Demand Interfaces are user-inputs that control motor speed and other variables. Traditionally analog signals were used; these were 4 to 20mA or 0 to 10V. Usually high resolution, 16-bit SAR ADCs are used to digitize the control signals. There is an increasing trend to convert to digital interfacing but given the level of installed analog infrastructure, there will be a need for A/D solutions for the user input for a while to come. The Network Interface uses industrial Fieldbus networks, such as profibus, interbus, modbus, and other proprietary systems. RS-485 and RS-232 are examples of transceivers for Fieldbus communications. Modern integrated isolated transceivers are making network interface easy to design minimizing the board space required.