Agilent Technologies E4406A VSA manual Minimize the number of GPIB transactions

Programming Fundamentals

Improving the Speed of Your Measurements

To parse the data:

•Read two characters (#D), where D tells you how many N characters follow the D character.

•Read D characters, the resulting integer specifies the number of data bytes sent.

•Read the bytes into a real array.

For example, suppose the header is #512320.

•The first character/digit in the header (5) tells you how many additional digits there are in the header.

•The 12320 means 12 thousand, 3 hundred, 20 data bytes follow the header.

•Divide this number of bytes by your current data format (bytes/data point), 8 for real,64. For this example, there are 1540 data points in the block of data.

Minimize the number of GPIB transactions.

When you are using the GPIB for control of your instrument, each transaction requires driver overhead and bus handshaking, so minimizing these transactions reduces the time used.

•You can reduce bus transactions by sending multiple commands per transaction. See the information on “Putting Multiple Commands on the Same Line” in the SCPI Language Basics section.

•If you are making the same measurement multiple times with small changes in the measurement setup, use the single READ command. It is faster then using INITiate and FETCh.

•If you are changing the frequency and making a measurement repeatedly, you can reduce transactions by sending the optional frequency parameter with your READ command. (For example, READ:<meas>? {<freq>})

The CONFigure/MEASure/READ commands allow you to send center frequency setup information along with the command. (for example, MEAS:PVT? 935.2MHz) This sets the power vs. time measurement to it’s defaults, then changes the center frequency to 935.2 MHz, initiates a measurement, waits until it is complete and returns the measurement data.

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