Appendix A. Modbus Communication 
A-15 
  Data structure of a response message: 
Byte NO.  Name  Byte 
Byte0 
Modbus ID 
Single byte 
Byte1 
Function code 
Single byte 
Byte2 
The start address of bit registers where to write values 
High byte 
Byte3  Low byte 
Byte4 
The number of bit registers where to write values 
High byte 
Byte5  Low byte 
Byte6 
Low byte of CRC check sum 
Low byte 
Byte7 
High byte of CRC check sum 
High byte 
  Data structure of an exception response message: 
Byte NO.  Name  Byte 
Byte0  Modbus ID  Single byte 
Byte1  16#80+ Function code  Single byte 
Byte2  Exception response code 
High byte 
Byte3 
Low byte of CRC check sum 
Low byte 
Byte4 
High byte of CRC check sum 
High byte 
Note: How many bytes of data in the request message depend on the number of bit registers in 
the request message. 
  Example 
The value of %QX0.0~%QX0.7 is set to 1000 0001 and the address of %QX0.0 is 16#A000 via 
function code 0F in DVP-15MC series motion controller.   
Request message: 01 0F A0 00 00 08 01 81 26 55 
Response message: 01 0F A0 00 00 08 76 0D 
 
A.6  Table of Registers and Corresponding Modbus 
addresses 
  Register numbers in the motion control module of DVP-15MC series and corresponding addresses 
are listed below: 
Register 
name 
Register number  Explanation  Address (hex)  Attribute 
I  %IX0.0~%IX127.7 
Bit registers 
6000 ~ 63FF 
Read only 
Q  %QX0.0~%QX127.7  A000 ~ A3FF 
Read/write 
I  %IW0~%IW63 
Word registers 
8000 ~ 803F 
Read only 
Q  %QW0~%QW63  A000 ~ A03F 
Read/write 
M  %MW0~%MW32767  0000 ~ 7FFF  Read/write