Most fieldbusses like PROFIBUS DP are limited in their transmission range. Connecting a modem or other long distance communication product to the fieldbus is often also impossible. To solve the range problem on Profibus a Westermo fieldbus adapter (FD-10) capable of supporting the fieldbus protocol and also equipped with an RS-232/RS-485 serial port is required. The serial port can be connected to a telephone modem, radio-modem, or other transmission equipment to transfer the data over the long distance. The Westermo Fieldbus converter (FD-40) can be used to connect unintelligent serial equipment like printers, barcode readers and measuring devices directly to a PROFIBUS DP network.