The CNV30xx serial converters are realized in digital technology to obtain high and constant performances. Of compact size, they are designed for DIN rail mounting. In each model the electrical isolation is between the input and output ports and also towards the power supply. This triple isolation solution avoids the problems related to ground loops and improves the noise immunity. The inputs are protected from electrostatic discharges while the outputs can be short circuited, even permanently, without damaging the module. For the RS485 converters the line commutation from receipt to transmission and vice versa can also be made in automatic mode, with an exclusive algorithm which removes any commutation delay. Particular attention deserve the model CNV3030, able to realize an RS485 line directly from the USB port of a PC, and the model CNV3020, which allows to extend over 500mt of distance a standard RS232 serial line maintaining all the control signals, granting a full-duplex communication and using a simple twisted pair cable for wiring.