All commands, unless specifically noted in the commands syntax descriptions, have a query form. As defined in IEEE-488.2, a query is a command with a question mark symbol appended: (examples: *IDN?) When a query form of a command is received, the current setting associated with the comm and is placed in the output buffer. Query commands always return the short form of the parameter unless otherwise specified. Boolean values are returned as 1 or 0, even when they can be set as on or off.
Data Parameters
Data parameters, referred to simply as “parameters,” are the quantitative values used as arguments for the command keywords. The parameter type associated with a particular SCPI command is determined by the type of information required to control the particular instrument function. For example, Boolean (ON | OFF) type parameters are used with commands that control switch functions.
Some command descriptions specify the type of data parameter to be used with each command. The most commonly used parameter types are numeric, extended numeric, discrete, and Boolean.
Numeric
Numeric parameters comprise integer numbers or any number in decimal or scientific notation, and may include polarity signs. This includes <NR1>, <NR2>, and <NR3> numeric data as defined in Data Parameter Notations below.
Extended Numeric
Extended numeric parameters include values such as MAXimum and MINimum.
Discrete
Discrete parameters, such as INTernal and EXTernal, are used to control program settings to a predetermined finite value or condition.
Boolean
Boolean parameters represent binary conditions and may be expressed as ON, OFF or 1, 0.
Data Parameter Notations
The following syntax conventions are used for data parameter descriptions in this manual:
Parameter Notations
<arg>
::=a generic command argument consisting of one or more of the other data types
<bNR1>
::=boolean values in <NR1> format; numeric 1 or 0
<boolean>
::=ON | OFF. Can also be represented as 1 or 0, where 1 means ON and 0 means OFF Boolean parameters are always returned as 1 or 0 in <NR1> format by query commands
<integer>
::=an unsigned integer without a decimal point (implied radix point)
<NR1>
::=a signed integer without a decimal point (implied radix point)
<NR2>
::=a signed number with an explicit radix point
<NR3>
::=a scaled explicit decimal point numeric value with and exponent (e.g., floating point number)
<NRf>
::=<NR1>|<NR2>|<NR3>
<numeric_value>
::=SCPI numeric value: <NRf>|MINimum|MAXimum|UP|DOWN|DEFault|NAN (Not A Number)|INFinity|NINFinity (Negative Infinity) or other types
<char>
::=<CHARACTER PROGRAM DATA> Examples: CW, FIXed, UP, and DOWN
<string>
::=<STRING PROGRAM DATA> ASCII characters enclosed by double quotes. For example: “OFF”
<block>
::=IEEE-488.2 block data format
<NA>
::=Not Applicable
Unit Suffixes
Unit suffixes are not required for data parameters, provided the values are scaled for the global default units. The instrument SCPI default units are: