Chapter 12 Installation and Wiring
12 −24
12.7 Terminal Resistance (In case of using RS-422/485)
(1) For communication via RS-422/RS-485 channel, terminal resistance from external must be connected.
(2) Terminal resistance has the function to prevent distortion of signal by reflected wave of cable for long-
distance communication, and the same resistance (1/2W) as characteristic impedance of cable must
be connected to terminal of network.
(3) When using the recommended cable in 12.6, connect terminal resistance of 120Ω to both ends of
cable. Also when using other cable than recommended, the same resistance (1/2W) as characteristic
impedance of cable must be connected to both ends of cable.
▶ Terminal R esistance: 1/2W , 120Ω, tolerance of 5%
(1) How to connect terminal resistance in case of RS-422
[Figure 12.7.1] Terminal resistance connection diagram in case of RS-422
(2) How to connect terminal resistance in case of RS-485
To Next Page
Loading...
Need help?
General
