About MPI, the "secret" is that the MPI port on a typical S7-300 is not isolated. It is this that limits the reach. The fact that there is no coprocessor to handle the comms is the reason why the baudrate is limited to 187.5k.
Extending the MPI reach with repeaters will make it almost as expensive as an ethernet solution. Also factor in that you can save the MPI card on the PC if you go with ethernet.
Extending the MPI reach with repeaters will make it almost as expensive as an ethernet solution. Also factor in that you can save the MPI card on the PC if you go with ethernet.
