An Alarm Annunciator is a device which is connected with the field devices. And keep continuous monitoring of the fault signal. However an Alarm Indicator is just to indicate the fault signal and is not connected in real with the field devices. 

An  8 channel Alarm Annunciator means, it has 8 inputs and can be connected with 8 different devices in the field. 

Yes, our Alarm Annunciator can be connected with the existing SCADA system. Our Alarm Annunciators have Modbus RTU communication protocols and can communicate with the existing SCADA system.