buses for industrial environments outside the box

Please note the parametres:
Industrial environments = noisy
outside the box = not on the controller board e.g. I have, in industrial environments, used IIC to communicate between the uC and peripherals on the board which is in a steel box.

IIC: no way, too noise suspectible

SPI: no way, too noise suspectible

Non isolated RS232: no way, too noise suspectible

Isolated RS232: still somewhat noise suspectible, not multinode.

Non isolated RS485: suspectible to common mode noise, require common ground. In well grounded environments and with shielded cables a good solution. Multinode.

isolated RS485: a Cadillac solution. Multinode.

RS422: see RS485 re isolated or not. "can" be multinode.

CAN: see RS485 re isolated or not. Multinode.

J1708: maybe? one with a true multimaster protocol, but slow and noise suspectible. Multinode.

Those are the ones I can think of right off the bat.

For 232 and 485 you must read the link "best serial appnotes" in links <<<

Re protocol, choose from the above to limit the discussion. e.g. CAN has a defined protocol, with 485 you roll your own. Also multimaster and master/slave are quite different

Erik