施耐德勾选 “启用编程协议”后，可使用502端口90功能码编程。

1和2功能码可用来转发%M内部位寄存器

3和4功能码可用来转发%MW字寄存器

把%I0寄存器映射到%MW0

把%Q0寄存器映射到%MW1

 

参考资料：

https://www.se.com/my/en/faqs/FA308725/

 

How can I read %I/Q or %M on my M221 M241 M251 M258 LMC058 using Modbus ?

Published date: 25 January 2018

 

2 cases have to be considered: M221 or (M241 M251 M258 LMC058).

M221 :

%M (internal bits) can be accessed using function codes from the table below (extracted from SoMachine Basic online help).
Note that %I (physical inputs) and %Q (physical outputs) can not be accessed directly by Modbus.



M241 M251 M258 LMC058:

%M (internal bits) cannot be accessed by Modbus.
But %I (physical inputs) and %Q (physical outputs) can be accessed using function codes from the table below (extracted from SoMachine online help).