场景：【硬触发】环境触发频率快时，相机内缓存图片（默认节点数量为1）有可能被不停刷新，导致无法及时捕捉到每次触发响应的图片。
方案：SDK中可以设置相机内部缓冲节点数量和取图策略。

nRet = MV_CC_SetImageNodeNum(handle, nImageNodeNum);
handle（相机句柄）
nImageNodeNum：节点数量（初始化为1）

MV_GrabStrategy_OneByOne  
从旧到新一帧一帧的获取图像（默认为该策略） MV_GrabStrategy_LatestImagesOnly  
获取列表中最新的一帧图像（同时清除列表中的其余图像） MV_GrabStrategy_LatestImages  
获取列表中最新的图像，个数由OutputQueueSize决定，范围为1-ImageNodeNum，设置成1等同于LatestImagesOnly,设置成ImageNodeNum等同于OneByOne MV_GrabStrategy_UpcomingImage  
等待下一帧图像 

示例：

#include <stdio.h>
#include <Windows.h>
#include <process.h>
#include <conio.h>
#include "MvCameraControl.h"// Wait for key press
void WaitForKeyPress(void)
{while(!_kbhit()){Sleep(10);}_getch();
}bool PrintDeviceInfo(MV_CC_DEVICE_INFO* pstMVDevInfo)
{if (NULL == pstMVDevInfo){printf("The Pointer of pstMVDevInfo is NULL!\n");return false;}if (pstMVDevInfo->nTLayerType == MV_GIGE_DEVICE){int nIp1 = ((pstMVDevInfo->SpecialInfo.stGigEInfo.nCurrentIp & 0xff000000) >> 24);int nIp2 = ((pstMVDevInfo->SpecialInfo.stGigEInfo.nCurrentIp & 0x00ff0000) >> 16);int nIp3 = ((pstMVDevInfo->SpecialInfo.stGigEInfo.nCurrentIp & 0x0000ff00) >> 8);int nIp4 = (pstMVDevInfo->SpecialInfo.stGigEInfo.nCurrentIp & 0x000000ff);printf("CurrentIp: %d.%d.%d.%d\n" , nIp1, nIp2, nIp3, nIp4);printf("UserDefinedName: %s\n\n" , pstMVDevInfo->SpecialInfo.stGigEInfo.chUserDefinedName);}else if (pstMVDevInfo->nTLayerType == MV_USB_DEVICE){printf("UserDefinedName: %s\n", pstMVDevInfo->SpecialInfo.stUsb3VInfo.chUserDefinedName);printf("Serial Number: %s\n", pstMVDevInfo->SpecialInfo.stUsb3VInfo.chSerialNumber);printf("Device Number: %d\n\n", pstMVDevInfo->SpecialInfo.stUsb3VInfo.nDeviceNumber);}else{printf("Not support.\n");}return true;
}static  unsigned int __stdcall UpcomingThread(void* pUser)
{Sleep(3000);printf("Trigger Software Once for MV_GrabStrategy_UpcomingImage\n");MV_CC_SetCommandValue(pUser, "TriggerSoftware");return 0;
}int main()
{int nRet = MV_OK;void* handle = NULL;unsigned char * pData = NULL;do {// Enum deviceMV_CC_DEVICE_INFO_LIST stDeviceList = {0};nRet = MV_CC_EnumDevices(MV_GIGE_DEVICE | MV_USB_DEVICE, &stDeviceList);if (MV_OK != nRet){printf("Enum Devices fail! nRet [0x%x]\n", nRet);break;}if (stDeviceList.nDeviceNum > 0){for (unsigned int i = 0; i < stDeviceList.nDeviceNum; i++){printf("[device %d]:\n", i);MV_CC_DEVICE_INFO* pDeviceInfo = stDeviceList.pDeviceInfo[i];if (NULL == pDeviceInfo){break;} PrintDeviceInfo(pDeviceInfo);            }  } else{printf("Find No Devices!\n");break;} printf("Please Input camera index:");unsigned int nIndex = 0;scanf_s("%d", &nIndex);if (nIndex >= stDeviceList.nDeviceNum){printf("Input error!\n");break;}// Select device and create handlenRet = MV_CC_CreateHandle(&handle, stDeviceList.pDeviceInfo[nIndex]);if (MV_OK != nRet){printf("Create Handle fail! nRet [0x%x]\n", nRet);break;}// Open devicenRet = MV_CC_OpenDevice(handle);if (MV_OK != nRet){printf("Open Device fail! nRet [0x%x]\n", nRet);break;}// Detection network optimal package size(It only works for the GigE camera)if (stDeviceList.pDeviceInfo[nIndex]->nTLayerType == MV_GIGE_DEVICE){int nPacketSize = MV_CC_GetOptimalPacketSize(handle);if (nPacketSize > 0){if(MV_CC_SetIntValue(handle,"GevSCPSPacketSize",nPacketSize) != MV_OK){printf("Warning: Set Packet Size fail nRet [0x%x]!", nRet);}}else{printf("Warning: Get Packet Size fail nRet [0x%x]!", nPacketSize);}}// Set Trigger Mode and Set Trigger SourcenRet = MV_CC_SetEnumValueByString(handle, "TriggerMode", "On");if (MV_OK != nRet){printf("Set Trigger Mode fail! nRet [0x%x]\n", nRet);break;}nRet = MV_CC_SetEnumValueByString(handle, "TriggerSource", "Software");if (MV_OK != nRet){printf("Set Trigger Source fail! nRet [0x%x]\n", nRet);break;}unsigned int nImageNodeNum = 5;// Set number of image nodenRet = MV_CC_SetImageNodeNum(handle, nImageNodeNum);if (MV_OK != nRet){printf("Set number of image node fail! nRet [0x%x]\n", nRet);break;}printf("\n**************************************************************************\n");printf("* 0.MV_GrabStrategy_OneByOne;       1.MV_GrabStrategy_LatestImagesOnly;  *\n");printf("* 2.MV_GrabStrategy_LatestImages;   3.MV_GrabStrategy_UpcomingImage;     *\n");printf("**************************************************************************\n");printf("Please Input Grab Strategy:");unsigned int nGrabStrategy = 0;scanf_s("%d", &nGrabStrategy);// U3V device not support UpcomingImageif (nGrabStrategy == MV_GrabStrategy_UpcomingImage && MV_USB_DEVICE == stDeviceList.pDeviceInfo[nIndex]->nTLayerType){printf("U3V device not support UpcomingImage\n");break;}switch(nGrabStrategy){case MV_GrabStrategy_OneByOne:{printf("Grab using the MV_GrabStrategy_OneByOne default strategy\n");nRet = MV_CC_SetGrabStrategy(handle, MV_GrabStrategy_OneByOne);if (MV_OK != nRet){printf("Set Grab Strategy fail! nRet [0x%x]\n", nRet);break;}}break;case MV_GrabStrategy_LatestImagesOnly:{printf("Grab using strategy MV_GrabStrategy_LatestImagesOnly\n");nRet = MV_CC_SetGrabStrategy(handle, MV_GrabStrategy_LatestImagesOnly);if (MV_OK != nRet){printf("Set Grab Strategy fail! nRet [0x%x]\n", nRet);break;}}break;case MV_GrabStrategy_LatestImages:{printf("Grab using strategy MV_GrabStrategy_LatestImages\n");nRet = MV_CC_SetGrabStrategy(handle, MV_GrabStrategy_LatestImages);if (MV_OK != nRet){printf("Set Grab Strategy fail! nRet [0x%x]\n", nRet);break;}// Set Output Queue SizenRet = MV_CC_SetOutputQueueSize(handle, 2);if (MV_OK != nRet){printf("Set Output Queue Size fail! nRet [0x%x]\n", nRet);break;}}break;case MV_GrabStrategy_UpcomingImage:{printf("Grab using strategy MV_GrabStrategy_UpcomingImage\n");nRet = MV_CC_SetGrabStrategy(handle, MV_GrabStrategy_UpcomingImage);if (MV_OK != nRet){printf("Set Grab Strategy fail! nRet [0x%x]\n", nRet);break;}unsigned int nThreadID = 0;void* hThreadHandle = (void*) _beginthreadex( NULL , 0 , UpcomingThread , handle, 0 , &nThreadID );if (NULL == hThreadHandle){break;}}break;default:printf("Input error!Use default strategy:MV_GrabStrategy_OneByOne\n");break;}// Start grab imagenRet = MV_CC_StartGrabbing(handle);if (MV_OK != nRet){printf("Start Grabbing fail! nRet [0x%x]\n", nRet);break;}// Send Trigger Software commandfor (unsigned int i = 0;i < nImageNodeNum;i++){nRet = MV_CC_SetCommandValue(handle, "TriggerSoftware");if (MV_OK != nRet){printf("Send Trigger Software command fail! nRet [0x%x]\n", nRet);break;}Sleep(500);}MV_FRAME_OUT stOutFrame = {0};if (nGrabStrategy != MV_GrabStrategy_UpcomingImage){while(true){nRet = MV_CC_GetImageBuffer(handle, &stOutFrame, 0);if (nRet == MV_OK){printf("Get One Frame: Width[%d], Height[%d], FrameNum[%d]\n", stOutFrame.stFrameInfo.nWidth, stOutFrame.stFrameInfo.nHeight, stOutFrame.stFrameInfo.nFrameNum);}else{printf("No data[0x%x]\n", nRet);break;}nRet = MV_CC_FreeImageBuffer(handle, &stOutFrame);if(nRet != MV_OK){printf("Free Image Buffer fail! nRet [0x%x]\n", nRet);}}}else//Only for upcoming{nRet = MV_CC_GetImageBuffer(handle, &stOutFrame, 5000);if (nRet == MV_OK){printf("Get One Frame: Width[%d], Height[%d], FrameNum[%d]\n", stOutFrame.stFrameInfo.nWidth, stOutFrame.stFrameInfo.nHeight, stOutFrame.stFrameInfo.nFrameNum);nRet = MV_CC_FreeImageBuffer(handle, &stOutFrame);if(nRet != MV_OK){printf("Free Image Buffer fail! nRet [0x%x]\n", nRet);}}else{printf("No data[0x%x]\n", nRet);}}// Stop grab imagenRet = MV_CC_StopGrabbing(handle);if (MV_OK != nRet){printf("Stop Grabbing fail! nRet [0x%x]\n", nRet);break;}// Close devicenRet = MV_CC_CloseDevice(handle);if (MV_OK != nRet){printf("Close Device fail! nRet [0x%x]\n", nRet);break;}// Destroy handlenRet = MV_CC_DestroyHandle(handle);if (MV_OK != nRet){printf("Destroy Handle fail! nRet [0x%x]\n", nRet);break;}} while (0);if (nRet != MV_OK){if (handle != NULL){MV_CC_DestroyHandle(handle);handle = NULL;}}printf("Press a key to exit.\n");WaitForKeyPress();return 0;