I am trying to let my c++ program communicate with simulink model via udp, and in particularly the plan is that data will be transmitted from c++ to simulink, and will be processed using some simulink models, then the result will be sent back to c++ for further programming, and data trasmissions will be realized through udp, (udp socket for c++, and udp real time send/receive block for simulink). And it will repeat a few times.
I've built a while loop, where c++ keeps reading data from a txt file and sends it to simulink via udp, which works well, the data has been multiplied by 2 and sent back towards c++, but c++ cannot receive correct data as was sent from simulink. The data it received during each cycle is "0". But if the data I sent was a constant, the receiving function in c++ works fine as well.
ifstream file_x("x1.txt");
ifstream file_y("y1.txt");
ifstream file_z("z1.txt");
double x;
double y;
double z;
int main()
{
//Local Varaiable definition
cout<<"\t\t--------------------UDP Server----------------"<<endl;
cout<<endl;
WSADATA WinsockData;
int iWsaStartup;
int iWsaCleanup;
SOCKET UDPSocketServer1;
SOCKET UDPSocketClient3;
struct sockaddr_in UDPClient1;
struct sockaddr_in UDPServer3;
char Buffer1[200];
char Buffer3[200];
int iBufferLen1 = 200+1;
int iBufferLen3 = 200+1;
int iBind3;
int iReceiveFrom;
int iSendTo;
int iUDPClientLen1 = sizeof(UDPClient1);
int iUDPClientLen2 = sizeof(UDPClient2);
int iUDPServerLen3 = sizeof(UDPServer3);
int iCloseSocket1;
int iCloseSocket3;
//STEP-1: initialization of Winsock
iWsaStartup = WSAStartup(MAKEWORD(2,2), &WinsockData);
if (iWsaStartup != 0)
{
cout<<"WSAStartUp Fun Failed!"<<endl;
}
else
{
cout<<"WSAStartUp Success"<<endl;
}
//STEP-2: Fill the UDPClient(SOCKET ADDRESS) Structure
UDPClient1.sin_family = AF_INET;
UDPClient1.sin_addr.s_addr = inet_addr("127.0.0.1");
UDPClient1.sin_port = htons(8001);
UDPServer3.sin_family = AF_INET;
UDPServer3.sin_addr.s_addr = inet_addr("127.0.0.3");
UDPServer3.sin_port = htons(8003);
//STEP-3: Socket Creation
UDPSocketServer1 = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (UDPSocketServer1 == INVALID_SOCKET)
{
cout<<"Socket1 Creation Failed & Error No ->"<<WSAGetLastError()<<endl;
}
else
{
cout<<"Socket1 Creation Success"<<endl;
}
UDPSocketClient3 = socket(AF_INET, SOCK_DGRAM, IPPROTO_UDP);
if (UDPSocketClient3 == INVALID_SOCKET)
{
cout<<"Socket3 reation Failed = "<<WSAGetLastError()<<endl;
}
else
{
cout<<"Socket3 Creation Success"<<endl;
}
//STEP-4: Bind the server
iBind3 = bind(UDPSocketClient3, (SOCKADDR*)&UDPServer3, sizeof(UDPServer3));
if (iBind3 == SOCKET_ERROR)
{
cout<<"Binding Failed & Error No ->"<<WSAGetLastError()<<endl;
}
//STEP-4-1: SendTo Fun send data to client
while (!file_x.eof())
{
file_x >> x;
file_y >> y;
file_z >> z;
sprintf_s(Buffer1,200,"%0.2f\r\n %0.2f\r\n %0.2f\r\n",x,y,z);
iSendTo = sendto(UDPSocketServer1, Buffer1, iBufferLen1, MSG_DONTROUTE, (SOCKADDR*)&UDPClient1, sizeof(UDPClient1));
if (iSendTo == SOCKET_ERROR)
{
cout<<"Sending Data Failed & Error No ->"<<WSAGetLastError()<<endl;
}
else
{
cout<<"Sending Data Success"<<endl;
}
iReceiveFrom = recvfrom(UDPSocketClient3, Buffer3, iBufferLen3, MSG_PEEK, (SOCKADDR*)&UDPServer3, &iUDPServerLen3);
if (iReceiveFrom == SOCKET_ERROR)
{
cout<<"Receiving failed & Error No ->"<<WSAGetLastError()<<endl;
}
else
{
cout<<"Receiving Success"<<endl;
cout<<"Receive Data ->"<<Buffer3<<endl;
}
}
//STEP-6: CloseSocket Function
iCloseSocket1 = closesocket(UDPSocketServer1);
if (iCloseSocket1 == SOCKET_ERROR)
{
cout<<"Socket1 Closing failed & Error No ->"<<WSAGetLastError()<<endl;
}
else
{
cout<<"Socket1 Closing Success"<<endl;
}
iCloseSocket3 = closesocket(UDPSocketClient3);
if (iCloseSocket3 == SOCKET_ERROR)
{
cout<<"Socket3 Closing failed & Error No ->"<<WSAGetLastError()<<endl;
}
else
{
cout<<"Socket3 Closing Success"<<endl;
}
//STEP-7: WSACleanUp Fun for Terminating from DLL
iWsaCleanup = WSACleanup();
if (iWsaCleanup == SOCKET_ERROR)
{
cout<<"WSA Cleanup Success"<<endl;
}
else
{
cout<<"WSA Cleanup Success"<<endl;
}
system("pause");
return 0;
}
I found that flag in recvfrom function matters in this issue, which can be referred to its document and I've changed MSG_PEEK to 0 and considering my application, I've used another project for only receiving data sent from simulink, and the issue has been solved.