Hi,

Sorry for the late response. I did moderate the email through, but it didn't 
immediately pop up.

On general it is possible so do what you want. Unfortunately the s7 driver is 
still missing a tiny feature to split up the one request into multiple ones, if 
the site of the memory block exceeds the max pdu size. Right now you would have 
to manually split it up into chunks.

I might fix this some time or someone here in the community, but right now 
there are limitations.

Chris

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________________________________
From: Łukasz Dywicki <[email protected]>
Sent: Monday, April 5, 2021 10:27:50 PM
To: [email protected] <[email protected]>
Subject: Re: Is it possible to read a full datablock (DB) from a S7 PLC ?

Hey Denis,
My knowledge of Siemens is fairly limited, but I recall S7 protocol has
support for %DB fields.

Their syntax is described as:



DB{Data-Block-Number}.DB{Short-Data-Type-Code}{Start-Byte-Address}.{Bit-Offset}:BOOL[{Count}]


DB{Data-Block-Number}.DB{Short-Data-Type-Code}{Start-Byte-Address}:{Data-Type-Code}[{Count}]

Shorter syntax is available:


    DB{Data-Block-Number}.{Start-Byte-Address}.{Bit-Offset}:BOOL[{Count}]

    DB{Data-Block-Number}.{Start-Byte-Address}:{Data-Type-Code}[{Count}]


DB{Data-Block-Number}.{Start-Byte-Address}:STRING({string-length})[{Count}]


Have you tried these?

Best,
Łukasz


On 05.04.2021 12:31, Denis Leite wrote:
> Hi,
>
> First of all, excellent work! We´re using PLC4x in innovative projects with
> 2 different multinational factories.
>
> The reason I am writing is that we couldn´t find on the documentation if
> it´s possible to read a full DB(data block) froma Siemens PLC.
>
> Regards,
>

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