User`s manual

CP-134U Series User’s Manual Connection Cables and Cable Wiring
5-8
Impedance Matching and Termination Resistors
When using RS-422/485 serial communications, an electrical signal that travels through two
different resistance junctions in a transmission line will sometimes give rise to signal reflection
due to the impedance mismatch. Signal reflection causes signal distortion, which in turn
contributes to communication errors. The solution to this problem is to establish the same
impedance at the ends of the transmission line, as in the line itself, by terminating the ends of the
line with resistors.