Properties of FB_TCPClient/FB

Properties of FB_TCPClient/FB_TCPClient2

General Information

The function blocks FB_TCPClient and FB_TCPClient2 provide several properties for their monitoring and control. The properties and their membership are listed in the following tables.

Common Properties of FB_TCPClient and FB_TCPClient2

Name	Data type	Access	Description
IsReadable	BOOL	Read	Indicates that data has been received that has not yet been processed by the Receive method.
IsWritable	BOOL	Read	Indicates that the connection is in a state where data can be sent to the server.
PeerHasDisconnected	BOOL	Read	Indicates that the connection has been closed by the remote site. If so, the method Shutdown is automatically called and the state changes to Shutdown.
Result	ET_Result	Read	Indicates the result of the last method call. If the result is different than Ok, the result value is maintained even if another method is called.
State	ET_State	Read	Indicates the state of the socket.
TotalBytesReceived	ULINT	Read	Counts the total number of bytes received. (Range: 1 ... 2⁶⁴-1)
TotalBytesSent	ULINT	Read	Counts the total number of bytes sent. (Range: 1 ... 2⁶⁴-1)
SockOpt_CustomPort	UDINT	Read/write	Is used to specify the TCP port to which the connection opened by the FB_TcpClient shall be bound. If the value is set to 0 (default), the next available port is used.
SockOpt_KeepAlive	BOOL	Read/write	If TRUE, instructs the TCP stack to send empty packets periodically to verify whether the remote site is reachable. If this is no longer the case, the connection state changes to Shutdown. NOTE: In most cases, set this option so that if the remote site is unreachable (powered off or cable disconnected), this is detected. NOTE: If the KeepAlive socket option is disabled for the server, it cannot be enabled for the connected clients.
SockOpt_NoDelay	BOOL	Read/write	If TRUE, instructs the TCP stack to send the data without waiting for a complete packet. This option reduces throughput but improves latency which is important in industrial applications.
SockOpt_ReceiveBufferSize	UDINT	Read/write	Is used to set or get the receive buffer size of the stack. It must always be greater than the amount of data received at one time to help avoid data loss. (Range: 1 ... 2147483647)
SockOpt_SendBufferSize	UDINT	Read/write	Is used to set or get the send buffer size of the stack. It must always be greater than the amount of data sent at one time. (Range: 1 ... 2147483647)

Additional Properties of FB_TCPClient

Name	Data type	Access	Description
BytesAvailableToRead	UDINT	Read	Indicates the number of bytes in the receive buffer available to be read using the Receive method. (Range: 0 ... 2147483647)
SockOpt_OutOfBandInline	BOOL	Read/write	If TRUE, instructs the TCP stack to send OutOfBand-data as part of the regular data stream.

Additional Properties of FB_TCPClient2

Name	Data type	Access	Description
TimeoutConnectTls	UDINT	Read/write	Indicates the timeout in seconds for establishing a connection using the method ConnectTls.
TlsUsed	BOOL	Read	Indicates if the TCP connection to the server has been established using the method ConnectTls.