I'm trying to write some calibration code for the m-series boards (I have a pci-6289). I can read the factory calibration coefficients from the eeprom (using the example code as a guide). However, what I want to be able to do is determine the coefficients on my own by reading the board's internal reference sources. By using the AI_Config_FIFO_Bypass register I can read various internal sources on the board, in particular 6.85V, 0.5V, 2V, 10V, and the analog outputs. Now, finally to get to my question.
Is it safe to assume the reference voltages are exactly 6.85V, 10V, etc. or is there information on the eeprom which gives the exact voltages of the references? There appears to be a floating point value in the eeprom at address 412 (the calibration area starts at 400) which looks like a voltage near 6.85V. But I don't see anything corresponding to the other voltage sources.
Also, I don't see any voltage references small enough to be used for the 0.2V or 0.1V input ranges. Am I supposed to just use a (calibrated) analog output channel to calibrate these input ranges?