TCP/IP Socket Communication via URScript with Universal Robots

Universal Robots provides an efficient method for establishing TCP/IP socket communication between a UR robot and external equipment. This guide demonstrates how to set up the robot as a client using URScript, communicating with a server (a PC in this case).

Server Setup

A C# console application, built using Visual Studio 2010, acts as the server. The server listens for connections on IP 127.0.0.1 and port 21. The following steps outline the server setup:

1. Initialize Server:

   IPAddress ipAddress = IPAddress.Parse("127.0.0.1");
   TcpListener tcpListener = new TcpListener(ipAddress, 21);
   tcpListener.Start();
   

2. Accept Connections:

   TcpClient tcpClient = tcpListener.AcceptTcpClient();
   NetworkStream stream = tcpClient.GetStream();
   

3. Handle Client Requests:

   while (tcpClient.Client.Connected) {
       byte[] arrayBytesRequest = new byte[tcpClient.Available];
       int nRead = stream.Read(arrayBytesRequest, 0, arrayBytesRequest.Length);
       if (nRead > 0) {
           string sMsgRequest = ASCIIEncoding.ASCII.GetString(arrayBytesRequest);
           // Process the request and send a response
       }
   }
   

Client Setup in URScript

The UR robot is programmed to act as a client, connecting to the server and exchanging data. Here is a basic URScript example for the client:

1. Open Socket:

   open≔socket_open("127.0.0.1",21)
   Loop open=False
     open≔socket_open("127.0.0.1",21)
   

2. Send Data:

   sendToServer≔'send to server'
   socket_send_string(sendToServer)
   

3. Receive Data:

   receiveFromServ≔socket_read_ascii_float(6)
   Loop receiveFromServ[0]≠6
     Wait: 0.3
     receiveFromServ≔socket_read_ascii_float(6)
   

4. Move Robot Based on Received Data:

   Loop counter<6
     targetPos[counter]=receiveFromServ[counter+1]
     counter≔counter+1
   MoveJ
     targetPos
   

Data Format Requirements

When using socket_read_ascii_float in URScript, ensure that:

• Data is surrounded by parentheses.

• Each data unit is separated by a comma.

• The message ends with \n.

Example:

• Server sends: "(0.4, 0, 0.5, 0, -3.14159, 0)\n".

• Client receives: [6,0.4, 0, 0.5, 0, -3.14159, 0].

For more details and to download the necessary files, visit the Universal Robots TCP/IP socket communication guide.