Delta Electronics DVP15MC11T Operation Manual page 546

Note:
The value of Byte 2 in the response message is determined by the values of Byte 4 and Byte 5
in the request message. For example, the number of the read bit registers in request message
is A. Dividing A by 8 produces B. If the quotient is an integer, the number of bytes of bit
registers in the response message is B. Otherwise the number of bytes will be B+ 1.
See the example below for details.

Example
Read the state value of %QX2.0~%QX3.4 in DVP15MC11T via function code 02. The address
of %QX2.0 is 0xA010. Suppose %QX2.0~%QX2.7=1000 0001, %QX3.0~%QX3.4=1 0001.
Request message: 01 02 A0 10 00 0D 9A 0A
Response message: 01 02 02 81 11 19 E4

Function code 0x05 writes one single bit register value

Data structure of a request message:
Byte NO.
Byte0
Byte1
Byte2
Byte3
Byte4
Byte5
Byte6
Byte7

Data structure of a response message:
Byte NO.
Byte0
Byte1
Byte2
Byte3
Byte4
Byte5
Byte6
Byte7
Name
Modbus ID
Function code
Modbus address of the bit register
The value written in the bit register
Low byte of CRC check sum
High byte of CRC check sum
Name
Modbus ID
Function code
Modbus address of the bit register
The value written in the bit register
Low byte of CRC check sum
High byte of CRC check sum
Appendix A. Modbus Communication
Byte
Single byte
Single byte
High byte
Low byte
High byte
Low byte
Low byte
High byte
Byte
Single byte
Single byte
High byte
Low byte
High byte
Low byte
Low byte
High byte
A_
A-13