The mixer is contained in a 8 DIN module box. Supplied from 230VAC mains, it has a dedicated output for power supply switching device art. 1224A. On input it receives a Simplebus 1 type signal and superimposes the monitor power supply for the riser. Up to 100 pieces of apparatus between telephones and monitors can be connected, distributed over 4 outputs. Fitted with LED which signals any shortcircuits on the lines. Fitted with 4 terminals for line termination art. 1216. Dimensions: 140X140X67 mm (8 DIN modules). From the RI013 it is compatible with all Simplebus 2 functions and products. Allows management of alarm signals and direct intercommunication between users without the aid of an interface or porter switchboard, It allows call addressing for up to 120000 users. It should be stressed that the mixer is not compatible with the Simplebus TOP system when main and secondary switchboards are used in the same system, when the intercom function without interface is present and active and when the alarm function is being managed on the system.