which one of the communication protocols are open source: modbus, modbus plus, profinet, profibus, foundationfieldbus, CANOPEN. which are main companies developing products using these technologies.

It probably depends on the kinds of devices being used. With the PLC's and VSD's that I've used recently I've found Modbus to be a fairly commonly used protocol for cross device communications. Also RS422 comms is still a common electrical interface standard for these kind of comms.