Rohde & Schwarz FSQ series, Quick Start Manual

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R&S FSQ Brief Introduction to Remote Control
Detailed Programming Examples
7.20 Quick Start Guide 1313.9652.62 - 02
7.2.3 Reading Out Trace Data
In the following example, the trace data obtained with the default setting is read from the
instrument and displayed in a list on screen. Readout occurs first in binary format and then in
ASCII format, once with the span > 0 and once with the span = 0.
In binary format, the header of the message with the length specification is evaluated and used
to calculate the x axis values.
In ASCII format, merely the list of level values is output.
Binary data is read out in three steps:
1. The number of digits in the length specification is read out.
2. The length specification itself is read out.
3. The trace data itself is read out.
The procedure is required in the case of programming languages that only support structures
with data types of the same type (arrays) (such as with Visual Basic), because the data types
of the header and data sections are different in binary data.
Note that the function viRead32 is not declared in VISA32.BAS and therefore needs to be
defined separately:
Declare Function viRead32 Lib "Visa32" Alias "viRead" (ByVal vi As Long, Values As
Any, ByVal count As Long, retCount As Long) As Long
REM ************************************************************************
Public Sub ReadTrace()
Dim status As ViStatus
Dim retCnt As Long
REM ------ Creating variables ---------------------------------------------
Dim traceData(1250) As Single
'Buffer for floating point binary data
Dim digits As Byte
'Number of characters in length specification
Dim traceBytes As Integer
'Len. of trace data in bytes
Dim traceValues As Integer
'No. of meas. values in buff.
asciiResult$ = Space$(25000)
'Buffer for ASCII trace data
result$ = Space$(100)
'Buffer for simple results
startFreq$ = Space$(100)
The arrays for the measured data are dimensioned in such a way that
they provide sufficient space for trace data of the R&S FSQ (625
measurement points).
The arrays for the measured data are dimensioned in such a way that
they provide sufficient space for trace data of the R&S FSQ (625
measurement points).