Sub-function Hi
1 byte
Sub-function Lo
1 byte
Data Hi
1 byte
Data Lo
1 byte
:
:
Data Hi
1 byte
Data Lo
1 byte
CRC
2 bytes
Example: Read Return Slave Message Count (address 529)
Query: 1,8,0,14,0,0,129,200
Slave address = 1 (0x01)
Function = 8 (0x08)
Sub-function Hi, Lo = 0, 14 (0x00,0x0E)
Data Hi, Lo = 0, 0 (0x00,0x00)
CRC = 129,200 (0x81, 0xC8)
Sub-function 0x000E = 14 = Read Return Slave Message Count
Response: 1,8,0,14,0,97,64,32
Slave address = 1 (0x01)
Function = 8 (0x08)
Sub-function Hi, Lo = 0, 14 (0x00,0x0E)
Data Hi, Lo = 0, 97 (0x00,0x65)
CRC = 64,32 (0x41, 0xE3)
Read Return Slave Message Count = 0x0065 = 97 message received
C.3
Changing Modbus communication settings
Changing communication parameters, for example Baud Rate, Modbus Parity Framing or Bus
Address effects the Modbus communication as follows:
• The new settings have effect only after a reset, either by restarting the device or writing the
value 1 to Modbus address 600 Restart communication.
• The new settings will not have effect until the Modbus driver has responded to any ongoing
Modbus request.
NOTICE
Setting addresses in a multidrop network
It is recommended NOT to use the default address in a multi-drop network. When setting
device addresses, make sure that each device has a unique address. Replication of addresses
may cause abnormal behavior of the entire serial bus and make the master unable to
communicate with all slaves on the bus.
Modbus communication FCT010
C.3 Changing Modbus communication settings
SITRANS MASS 2100 & FC300 (FCT010/DSL)
156
Operating Instructions, 06/2020, A5E39788682-AB