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From Christofer Dutz <>
Subject Re: Doing some read-tests with S7
Date Sun, 25 Oct 2020 22:42:00 GMT
Ok ... so I fixed most of the issues.

So-far the problems I need to address are the following:

- When using "BOOL[]" we have to read a bit-string (byte, word, dword) instead and filter
out the bits that are not asked for.
- When reading "STRING(x)[]" (limited strings), we have to split up the request into multiple
items as the typical array notation doesn't work.
- When reading bit-strings the order of the bits looks the wrong way around
- When reading bit-string arrays, I would like to concatenate the values to one bit-string
instead of returning lists of lists


Am 25.10.20, 21:59 schrieb "Christofer Dutz" <>:

    Hi all,

    in order to have some good tests for the S7 protocol, I defined a lot of variables in
one of the data-blocks of one of my S7 devices.
    I then created a little test program that should simply use this to read all sorts of
types of elements.
    With these tests I found some things:

      *   In general all Bit-String operations, when reading arrays, produce lists of lists
… I think it would be cooler if for bit-strings they would return one large List
      *   STRING handling seems to be messed up again
      *   When reading a BOOL array, it seems the S7 only returns the first bit (I would have
expected it to send up to 8 bits in one byte and after that to add more bytes, but it’s
always just one and that always just contains the first bit) -> We need to translate BOOL-array
reads into bit-string operations which return partial lists.
      *   Reading of DATE_AND_TIME arrays seems to be messed up as only the first item is
correct and the succeeding elements are always “null”
      *   Reading of CHAR values seems messed up

    I’ll be working on addressing this asap


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