Delta DVP-15MC Series, Руководство по эксплуатации

Страница: 917 / 972

Appendix A. Modbus Communication
A-13
A_
Byte NO. Name Byte
Byte2
Exception response code
Single byte
Byte3
Low byte of CRC check sum Low byte
Byte4
High byte of CRC check sum High byte
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 DVP-15MC series motion controller via function
code 02. The address of %QX2.0 is 16#A010. 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 16#05 writes one single bit register value

Data structure of a request message:
Byte NO. Name Byte
Byte0
Modbus ID
Single byte
Byte1
Function code
Single byte
Byte2
Modbus address of the bit register
High byte
Byte3 Low byte
Byte4
The value written in the bit register
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 a response message:
Byte NO. Name Byte
Byte0
Modbus ID
Single byte
Byte1
Function code
Single byte
Byte2
Modbus address of the bit register
High byte
Byte3 Low byte
Byte4
The value written in the bit register
High byte
Byte5 Low byte
Byte6
Low byte of CRC check sum Low byte