有熟悉NI采集卡的坛友么？如何让外触发一次AD就采集一次？

68336016

如果是自己做板用单片机是很简单的事情，但是用上采集卡涉及到硬件软件之间来回协调，就有些费解了。

用法很直观：NI USB-6210采集卡（AD速度250kps/s），计数器接口外接编码器，信号下降沿计数。
                  编码器转速是变化的，信号频率最大为25kHz，在每个脉冲到来的时候触发一次AD采集，采集完等下一个脉冲。

看了NI的范例，然后用手头有的低端6008采集卡试了下，外触发只能用一次，也就是说让AD采集启动后，就不能再次触发了。
6210贵一点，好像可以重复触发，但暂时没收到，不过看代码觉得就25kHz这个触发频率有些难实现。

范例是    收到触发信号--->回调函数处理数据--->然后继续等待触发信号--->回调函数处理数据

1. /*********************************************************************
   
2. *
   
3. * ANSI C Example program:
   
4. *    ContAcq-IntClk-DigStart-Retrig.c
   
5. *
   
6. * Example Category:
   
7. *    AI
   
8. *
   
9. * Description:
   
10. *    This example demonstrates how to acquire finite amounts of data
    
11. *    on each digital trigger.
    
12. *
    
13. * Instructions for Running:
    
14. *    1. Select the physical channel to correspond to where your
    
15. *       signal is input on the DAQ device.
    
16. *    2. Enter the minimum and maximum voltage range.
    
17. *    Note: For better accuracy try to match the input range to the
    
18. *          expected voltage level of the measured signal.
    
19. *    3. Select the number of points to acquire per channel.
    
20. *    4. Specify the rate of the sample clock.
    
21. *    5. Select a source for the digital edge start trigger.
    
22. *    6. Select the edge, rising or falling, on which to trigger.
    
23. *
    
24. * Steps:
    
25. *    1. Create a task.
    
26. *    2. Create an analog input voltage channel.
    
27. *    3. Setup the timing for the acquisition. In this example, the
    
28. *       Sample Clock is generated internally by the board. Rate
    
29. *       specifies the rate of the internal clock. The timing is set
    
30. *       to take a finite number of samples. The number of samples is
    
31. *       specified by the Samples per Channel control. For a
    
32. *       retriggerable acquisition, the Samples per Channel defines
    
33. *       the number of samples to acquire for each trigger.
    
34. *    4. Set the parameters for a digital edge start trigger.
    
35. *    5. Set the Trigger Attribute to set the operation for
    
36. *       retriggerable.
    
37. *    6. Call the Start function to start the acquistion.
    
38. *    7. Read the data in the EveryNCallback function until the stop
    
39. *       button is pressed or an error occurs.
    
40. *    8. Call the Clear Task function to clear the task.
    
41. *    9. Display an error if any.
    
42. *
    
43. * I/O Connections Overview:
    
44. *    Make sure your signal input terminal matches the Physical
    
45. *    Channel I/O control. Also, make sure your analog trigger
    
46. *    terminal matches the Trigger Source Control. For further
    
47. *    connection information, refer to your hardware reference manual.
    
48. *
    
49. *********************************************************************/
    
50. 
    
51. #include <stdio.h>
    
52. #include <NIDAQmx.h>
    
53. 
    
54. #define DAQmxErrChk(functionCall) if( DAQmxFailed(error=(functionCall)) ) goto Error; else
    
55. 
    
56. int32 CVICALLBACK EveryNCallback(TaskHandle taskHandle, int32 everyNsamplesEventType, uInt32 nSamples, void *callbackData);
    
57. int32 CVICALLBACK DoneCallback(TaskHandle taskHandle, int32 status, void *callbackData);
    
58. 
    
59. int main(void)
    
60. {
    
61.         int32       error=0;
    
62.         TaskHandle  taskHandle=0;
    
63.         char        errBuff[2048]={'\0'};
    
64. 
    
65.         /*********************************************/
    
66.         // DAQmx Configure Code
    
67.         /*********************************************/
    
68.         DAQmxErrChk (DAQmxCreateTask("",&taskHandle));
    
69.         DAQmxErrChk (DAQmxCreateAIVoltageChan(taskHandle,"Dev1/ai0","",DAQmx_Val_Cfg_Default,-10.0,10.0,DAQmx_Val_Volts,NULL));
    
70.         DAQmxErrChk (DAQmxCfgSampClkTiming(taskHandle,"",10000.0,DAQmx_Val_Rising,DAQmx_Val_FiniteSamps,1000));
    
71.         DAQmxErrChk (DAQmxCfgDigEdgeStartTrig(taskHandle,"/Dev1/PFI0",DAQmx_Val_Falling));
    
72.         DAQmxErrChk (DAQmxSetStartTrigRetriggerable(taskHandle,1));
    
73. 
    
74.         DAQmxErrChk (DAQmxRegisterEveryNSamplesEvent(taskHandle,DAQmx_Val_Acquired_Into_Buffer,1000,0,EveryNCallback,NULL));
    
75.         DAQmxErrChk (DAQmxRegisterDoneEvent(taskHandle,0,DoneCallback,NULL));
    
76. 
    
77.         /*********************************************/
    
78.         // DAQmx Start Code
    
79.         /*********************************************/
    
80.         DAQmxErrChk (DAQmxStartTask(taskHandle));
    
81. 
    
82.         printf("Acquiring samples continuously. Press Enter to interrupt\n");
    
83.         getchar();
    
84. 
    
85. Error:
    
86.         if( DAQmxFailed(error) )
    
87.                 DAQmxGetExtendedErrorInfo(errBuff,2048);
    
88.         if( taskHandle!=0 ) {
    
89.                 /*********************************************/
    
90.                 // DAQmx Stop Code
    
91.                 /*********************************************/
    
92.                 DAQmxStopTask(taskHandle);
    
93.                 DAQmxClearTask(taskHandle);
    
94.         }
    
95.         if( DAQmxFailed(error) )
    
96.                 printf("DAQmx Error: %s\n",errBuff);
    
97.         printf("End of program, press Enter key to quit\n");
    
98.         getchar();
    
99.         return 0;
    
100. }
     
101. 
     
102. int32 CVICALLBACK EveryNCallback(TaskHandle taskHandle, int32 everyNsamplesEventType, uInt32 nSamples, void *callbackData)
     
103. {
     
104.         int32       error=0;
     
105.         char        errBuff[2048]={'\0'};
     
106.         static int  totalRead=0;
     
107.         int32       read=0;
     
108.         float64     data[1000];
     
109. 
     
110.         /*********************************************/
     
111.         // DAQmx Read Code
     
112.         /*********************************************/
     
113.         DAQmxErrChk (DAQmxReadAnalogF64(taskHandle,1000,10.0,DAQmx_Val_GroupByScanNumber,data,1000,&read,NULL));
     
114.         if( read>0 ) {
     
115.                 printf("Acquired %d samples. Total %d\r",read,totalRead+=read);
     
116.                 fflush(stdout);
     
117.         }
     
118. 
     
119. Error:
     
120.         if( DAQmxFailed(error) ) {
     
121.                 DAQmxGetExtendedErrorInfo(errBuff,2048);
     
122.                 /*********************************************/
     
123.                 // DAQmx Stop Code
     
124.                 /*********************************************/
     
125.                 DAQmxStopTask(taskHandle);
     
126.                 DAQmxClearTask(taskHandle);
     
127.                 printf("DAQmx Error: %s\n",errBuff);
     
128.         }
     
129.         return 0;
     
130. }
     
131. 
     
132. int32 CVICALLBACK DoneCallback(TaskHandle taskHandle, int32 status, void *callbackData)
     
133. {
     
134.         int32   error=0;
     
135.         char    errBuff[2048]={'\0'};
     
136. 
     
137.         // Check to see if an error stopped the task.
     
138.         DAQmxErrChk (status);
     
139. 
     
140. Error:
     
141.         if( DAQmxFailed(error) ) {
     
142.                 DAQmxGetExtendedErrorInfo(errBuff,2048);
     
143.                 DAQmxClearTask(taskHandle);
     
144.                 printf("DAQmx Error: %s\n",errBuff);
     
145.         }
     
146.         return 0;
     
147. }
     

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zenger_xu

用labview，上手很快的。

handshake

CVI也很方便，没折腾过NI USB-6210采集卡，不懂，帮顶。