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TTI-7 Iss.02 – 06/11
PROGRAMMING THE INTERFACE
Introduction
All interfaces are programmed in a common language which is based on SCPI (Standard Commands for
Programmable Instruments). Although similar in style, full conformance to the SCPI and IEEE488.2 standards is not
guaranteed.
The following is a brief guide to the structure and syntax of the programming language.
Command Tree
Commands are arranged as a hierarchical “tree”, similar to the filing system trees found in personal computers.
Commands start at the root level and progress down each level in more detail. The complete path must be specified
to access the lower level commands.
For the instrument series, only one command path per line is accepted.
Colon (:)
The colon is used to separate command keywords and automatically move the path down to the next level. All new
command lines automatically start at the root-level.
For the instrument series, a colon must not be sent as the first character. This is treated as a non-recognised
character and the “command error” bit (5) of the Standard Event Register is
set.
Semicolon (;)
The semicolon is also used to separate command keywords, but in this case the path remains at the same level.
This is not implemented for the instrument series. The semicolon is treated as a non-recognised character and the
“command error” bit (5) of the Standard Event Register is set.
Whitespace (TAB or SPACE)
A whitespace character must be used to separate the first parameter from a command keyword. If omitted, the
“command error” bit (5) of the Standard Event Register is set.
The instrument series will not accept whitespace characters in subsequent parameter lists. These will set the
“command error” bit (5) of the Standard Event Register.
Comma (,)
If a command requires multiple parameters, a comma must be used to separate parameters from one another in the
parameter list.
Query (?)
Commands ending in a query (?) indicate that a response is expected from the instrument. This is usually a measured
value or status message. Commands sent without a query instruct the instrument to perform a function only without
any response. The instrument will not output a response without a query command (except in Talk Only mode).
Common Commands (*)
Commands beginning with a “*” are called common commands and have a precise function as defined by the IEEE-
488.2 standard. All instruments behave in an identical way. These commands are primarily concerned with control,
reset, self-test and status.
