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A Brief Introduction to the SCPI Language
SCPI Language Basics
<trace> Is an array of rational numbers corresponding to displayed trace data. See
FORMat:DATA for information about available data formats.
A SCPI command often refers to a block of current trace data with a variable name
such as: Trace1, TRACE2, or trace3, depending on which trace is being accessed.
<arbitrary block data> Consists of a block of data bytes. The first information sent in the block is an
ASCII header beginning with #. The block is terminated with a semi-colon. The
header can be used to determine how many bytes are in the data block. There are no
units. (You do not get block data if your data type is ASCII, using FORMat:DATA
ASCII command. Your data is comma separated ASCII values.
Block data example: suppose the header is #512320.
• The first digit in the header (5) tells you how many additional digits/bytes there are
in the header.
• The 12320 means 12 thousand, 3 hundred, 20 data bytes follow the header.
• Divide this number of bytes by your current data format (bytes/data point), either 8
(for real,64), or 4 (for real,32). For this example, if you’re using real64 then there
are 1540 points in the block.
Putting Multiple Commands on the Same Line
Multiple commands can be written on the same line, reducing your code space requirement. To do this:
• Commands must be separated with a semicolon (;).
• If the commands are in different subsystems, the key word for the new subsystem must be preceded
by a colon (:).
• If the commands are in the same subsystem, the full hierarchy of the command key words need not be
included. The second command can start at the same key word level as the command that was just
executed.
SCPI Termination and Separator Syntax
All binary trace and response data is terminated with <NL><END>, as defined in Section 8.5 of IEEE
Standard 488.2-1992, IEEE Standard Codes, Formats, Protocols and Common Commands for Use with
ANSI/IEEE Std 488.1-1987. New York, NY, 1992. (Although one intent of SCPI is to be interface
independent, <END> is only defined for IEEE 488 operation.)