Yong Da Li date created: Thursday, September 29, 2022
This describes how to interface with the oscilloscope.
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Tektronix 3-series mixed domain oscilloscope
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"MDO34" = 200HMz, 2.5GS/s
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it's got a touchscreen, so you've got to look at both the touchscreen and right-side physical buttons when looking for a function
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ex. the "utility" menu is on the top left of the touchscreen
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programming manual: https://www.tek.com/en/manual/oscilloscope/3-series-mixed-domain-oscilloscope-programmer-manual-3-series-mdo
The oscilloscope can do stuff like connect over ethernet or remote access. But for us, we're just sticking with USB. It's got a USB2.0 port on the back side, that you connect to your computer. Once you plug it in, it should be auto-detected by your computer. On Windows 11 device manager, it showed up as "MDO34" under other devices.
You'll need a VISA (Virtual Instrument Software Architecture) driver to talk to it. To download it it, follow the instructions on this page. Note that the bit-ness of the driver should match the same as your Python installation.
The installation happens through NI (National Instruments). They install a bunch of other crap as well, but just go with the default settings out of fear that it'll screw up something later on. The install look a good 20min for Yong Da's laptop.
We're using a nice Python wrapper around the VISA library called PyVISA. Install it with:
pip install pyvisa
Your first program should be something like:
import pyvisa
rm = pyvisa.ResourceManager()
# using the printed resources, open up the one that is the oscilloscope
print(rm.list_resources())
# change this as necessary
hardCodedResource = 'USB0::0x0699::0x052C::B014430::INSTR'
inst = rm.open_resource(hardCodedResource)
# send a query to see what the current acquisition settings are
query = "ACQuire?"
print(inst.query(query))
The process for getting data is like:
- setup data output
- check that the data output is correct
- send data
- use the data output header and the raw data to produce the real data
For example, the voltage-time series data sent is neither voltage or time. It sends stuff like {64,23,43} and you have to use the YMULt=4.000E-3 parameter to multiply that array of data to get the actual voltages which are {0.256V, 0.092V, 0.172V}.
For the timing information, you will get stuff like
NR_PT 100
XUNIT "s"
XINCR 400.0000E-9
XZERO -2.0000E-3
So you have to do 100 points * 4e-9s time increment = 400ns of data. With the data actually starting at -2ms before the trigger.
The oscilloscope communication is based on IEEE488.2. You can read the manual for the full description of all commands.
- programming manual: https://www.tek.com/en/manual/oscilloscope/3-series-mixed-domain-oscilloscope-programmer-manual-3-series-mdo
- query current acquisition status, if error or stop handle it
- get the waveform of the current status