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SCPI Introduction

The Example indicates the effect of semicolon and explains the concept of

head path. Since the head path is defined to be "CURR" after "curr: lev 3",

the head of the second command, "curr", is deleted and the instrument

explains the second command as:

CURR:PROT:STAT OFF

If "curr" is explicitly included in the second command, it is semantically

wrong. Since combining it with the head path will become

"CURR:CURR:PROT:STAT OFF", resulting in wrong command.

Movement in the Subsystem

In order to combine commands from different subsystems, you need to be

able to reset the header path to a null string within a message. You do this

by beginning the command with a colon (:), which discards any previous

header path. For Example, you could clear the output protection and check

the status of the Operation Condition register in one message by using a

root specifier as follows:

PROTection:CLEAr;:STATus:OPERation:CONDition?

The following message shows how to combine commands from different

subsystems as well as within the same subsystem:

POWer:LEVel 200;PROTection 28; :CURRent:LEVel 3;PROTection:STATe ON

Note the use of the optional header LEVel to maintain the correct path

within the voltage and current subsystems, and the use of the root specifier

to move between subsystems.

Including Common Commands

You can combine common commands with subsystem commands in the

same message. Treat the common command as a message unit by

separating it with a semicolon (the message unit separator). Common

commands do not affect the header path; you may insert them anywhere in

the message.

Case Sensitivity

Common commands and SCPI commands are not case sensitive. You can

use upper or lower, for Example:

*RST = *rst

Long-Form and Short-Form Versions

A SCPI command word can be sent in its long-form or short-form version.

However, the short-form version is indicated by upper case characters.

Examples:

:SYSTem:ERRor? long-form

:SYST:ERR? short form

:SYSTem:ERR? long-form and short-form combination

Note that each command word must be in long-form or short-form, and not

ITech IT8200 Series Programming Guide

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