Measurement Computing USB-1616FS User Manual page 25

USB-1616FS User's Guide
Figure 3-8 shows an ideal, error-free, USB-1616FS transfer function. The typical calibrated accuracy of the
USB-1616FS is range-dependent, as explained in Chapter 4, "Specifications." We use a ±10V range as an
example of what you can expect when performing a measurement in this range.
The accuracy plot in Figure 3-8 is drawn for clarity and is not drawn to scale.
The USB-1616FS offset error is measured at mid-scale. Ideally, a zero volt input should produce an output
code of 32768. Any deviation from this is an offset error. Figure 3-9 shows the USB-1616FS transfer
function with an offset error. The typical offset error specification for the USB-1616FS on the ±10 V range
is ±1.66 mV. Offset error affects all codes equally by shifting the entire transfer function up or down along
the input voltage axis.
The accuracy plots in Figure 3-9 are drawn for clarity and are not drawn to scale.
Input Voltage
+ 10V
0
-10V
Figure 3-8. Ideal USB-1616FS transfer function
Input Voltage
+ 10V
Offset= 1.66mV
32768
0
Actual
-10V
Figure 3-9. USB-1616FS transfer function with offset error
Output Code
32768 65535
Ideal
Output Code
1.66mV
65535
3-9
Functional Details