https://youtu.be/WfGRIGWz9jg?si=l-m82a9vcd6PPN_C

Hey,

I doesn't know if it is possible directly from the S7 Protokol (with the SZL Headers), I have no experience with them.
As mentioned, it is possible to do it by generating the files described in my last reply.

Is a Read_SZL functionality implemented in the snap-S7 lib ?

Seems implemented but not documented.

        snap7/client/__init__.py:    def read_szl_list(self) -> bytearray
        snap7/client/__init__.py:    def read_szl(self, ssl_id: int, index: int = 0x0000) -> S7SZL
        snap7/types.py:class S7SZL(ctypes.Structure)

I'm trying to read and effectly it return somthing:

        client = snap7.client.Client()
        #p = client.read_szl_list()
        
        p = client.read_szl(0,0)
        h = p.Header
        for field in h._fields_:
            header = field[0]
            headerVal = getattr(h, field[0])
            print(h,header,headerVal)
        print(p.Data)

return:

        <S7SZLHeader LengthDR: 8, NDR: 113> LengthDR 8
        <S7SZLHeader LengthDR: 8, NDR: 113> NDR 113
        <snap7.types.c_byte_Array_16380 object at 0x7efef366d130>

From s7 siemens documentation:
SZL_ID (W#16#...)

        0111 -> identification
        0012 -> category
        0F12 -> partial headers 
        0113 -> 1 record on the memory zone pointed
        0113 + index 1 -> working memory
        .....

But i don't know how arrange data readed in S7SZL(ctypes.Structure) and i do not understand why it ask un ssl_id as argoument and non un SZL_ID (W#16#...) and how to convert this

Thanks for any suggestion

I will give some tries next week !
Links about your S7 Siemens documentation ?

(tested on s7-1500 with ssl_id=0x0000, index=0x0000)
That how Wireshark understands the S7SZL.Data.

(tested on s7-1500 with ssl_id=0x0011, index=0x0000)

list of possible ssl_id:
ssl_id = [0x0000, 0x0011, 0x001c, 0x0024, 0x0074, 0x0124, 0x0424, 0x0524, 0x0f00, 0x0f11, 0x0f1c, 0x0f24, 0x0f74]

hope it will help you all, I'm also interested in getting data block layout "programmably".

@luewh I will add this to documentation as soon as possible on my side