Bowers M1 - MODBUS RTU Protocol

M1 – M3 Display Units
Page 76
12. MODBUS RTU Protocol
This process allows to connect the M3 to a compatible and programmable automate.
This process allows to control all the functionality of the M3 thanks to a lot of register.
A maximum of 256 register can be read.
Example of a RTU Modbus communication with an automate Pro-Face.
Address: always equal to1
Code: the M3 supports codes « 3 » by reading and « 16 » by written
Data: 1 to 256 register
CRC16: verification code on 2 octets
The following functionality are available:
- Reading of the position of 2 probes
- Instant reading of the value of 2 characteristics
- Preset
- Reading / programing of the tolerances, of the master value, the formula…
Register are compounded by one or a couple of 16 bits words.
Function
Address
Size
(word)
Value
Preset (W)
0
1
1
Start a dynamic measure (W)
1
1
1
Active program (R/W)
4
1
0 or 1
Life word (change each 100ms) (R)
6
1
0 or 1
Stop
7
1
1
Active M3
8
1
1 = measure