EC3 series is the most economical solution for sequential control and communication monitoring and can operate independently, allowing the user to achieve stand-alone monitor, e.g. monitoring phototransistor coupler, proximity switch, optical sensor, indicator and illumination switch. Through serial ports, EC3 is able to connect to control devices such as PLC, frequency inverter and temperature controller, which can be said to be a programmable application solution that is cost-friendly and highly reliable.