TAC Xenta 401 belongs to a family of freely programmable controllers, with communication features, designed for heating and air handling systems. A TAC Xenta 401 holds full HVAC functionality including control loops, curves, time control, alarm handling etc. The controller does not have any inputs or outputs. Instead, required I/O modules from the TAC Xenta 400 series are used. Up to 10 I/O modules can be connected to the TAC Xenta 401. The controller is designed for cabinet mounting. A TAC Xenta controller is simple to program and to put into operation, using the graphical tool TAC Menta. A number of controllers can form a network and interchange data, typically in an office building with a number of air handling units and heating plants. TAC Xenta 401 can be connected to a central system, TAC Vista; also via a modem. For local use the TAC Xenta OP operator panel can be connected to TAC Xenta. It has a display with backlight and a minimum number of push buttons for taking readings and altering settings. The operator panel can be mounted in the cabinet front or be used as a portable terminal.