I have multiple climate chambers from different brands. Can I buy one MTCI unit and switch it between the chambers?

The answer is yes and no.

Yes, if those chambers use the same communication protocol.

For example, Votsch VT4002 and Weiss WT20/40 use the Votsch L4006 protocol. If you have these two chambers, you only need one MTCI unit.

However, if you have another chamber like Espec SU-241 that uses the Espec SCP220/SCP-N300/SCP310 protocol, you need to purchase another MTCI unit.