Explorer 4 is the multichannel control unit gathering just one rack till 4 acquisition channels. The system has been planned for the monitoring in continuous of gas and other different parameters, through the related alarms check. All is included in a rack of easy installing container. The rack can be 8 or 16 channels made, useful to monitoring more point. Each independent channel is supplied with 3 relays in outlet. The setup is done through the 3 buttons placed on the front side. The unit gives the power supply to the sensors transmitters in 4-20 mA and a serial unit RS232 for the configuration can be added.