RS232 or Recommended Standard 232 is a serial communication standard that is used to transmit data by encoding the data into a series of bits that is transmit by differing levels of output voltage. Where a positive voltage (between +3V and +15V) change is equivalent to a binary 0 and a negative voltage (between -3V and -15V) is equivalent to a binary 1. These binary values make up the basics of the packet structure for each of the different serial string options.
Traditionally RS232 has been used for point to point communication between a computer and an end device (for example a router). However since the use of USB and Ethernet for point to point communication serial and RS232 has been largely unused. The exception to this is for connection and outputting of legacy devices in many industrial networking environments.
Much like RS 232, RS 422 (recommended standard 422) is a serial communication standard that is used to transmit data by encoding a series of data bits into differing levels of output voltage. The difference between the two standards is around the capability and capacity of each standard. In general RS422 promises higher transfer speeds and better noise immunity this is in part due to a lower voltage threshold and changes to the reference ground voltage