Programming instructions

Command Reference
SCPI Basics
Chapter 4144
Command Parameters and Responses
SCPI defines different data formats for use in program and response messages. It does this to
accommodate the principle of forgiving listening and precise talking. For more information on
program data types refer to IEEE 488.2.
Forgiving listening means the command and parameter formats are flexible.
For example, with the :FREQuency:REFerence:STATe ON|OFF|1|0 command, the signal
generator accepts :FREQuency:REFerence:STATe ON, :FREQuency:REFerence:STATe 1,
:FREQ:REF:STAT ON, :FREQ:REF:STAT 1 to turn on the source’s frequency reference mode.
Each parameter type has one or more corresponding response data types. A setting that you
program using a numeric parameter returns either real or integer response data when
queried. Response data (data returned to the controller) is more concise and restricted and is
called precise talking.
Precise talking means that the response format for a particular query is always the same.
For example, if you query the power state (:POWer:ALC:STATe?) when it is on, the response is
always 1, regardless of whether you previously sent :POWer:ALC:STATe 1 or
:POWer:ALC:STATe ON.
Numeric Parameters
Numeric parameters are used in both common and subsystem commands. They accept all
commonly used decimal representations of numbers including optional signs, decimal points,
and scientific notation.
If a signal generator setting is programmed with a numeric parameter which can only assume
a finite value, it automatically rounds any entered parameter which is greater or less than the
finite value. For example, if a signal generator has a programmable output impedance of 50 or
75 ohms, and you specified 76.1 for the output impedance, the value is rounded to 75.
Table 4-3 Parameter and Response Types
Parameter Types Response Data Types
Numeric Real, Integer
Extended Numeric Real, Integer
Discrete Discrete
Boolean Numeric Boolean
String String