LRF-3000S Ultrasonic Transit-time Flow meter
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8.
Appendix3 – Serial Interface Network Use
and Communications Protocol
8.1.
Overview
The flow meter has perfect communication protocol. It can also be connected to a RS-485 Modbus .
Two basic schemes can be chosen for networking, i.e. the analog current output method only using the flow meter
or the RS232 communication method via serial port directly from the flow meter. This method is suitable to
replace dated instruments in old monitoring networks. The later method is used in new monitoring network
systems. It has advantages include low hardware investment and reliable system operation.
When the serial port communications method is directly used to implement a monitoring network system, the
address identification code of the flow meter is used as a network address code. Expanded command set with [W]
is used as communication protocol.
RS-232 (Cable length 0 ~ 15m ) or RS-485 ( cable length 0 ~ 1000m ) can be directly used for data transmission
links for a short distance. Current loop can be used in medium or long distance transmission.
When the flow meter is used in a network environment, various operations can be performed by a host device,
except for programming of the address identification code, which needs to be done via the flow meter keyboard.
The command answer mode is used in data transmission, i.e. the host device issues commands and the flow meter
answers correspondingly.
Common/special flow / thermal data monitoring system developed by our company can be used for flow data
collection. Based on characteristics of the flow meter, the system makes full use of software and hardware designs
with flow meter features. The system is simple, clear, economical, and reliable in operation.
Attention
In the communication protocol used functions, RS232 and RS485 serial communications cannot
be used at the same time.
8.2.
Serial port definitions
Flow meter - RS232:
TXD send
RXD receive
GND ground
PC:
PIN 1 empty
PIN 2 RXD send
PIN 3 TXD send
PIN 4 ground
PIN 5 ground
PIN 6 empty
PIN 7 empty
PIN 8 empty
PIN9empty
