ERT-04 transmitter is intrinsically safe (Ex ia IIC T4 Ga) with ability to obtain metal loss/corrosion rate from all ER probes manufactured in PZD. Data transmission and powering of the transmitter with one cable (with four strands of wire) is done. Each probe is connected to the Modbus loop (RS-485) by an identifier (deep) switch. Each Modbus ring has the ability to connect 32 transmitters. ERT-04 transmitter is suitable for refineries, factories and all chemical processing systems where the probes are not far from each other and it is possible to gather their information in DCS.