SCPI(Standard Commands for Programmable Instruments)

Standard Commands for Programmable Instruments

 

The Standard Commands for Programmable Instruments (SCPI) (often pronounced "skippy") defines a standard set of commands to control programmable test and measurement devices in instrumentation systems.

 

The SCPI Standard specifies the syntax, the command structure, and data formats for programmable instrument control. The physical communications link, such as GPIB (IEEE-488) , RS232, USB, VXIbus etc, is notdefined by SCPI.

 

SCPI also includes standard command sets for several classes of instruments, e.g. power supplies, loads, and measurement devices such as voltmeters and oscilloscopes. A predecessor of SCPI, but with more limited scope, was IEEE 488.2 in 1987.

 

SCPI commands are ASCII textual strings, which are sent to the instrument over the physical layer, such as GPIB. Responses to query commands are typically ASCII strings, too. However, for bulk data, such as acquired signal data, binary formats can be used.

 

Two examples: With the command SYSTem:COMMunicate:SERial:BAUD 2400 the baudrate of an RS232 interface can be set to 2400 bit/s. With the command SYSTem:COMMunicate:SERial:BAUD? the current baudrate of an RS232 interface can be queried. Commands can be abbreviated to their upper case parts, for instance SYST:COMM:SER:BAUD?.

 

Some instrument manufacturers, notably Agilent, Berkeley Nucleonics and Tektronix, have implemented SCPI on many new general purpose instruments. Many smaller companies follow their lead. Typically their SCSI implementations roughly follow the spirit of the standard, but don't implement all finer details of the syntax, and don't follow the standard instrument classes commands in detail.

 

In 2002-2003, the SCPI Consortium voted to become part of the IVI Foundation (Interchangeable Virtual Instruments).