Meilhaus Electronic redlab 1208fs, Руководство пользователя

Страница: 23 / 34

RedLab 1208FS User's Guide Functional Details
23
The RedLab 1208FS offset error is measured at mid-scale. Ideally, a zero volt input should produce an output
code of 2048. Any deviation from this is an offset error. Figure 12 shows the RedLab 1208FS transfer function
with an offset error. The typical offset error specification on the ±10 V range is ±9.77 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 12
are drawn for clarity and are not drawn to scale.
-FS
+ FS
Input Voltage
0
4095
2
Offset= 9.77mV
Ideal
Actual
Output Code
9.77mV
2048
Figure 12. ADC transfer function with offset error
Gain error is a change in the slope of the transfer function from the ideal, and is typically expressed as a
percentage of full-scale. Figure 13 shows the RedLab 1208FS transfer function with gain error. Gain error is
easily converted to voltage by multiplying the full-scale (
FS
) input by the error.
The accuracy plots in
Figure 13
are drawn for clarity and are not drawn to scale.
-FS
+ FS
Input Voltage
0
4095
Actual
Ideal
Output Code
Gain error= + 0.2%, or + 20 mV
Gain error= -0.2%, or -20 mV
2048
Figure 13. ADC Transfer function with gain error
For example, the RedLab 1208FS exhibits a typical calibrated gain error of ±0.2% on all ranges. For the ±10 V
range, this would yield 10 V × ±0.002 = ±20 mV. This means that at full scale, neglecting the effect of offset for