ICS ELECTRONICS 4809A, Instruction Manual

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A1.3 SCPI COMMANDS
A1.3.1 Introduction
SCPI (Standard Commands for Programmable Instruments) builds on the
programming syntax of 488.2 to give the programmer the capability handling
a wide variety of instrument functions in a common manner. This gives all
instruments a common "look and feel".
SCPI commands use common command words defined in the SCPI specifi-
cation. Control of any instrument capability that is described in SCPI shall
be implemented exactly as specified. Guidelines are included for adding
new defined commands in the future as new instruments are introduced
without causing programming problems.
SCPI is designed to be laid on top of the hardware - independent portion
of the IEEE 488.2 and operates with any language or graphic instrument
program generators. The obvious benefits of SCPI for the ATE programmer
is in reducing the learning time on how to program multiple SCPI instru-
ments since they all use a common command language and syntax.
A second benefit of SCPI is that its English like structure and words are self
documenting, eliminating the needs for comments explaining cryptic instru-
ment commands. A third benefit is the reduction in programming effort to
replace one manufacturer's instrument with one from another manufacturer,
where both instruments have the same capabilities.
This consistent programming environment is achieved by the use of defined
program messages, instrument responses and data formats for all SCPI
devices, regardless of the manufacturer.
A1.3.2 Command Structure and Examples
SCPI commands are based on a hierarchical structure that eliminates the
need for most multi-word mnemonics. Each key word in the command
steps the device parser out along the decision branch - similar to a squirrel
hopping from the tree trunk out on the branches to the leaves. Subsequent
keywords are considered to be at the same branch level until a new com-
plete command is sent to the device. SCPI commands may be abbreviated
as shown by the capital letters in Figure A-4 or the whole key word may
be used when entering a command. Figure A-4 shows some single SCPI