Interfacing ROS2 with Ethenet/IP

Question

I have an ABB robot that I have interfaced with ROS2 via abb_ros2. I have an industrial equipment that I need to read from and write data to using ethernet/ip and command the robot using some logic based on these ethernet/ip values. I don't have this device with me yet so I do not know what to expect. However, what is the right approach to accomplish this?

1. Is there a way I can interface a micro-ros supported micro-controller with ethernet/ip so that I can publish "natively" in ros2?
2. Is there a way I can interface the underlying DDS with ethernet/ip "directly"?
3. Can I take for granted that the device providing with the ethernet/ip interface may probably have a means of communicating with it using a library. I've seen libraries on git like pylogix made to work with specific PLC's over ethernet/ip or general purpose libraries like EIPScanner. I would be in principle able to write ros2 nodes that use these libraries.

I'm quite new to both fieldbuses and ros2 so please excuse my ignorance.

Answer 1

Is there a way I can interface a micro-ros supported micro-controller with ethernet/ip so that I can publish "natively" in ros2?

Most likely, looking at the list of micro-ros controllers that are linked, you have some options

• Arduino Portenta H7 (WiFi)
• Teensy 4.0/4.1 (Ethernet UDP)
• STM32L4 Discovery kit IoT (Ethernet UDP)
• Olimex LTD STM32-E407 (Ethernet UDP - F,N)

The other boards listed there are UART and there is a way to use the UART interface to connect to ethernet, such as with this board: KUBII - UART to Ethernet converter (WV20655)

Is there a way I can interface the underlying DDS with ethernet/ip "directly"?

I would say yes by using HTTP methods. See below for a possible implementation.

Can I take for granted that the device providing with the ethernet/ip interface may probably have a means of communicating with it using a library. I've seen libraries on git like pylogix made to work with specific PLC's over ethernet/ip or general purpose libraries like EIPScanner. I would be in principle able to write ros2 nodes that use these libraries.

It is never safe to assume to but to look into the a specific hardware module and see if it could do what you want. Look at the Arduino Portenta H7. Because it is Arduino, there is already support for making web servers. See Portenta H7 as a Wi-Fi Access Point. For this specific module, there is a means of communication with using an existing library.

For this specific module, you could write a function that connects to your ROS network and listens to the state of your robot via a Listener. On the same module, you could write an Arduino side that is able to talk to a network (such as by HTTP methods or by being a web server) and then some functions inside that convert anything you send to this web server into instructions that you could publish back onto the ROS 2 Network. I think this could be done using the services methodology.

I don't have much experience in services but reading about it, it looks promising for your given application. See ROS 2 - Understanding services

This is how I would implement what you are trying to do using the ROS 2 Talker/Listener methodology.

Assumptions:

• You have some board that can be interfaced with a network

1. Build a ROS 2 Listener that subscribes to whatever ROS 2 node that keeps up with the state of your current robot
2. In the ROS 2 listener, configure how you want the state of your machine to be communicated. I would recommend a JSON structure because you can configure on the controller machine (be it on your machine or another endpoint) how you want the JSON to be represented (such as parsing it and then displaying it in a GUI) and then POST to that endpoint, or replies to a GET, that is up to you. This gives you the flexibility to create your own application on how to control your robot because all it needs is a JSON object to understand what your robot is doing, what state it is in, or any other information you may need.
3. Then, build a ROS 2 Talker that accepts POST messages from a given endpoint, this is how you can submit commands to the ROS 2 network. Assume that you are posting JSON messages to the ROS 2 Talker node, then it can convert the incoming JSON structure into messages that can be communicated across the the ROS 2 network that controls your machine can understand.

See also:

Writing a simple publisher and subscriber (C++)

Writing a simple publisher and subscriber (Python)

Read more about HTTP methods like POST and GET