Shared use of EL60xx bus terminal from PLC

If an EL60xx bus terminal is utilized from PLC and as virtual COM port, then access to the bus terminal must be coordinated by a superior mechanism. On opening the respective virtual COM port, accesses by PLC are blocked if the virtual COM port is open. When the virtual COM port is closed, PLC can access the bus terminal again. However, the driver will not regard any running transfers. It will also not restore the bus terminal configuration like baud rate, or stop bit settings, even if it has been modified by an application which used it through a virtual COM port.