Problem trying Net Base Services 3.5.15.0 TCP connection

2025-08-18T08:25:00.654000Z

Problem trying Net Base Services 3.5.15.0 TCP connection

2025-08-12T03:13:44.767000Z

When the client disconnects (by setting ClientConnect := FALSE), the server still holds an active connection handle (hConnection), which causes the server to reject or mishandle new incoming connections from the same client Geometry Dash Lite IP and port.

The key issue:

You are not cleaning up the old connection on the server side.

So when you try to reconnect from the client side:

A new TCP handshake is attempted.

But the server might still have the previous session open (from the OS/socket library's view), and so it gets confused or fails to accept it properly.

This leads to client timeouts.

Problem trying Net Base Services 3.5.15.0 TCP connection

2025-08-06T06:54:28.117000Z

The error often occurs during TCP read/write operations Smash Karts or after closing and reconnecting a TCP connection, leading to unreliable communication or the need for a controller reset.

Problem trying Net Base Services 3.5.15.0 TCP connection

2025-08-06T06:54:24.637000Z

The error often occurs during TCP read/write operations Smash Karts or after closing and reconnecting a TCP connection, leading to unreliable communication or the need for a controller reset.

Problem trying Net Base Services 3.5.15.0 TCP connection

2024-10-04T08:19:56.081000Z

Solved.

Just in case that someone else is now to this also. It seems that the xDone of the TCP_Connection FB goes true once client disconnects and then you need to reset the FB by setting the xEnable to false.

Problem trying Net Base Services 3.5.15.0 TCP connection

2024-10-03T12:37:37.650000Z

I have a need to send messages between 2 PLCs and I cant use network variables (because of size limit) so I tried writing this simple test program.

This seems to work fine. I can send messages back and forth when a first "Start server" and then "Connect client"

However, if I disconnect the client by setting ClientConnect to false and try to re-connect then the TCP_Client just gives me TIMEOUT error.

How is this supposed to work? Why reconnecting wont work. There is not other way of disconnecting the client than setting xEnable of the TCP_Client to false.

PROGRAM PLC_PRG
VAR CONSTANT
    mySize : UDINT := 255;
END_VAR
VAR
    Server: NBS.TCP_Server;
    ServerIpStr: STRING := '127.0.0.1';
    ServerIP: NBS.IP_ADDR;
    ServerPort: UINT := 50000;

    ServerConnection: NBS.TCP_Connection;

    Client: NBS.TCP_Client;

    ServerRead: NBS.TCP_Read;
    ServerWrite: NBS.TCP_Write;
    ServerSend: STRING(mySize);
    ServerReceive: STRING(mySize);
    ServerConnect: BOOL;
    bServerSend: BOOL;
    IP: NBS.INADDR;
    ConnectedClientIP: STRING;

    ClientPort: UINT := 50000;
    ClientIpStr: STRING := '192.168.1.49';
    ClientIP: NBS.IP_ADDR;

    ClientRead: NBS.TCP_Read;
    ClientWrite: NBS.TCP_Write;
    ClientSend: STRING(mySize);
    ClientReceive: STRING(mySize);
    ClientConnect: BOOL;
    bClientSend: BOOL;

    Error: BOOL;
    Message: BOOL;
END_VAR
// Server

ServerIP.sAddr := ServerIpStr;
Server(
    ipAddr := ServerIP,
    uiPort := ServerPort
);

ServerConnection(
    xEnable := Server.xEnable,
    hServer := Server.hServer,
);

IP := ServerConnection.IPAddress;

ConnectedClientIP := F_Concat7(
                        BYTE_TO_STRING(IP.S_un_b.s_b1),'.',
                        BYTE_TO_STRING(IP.S_un_b.s_b2),'.',
                        BYTE_TO_STRING(IP.S_un_b.s_b3),'.',
                        BYTE_TO_STRING(IP.S_un_b.s_b4));

ServerRead(
    xEnable := ServerConnection.xActive,
    hConnection := ServerConnection.hConnection,
    szSize := SIZEOF(ServerReceive),
    pData := ADR(ServerReceive)
);

IF ServerRead.xReady AND ServerRead.szCount > 0 THEN
    Message := TRUE;
END_IF

IF ServerRead.eError > 0 THEN
    Error := TRUE;
END_IF

ServerWrite(
    xExecute := ServerConnection.xActive AND bServerSend,
    hConnection := ServerConnection.hConnection,
    szSize := LEN(ServerSend)+1,
    pData := ADR(ServerSend)
);

IF ServerWrite.xDone THEN
    bServerSend := FALSE;
END_IF

IF ServerWrite.eError > 0 THEN
    Error := TRUE;
END_IF

// Client
ClientIP.sAddr := ClientIpStr;
Client(
    xEnable := ClientConnect,
    ipAddr := ClientIP,
    uiPort := ServerPort,
    udiTimeOut := 10000000
);

ClientRead(
    xEnable := Client.xActive,
    hConnection := Client.hConnection,
    szSize := SIZEOF(ClientReceive),
    pData := ADR(ClientReceive)
);

IF ClientRead.xReady AND ClientRead.szCount > 0 THEN
    Message := TRUE;
END_IF

IF ClientRead.eError > 0 THEN
    Error := TRUE;
END_IF

ClientWrite(
    xExecute := Client.xActive AND bClientSend,
    hConnection := Client.hConnection,
    szSize := LEN(ClientSend)+1,
    pData := ADR(ClientSend)
);

IF ClientWrite.xDone THEN
    bClientSend := FALSE;
END_IF

IF ClientWrite.eError > 0 THEN
    Error := TRUE;
END_IF

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