ETC4420 is programable digital thermostat based on a microprocessor with a selectable relay or SSR control output for On/Off, P, PI, PD, PID action and soft start or self-tuning function. For the alarm output selectable NO or NC relay offers 4 different output types. The unit is provided with a configurable input for Pt 100 and thermocouples (j, K, T, S,R). Optional RS 485 module is available for communication via Modbus RTU protocol. Both the set and process values are viewed on a 2x4 digit display. ETC4420 allows 3 levels paremeter protection to prevent authorized access to setting.