590 Keysight M8000 Series of BER Test Solutions User Guide
9 Utilities
Query Responses
It is possible to interrogate the individual settings and status of a device
using query commands. Retrieving data is a two-stage operation.
The query command is sent from the controller using the OUTPUT
statement and the data is read from the device using the ENTER
statement. A typical example is the SCPI IEEE 488.2 Common Command
*IDN? which queries the identity of a device.
Command Separators
The SCPI command structure is hierarchical and is governed by commas,
semicolons and colons:
• Commas are used to separate parameters in one command.
• Colons are used to separate levels.
• Semicolons are used to send more than one command to the
instrument at a time.
It is possible to send several commands in one pass, as long as the
commands all belong to the same node in the SCPI tree. The commands
have to be separated by semicolons.
The following SCPI commands provide examples of this.
SOURce:VOLTage:OFFSet ‘M2.DataOut2’,-0.99
SOURce:VOLTage:AMPLitude ‘M2.DataOut2’,1.11
These commands can also be sent as follows:
VOLT:OFFS ‘M2.DataOut2’,-0.99; ‘M2.DataOut2’,AMPL
1.11
SCPI Command Structure
The SCPI command structure can be best examined by means of an
example. For example, the command to set the generator's output
amplitude is:
[:SOURce]:VOLTage[:AMPLitude] ‘M1.DataOut1’,1.11
When sending strings to the instrument, either the double quote (") or
the single quote may be used ('), the latter being more suited to PASCAL
programs, which make use of a single quote; the former being more
suited to use in BASIC programs, which use a double quote as a
delimiter.
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