The differential pressure transmitter DPT 100 has been especially designed for fast test processes in leakage and flow measurement, where a fast response time and high sampling rate are necessary. The compact design of the DPT 100 facilitates the use in standardised applications, e. g. and the installation in 19 in Rack. The DPT 100 with optionally RS-485 interface uses the Communication protocol Modbus RTU which has found the way in industrial communication as an open protocol. The Modbus proto-col is based on a master Slave architecture with which up to 247 Slaves can be questioned by a master - the data will transfer in binary form.