I have a few licensing questions about electronic designs.

For model railroad electronics, the company Digitrax has developed a communication bus called Loconet. This bus allows hand throttles, boosters, switch modules and centrals to be connected to a single bus.

If another company wants to sell devices which work on this Loconet bus, that company must obtain a license which dictates that they have to pay 1% of their sells of these products to the company Digitrax. The protocol is open on the internet, so every DIY guy can make his own Loconet devices.

This bus is currently by far the best bus in model train world, so it is quite populair and there are many companies selling these Loconet devices.

If anybody makes and sells a Loconet compatible shield to be used with an Arduino, then he is selling a shield which does not do anything with the Loconet bus until an Arduino is plugged in and the right code is uploaded.

If one sells bare PCBs, posts a link to an Arduino clone on Aliexpress, and hosts self written software with which a private person can assemble his own Loconet capable device, does one still need such a license?

In other words: As company, can one always sell a bare unsoldered PCB, no matter what it's for?

If the PCB is already assembled, do these rules change? The shield is without an Arduino and without code useless.

In other words: As company, can you sell a fully assembled Arduino compatible shield, no matter what it's for?

If the answer on the second question is a "No": As company, can you sell a bag or 2 separate bags with PCB and components with which a private person can assemble the shield himself?

Are all or some of the answers to these questions license specific?

Also The PCB designs would not be having any labels on it. So the words "Arduino" or "Loconet" would not be used.

  • 1
    I think this question could be improved by adding links to the licence and claims made by the company. It will depend on if they are asserting copyright or patent protections (or perhaps trademark).
    – Dave
    Oct 27, 2021 at 11:57
  • That particular license is not online, I can request one I believe. But this question is not just confined to this particular line of products. The question is about if you only sell a small part of a product which is useless alone. This is their website digitrax.com/support/loconet/home
    – bask185
    Oct 27, 2021 at 12:06
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    I am not sure if there is a technicality, and I am not a lawyer, but you should probably be aware that judges do have brain cells. You're selling a thing; the customer assembles the thing and it connects to Loconet; the fact that you sold it as a kit instead of an assembled product doesn't change anything according to my common sense, so it probably won't change anything according to the judge's common sense either. Unless there is some specific loophole. Oct 27, 2021 at 13:00
  • In my mind, the real question is whether avoiding the words "Arduino" and "Loconet" will convince the judge that you didn't sell an Arduino Loconet product, just a product that is completely by coincidence compatible with Loconet (Arduino doesn't matter). Oct 27, 2021 at 13:01
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    @user253751 the question of whether intellectual property can be enforced on a transmission protocol is an important question, and it is important that we do not allow unjustified claims to succeed. Many other protocols have been found to not trigger IP rights. From here it seems there are patents involved, so I cannot answer the question. From the OP it would seem the trade secret claims may not hold weight.
    – Dave
    Oct 27, 2021 at 13:18

1 Answer 1


Royalty fees for the use of proprietary technologies are somewhat common. The key is usually how you market the device. For example this "Loconet" will be a trade mark - if you claim Loconet compatibility, or use their branded product names or logotypes without permission, then it may count as a trademark infringement. You mainly pay the royalty fee to them for the right to use their brand in marketing.

Similarly if it is a patented technology (I very much doubt so in this case) then it could be a patent infringement if your product is designed to be compatible.

(A common product you can use for reference for similar scenarios is Bluetooth/BLE, which is a trademark owned by a special interest group that requires a membership fee.)

As company, can one always sell a bare unsoldered PCB, no matter what it's for?

You can sell it as long as you don't market it as something to do with "Loconet". As far as trademark/patents go, the state of assembly of the product doesn't matter, only how you market it. Obviously you can't use any labels etc either under that trademark. And well, how are you going to sell it if you don't market or hint about compatibility.

Whether "hinting" would count as trademark infringement, I can't answer - suppose you write "compatible with popular model railroad communication protocols". That might call for a separate question.

I think from a legal perspective we'd need a specific scenario described more in detail to tell if it is a trademark infringement or not and how it might get treated in court.

In more general terms, electronic end products put on market also need to conform with relevant electronics directives of the country where you sell it. The rules are slightly different across the world. But to take Europe (EU) as one example:

  • If you sell something which is not a finished product but a component sold to other companies as a part of a supplier chain, you need not conform with the various electronics-related directives other than the environmental ones.

  • You will have to claim RoHS compliance or CE marked end products cannot use your component. You also need to conform to the WEEE directive regarding electronics recycling. Naked PCB is a typical product that may be subject to scrutiny by authorities since many of the substances in the RoHS directive are specifically targeting PCBs and flame retardants.

  • If you sell something like a soldering kit or Arduino board, for the purpose assembly or use by end user hobbyists, then that is a product which you put on market. You have to CE mark it and take responsibility regarding all the electronics directives: EMC, RED, LVD, RoHS. I would imagine that this also includes any non-conformance problems caused by poor soldering skills, so it sounds preferable to sell fully assembled boards.

When unsure, it is best to consult a test house regarding which directives that apply in the country where you put the product on the market.

Most product on Aliexpress and similar sites may therefore be illegal to import in one particular country, unless the seller claims that they are conforming to local electronic regulations (CE mark in Europe, FCC in USA etc).

  • 1
    You don't think that explicitly stating compatibility with Loconet would be nominative use?
    – Sneftel
    Sep 5, 2023 at 8:38

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