The Westermo Fieldbus devices are industrial PROFIBUS DP modules. There are different types of slave modules and one Master module. PROFIBUS adapters that is able to transfer PROFIBUS DP I/O data via serial communication. I.e leased lines, dial up modems, Ethernet adapters, GSM modems or radio modems without any use of special drivers or special PLC bords. The FD-20, PROFIBUS DP Master module act the same way as the adapters on the serial side and act as a stand alone master on the PROFIBUS side. A combination with our Ethernet adapter gives the opportunity to connect PROFIBUS to Ethernet PROFIBUS DP converter to make a transparent connection for a different serial interfaces to a PROFIBUS DP network.