Agilent Technologies 8712ET Programmer's Manual page 12

Introduction to GPIB Programming
Introduction to GPIB Programming
Introduction to GPIB Programming
GPIB—the general purpopse interface bus—is a high-performance bus
that connects individual instruments and computers together to make
integrated test systems. The bus and its associated interface operations
are defined by the IEEE 488.1 standard. The IEEE 488.2 standard
defines the interface capabilities of instruments and controllers in a
measurement system, including some frequently used commands.
GPIB cables provide the physical link between devices on the bus. There
are eight data lines on each cable that are used to send data from one
device to another. Devices that send data over these lines are called
Talkers. Listeners are devices that receive data over the same lines.
There are also five control lines on each cable that are used to manage
traffic on the data lines and to control other interface operations.
Controllers are devices that use these control lines to specify the talker
and listener in a data exchange. When a GPIB system contains more
that one device with controller capabilities, only one of the devices is
allowed to control data exchanges at any given time. The device
currently controlling data exchanges is called the Active Controller.
Also, only one of the controller-capable devices can be designated as the
System Controller, the one device that can take control of the bus even
if it is not the active controller. The network analyzer can act as a talker,
listener, active controller or system controller at different times.
GPIB addresses provide a way to identify devices on the bus. Each device
on the bus must have a unique address. The active controller uses GPIB
addresses to specify which device talks and which device listens during a
data exchange. Device addresses are set on each device using either a
front-panel key sequence or a rear-panel switch.
To set the GPIB address on the analyzer, use the softkeys located in the
GPIB menu. The factory default address for the
SYSTEM OPTIONS
analyzer is 16.
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