Appendix C - Modbus Communication Examples - Siemens SITRANS F M MAGFLO series Operating Manual

Modbus RTU RS-485
APPENDIX C
Modbus communication
examples
28
APPENDIX C
01 (0x01) Read coil status
Query
Slave address
Function
Starting Address Hi
Starting Address Lo
No. of Points Hi
No. of Points Lo
CRC
Example:
Read Hold Totalizer 1 (0:00011)
Query: 1,1,0,10,0,1,221,200
Response: 1,1,1,0,81,136
03 (0x03) Read holding registers
Query
Slave address
Function
Starting Address Hi
Starting Address Lo
No. of Points Hi
No. of Points Lo
CRC
Examples
Read absolute mass flow (4:03001)
Query: 1,3,11,184,0,2,70,10
Response: 1,3,4,64,195,82,139,98,200
Absolute mass flow = 6.10383 kg/sec.
Read absolute density (4:03005)
Query: 1,3,11,188,0,2,7,203
Response: 1,3,4,68,54,162,145,182,1
Absolute density = 730.54010 kg/m
Read sensor temperature (4:03007)
Query: 1,3,11,190,0,2,166,11
Response: 1,3,4,189,216,115,34,251,77
Sensor temperature = −0.10569 °C
SFIDK.PS.023.D2.02
Response
Slave address
1 byte
1 byte Function
Byte Count
1 byte
1 byte Data Coil
1 byte :
1 byte Data Coil
2 bytes CRC
Response
1 byte Slave address
1 byte Function
Byte Count
1 byte
1 byte Data Hi
1 byte Data Lo
1 byte :
2 bytes Data Hi
Data Lo
CRC
3
1 byte
1 byte
1 byte
1 byte
:
1 byte
2 bytes
1 byte
1 byte
1 byte
1 byte
1 byte
:
1 byte
1 byte
2 bytes