Chapter 9 Appendix-Serial interface network use and communications protocol
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Chapter 9 Appendix-Serial interface network use and
communications protocol
9.1. Overview
The transmitter has perfect communication protocol. It can also be connected to a
RS-485. Two basic schemes can be chosen for networking, i.e. the analog current
output method only using the flowmeter or the RS485 communication method via
serial port directly using the flowmeter. The former is suitable to replace dated
instruments in old monitoring networks. The later is used in new monitoring
network systems. It has advantages such as low hardware investment and reliable
system operation.
When the serial port communication method is directly used to implement a
monitoring network system, the address identification code (in window M46) of the
flowmeter is used as network address code. Expanded command set with [W] is
used as communication protocol. Thus analog current loop and OCT output of
flowmeter can be used to control the opening of a control valve. The relay output
can be used to power-on/off other equipment. The analog input of the system can
be used to input signals such as pressure and temperature. The system provides
an RTU function for flow measurement.
RS-485(0~1000m) can be directly used for data transmission link for a short
distance. The command answer mode is used in data transmission, i.e. the host
device issues commands and the flowmeter answers correspondingly.
