Operating Manual R&S SMIQ - Volume 1 - Rohde & Schwarz

Structure and Syntax of the Device MessagesSMIQ3.4.2 Structure of a CommandThe commands consist of a so-called header and, in most cases, one or more parameters. Header andparameter are separated by a "white space" (ASCII code 0 to 9, 11 to 32 decimal, e.g. blank). Theheaders may consist of several key words. Queries are formed by directly appending a question mark tothe header.Note:The commands used in the following examples are not in every case implemented in theinstrument.Common Commands Common commands consist of a header preceded by an asterisk "*"and one or several parameters, if any.Device-specific commandsExamples: *RST RESET, resets the device*ESE 253EVENT STATUS ENABLE, sets the bits of theevent status enable registers*ESR? EVENT STATUS QUERY, queries thecontents of the event status register.Hierarchy: Device-specific commands are of hierarchical structure (see Fig. 3-1).The different levels are represented by combined headers. Headers ofthe highest level (root level) have only one key word. This key worddenotes a complete command system.Example: SOURce This key word denotes the commandsystem SOURce.For commands of lower levels, the complete path has to be specified,starting on the left with the highest level, the individual key words beingseparated by a colon ":".Example: :SOURce:FM:EXTernal:COUPling ACThis command lies in the fourth level of the SOURce system. It sets thecoupling of the external signal source to AC.SOURcePOWer AM FMPOLarityMODE INTernal EXTernal STATePOLarityCOUPlingFig. 3-1Tree structure of the SCPI command systems using the SOURce system by way ofexample1125.5555.03 3.6E-7