RS232/RS422/RS485 -What are the differences?
This serial interface is the most common serial interface. It uses a
2 wire system to communicate. Most serial devices are compatible with
this interface, and most older computers come with this port. However,
this interface does have its weaknesses:
-It can only send a signal up to 50ft without any active serial
-It is limited in its data transfer speed(20kb/s).
-Since its transmit and receive lines are linked through the same
ground(single-ended referenced) it tends to pick up noise.
-Only one device can connect to the port at a time(there are some rare
does have its advantages to RS232,
it also has its disadvantages. RS422 is not supported by as many
devices as RS232. It also has a lot of advantages over RS232. Its main
difference is that it uses 4 wires to communicate rather than 2. Some
of it’s specs are as follows:
-Can support up to 32 devices on one port, through multiple switches
-Can transfer data at a higher speed than RS232(10Mb/s-100Kb/s).
-Can extend longer distances than RS232(from
500 to 4000 ft).
-It has a differential reference for its transmit and receive
RS-485 has even more commonalitites with RS422
than RS232. They both support up to 32 devices, and they both have the
same data transfer rate(10Mb/s-100Kb/s) and can be extended to the same
length(from 500 to 4000 ft). RS485 does use less cables than RS422
since it is a 2 wire system, reducing clutter. However, RS485 is more
difficult to program than RS422.