Standard Commands for Programmable Instruments: Difference between revisions

Revision as of 23:35, 18 November 2024

Revision as of 23:54, 18 November 2024

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SCPI was defined as an additional layer on top of the {{nowrap|IEEE 488.2-1987}} specification "Standard Codes, Formats, Protocols, and Common Commands".<ref>[http://zone.ni.com/devzone/cda/tut/p/id/3419 ni.com - History of GPIB - Developer Zone]</ref> The standard specifies a common [[syntax]], [[command (computing)|command]] structure, and [[Data type|data format]]s, to be used with all instruments. It introduced generic commands (such as <code>CONFigure</code> and <code>MEASure</code>) that could be used with any instrument. These commands are grouped into subsystems. SCPI also defines several classes of instruments. For example, any controllable [[power supply]] would implement the same <code>DCPSUPPLY</code> base functionality class. Instrument classes specify which subsystems they implement, as well as any instrument-specific features.

The physical hardware communications link is not defined by SCPI. While it was originally created for the [[IEEE-488]].1 (GPIB) bus, SCPI can also be used with [[RS-232]], [[RS-422]], [[EthernetRS-485]], [[Universal Serial Bus|USB]], [[Ethernet]], [[VME eXtensions for Instrumentation|VXIbus]], [[HiSLIP]], etc.

SCPI commands are [[ASCII]] textual strings, which are sent to the instrument over the physical layer (e.g., IEEE-488.1). Commands are a series of one or more keywords, many of which take parameters. In the specification, keywords are written <code>CONFigure</CODE>: The entire keyword can be used, or it can be abbreviated to just the uppercase portion. Responses to query commands are typically ASCII strings. However, for bulk data, binary formats can be used.<ref name="SCPI-1999-spec"/>