DVP-15MC Series Motion Controller Operation Manual
B-2
B.1 Modbus TCP Message Structure
Modbus TCP message structure
Byte NO. Name Explanation
Byte0
Transaction identifier
High byte
0
Byte1
Low byte
Byte2
Protocol identifier
High byte
0
Byte3
Low byte
Byte4
Modbus data length
High byte
The number of bytes of
Modbus address and the
data after it.
Byte5
Low byte
Byte6
Modbus ID Single byte
0~16#FF
Byte7
Function code Single byte
Byte8
Register address in the
controller
High byte
0~16#FFFF
Byte9
Low byte
Byte10
Modbus data
High byte
The number of bytes of
Modbus data is
determined by function
code.
B.2 Modbus Function Codes Supported in Modbus TCP
Modbus function codes which DVP-15MC series motion controller supports
Function
code
Function Register
16#02
Read bit register value; maximum 256 bits of data could
be read at a time.
%IX and %QX
16#03
Read one single or multiple word register values;
maximum 100 words of data could be read at a time.
Write one single bit register value.
Write one single word register value.
16#0F
Write multiple bit register values; maximum 256 bits of
data could be written at a time.
% QX
16#10
Write multiple word register values; maximum 100 words
of data could be written at a time.
%QW and %MW