The previous proposal included a lot of data/address/function pins that actually is a bit obsolete design as we use multiple RS-X channels. This smaller bus uses 2×20. I can use the same width as for a Hat, but maybe a bit deeper boards.
I need the PLC system to be small and mobile to fit robots. I wanted a wider system to get more connector space, but I can add 2nd slots for those few cases. In short – I feel that increasing the size would be a mistake.
It is an alternative – and I could even do both …