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:

Initialize Server:

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

Accept Connections:

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

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:

Open Socket:

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

Send Data:

sendToServer≔'send to server'
socket_send_string(sendToServer)

Receive Data:

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

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.