The length of total register requested by a single reading command must be less than or equal to 20 registers. Instructions longer than this will be ignored.
Format of command (03) from master
Description of master command
The example will read A01 pipe diameter options and A02 Scale Factor.
slave address: 01(address of this flowmeter)
function code: 03(read instruction)
Address of first reading register: 0000(Address of first register to read)
Quantity of registers to be read: 0003 (need to read 2 registers from 0000)
CRC: 05 CB (Calculating error correcting code according to CRC algorithm)
Format of flowmeter response(03)
Description of flowmeter response example
slave address: 01(address of this flowmeter)
function code: 03(read instruction)
Amount of response Byte: 06 (3 register=6byte)
Data Byte:
00 00(Current pipe diameter is 1inch PVC)
3F 80 00 00(Current Scale Factor is 1.0)
CRC: 2C 89 (Calculating error correcting code according to CRC algorithm)
Byte#
1
2
3
4
5
6
7
8
Node ID
Slave Address
Function Code
Address of first reading register
Address of first reading register
Quantity of registers to be read
Quantity of registers to be read
CRC
CRC
Example 01~FF
01
03
00
00
00
03
05
CB
Byte#
1
2
3
4
5
6
7
8
9
10
11
Node ID
Slave Address
Function Code
Amount of response Byte
Data Byte #1
Data Byte
#2
Data Byte
#3
Data Byte
#4
Data Byte #5
Data Byte
#6
CRC
CRC
Example
01~FF
01
03
06
00
00
3F
80
00
00
2C
89