Rs232 Serial Communication; Rs485 Serial Communication; Direct Connection Between Rs485 And Rs232 Without Converter - LCD C-DESK-BR User Manual

INSTRUMENT
INSTRUMENT
If the RS485 network exceeds 100 metres in length or baud-rate over 9600 are
used, two terminating resistors are needed at the ends of the network. Two
120 ohm resistors must be connected between the "+" and "–" terminals of the
line, on the terminal strip of the furthest instruments. Should there be different
instruments or converters, refer to the specific manuals to determine whether it is
necessary to connect the above-mentioned resistors.

DIRECT CONNECTION BETWEEN RS485 AND RS232 WITHOUT CONVERTER

Since a two-wire RS485 output may be used directly on the RS-232 input of a PC or remote display,
it is possible to implement instrument connection to an RS-232 port in the following manner:
INSTRUMENT
RS 485 – →
RS 485 + →
This type of connection allows A SINGLE instrument to be used in a ONE WAY
mode.

RS232 SERIAL COMMUNICATION

RS232 TXD
RS232 RXD
GND

RS485 SERIAL COMMUNICATION

max 500 m
24 VDC
+
VIN
0
CONVLAU
TX
RX
RS232
RXD
GND
- 21 -
INSTRUMENT
RS485 +
TX+
RS485 -
TX-
RX+
RX-
2
3
PC
5
DB9-F
INSTRUMENT
RS485 +
RS485 -