Siemens S7200 and Modbus RTU

[micky]

I've got a CPU226 talking via modbus serially then converted to ethernet and being displayed in wonderware. My question is how do read/write bits say like M0.1? I can read the I's and Q's find but I dont understand how to link the modbus address with internal bits in the CPU226.

 

[jvdcande]

Without more info there's no way we can help you out. How do you communicate over modbus with the S7-226? There isn't a native modbus driver for the S7-226, you must have found it here or there or you must have written it yourself, based on info found out somewhere. It all depends on how the translation of S7-22X addresses to modbus addresses is done.

Kind regards,

 

[micky]

I'm using the modbus library that siemens has for the S7-200.

 

[m_turk]

I think you can read V-memory only, not M.

 

[jvdcande]

I think you can read V-memory only, not M.

That's correct. But since there is much more V-memory than M-memory, it should be fairly easy to copy the M-memory to V-memory in order to make it possible to read out the M-memory.

Kind regards,

 

[rohitmane]

That's correct. But since there is much more V-memory than M-memory, it should be fairly easy to copy the M-memory to V-memory in order to make it possible to read out the M-memory.
i have used s7-200 224x cpu as RTU i have update all data to scada that is in single integer but now i have to show data of double integer using counter library vd to scada just want confirmation will double integer update on scada or not