© Adolf Thies GmbH & Co. KG · Hauptstraße 76 · 37083 Göttingen · Germany
021408/04/21
Phone +49 551 79001-0 · Fax +49 551 79001-65 · [email protected] ·
Page 19 of 20
Advice for RS422:
Interferences on long lines can affect serial transmission. Excess voltage can destroy the
serial interface. We therefore recommend:
•
The transmission line should be screened. The screen must be connected to central earth
potential.
•
For cable connections exceeding 100m in length, twisted cable pairs should be used for
signal lines +RX/-RX and +TX/-TX.
•
The ground pins (GND) should be connected in addition to the twisted signal lines. If
major differences in potential between transmitter and receiver result in high
compensating currents, interface adapters for potential separation must be used.
•
The cable must at all events be terminated with is characteristic impedance (100
Ω
to
600
Ω
according to cable). In the event of several Winddisplay LED’s (Slaves), the resistor
must be fitted to the receiver that is the farthest away from the transmitter.
•
The integrated termination resis
tor (RT=200Ω) can be activated (
) through use of a Jumper (X7) on the receiver (slave).
6.2.2.2 COM 2, 3, 4, 5
•
COM2: For input HDT or DDC telegram
•
COM3: For input VBW, VHW or VTG or DDC telegram
•
COM4: For output NACOS telegram.
•
COM5: For output CUSTOMER telegram.
Description of the NMEA-inputs and the output telegrams refer to chapter 8.
Connection respectively takes place via the clamp connectors labelled COM 2-5.
Des.
Clamp connector:
COM 2, 3, 4, 5
TX-
transmitter
TX+
GND
ground
RX-
receiver
RX+
Output cycle (NACOS , CUSTOMER):
The output cycle for the respective telegram package of NACOS and CUSTOMER interface
takes less than 1 second. The output cycle of maximum1 second is warranted with the
default baud rate of 4800Bd or higher. There are intervals of respectively at least 20ms
between the individual telegrams.
