MB_CLIENT Error

[robror_]

 

Hi there!

I'm trying to communicate a S7-1500 CPU via Modbus TCP with an CJ2 PLC using a CP1W-MODTC61 card.

I configurated the MB_Client and the CP1W-MODTC61 was also configured as the attached files show. The thing is that I could not read any data from the PLC (the registers are in the correct address and memory area) and I tried different combinations until I started to get data (with the correct values) for a moment, even with a configuration I already tried.

After that the block kept writing a 8200 error in the status word and no data was received. According to the manual that reads:

    A different Modbus request is currently being processed via the port.
    Another instance of MB_CLIENT with the same connection parameters is processing an existing Modbus request.

I can confirm that there is no other device doing a Modbus request in either the 1500 or the CJ2, and I only have one MB_CLIENT block in the entire program.

So that's where my question comes, is the CPU detecting another "ghost" request, even if there shouldn't be any? Or am I missing something in the CONNECT structure of the block?

Thanks in advance for your support!

 

 

Click to choose files

[Moggie]

Try putting a normally closed of "BUSY" in series with "M0.7" in the "REQ" input

[Hati]

On 9/14/2024 at 10:24 AM, Moggie said:

Try putting a normally closed of "BUSY" in series with "M0.7" in the "REQ" input

Yeah, using a clock bit for the REQ is a bad idea. You need to evaluate the status of the block for the REQ activation. BUSY, DONE and ERROR evaluation needs to be the conditions for the REQ activation.