What is the difference between RS232 and RS485?
RS232 operates in an “unbalanced” (single-ended) transmission method; where the receiving device monitors the difference between the signal voltage and a common ground. RS485 is a balanced (differential) transmission method; where each signal has a dedicated pair of wires, with the voltage on one wire equal to the complement of the voltage on the other. The receiving device monitors the difference between these voltages to determine the signal. When the “A” terminal is negative with respect to the “B” terminal the logic “1” state exists. When the “A” terminal is positive with respect to the “B” terminal then a logic 0 state exists. Consult Trans-Cal engineering for termination resistor recommendations when connecting more than 2 devices on a RS485 port or if interference with the digitizer data is suspected due to RF noise considerations.
