Data communication interfaces, Figure 25 – Vaisala WXT520 User Manual
Page 52
User’s Guide ______________________________________________________________________
50 __________________________________________________________________ M210906EN-C
Data Communication Interfaces
0505-206
Figure 25
Data Communication Interfaces
With RS-485 and RS-422 interfaces, termination resistors should be
used at both ends of the line, if data rate is 9600 Bd or higher and
distance is 600 m (2000 ft) or longer. Resistor range 100 ... 180
Ω
is
suitable for twisted pair lines. Resistors are connected across RX- to
RX+ and across TX- to TX+ (with RS-485 only one resistor needed).
The termination resistors will remarkably increase power consumption
during data transmission. If low power consumption is a must, a 0.1 uF
capacitor should be connected in series with each termination resistor.