Vaisala HMP243 Guide de l'utilisateur télécharger pdf (Page 97)

HMP240

M210300en Appendix 2: RS 485/422 serial port module

3. NETWORK CONFIGURATION

3.1 Single loop operation

Bi-directional data on one pair is one of the great advantages of the RS 485

line. Set jumpers in connector X4 on the module board as shown in the figure

below.

X1 X2

This jumper setting connects RX HI to TX HI and RX LO to TX LO and se-

lects only one common line termination. The HI and LO terminals of the RX

pair can now be used for operation.

Supplying power from the same end to the whole network prevents common

mode voltages from rising too high (over 7 V).

• Connect wires to the transmitter's serial connector.

• Check the wiring.

The following procedure must be repeated with all transmitters.

• Open the transmitter cover.

• Pull out the RS 485/422 serial port module, if it is already mounted.

• Set the serial port of the terminal to 4800 baud, even parity, seven

data bits and one stop bit, full duplex (4800 E 7 1 FDX).

RX GND TX

X17

• The serial settings of the transmitter must also be 4800 E 7 1 FDX

and the transmitter must be in STOP mode. If these factory settings

have been changed, they must be returned. Connect the RS 232C port

of the terminal to connector X17 on the top of the main board and

switch the power on.

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Vaisala HMP243 Guide de l'utilisateur Page 97