Which standalone head units would work with Tacx i.Flow T2270? I'd like to be able to use my Tacx i.Flow T2270 trainer without a PC.

Apart from the T2202, which current or older standalone head units would be compatible? Would T1682 work? What about head units from other Tacx models?

(I am looking to buy secondhand, so would like to understand my options.)
The Tacx i-Flow is only compatible with the T2202 head unit for standalone use. 

The T1982 Bushido head unit does not connect in my experience, although I have had Tacx support tell me it should work. 

The T1962 Flow head unit firmware is not compatible withe I-Flow. 

Your best guaranteed option is the T2022.