This card is destined for a control slot of every control unit and it offers 4 independent loudspeaker line outlets. Measurement of the lines can be done by 2 methods: the impedance method or LOOP method. The card detects failure of the amplifier and switches the 100 V signal between internal buses and individual amplifier input on the card. Thanks to built-in dedicated measuring component on an SCUE-4CTRLN card monitors the status of the internal rail.