Accuracy Table for SCXI-1521?

[KPRDaytonOH]

     Is there an Accuracy Table for the SCXI-1521 Strain Module?  I've found the Accuracy Table for the SCXI-1520 module, but I can't find one for the SCXI-1521.  Is the absolute accuracy of the SCXI-1521 calculated using the values for the entries for the 1/4-bridge configuration of the SCXI-1520?

[TheWoost]

Hi,

There is no accuracy table for the SCXI-1521 because there is only one fixed gain setting.  To calculate the absolute accuracy just take the info from the device specifications:

AA = (Vin * % Gain error) + offset + noise + temp drift

Temperature drift will be 0 if the temperature stays between 15 and 35 degC.  So...

AA = (0.001)*Vin + 0.007V + 0.0000025V

If we assume the input voltage will not go above 20mV...

AA = (0.001)*(0.02V) + 0.007V + 0.0000025V
AA = 0.007023V

Note that the absolute accuracy is very much dominated by the offset specification in the calculation.  You can replace the 0.007V with the typical spec 0.001V for a much more realistic expectation.  Also, it is very important to note that this is the accuracy before any bridge calibration, so performing nulling and shunt calibrations before measurements will greatly reduce the gain and offset components of this calculation.

Regards,
Andrew W
National Instruments