Could someone give advise where is the problem?

 Hello

Duris_I

Where you did that cfg of QB_Start and Count? 

This is not a problem, this is the reason why I want to update old modbus blocks in the program to newer version.

The problems is that new V3.0 blocks can not establish communication with same hardware setup, which is working fine with older modbus blocks.

Yes, I did check all error codes and they are not helpful: check port, check wires and blablabla.

This port and wiring work fine with example 1 from pdf.

Comm Load: STATUS #7000 means "block idle" - thats all. Not helpful.

Slave STATUS: #7000 means block idle and 8280 = "

Negative acknowledgment when reading module"

You can find more detailed information on error causes in theRDREC.STATUS static parameters and in the description of the SFB RDREC.

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  Help

  Check the input at the PORT parameter

   

  - What does mean "check" ?? I have checked. Whats now? Port is same as in working example.

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  Help

  Set the COM_RST parameter prior to the initial call.

   

  - Where is this parameter and "set" means set to "true" or set to some value? To which value?

I can trigg it witjh #initial call, #first scan or always true - no difference

Before I wrote to support forum I did quite several memory resets, start/stop and upgraded PLC now to latest firmware. It just does not work as it should if you take into account that same PLC and setup can run older versions of MB blocks with no problem.

Really?

I thought it is shown in PDF, which is attached, that DONE is not on. And this is the problem.

How the hell I can troubleshoot Comm instruction if all that I have from Siemens is status 7000, which tells that instruction is idle? :)

You can not start Comm without Slave MB_DB or Master MB_DB , sorry. But you can try.

Every instruction has EN input, which can/may be true all the time.. No written known restrictions about that.

Then some instructions have REQ inputs - they must be executed only upon needs. 

If it would be Master, it has REQ, then you need sequence. If you have Slave, it does not have REQ - can be straight forward.

Why should I change HW/SW configuration if it actually works with older blocks? The program only consists of Modbus FB and DB , HW is not changed from previous version. Port setup is correct, CB1241 - hard to make a mistake. Nothing else attached to CPU:

Could you actually show print screen of your working sequence?

https://support.industry.siemens.com/cs/ww/en/view/47756141

Same result. 7000 + 8280

And SAME "sequence" recommended by Siemens (had to change RS485 port to match HW config)