do you have source ?

Thanks,
Chuan

Quick notes:

Regarding ncat:

With version 7.93, “ncat -vv -u localhost 8888” translates “localhost” to the value “1”. When sending text , ncat reports…

Ncat: Connected to ::1:8888.

…and subsequently reports a read error, and that the connection was forcibly closed by the remote host.

If you instead use 127.0.0.1 for the server address, everything else works as written above.

FWIW, ncat correctly translates other hostnames to their IP address. So version 7.93 apparently does not handle “localhost” in particular, which is surprising.

Regarding winsock2:

In a source file that includes windows.h, it can be important to include winsock2.h before that, otherwise winsock.h will define symbols that conflict with those in winsock2.h.

I hope that helps.

Thanks again!

First time that I use UDP to communicate with Arduino as a server and my program on the pc as a client that sends a 2-byte command to the Arduino and it works perfectly.

However. I have a little doubt: once the socket is closed, can I flip the roles? that is, make the arduino as a client and the program as a server to monitor events such as hardware interrupts?.

Maybe by the time you answer I will have solved it, but anyway, thank you very much in advance.

It’s the other way around. The connect() function will return an error on a datagram-type socket like UDP, whereas binding a socket to a hint structure is always required for servers (which is NOT, despite your claim, TCP/IP exclusive).

I want to use UDP to communicate between two program (script and SIMULINK) . So I tried to open one Socket (IP (127.0.0.1 ) ,remote address 1234 Local port 25) for transmit and one socket for Receive (IP (127.0.0.1 ) ,remote address 4321 Local port 88).
but when i open two sockets and try a send to im getting a WSAERROR (10047)) .
If i remove the receive socket and try it starts to send .
Can you please help me ??

#define SERVER “127.0.0.1”