker/Listener/Controller with
complete communications and bus management capability.
LabVIEW is an easy-to-use, graphical programming environment you can use to acquire data
from thousands of different instruments, including IEEE 488.2 devices, VXI devices, serial
devices, PLCs, and plug-in data acquisition boards. After you have acquired raw data, you can
convert it into meaningful results using the powerful data analysis routines in LabVIEW.
LabVIEW also comes with hundreds of instrument drivers, which dramatically reduce software
development time, because you do not have to spend time programming the low-level control of
each instrument.