Vcc
GND
Pulse
Vcc
GND
Data
Clock
TX -
TX +
GND
RX -
RX +
CO
M1
CO
M1'
Windsensor
TX -
TX +
GND
RX -
RX +
Dir
ecti
on
Vel
ocit
y
RX-
RX+
X7
X7
X8
K4
K5
Jumper
RT
Jumper
Rear panel
Weather Display-LED
Transmitter
e.g.
data logger
Fig. 3: Example of connection
Information for RS422:
Faults on long cables may affect serial transmission may affect serial transmission, with the serial
interface possibly being destroyed by over voltages. We therefore recommend:
•
The transmission line should be shielded. The shield must be connected to a central earth
potential.
•
With cable connections longer than 100 m twisted pairs should be used for the signal lines +RX/-
RX and +TX/-TX.
•
The ground pins (GND) should also be connected in addition to the twisted signal lines. If major
differences in potential between the transmitter and receiver result in high compensating
currents, isolating interface adapters have to be used.
•
The cable must always be terminated with its surge impedance (100
Ω
to 600
Ω
depending on
cable). With more than one Weather Display LED (slaves) the resistor must be located at the
receiver furthest from the transmitter.
•
The integrated termination resistor (RT=200
Ω
) has to be activated with the use of a jumper (X7)
at the receiver (slaves)(see Fig. 3.).
11 - 30
021503/10/07
