Model FL3102
29
7.4 MODBUS Write Command Protocol (Query/Response)
7.4.1 MODBUS Write Query Message
Byte
MODBUS
Range
Referenced to FL3102
1
st
Slave Address
1-247* (Decimal) FL3102 ID (Address)
2
nd
Function Code
06
Preset Single Register
3
rd
Register Address Hi**
00
Not used by FL3102
4
th
Register Address Lo**
00-FF (Hex)
FL3102 Command Registers
5
th
Preset Data Hi
00-FF (Hex)
FL3102 Hi Byte Command Data
6
th
Preset Data Lo
00-FF (Hex)
FL3102 Lo Byte Command Data
7
th
CRC Lo
00-FF (Hex)
CRC Lo Byte
8
th
CRC Hi
00-FF (Hex)
CRC Hi Byte
Figure 35 MODBUS Write Query Message
NOTE* –
Address 0 is reserved for broadcast mode and will not be supported at
this time.
NOTE** –
Register Address can be maximum of 9999 Address Locations (0000-
270E)
7.4.2 MODBUS Write Response Message
Byte
MODBUS
Range
Referenced to FL3102
1
st
Slave Address
1-247*(Decimal)
FL3102 ID (Address)
2
nd
Function Code
06
Preset Single Register
3
rd
Register Address Hi**
00
Not used by FL3102
4
th
Register Address Lo**
00-FF (Hex)
FL3102 Command Registers
5
th
Preset Data Hi
00-FF (Hex)
FL3102 Hi Byte Command Data
6
th
Preset Data Lo
00-FF (Hex)
FL3102 Lo Byte Command Data
7
th
CRC Lo
00-FF (Hex)
CRC Lo Byte
8
th
CRC Hi
00-FF (Hex)
CRC Hi Byte
Figure 36 MODBUS Write Response Message
NOTE* -
Address 0 is reserved for broadcast mode and is not be supported at
this time.
NOTE
**
-
Register Address can be a maximum of 9999 Address Locations (0000-
270E)
7.4.3 Function Codes Supported
Function Code 03 (Read Holding Registers) is used to read status from the slave
unit. Function Code 06 (Preset Single Register) is used to write a command to
the slave unit.