ADLINK Technology USB-2401, User Manual

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36 Operation
Table 3-2: Analog Input Range and Output Digital Code (cont’d)
3.5 ADC Sampling Rate
Sampling Rate refers to ADC internal conversion speed as set by
the user. When programming through a software API, the desired
ADC sampling rate must be set, whether for single value, using a
software polling command, or block data in continuous buffer
mode. Available sampling rates are 20SPS, 40SPS, 80SPS,
160SPS, 320SPS, 500SPS, 1000SPS, and 2000SPS.
3.5.1 Software Polling Data Transfer (Non-Buffering Pro-
grammed I/O)
Polling mode benefits flexible timing and is suitable for retrieving
the latest data without FIFO buffering latency. The USB-2401 con-
tinuously updates the latest acquired data onto a data port for spe-
cific channels. Data not retrieved in time is overwritten with new
data without notice. As the software polling rate (here equaling
data rate) of a PC may exceed the ADC sampling rate, it is possi-
ble to receive multiple identical data before a new conversion has
Description
Bipolar Analog
Input Range
Digital Code
Full-scale range ±78.125 mV N/A
Least significant
bit 9.313nV N/A
FSR-1LSB 78.1249907 mV 7FFFFF
Midscale
+1LSB 9.313nV 000001
Midscale 0 V 000000
Midscale
-1LSB -9.313nV FFFFFF
-FSR -78.125mV 800000
NOTE:
NOTE:
Accuracy frequently deteriorates with increased ADC sampling
rate.