The Central Interface module is needed to connect the instruments with Flight Simulator. The CIM can hold 4 strings of modules. Each string can have up to 16 modules connected, so a total of 64 modules can be attached. A module can be a gauge, a Input / Output device or a radio module. For normal operations, 1 Central interface module is enough. Only when you want to drive the gauges by PMsystems from Project magenta, will you need another Central Interface module. This is due to the fact that each interface needs his own port. The interface is powered by any PC power outlet (NOT included) or one of our power supplies and runs on 5/12 v. A USB cable (NOT included) is needed to connect the interface to the computer.