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Syntax
Creating Commands
Creating Queries
Command Arguments
Parameter Types
2 2
SCPI commands are created by stringing together the nodes of a subsystem
hierarchy and separating each node by a colon.
In Figure 2-1, SENSe is the root node and AVERage, TYPE, COUNt, and RESet
are lower-level nodes. To create a SCPI command, start with the root node
SENSe and move down the tree structure adding nodes until you reach the end of
a branch. Most commands and some queries have parameters; you must include
a value for these parameters. If you specify a parameter value that is out of range,
the parameter will be set to a default value. The command descriptions, which
start on page 2-15, list the valid values for all parameters.
For example, SENSe:AVERage:TYPE OFF is a valid SCPI command created
from the hierarchy tree in Figure 2-1.
To create a query, start at the root node of a tree structure, move down to the end
of a branch, and add a question mark. SENSe:AVERage:TYPE? is an example of
a valid SCPI query using the hierarchy tree in Figure 2-1.
Many commands accept either string or numeric arguments. For example: a
boolean argument can either be "1" or "ON".
Select signal parameter commands accept either a numeric value or one of the
following strings:
MINimum. Use this argument to query the minimum value or set the parameter
value to the minimum acceptable value.
MAXimum. Use this argument to query the maximum value or set the parameter
value to the maximum acceptable value.
NOTE. If the realtime spectrum analyzer does not return a value in response to a
MIN or MAX query, then the values are undefined and an error message is
generated.
Every parameter in the command and query descriptions is of a specified type.
The parameters are enclosed in brackets, such as <pattern>. The parameter type
is listed after the parameter and is enclosed in parentheses, for example,
(discrete). Some parameter types are defined specifically for the realtime
spectrum analyzer command set and some are defined by ANSI/IEEE
488.2-1987 (see Table 2-1).
3026 Programmer Manual
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