Chapter 2: Installation and Connection Setup

About This Chapter

This chapter describes how to connect a PC to a UR robot and configure the system so that Python can communicate with the robot.

After completing this chapter, you should be able to:

Communicate with the robot
Configure Remote Control
Verify connectivity from Python

2.1 System Configuration

This documentation combines Universal Robots’ official communication interfaces with the third-party open-source SDU Robotics ur_rtde library. The assumed configuration is:

+--------------------+
|      Python PC     |
|                    |
|  ur_ctrl.py        |
|  ur_rtde           |
+---------+----------+
          |
      Ethernet
          |
+---------+----------+
|      UR Robot      |
|                    |
|  Control Box       |
|  Teach Pendant     |
+--------------------+

Connect the PC and robot with an Ethernet cable. A network switch may also be used.

2.2 Required Software

Python 3.10 or later is recommended.

For PC-side motion control, state acquisition, and I/O, this documentation uses SDU Robotics ur_rtde. Although it is not an official Universal Robots SDK, it communicates using the official Universal Robots RTDE protocol.

Install the required library:

pip install ur_rtde

The following interfaces are used:

RTDEControlInterface
RTDEReceiveInterface
RTDEIOInterface

2.3 Installation by Operating System

Windows

Installation is generally straightforward:

pip install ur_rtde

The Visual C++ Runtime may be required.

Ubuntu

On Ubuntu, dependencies such as Boost may be necessary. For example:

sudo apt install \
    build-essential \
    cmake \
    libboost-all-dev

Then run:

pip install ur_rtde

macOS

Use Homebrew:

brew install cmake
brew install boost

If necessary, configure the environment:

export PATH=/opt/homebrew/bin:$PATH

Depending on the environment, a source build may be required. Note that library paths differ between Intel Macs and Apple Silicon Macs.

2.4 Robot IP Address

On the Teach Pendant, open:

Settings
    ↓
System
    ↓
Network

Check the IP address, for example:

192.168.0.10

Configure the PC on the same subnet. For example:

Robot

192.168.0.10

PC

192.168.0.100

The subnet mask is usually:

255.255.255.0

2.5 Verifying Network Connectivity

First, verify that the robot responds to ping.

Linux/macOS:

ping 192.168.0.10

Windows:

ping 192.168.0.10

If a response is received, basic network connectivity is working.

2.6 What Is Remote Control?

To send motion commands from Python, Remote Control must be enabled.

If it is not enabled, the following error may occur:

Please enable remote control on the robot!

This is one of the most common errors returned by ur_rtde.

2.7 Enabling Remote Control

On e-Series robots, enable Remote Control under:

Settings
    ↓
System
    ↓
Remote Control

Then switch the robot to Remote Mode. External control is unavailable in Local Mode.

2.8 Remote Mode

The upper-right corner of the Teach Pendant displays either:

Local

or:

Remote

For Python-based control, it must display:

Remote

2.9 Connecting from Python

A minimal example is:

from rtde_control import RTDEControlInterface

ROBOT_IP = "192.168.0.10"

rtde = RTDEControlInterface(ROBOT_IP)

print("Connected")

If no exception occurs, the connection has succeeded.

2.10 Receive Interface

Robot state is obtained through a separate interface:

from rtde_receive import RTDEReceiveInterface

rtde_r = RTDEReceiveInterface(ROBOT_IP)

print(rtde_r.getActualQ())

If joint angles are returned, the interface is working.

2.11 IO Interface

Use the following interface to control digital I/O:

from rtde_io import RTDEIOInterface

rtde_io = RTDEIOInterface(ROBOT_IP)

2.12 Common Errors

Please enable remote control on the robot!

Remote Control is disabled.

Connection refused

The IP address is incorrect, or the network configuration does not match.

Robot is not running

The robot is not powered on or running. This may also occur when Emergency Stop is active.

Protective Stop

A safety stop is active. Clear it using the Teach Pendant. If necessary, execute Unlock Protective Stop through the Dashboard Server.

2.13 Connection Checklist

If the connection fails, check the following:

[ ] Ethernet cable
[ ] Ping response
[ ] IP address
[ ] Firewall
[ ] Remote Control
[ ] Remote Mode
[ ] Robot Power ON
[ ] Brake Release completed
[ ] Emergency Stop cleared
[ ] Protective Stop cleared

Checking these items in order helps isolate many common problems.

Next Chapter

The next chapter explains the following in detail:

How RTDE works
RTDEControl
RTDEReceive
RTDEIO