
Command
Categories
Used in This
Manual
The 360B VNAGPIB interface responds to more
than 400 commands to implement the set of 360B
network analyzer functions. For descriptive pur-
poses, these commands are organized into the fol-
lowing functional classifications:
Basic Front Panel Functions
These commands produce basic 360B VNA measure-
ment operations identical to those produced by the
corresponding key functions on the 360B front
panel. These commands are described in Chapter 3.
Calibration Functions
The set of calibration commands can be used to set
up the calibration parameters under program con-
trol and to guide an operator through the 360B VNA
calibration process. These commands are described
in Chapter 4.
GPIB Unique Functions
These commands produce 360B VNA operations
that are unique to the GPIB mode of operation or
are operations that are best done using computer
control of the system. They are described in
Chapter 5.
1-2
DESCRIPTION OF THE
IEEE-488 (IEC-625)
INTERFACE BUS
The IEEE-488 General Purpose Interface Bus (GPIB) is an instrumen-
tation interface for integrating instruments, computers, and other con-
trollers into systems. The bus uses 16 signal lines to effect transfer of
data and commands to all instruments connected on the bus.
No more than 15 instruments may be connected to the interface bus
(however, a system may contain more than one interface bus). The
maximum total accumulative cable length for one interface bus may
not exceed twice the number of instruments connected (in meters) , or
20 meters—whichever is less.
The instruments on the bus are connected in parallel, as shown in
Figure 1-1. Eight of the signal lines (DIO1 thru DIO8) are used for
the transfer of data and other messages in a byte-serial, bit-parallel
form. The remaining eight lines are used for communications timing
(handshake), control, and status information. Data are transmitted on
the eight GPIB data lines as a series of eight-bit characters, referred
to as bytes.
Data transfer is by means of an interlocked handshake technique
(Figure 1-2). This technique permits asynchronous communications
over a wide range of data rates. The following paragraphs provide an
overview of the data, and handshake buses, and describe how these
buses interface with the 360B VNA.
GENERAL GPIB DESCRIPTION OF THE IEEE-488
INFORMATION (IEC-625) INTERFACE BUS
360B GPIB PM 1-5