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National Instruments Corporation
57
NI 9144 User Guide and Specifications
NI 9237 Example Data Rates
Example data rates use a 12.8 MHz clock source.
Offset Cal Enable <3..0>
Controls the offset calibration mode. Offset calibration mode disconnects both signal input pins and
forces the channel inputs to zero volts, enabling measurement of the channel’s offset voltage. A
logic 1 in any bit enables offset calibration for the respective channel, while a logic 0 disables it.
Clock Divisor
The NI 9237 divides the clock source (internal or external) by this value and uses it as the
converters’ oversample clock. The data rate is equal to 1/256 times this oversample clock frequency.
The final data rate must be between 391 kS/s and 52.734 kS/s. This means that while all values from
1 to 31 are within the specified operating range when using the 12.8 MHz internal clock source, for
external clock sources of more than 13.5 MHz or less than 3.1 MHz the valid divisors are limited to
those that provide data rates within the specified range.
Table 52.
NI 9237 Example Data Rates
Data Rate
Clock Divisor
Clock Source
Rate Byte
Oversample
Clock Rate
50.000 kS/s
00001
10
0x06
12.80 MHz
25.000 kS/s
00010
10
0x0A
6.40 MHz
16.667 kS/s
00011
10
0x0E
4.27 MHz
12.500 kS/s
00100
10
0x12
3.20 MHz
10.000 kS/s
00101
10
0x16
2.56 MHz
6.250 kS/s
01000
10
0x22
1.60 MHz
5.000 kS/s
01010
10
0x2A
1.28 MHz
3.333 kS/s
01111
10
0x3E
853.3 KHz
2.500 kS/s
10100
10
0x52
640.0 KHz
2.000 kS/s
11001
10
0x66
512.0 KHz
