I had written and executed a test (written in C) to measure a differential signal on all 4 channels of my USB-231 using the cbVIn() function passing a gain of UNI5VOLTS and was very happy with the resolution of the readings. I had to put that project on hold for several months and since that time my laptop was upgraded to windows 11. Now when I execute that same code I get readings that don't match the signal present on the inputs, its a few hundred millivolts off. The signals I am measuring are around 3.3VDC but the input is reading 3.47VDC. I played around with the gain settings and set it to UNI10VOLTS and instead of 3.47 its returning 6.94VDC. This is odd behaviour since I have to assume the gain values are known by the internal method that converts the binary 16 bit reading to a float should know the gain used for the reading and adjust it as necessary. I then tried to set the gain to BIP5VOLTS and it reads 1.74VDC so it seems that the gain is not being accounted for in the conversion. The only setting I can get working with BIP10VOLTS. It does return the correct voltage at the inputs, however at that gain setting the resolution of the reading is far too inaccurate for this particular application. The entire reason I purchased the USB-231 was for the 16 bit ADC so I can measure the signal with sub-millivolt accuracy. Did something change in the driver between windows 10 and win11? It used to work extremely well and exceeded the accuracy requirements I needed with UNI5VOLTS set as my gain.
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jcoigny
I had written and executed a test (written in C) to measure a differential signal on all 4 channels of my USB-231 using the cbVIn() function passing a gain of UNI5VOLTS and was very happy with the resolution of the readings. I had to put that project on hold for several months and since that time my laptop was upgraded to windows 11. Now when I execute that same code I get readings that don't match the signal present on the inputs, its a few hundred millivolts off. The signals I am measuring are around 3.3VDC but the input is reading 3.47VDC. I played around with the gain settings and set it to UNI10VOLTS and instead of 3.47 its returning 6.94VDC. This is odd behaviour since I have to assume the gain values are known by the internal method that converts the binary 16 bit reading to a float should know the gain used for the reading and adjust it as necessary. I then tried to set the gain to BIP5VOLTS and it reads 1.74VDC so it seems that the gain is not being accounted for in the conversion. The only setting I can get working with BIP10VOLTS. It does return the correct voltage at the inputs, however at that gain setting the resolution of the reading is far too inaccurate for this particular application. The entire reason I purchased the USB-231 was for the 16 bit ADC so I can measure the signal with sub-millivolt accuracy. Did something change in the driver between windows 10 and win11? It used to work extremely well and exceeded the accuracy requirements I needed with UNI5VOLTS set as my gain.
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