RS232, RS485 and RS422 Converter for Serial Data Communication

Many PCs and compatible computers are equipped with one or two serial RS232 ports.
Most of the time this is a male sub-D connector with 9 pins. Sometimes you see sub-D connectors with 25 pins.
The serial port on a PC is a full-duplex device meaning that it can send and receive data at the same time. In order to be able to do this, it uses separate lines for transmitting (Tx) and receiving (Rx) data therefore a 3 wire cable or a shielded 2 wire can be used, where the shield is used for signal ground (GND).
 

RS232 Mini Converter	RS232 DIN-rail Converter	RS232 Converter with Galvanic Isolation	RS232 Procol Converter

RS232 to RS485 or RS422 converter

In the industry a lot of field equipment does not have a RS232 port but a RS422  for full duplex data communication or a RS485 port for half duplex data communication. RS485 or RS422 has better noise immunity than RS232 and with RS422 or RS485, communication at max. baud rate is possible over a much longer distance (1km).  In cases where a computer with a RS232 port has to communicate with a RS422 or RS485 device, you will need a converter. These converters are available in all kind of versions. There are the mini converters who take their power from the RS232 port (RTS and DTR signals). Then you have desktop and DIN-rail versions. All these converters are available with or without galvanic isolation between the RS232 computer port and the RS422 or RS485 device. Galvanic isolation avoids ground loops which can destroy the RS232 port of the computer. It is also possible to use optic fiber converters with a RS232, RS422 or RS485 interface. In that case there is also galvanic isolation between the computer and field equipment.