These are standards for SERIAL communications that define the pin outs, cabling, signal levels, transmission baud rates and parity checking.

• RS-232 only allows for one master and one slave and is limited to distances of up to 15 meters.
• RS-422 can address up to 10 slaves USING four wires (full duplex) and has a distance capacity of 4000 feet.
• RS-485 can address up to 32 slaves using either a two WIRE (half duplex) or four wire system (full duplex) and has a distance capacity of 4000 meters.

A common mistake is to confuse the electrical standard with the protocol. PROTOCOLS define how the data is structured while the electrical standards determine how the data is physically transmitted. There are many different protocols (i.e. Modbus, DF1, AS511) that can be used on RS-232, RS-422 or RS-485 wired SYSTEMS.

These are standards for serial communications that define the pin outs, cabling, signal levels, transmission baud rates and parity checking.

A common mistake is to confuse the electrical standard with the protocol. Protocols define how the data is structured while the electrical standards determine how the data is physically transmitted. There are many different protocols (i.e. Modbus, DF1, AS511) that can be used on RS-232, RS-422 or RS-485 wired systems.