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31
B.
Appendix: Communications with QNA-412 (RS485).
The QNA-412 has the option for RS-485 communication with a PC. This
connection is via the R2 port on the QNA.
This type of communication is done when the equipment is at a considerable
distance (maximum 1200m) from the computer from which readings are to be made.
To connect in this way, the cables that must be used are:
•
PC. RS-232 / RS-485 Converter
RS-232
P.C. (DB9)
P.C. (DB25) RS-232/485 (DB9) Converter
3–Tx 2–Tx
2–Rx
2–Rx 3–Rx
3–TX
7–RTS
8–CTS
5–GND 5–GND
5–GND
•
QNA-412 RS-232 / RS-485 Converter
RS-485
QNA-412
QNA-412
RS-232/485 (DB9) Converter
2–Tx/Rx(-) 2–Tx/Rx
(-)
3–Tx/Rx(+) 1–Tx/Rx
(+)
6–GND 5–GND
Front view
1
6
2 3 4 5
Ensure that the RS-232 cable is not connected to the PC. This is a priority port for
the RS-485.
This connection will prevent the QNA from communicating via the RS-485 port.
