Choosing a KNX OEM partner in China: nine questions that separate factories from forwarders

Every supplier in Shenzhen will tell you they are a factory. Most of them are trading companies with a good photo library, and a few are factories with a good photo library and no idea what KNX actually is. The difference surfaces six months later, usually when a certification test fails or a mould turns out to be owned by someone else.

These are the nine questions I would ask if I were on the buying side — and the answers that should make you walk away.

1. Who owns the ETS database?

Good answer: we write it, here is a sample application program, here is the parameter set, here is who maintains it.

Bad answer: “the software team will handle it” with no name, no sample database, and no idea what a manufacturer ID is. If the ETS database is a black box, your product is a black box — and configuration support in year two will be a hostage situation.

2. Which KNX stack, and is it certified?

There are a handful of commercial KNX stacks and several open ones. A serious partner names the stack, the version, and whether the bus coupling unit is certified. A weak one says “we support KNX” and changes the subject.

3. Can I see the test protocol you use for batch QC?

Not “we test everything” — the actual document: what is measured, on how many units, what the pass criteria are, and what happens to a failing unit. If this document does not exist, quality control is a person's opinion.

4. Are the moulds mine?

Tooling should be invoiced at cost, documented, and transferred with cavity records. Ask directly: “if I move to another supplier, do I take the moulds?” The answer should be an unhesitating yes, in the contract, not in a WeChat message.

5. What certification have you actually completed?

Ask for certificate numbers, the certificate holder's name, and the tested model list. Then check the numbers. A partner who has been through EMC and safety testing will talk about test reports, DoC structure, and the technical file. A forwarder will talk about “CE available”.

6. Who is my technical contact after the order?

The salesperson who quoted is rarely the person who solves a firmware bug. Ask who owns the project technically, what their background is, and whether you can talk to them before signing. If the answer is “our engineering team”, ask for a name.

7. What is the real MOQ, and why?

A low MOQ quoted to win the deal becomes a high MOQ at the tooling discussion. Ask what drives the number: mould amortisation, SMT setup time, minimum panel order from the glass supplier. The explanation tells you more than the number.

8. How do you handle a firmware change mid-production?

Version control is where cheap manufacturing shows itself. Good answer: version locked at golden sample, change requires written approval, units in the field identifiable by serial. Bad answer: “we will update it, no problem”.

9. Can I speak to a customer in my market?

Not a logo wall — an actual reference you can call, ideally in your region, ideally selling a product comparable to yours. A partner with real customers will make this happen. A partner without them will explain why it is complicated.

The commercial terms that matter more than the price

• Tooling ownership and transfer — in writing, with a named exit process.
• Design and firmware rights — who owns the mechanical design, who owns the source, what happens on termination.
• No-competition clause — your design should not appear in another brand's catalogue six months later.
• Certification holder — your company's name on the certificate, not the factory's.
• Warranty terms and field failure handling — who pays for the container of returns, and at what failure rate.

The cheapest quote usually comes from the partner who has understood your project least.

None of this requires a large organisation on the other side. It requires one person who can read a specification, test a sample, and tell you the truth about a factory — which is a different skill from sourcing on price, and considerably rarer.