Queries And Commands; Commands - Quantum Data 881 User Manual

Queries and commands

Commands

882 Video Test Instrument User Guide (Rev A.35)
The GPIB interface is an ASCII command line interface like the RS-232 command line
interface. The communications protocol is per IEEE-488.2 specification. Queries and
commands consist of four ASCII upper/lower case characters. Commands do not require
a response from the generator, while queries cause the generator to respond with the
required data.
You can send multiple commands on the same line by separating the commands with a
semicolon (;) followed by a terminator. A terminator is defined as the NL character (ASCII
10), or EOI sent with the last byte of the command. The generator will not parse any
commands received until a terminator is received. All commands are executed
sequentially; that is, when a command is parsed it is allowed to finish execution before the
next command is parsed, as illustrated in the following figure.
Separator ( ; )
Message
Program Message Syntax
Command/Query
(white space)
Header
Message Unit Syntax
Commands instruct the generator to set a parameter to the value given or perform some
function not requiring any additional data. Commands which have an asterisk (*) as their
first character are common commands as defined by the IEEE-488.2 standard and
generally operate the same in all instruments. All commands are listed and described in
Appendix A, "Command
Commands which do not require any additional data from the controller are self-contained
and should be followed by either a message separator (;) or message terminator. Any
other characters (except whitespace characters) will cause a command error.
Commands which require numeric data must be followed by at least one separator
character (whitespace), and then the data. Numeric data sent with a command is in
decimal format. Numeric data can be represented in one of three methods: integer,
floating point, or scaled floating point.
Terminator
Separator
( ; )
Separator
Data
Reference."
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