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User and Programming Manual - Rev H
California Instruments
P Series
May 2000
59
The basic parts of the above message are:
Message Component
Example
Headers
SOURC VOLT FREQ CURR
Header Separator
The colon in SOUR:VOLT
Data
80
60
Data Separator
The space in VOLT 80 and FREQ 60
Message Units
VOLT 80
FREQ 60
CURR?
Message Unit Separator
The semicolons in VOLT 80; and FREQ 60;
Root Specifier
The colon in :CURR?
Query Indicator
The question mark in CURR?
Message Terminator
The <NL> (newline) indicator. Terminators are not part of the
SCPI syntax
Note:
The use of compound messages such as the one shown in this example is not
recommended as they typically exceed the available receive buffer length of the P Series
interface.
12.4.3 Headers
Headers are instructions recognized by the AC source. Headers (which are sometimes known
as "keywords") may be either in the long form or the short form.
Long Form
The header is completely spelled out, such as VOLTAGE, SYSTEM, and
OUTPUT.
Short Form
The header has only the first three or four letters, such as VOLT, SYST, and
OUTP.
The SCPI interface is not sensitive to case. It will recognize any case mixture, such as
VOLTAGE, VOLTage,Voltage. Short form headers result in faster program execution.
In view of the 21 character receive buffer size of the P Series, the short form is recommended
under all circumstances.
Header Convention
In the command descriptions in chapter 0 of this manual, headers are emphasized with
boldface type. The proper short form is shown in upper-case letters, such as DELay.
Header Separator
If a command has more than one header, you must separate them with a colon
(SYSTem:ERRor LIMit:FREQuency:LOW).
Optional Headers
The use of some headers is optional. Optional headers are shown in brackets, such as
VOLTage[:LEVel] 100.
12.4.4 Query Indicator
Following a header with a question mark turns it into a query (VOLTage?, VRANGe?).