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To test the TCP socket connection from a host (PC) to a Universal-Robots the program Sockettest can be used.

In this example the robot is connected to a router with a RJ-45 Ethernet cable – and the computer is connected to the same router via WiFi. Notice that the computer is not connected directly to the robot Ethernet port because that is a unliekly situation in an application.

The computer IP address configuration can be found on a Windows computer by running a DOS box  – which can be done by Run and “cmd”.


In the DOS box the IP configuration can be found with “ipconfig”


In this example the computer has the IP address – the Subnet setting is and the default gateway is

So In this example the robot IP address is configured to – subnet and gateway and DNS is configured for the router address i.e.


The host and robot needs each their own IP address and in the same subnet so they can communicate .

A good start is to see if it is possible to ping the robot from the host (computer).


Here is a good reply from the robot.

Below shows the Sockettest connected to a robot with IP address Notice that the PC where the Sockettest is running is the client and it connects to the robot at address and port 30002.

See also this page for port description on the UR. Link to UR real time server.


Notice the data that is shown in the “Conversation with host” screen. It looks like random data, but it is Matlab data send out from the robot – so this is normal.

When the communication has been verified – Then a simple test can be performed by sending a script command that set an output high.

Below shows the I/O screen before sending a command.


Then the command set_digital_out(1, True) is send to the robot via the TCP socket connection.


Which sets the digital output high on the robot.


To set the output low again the script command set_digital_out(1, False) is send over the TCP socket connection.


And the out number 1 go low again.



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By Zacobria Lars Skovsgaard
Accredited 2015-2018 Universal Robots support Centre and Forum.


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