أنشئ حسابًا أو سجّل الدخول للانضمام إلى مجتمعك المهني.
in case of siemens plc s7300 and s7400 commnication is done by ethernet or mpi
in general
you can connect between two control system by hard wire such as relay in on plc and concoct input in other
also you can use modbus or opc to interchange the data by software