TCPComm

TCPComm Library

The TCPComm library is a wrapper for the AsTCP library provided by B&R. This library both manages and simplifies the TCP communication interface.

TCPComm Data Structures and Enums

Mode Enums

• TCPCOMM_MODE_SERVER - Set CPU as the TCP communication server.
• TCPCOMM_MODE_CLIENT - Set CPU as the TCP communication client.

State Enums

• TCPCOMM_ST_CLOSED - TCP state after a connection has been successfully closed.
• TCPCOMM_ST_OPENING - TCP state while connection is being established.
• TCPCOMM_ST_IOCTL - TCP state that changes or retrieves settings.
• TCPCOMM_ST_LISTEN - TCP state while connection is established and idle.
• TCPCOMM_ST_CLOSING - TCP State while connection is being closed.
• TCPCOMM_ST_ERROR - TCP state when an error has occurred.

Send State Enums

• TCPCOMM_SEND_ST_IDLE - TCP send state while connection is not actively sending.
• TCPCOMM_SEND_ST_SEND - TCP send state while connection is actively sending.

Receive State Enums

• TCPCOMM_RECV_ST_READ - TCP read state.

TCPConnection_typ

This structure is used to establish and monitor a TCP connection.

Commands

• Enable - Boolean that enables the TCP connection.
• AcknowledgeConnection - Boolean that commands the function to initiate a connection.
• AcknowledgeError - Boolean that clears a non persistent error.

Configuration

• Mode - Enum that determines whether the CPU will be a TCP client or server.
• LocalIPAddress - IP Address of the CPU.
• LocalPort - Port of the CPU.
• RemoteIPAddress - IP Address of device intended to connect to CPU.
• RemotePort - Port of device intended to connect to CPU.
• SendBufferSize - Maximum length of data in bytes (length of the data buffer specified).
• UseSSL - Boolean used to signify an SSL connection is required.
• SSLCertificate - Storage for required SSL certificate information.

Outputs

• NewConnectionAvailable -
• Connection - data associated with current connection
  • IPAddress - IP Address of connected device.
  • Port - Port of connected device.
  • Ident - Socket ident.
  • UID - Unique identifier for the connection. 0 implies the connection is not valid.
• Error - Boolean used to signify a error has occurred.
• ErrorID - Error ID associated with the error that has occurred.
• ErrorString - Error string to inform the user about the error that has occurred.

Initialization

//Set the IP Address and port of server 
TCPServer.IN.CFG.RemoteIPAddress:=	'192.168.10.1';
TCPServer.IN.CFG.RemotePort:=		8000;

//Set CPU's Ip Address and port
TCPServer.IN.CFG.LocalIPAddress:=	'192.168.10.2';
TCPServer.IN.CFG.LocalPort:=		8001;

//Set the mode to be either Client or Server
TCPServer.IN.CFG.Mode:=				TCPCOMM_MODE_CLIENT;
TCPServer.IN.CMD.Enable:=    		1;

Cyclic Operation

//cyclically called function
TCPManageConnection(TCPServer);

//Acknowledge a new connection
IF( TCPServer.OUT.NewConnectionAvailable)THEN
    TCPServer.IN.CMD.AcknowledgeConnection:=	1;
END_IF

TCPStream_typ

This structure is used to send and receive data via TCP communication.

Commands

• Receive - Command for receiving a new TCP packet.
• Send - Command for sending a new TCP Packet
• Close - Command to close the current connection.
• AcknowledgeData - Command to acknowledge new data has been received.
• AcknowledgeError - Command to acknowledge an error has occurred.

Parameters

• Connection - data associated with current connection
  • IPAddress - IP Address of connected device.
  • Port - Port of connected device.
  • Ident - Socket ident.
• pReceiveData - Pointer to string containing received TCP packet.
• MaxReceiveLength - Maximum length of data in bytes (length of the data buffer specified).
• ReceiveFlags - Flag parameter associated with receiving a TCP packet. See Automation Studio TCPRecv() for list of flags.
• AllowContinuosReceive - Boolean that allows for continuously receiving TCP packets.
• pSendData - Pointer to string containing TCP packet being sent.
• SendLength - Length of the SendData string.
• SendFlags - Flag parameter associated with sending a TCP packet. See Automation Studio TCPSend() for list of flags.
• AllowContinuosSend - Boolean that allows for continuously sending TCP packets.

Outputs

• Connection - data associated with current connection
  • IPAddress - IP Address of connected device.
  • Port - Port of connected device.
  • Ident - Socket ident.
• Active - Boolean signifying an active connection.
• Receiving - Boolean signifying a TCP received packet is being processed.
• DataReceived - Boolean signifying a TCP received packet is has been processed.
• ReceivedDataLength - Length of the TCP packet last received.
• Sending - Boolean signifying a TCP packet is currently being sent.
• DataSent - Boolean signifying A TCP packet was successfully sent.
• SentDataLength - Length of the most recently sent TCP packet.
• Error - Boolean used to signify a error has occurred while sending or receiving TCP packets.
• ErrorID - Error ID associated with the error that has occurred.
• ErrorString - Error string to inform the user about the error that has occurred.

Initialization

//set the send data string to avoid sending garbage
sendData:= 'Hello Server';

Cyclic Operation

//When a new connection is available set the pointers for the send and receive strings and set the commands high 
IF( TCPServer.OUT.NewConnectionAvailable )THEN
    TCPServer.IN.CMD.AcknowledgeConnection:=	1;
    TCPDataManager.IN.PAR.Connection:=			TCPServer.OUT.Connection;
    TCPDataManager.IN.PAR.pSendData:=			ADR(sendData);
    TCPDataManager.IN.PAR.pReceiveData:=		ADR(recvData);
    TCPDataManager.IN.PAR.MaxReceiveLength:=	SIZEOF(recvData);
    TCPDataManager.IN.CMD.Receive:=				TRUE;
    TCPDataManager.IN.CMD.Send:=				TRUE;
END_IF

//Acknowledge new connection and cyclically check for received data
TCPDataManager.IN.CMD.AcknowledgeData:= 1;
TCPStreamReceive(TCPDataManager);

//When ot sending recalculate the length of the data to be sent.
IF( NOT TCPDataManager.OUT.Sending ) THEN
    TCPDataManager.IN.PAR.SendLength:=	brsstrlen(ADR(sendData));
END_IF

//Function that performs the TCP sending functionality when the send command is high
TCPStreamSend(TCPDataManager);

//Clean up commands for next cycle
TCPDataManager.IN.CMD.Send:= 			0;
TCPDataManager.IN.CMD.Close:= 			0;

Snippets

Disconnect handling

// Handle a disconnect error
if (TCPDataManager.OUT.ErrorID == tcpERR_NOT_CONNECTED) {
  TCPDataManager.IN.CMD.Send = 0;
  TCPDataManager.IN.CMD.Receive = 0;
  TCPDataManager.IN.CMD.Close = 1;
  TCPDataManager.IN.CMD.AcknowledgeError = 1;
}

Note: In TCP an empty packet is also a disconnect packet

if (TCPDataManager.OUT.DataReceived) {
  if (TCPDataManager.OUT.ReceivedDataLength == 0) {
    TCPDataManager.IN.CMD.Send = 0;
    TCPDataManager.IN.CMD.Receive = 0;
    TCPDataManager.IN.CMD.Close = 1;
  }
}

Handling config changes

  // Handle user changes in Configuration.Connection
	IF brsmemcmp(ADR(TCPClient.IN.CFG),ADR(Configuration.Connection),SIZEOF(Configuration.Connection)) <> 0 THEN
		TCPClient.IN.CFG:=	Configuration.Connection;
		TCPClient.IN.CMD.Enable:= FALSE; // Client (or server) needs to restart to accept configuration
	END_IF	

Keep alive

// Temp variable 
sending := TCPDataManager.OUT.Sending OR TCPDataManager.IN.CMD.Send; // Is data being sent or about to be sent

Ping.IN:= connected AND NOT sending AND NOT Ping.Q; 	
Ping.PT:= Configuration.Ping;
Ping(); // Ping TON

IF Ping.Q AND Configuration.Ping > 0 THEN
  FormattedData := 'ok?'; // Ping message
  TCPDataManager.IN.PAR.SendLength := 3; // Ping message len (strlen('ok?') == 3)
  TCPDataManager.IN.CMD.Send := TRUE;
  TCPDataManager.IN.PAR.pSendData := ADR(FormattedData);
END_IF

Errors

• 50000 - TCPCOMM_ERR_INVALIDINPUT
• 50001 - TCPCOMM_ERR_SENDDATATOOLARGE
• 50002 - TCPCOMM_ERR_