Taking Sweeps. Agilent Technologies 8712ES, 8714ET, 8714ES, 8712ET

Trace Data Transfers

Taking Sweeps

Taking Sweeps

When making measurements and querying traces, your program should perform the following steps:

1. Place the analyzer's sweep in hold.

2. Initiate a single sweep.

3. Wait for the sweep to complete.

4. Query the measurement trace.

Use the following program lines to perform these steps:

10 OUTPUT @Hp8711;"ABORT;:INIT1:CONT OFF"

20 OUTPUT @Hp8711;"INIT1"

30 OUTPUT @Hp8711;"*OPC?"

35 ENTER @Hp8711;Opc

40 OUTPUT @Hp8711;"TRACE:DATA? CH1FDATA"

45 ENTER @Hp8711;Fmt(*)

If you query the measurement trace while the analyzer is in continuous sweep, the query will still work, but the data may not be correct. Using

INIT and *OPC?

ensures that a complete sweep has finished before you query the measurement data. In many cases, you can also use the command " *WAI " in place of the " *OPC?

" query, replacing lines 30 and 35 above with:

30 OUTPUT @Hp8711;"*WAI"

However, there are cases where "*WAI" will produce incorrect results.

One case is when using IBASIC's high-speed subprograms to query the trace data.

"*WAI" only ensures that the SCPI commands following the

"*WAI" are not executed until the commands before the "*WAI" are complete. Since IBASIC subprograms don't use SCPI commands to access the trace data, "*WAI" is ineffective, and "*OPC?" should be used.

When using "*OPC?" , the ENTER statement following the "*OPC?" will wait until the previous SCPI commands are complete, preventing your program from executing beyond the ENTER statement. When using

"*WAI" , your program can continue to run and send SCPI commands, and the analyzer will buffer them and act upon them in order.

Chapter 2, “Synchronizing the Analyzer and a Controller,”

provides additional details.

Programmer’s Guide 6-11