Command Syntax
SCPI commands to an instrument may either perform a set operation (e.g. switching a power supply on) or a query operation (e.g. reading a voltage). Queries are issued to an instrument by appending a question-mark to the end of a command. Some commands can be used for both setting and querying an instrument. For example, the data-acquisition mode of an instrument could be set by using the ACQuire:MODe command or it could be queried by using the ACQuire:MODe? command. Some commands can both set and query an instrument at once. For example, the *CAL? command runs a self-calibration routine on some equipment, and then returns the results of the calibration.
Similar commands are grouped into a hierarchy or "tree" structure. For example, any instruction to read a measurement from an instrument will begin with "MEASure". Specific sub-commands within the hierarchy are nested with a colon (:) character. For example, the command to "Measure a DC voltage" would take the form MEASure:VOLTage:DC?, and the command to "Measure an AC current" would take the form MEASure:CURRent:AC?.
Read more about this topic: Standard Commands For Programmable Instruments
Famous quotes containing the word command:
“But as some silly young men returning from France affect a broken English, to be thought perfect in the French language; so his Lordship, I think, to seem a perfect understander of the unintelligible language of the Schoolmen, pretends an ignorance of his mother-tongue. He talks here of command and counsel as if he were no Englishman, nor knew any difference between their significations.”
—Thomas Hobbes (1579–1688)