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Error in Python u3.py, readDefaultsConfig()?

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#1 Miky

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Posted 24 March 2015 - 03:47 AM

The default config DAC values in readDefaultsConfig():


defaults = self.readDefaults(2)
results['DAC0'] = struct.unpack( ">H", struct.pack("BB", *defaults[16:18]) )[0]
results['DAC1'] = struct.unpack( ">H", struct.pack("BB", *defaults[20:22]) )[0]


'>' means big endian architecture, or H value in first byte and L value in second byte.


But it seems that DAC byte order ist L byte first, same als TMRx according to section 5.2.22 - ReadDefaults. The DAC byte order is not shown there.


If I change byte order, voltageToDACBits() matches with DAC values from readDefaultsConfig(), otherwise not.

#2 LabJack Support

LabJack Support
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Posted 24 March 2015 - 04:56 PM

Values are stored on the U3 as little endian (LSW, MSW), so this is an error in readDefaultsConfig. I fixed this on our github repository, so download and install that version of LabJackPython for the change:




Thanks for making us aware of the issue.

#3 Miky

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Posted 26 March 2015 - 11:54 PM

Thank you very much!

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