Dynaflox ultraD - Modbus Communication Protocol; Modbus-RTU Protocol Introduction; Modbus-RTU Protocol Message Frame

ultraD Series Water Meter Manual
7
 Flow direction
 Alarm, means empty pipe or error

The pulse output function has been open
 Infrared communication
 The battery power is low, please replace the battery as soon as possible

Leakage occurred in the pipe
 m
3
Volume units (can be set GAL (US gallons) and L units according to customer requirements)
 m
3
/h Flowrate units (can be set GPM (US gallons) and L/min units according to customer
requirements)
5. Modbus Communication Protocol
5.1 Modbus-RTU Protocol Introduction
Ultrasonic water meter supports Modbus-RTU protocol. Baud rate: 1200, 2400, 4800, 9600 optional.
Character type 8 data bits, no parity bit, 1 stop bit
5.2 Modbus-RTU Protocol Message Frame
Start Bit
Address
Code
Function
Code
Data Area
CRC Code
Terminator
4 characters’
time
1 byte
1 byte
2 bytes
(register
address)
2 bytes
(number of
register)
16 digital
4 characters’
time

Start Bit: under RTU mode, messages start to send by interval time of 4 characters.

Address Code: Within a network, the address code is unique, range: 1--247. Address 0 is used as a
broadcast address, not for stand-alone communications.

Function Code: the water meter only uses function code 03, namely: read register data.

Data Area: corresponds to the function code 03, there are a total of four bytes when the mainframe sends
commands: