F_CreateServerHnd

The function F_CreateServerHnd is used to initialize/set the internal parameters of a server handle variable hServer. The server handle is then transferred to the instances of the function block FB_ServerClientConnection via VAR_IN_OUT. An instance of the FB_ServerClientConnection function block can be used to manage (establish or remove) a sever connection in a straightforward manner. The same server handle can be transferred to several instances of the function block FB_ServerClientConnection, in order to enable the server to establish several concurrent connections.

Syntax

FUNCTION F_CreateServerHnd : BOOL
VAR_IN_OUT
    hServer         : T_HSERVER; 
END_VAR
VAR_INPUT
    sSrvNetID       : T_AmsNetID := ''; 
    sLocalHost      : STRING(15) := ''; 
    nLocalPort      : UDINT := 0;
    nMode           : DWORD := LISTEN_MODE_CLOSEALL (* OR CONNECT_MODE_ENABLEDBG*);
 bEnable            : BOOL := TRUE;
END_VAR

Return value

Name	Type	Description
F_CreateServerHnd	BOOL	Returns TRUE if everything is OK, FALSE if there is an incorrect parameter value.

Inputs

Name	Type	Description
sSrvNetID	T_AmsNetID	String containing the AMS network address of the TwinCAT TCP/IP Connection Server. For the local computer (default) an empty string may be specified.
sLocalHost	T_IPv4Addr	Local server IP address (Ipv4) in the form of a string (e.g. '172.13.15.2'). For a server on the local computer (default), an empty string may be entered.
nLocalPort	UDINT	Local server IP port (e.g. 200).
nMode	DWORD	Parameter flags (modes). The permissible parameters are listed here and can be combined by ORing. LISTEN_MODE_CLOSEALL: All previously opened socket connections are closed (default). CONNECT_MODE_ENABLEDBG: Enables logging of debug messages in the application log. In order to view the debug messages open the TwinCAT System Manager and activate log view.
bEnable	BOOL	This input determines the behavior of the listener socket. A listener socket opened beforehand remains open as long as this input is TRUE. If this input is FALSE, the listener socket is closed automatically, but only once the last (previously) accepted connection was also closed.

/ Inputs/outputs

Name	Type	Description
hServer	T_HSERVER	Server handle variable whose internal parameters are to be initialized.

Example:

See FB_ServerClientConnection.

Requirements

Development environment	Target system type	PLC libraries to include (category group)
TwinCAT v3.1.0	PC, or CX (x86, X64, Arm®)	Tc2_TcpIp (communication)