Algodue ELETTRONICA UPM209 Manuel Utilisateur page 46

INDEX • Modbus protocol
1. Description ....................................................................................................................47
1.1 LRC GENERATION.................................................................................................................................................................... 48
1.2 CRC GENERATION ................................................................................................................................................................... 49
2. Command structure ......................................................................................................52
2.1 MODBUS RTU/ASCII ................................................................................................................................................................ 52
2.2 MODBUS TCP ........................................................................................................................................................................... 54
2.3 FLOATING POINT AS PER IEEE STANDARD ............................................................................................................................ 56
3. Exception codes .............................................................................................................57
3.1 MODBUS RTU/ASCII ................................................................................................................................................................ 57
3.2 MODBUS TCP ........................................................................................................................................................................... 57
4. Register tables ..............................................................................................................59
4.1 READING REGISTERS (FUNCTION CODE $03 / $04) .............................................................................................................. 60
4.2 READING AND WRITING REGISTERS (FUNCTION CODE $03 / $04 / $10) ............................................................................. 70
4.3 CONSIDERATIONS ON THE FULL SCALE VALUE CALCULATION ........................................................................................... 85
5. Reading command examples ........................................................................................87
5.1 MODBUS RTU/ASCII ................................................................................................................................................................ 87
5.2 MODBUS TCP ........................................................................................................................................................................... 89
6. Writing command examples ..........................................................................................91
6.1 MODBUS RTU/ASCII ................................................................................................................................................................ 91
6.2 MODBUS TCP ........................................................................................................................................................................... 97