What is a difference between various communication systems? i.e. modbus, fieldbus, ethernet, and others.

 

Exist any dependencies, commercial from something suppliers, look that comparative.

How much network card from pc?

How much network card branded(any supplier) from pc?

Electronic is simple and cheap,but copyright is expensive.

To use any protocol its necessary to check many benefits to low cost, flexible, and Open as ODVA associated standards.

Sorry for English