Converters constitute a separate family. They act as intermediate equipment between various standards of digital interfaces. The digital automation equipment is usually based on the RS-485 standard as the basic transmission system, regardless of the actual protocol. PC computers, on the other hand, are most commonly used as HMI or master stations, typically equipped with RS-232 or USB connections. These standards are incompatible and it is required to use an appropriate converter to provide a conflictless coupling of these different interfaces.