What is a RS232 to RS485 converter?

The main differences between these RS232 to RS485 converter units are that some of them can have a DB9 connector whereas others have a terminal screw header or RJ11 connector, some are isolated some are not, some has more than one RS485 port, some has LED lights for indicating RX/TX data flow, some are port-powered and some needs an external power supply, some are industrial strength, some are consumer products.

The RS232 to RS485 itself, regardless of what model you choose, is simply a device which can convert standard RS232 data signals into RS485 signals and vice versa. Most RS232 to RS485 converters can convert data in both directions, from RS232 to RS485 and from RS485 to RS232, this is also called a bi-directional converter.


When should I use a RS232 to RS485 converter?

RS232 to RS485 converters are mostly used in industrial and commercial environments. The reason is that the RS485 converter can be used for multi-drop networks, meaning that you for example can connect multiple RS485 devices to one computer. Up to 32 devices can be connected in one network to communicate on a single pair of wires (plus a ground wire), and the number can even be increased by using RS485 repeaters. This type of communication is called half-duplex communication. Most quality RS485 converters can communicate in this manner of up to 4000 feet (1200 meters). The RS485 converter is also fairly resistant to noise which is one more reason why it is favored in industrial environments.
Examples of uses for a RS232 to RS485 converter could be for connecting cameras, scales, meters, scanners, PLCs or most other industrial equipment to a computer.


Connecting a RS232 to RS485 converter.

The RS232 to RS485 converter can be used for point-to-point connections (connecting one RS232 to RS485 converter directly to another RS232 to RS485 converter) and point-to-multipoint networks (connecting one RS232 to RS485 converter to multiple RS232 to RS485 converters.
In a RS485 network only one slave and one master can communicate at a time, either transmitting or receiving, but not at the same time, so you might wonder how this is accomplished. Simply speaking the slaves (also called nodes) must be addressed, for example node 1 has address 001, node 2 has address 002 and so forth. These addresses are usually assigned and controlled by software, either the software running at the RS485 master (PC), or software programmed in each of the slaves. Sometimes the equipment connected at the RS485 slaves is addressable by hardware instead of software. Finally, some RS232 to RS485 converters are addressable (by DIP switches) itself, this is however not used very often.



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