INITiate Subsystem

Last updated: January 16, 2009

Syntax Diagrams and Command Descriptions

Description

INITiate Command Functions

The INITiate subsystem is used to:

Start (activate) individual or multiple (concurrent) measurements.
Turn individual measurements off.
Determine the number of measurements currently active (INIT:COUNT?).
Determine the names of the measurements currently active (INIT:ON?).
Determine which measurements are finished (INIT:DONE?).

What Happens When a Measurement is INITiated?

When a measurement is started using INITiate commands, a new measurement cycle is started. If the selected measurement is currently in a measurement cycle, it is aborted. If a timeout is specified, the timeout period begins when a measurement is initiated.

NOTE

The INITiate subsystem is derived from SCPI, but has some modifications to make it more compatible with the manual operation of the test set. Most notably, the choice of single or continuous measurement triggering is made using the SETup subsystem.

INITiate Programming Examples (how INIT commands are used)

The INITiate command is used to start measurements. INITiate commands allow multiple measurements to be started without waiting for other measurement processes to complete. For example, the following code starts the Digital Average Power and Waveform Quality measurements, and then uses the INITiate:DONE? command in a loop to query the status of these measurements, see Measurement Event Synchronization .

When the measurements are done, the FETCh command is used to acquire the results, and the results are entered into variables in the controlling application. The program ends when the INITiate:DONE? command returns the string "NONE" indicating that all initiated measurements have gone through the measuring state see Measurement States .

Trigger arming for each measurement is controlled in the SETup subsystem. The choices are single or continuous. The best practice (during remote operation) is to use single measurement mode. This simplifies the tasks of starting concurrent measurements, then using the INIT subsystem commands to determine which measurements are ready to be FETChed.

 
10 OUTPUT 714;"SETup:ALL:CONTinuous:OFF" ! selects single trigger  mode.
20 OUTPUT 714;"INITiate:WBERror;WCPower" ! starts loopback BER  and
30                                       !channel power  measurements.
40 LOOP
50 OUTPUT 714;"INITiate:DONE?" !query to find out if any measurements are done.
60 ENTER 714;Meas_complete$
70 SELECT Meas_complete$
80 CASE "WBER" !tests for the string "WBER", indicating loopback BER measurement is done.
90 OUTPUT 714;"FETCh:WBERror?" !Queries loopback BER results.
100 ENTER 714;Integrity,Ber,Ber_count,Bits_tested
110 CASE "WCP" !tests for the string "WCP", indicating channel power measuremenet is done.
120 OUTPUT 714;"FETCh:WCPow?" !Queries the channel power results.
130 ENTER 714;Integrity,Avg_chan_pow
140 END SELECT
150 EXIT IF Meas_complete$="NONE"
160 END LOOP
170 END