Start situation:
a GPIB-USB HS hub connected to a laptop running LV 2013 is used to talk to ONE Agilent 3458 DMV.
This configuration and a simple piece of code (VISA) works as expected. For instance, configure instrument, arm trigger and trigger data taking in order to acquire, store and retrieve 100 points delivers 100 points as expected.
Strange observation:
I use the exact same code, duplicate it to talk to TWO identical instruments (see attached file) and observe strange results.
Both instruments are addressed through their corresponding GPIB addresses, are asked to perform the SAME tasks but deliver a different number of readings, although they are given the same commands. One instrument yields 160 to 170 points instead of 100, as instructed. The number of points available in the buffer of this particular instrument is indeed larger. This observation is consistent with the fact that the second instrument measures more points than instructed, as can be seen on the display panel.
I fail to understand why the same code would convince one instrument to measure 100 points and a different number for the other. If I swap GPIG addresses, instruments are swapped, but the channel reading more points than expected remains the same.
Hints and/or comments are welcome.
Regards, Philippe