Trace Header Transfer

Returns trace header information for the trace. Use the commands in the MMEMory subsystem to store and recall traces from the instrument memory. The response begins with an ASCII header. The header specifies the number of following bytes. It looks like #AX, where A is the number of digits in X and X is the number of bytes that follow the header. Parameters are returned in comma-delimited ASCII format. Each parameter is returned as “NAME=VALUE[ UNITS],” Note that currently only Trace A header is retrieved. Valid parameters are shown in Cable & Antenna Parameter Names.

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Trace Data Query

Transfers the current active trace data from the instrument to the controller. The format of the block data that is returned can be specified by the command :FORMat:DATA. The block data in the command form is always sent in ASCII format.

The response begins with an ASCII header that specifies the number of data bytes. It looks like #AX, where A is the number of digits in X and X is the number of bytes that follow the header. Each data point is separated by a comma delimiter. Except for the group delay, each data point consists of real and imaginary pair scaled by 10^6. Thus for a 551 point trace there is a total of 1102 points.

Trace setup information can be acquired using :TRACe[:DATA]:PREamble?.

By default this command will return a 551 data points regardless of the data point setting. At 275 data points the values returned are paired and at 137 data points the values are in fours. To get the same number of data points as the data points setting, use the command :FORMat[:READings][:DATA]:DPoints to set whether the data returned should be based on the data points setting.

When in dual overlay mode, a second set of data is returned when no parameter is passed in with the query. The response starts with an ASCII header that is exactly like the one described above. The header will have the format #AX where A is the number of digits in X and X is the number of bytes that follow the header. When there are two sets of data, a second ASCII header will trail the first header. The second header will have the format $AX where A is the number of digits in X and X is the number of bytes in the first set of data. The starting point of the second set of data can be found by subtracting the total byte size of the first set of data from the byte size located in the first header. For example, if the first header is #540000 and the second header is $41000, the beginning of the second set of data is 40000 (size of total packet size) – 1000 (size of first data set). Alternatively, the two headers can be skipped and after 551 points are read from the first set, the second set starts.

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