c语言代码演示编写NI采集程序，如何使用daqmx_val_contSamps模式回调函数DAQmxRegisterEveryNSamplesEvent和如何停止回调函数DAQmxRegisterEveryNSamplesEvent和DAQmxRegisterDoneEvent

以下是一个简单的NI采集程序示例，展示如何使用DAQmxRegisterEveryNSamplesEvent回调函数和DAQmxRegisterDoneEvent回调函数：

#include <stdio.h>
#include "NIDAQmx.h"

#define DAQmxErrChk(functionCall) { if( DAQmxFailed(error=(functionCall)) ) goto Error; }

#define SAMPLE_RATE 1000.0
#define NUM_CHANNELS 1
#define BUFFER_SIZE 1000

TaskHandle taskHandle = 0;
int32 error = 0;
float64 dataBuffer[BUFFER_SIZE];

int32 EveryNSamplesCallback(TaskHandle taskHandle, int32 everyNsamplesEventType, uInt32 nSamples, void *callbackData);
int32 DoneCallback(TaskHandle taskHandle, int32 status, void *callbackData);

int main(void) {
    // Create task
    DAQmxErrChk(DAQmxCreateTask("", &taskHandle));

    // Add analog input channel
    DAQmxErrChk(DAQmxCreateAIVoltageChan(taskHandle, "Dev1/ai0", "", DAQmx_Val_RSE, -10.0, 10.0, DAQmx_Val_Volts, NULL));

    // Set sample rate
    DAQmxErrChk(DAQmxCfgSampClkTiming(taskHandle, "", SAMPLE_RATE, DAQmx_Val_Rising, DAQmx_Val_FiniteSamps, BUFFER_SIZE));

    // Register EveryNSamplesEvent callback function
    DAQmxErrChk(DAQmxRegisterEveryNSamplesEvent(taskHandle, DAQmx_Val_Acquired_Into_Buffer, BUFFER_SIZE, 0, EveryNSamplesCallback, NULL));

    // Register DoneEvent callback function
    DAQmxErrChk(DAQmxRegisterDoneEvent(taskHandle, 0, DoneCallback, NULL));

    // Start task
    DAQmxErrChk(DAQmxStartTask(taskHandle));

    // Wait for user input to stop task
    printf("Press Enter key to stop acquisition.\n");
    getchar();

    // Stop task
    DAQmxErrChk(DAQmxStopTask(taskHandle));

    // Clear task
    DAQmxErrChk(DAQmxClearTask(taskHandle));

    printf("Acquisition stopped.\n");
    return 0;

Error:
    DAQmxGetExtendedErrorInfo(errBuff, 2048);
    printf("DAQmx Error: %s\n", errBuff);
    DAQmxStopTask(taskHandle);
    DAQmxClearTask(taskHandle);
    return -1;
}

int32 EveryNSamplesCallback(TaskHandle taskHandle, int32 everyNsamplesEventType, uInt32 nSamples, void *callbackData) {
    int32 readCount = 0;
    DAQmxErrChk(DAQmxReadAnalogF64(taskHandle, nSamples, 10.0, DAQmx_Val_GroupByScanNumber, dataBuffer, BUFFER_SIZE, &readCount, NULL));

    // Process data here

    return 0;

Error:
    return -1;
}

int32 DoneCallback(TaskHandle taskHandle, int32 status, void *callbackData) {
    printf("Acquisition complete.\n");
    return 0;
}

在此示例中，我们创建了一个任务，并添加了一个模拟输入通道。然后，我们设置了采样率和每个缓冲区的大小，并使用DAQmxRegisterEveryNSamplesEvent函数注册了一个回调函数。该回调函数将在每个缓冲区中收集足够的数据时调用，并读取数据。我们还使用DAQmxRegisterDoneEvent函数注册了一个DoneCallback回调函数，以便在任务完成时通知我们。最后，我们启动任务，并在用户按下Enter键时停止任务。在停止任务后，我们清除任务并结束程序。

需要注意的是，我们可以通过调用DAQmxRegisterDoneEvent函数注册DoneCallback回调函数来通知我们任务何时完成。同时，我们还可以随时调用DAQmxStopTask函数来停止任务。