China Electronics Technology Instruments AV3672 Series, User Manual

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9 Remote control
9.1 Basis of Remote Control
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exchange requirements, and connection interruptions can be identified to prevent the loss of information.
3) Socket communication
The TCP/IP protocol is connected to the network analyzer in the network through the LAN socket. Socket is a basic
approach used in computer network programming, which enables network communication among applications
employing different hardware and operating systems. In this method, the vector network analyzer is connected to
the computer through the port for two-way communication.
Socket is a kind of software specially programmed and has defined the information necessary for network
communication such as IP address and device port number and integrated some basic operations of network
programming. Socket can be used as long as the packaged libraries are installed in the OS. Berkeley Socket Library
applied in UNIX and Winsock Library applied in Windows constitutes the two common socket libraries.
The socket of the vector network analyzer is compatible with the Berkeley socket and Winsock through the
application program interface (API). Besides, it is also compatible with other standard socket API. The command
will be sent by the socket program to control the vector network analyzer through SCPI commands. The socket port
number of the vector network analyzer must be set before the LAN socket is used. The socket port number of the
vector network analyzer is 1024.
9.1.1.2 GPIB Interface
The GPIB is a kind of remote control interface which is widely applied at present. Various kinds of instruments can
be connected through GPIB cables to form a test system with the master control computer. In order to realize
remote control, the master control computer should be configured with the GPIB bus card, drive program and VISA
library in advance. In the communication process, the controlled instrument is addressed by the master control
computer according to the GPIB bus address, and the user can set the GPIB address and ID query string. The
default GPIB communication language is SCPI command.
Refer to ANSI/IEEE 488.1-1987 and ANSI/IEEE 488.2-1992 for detailed definitions and descriptions on GPIB and
relevant interface operations. For details, visit the IEEE website http://www.ieee.org.
The byte is used in information processing of GPIB. The data transmission rate can reach 8MBps. Therefore, the
velocity of data transmission of GPIB is high. The data transmission velocity is limited by the distance between the
equipment/system and computer, pay attention to the following items in GPIB connection.
➢
At most 15 instruments can be connected through GPIB interfaces.
➢
The total length of the transmission cable must not exceed 15m or twice of the number of instruments in the
system. Generally, the maximum length of the transmission cable between devices must not exceed 2m.
➢
For parallel connection of instruments, use “or” connecting lines.
➢
Connect the terminal of the IEC bus cable to the instrument or controlling computer.
9.1.2 Message
Messages transmitted through the data lines are divided into the following two types.
1) Interface message
The low attention line should be installed for communication between the instrument and master control computer,
and then interface messages can be transmitted to the instrument through the data line. Interface messages must be
transmitted by the instrument with the GPIB bus function.
2) Instrument message
For the structure and grammar of instrument messages, refer to “5.1.4 SCPI Commands”. According to the
transmission direction, instrument messages can be divided into the command and instrument response. Unless
otherwise specified, the same method should be applied for use of instrument messages with the remote control
interface.
a) Command:
The command (programming message) is a kind of message transmitted by the master control computer to the
instrument, used for remote control of the instrument function and query of the state information. Commands are