FB_SocketUdpReceiveFrom

VAR_INPUT

VAR_INPUT
    sSrvNetId   : T_AmsNetId := '';
    hSocket     : T_HSOCKET;
    cbLen       : UDINT; 
    pDest       : DWORD;
    bExecute    : BOOL;
    tTimeout    : TIME := T#5s;
END_VAR

sSrvNetId: string containing the network address of the TwinCAT TCP/IP Connection Server. For the local computer (default) an empty string may be specified.

hSocket: the handle of an opened UDP socket whose data are to be received.

cbLen: the maximum available buffer size (in bytes) for the data to be read. The maximum number of data bytes to be received is limited to 8192 bytes by default (by declaring the TCPADS_MAXUDP_BUFFSIZE constant in the library to conserve memory resources).

pDest: the address (pointer) of the receive buffer.

bExecute: the function block is enabled via a positive edge at this input.

tTimeout: maximum time that may not be exceeded when the function block is executed.

From product version: TwinCAT TCP/IP Connection Server v1.0.50 and higher, the maximum number of data bytes to be sent can be increased (if absolutely necessary).

1) In the PLC project, redefine the global constant (in our sample we want to increase the maximum number of data bytes to 32000 bytes):

VAR_GLOBAL CONSTANT
    TCPADS_MAXUDP_BUFFSIZE : UDINT :=32000;
END_VAR

2) Then activate the option "Replace constants" in TwinCAT PLC Control->"Project->Options...->Build" dialog box.

3) Compile the project.

VAR_OUTPUT

VAR_OUTPUT
    bBusy       : BOOL;
    bError      : BOOL;
    nErrId      : UDINT;
    sRemoteHost : STRING(15);
    nRemotePort : UDINT;
    nRecBytes   : UDINT;
END_VAR

bBusy: When the function block is activated this output is set. It remains set until and acknowledgement is received.

bError: If an error should occur during the transfer of the command, then this output is set once the bBusy output was reset.

nErrId : If the bError output is set, this parameter returns the TwinCAT TCP/IP Connection Server error number.

sRemoteHost: If successful, IP address (Ipv4) of the remote device whose data were received.

nRemotePort: If successful, IP port number of the remote device whose data were received (e.g. 200).

nRecBytes: Number of the last successfully receive data bytes.

Requirements