BNC 845-M - Manual (Page 12)

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Model 845-M Programmer’s Manual V1.1 2011
4. SCPI Commands
This chapter provides an introduction to SCPI programming that includes descriptions of the command
types, hierarchical command structure, data parameters, and notational conventions. Information on
status system and trigger system programming is also provided.
Introduction
Standard Commands for Programmable Instruments (SCPI) is the new instrument command language for
controlling instruments that goes beyond IEEE 488.2 to address a wide variety of instrument functions
in a standard manner. SCPI promotes consistency, from the remote programming standpoint, between
instruments of the same class and between instruments with the same functional capability. For a
given measurement function such as frequency or voltage, SCPI defines the specific command set that is
available for that function. Thus, two oscilloscopes made by different manufacturers could be used to
make frequency measurements in the same way. It is also possible for a SCPI counter to make a
frequency measurement using the same commands as an oscilloscope. SCPI commands are easy to learn,
self-explanatory and account for both novice and expert programmer’s usage. Once familiar with the
organization and structure of SCPI, considerable efficiency gains can be achieved during control
program development, independent of the control program language selected.
A key to consistent programming is the reduction of multiple ways to control similar instrument
functions. The philosophy of SCPI is for the same instrument functions to be controlled by the same SCPI
commands. To simplify learning, SCPI uses industry-standard names and terms that are manufacturer
and customer supported.
The advantage of SCPI for the ATE system programmer is reducing the time learning how to
program new SCPI instruments after programming their first SCPI instrument.
Programmers who use programming languages such as BASIC, C, FORTRAN, etc., to send instrument
commands to instruments will benefit from SCPI. Also, programmers who implement instrument
device drivers for ATE program generators and/or software instrument front panels will benefit by
SCPI’s advantages. SCPI defines instrument commands, parameters, data, and status. It is not an
application package, programming language or software intended for instrument front panel
control.
SCPI is designed to be layered on top of the hardware-independent portion of IEEE 488.2.