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Bit representation of word

8/31/2023 9:11 PM	Rate (0)
秋菊披霜 Posts: 4 Rating: (0)	??? [snip]
秋菊披霜 Posts: 4 Rating: (0)	Last edited by: Jen_Moderator at: 09/12/2023 05:11:29 Neue Überschrift nach Splitten Last edited by: Jen_Moderator at: 09/12/2023 05:33:51 Post edited to make it accessible.
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9/12/2023 5:42 AM	Rate (0)
Stefan Arcularius Platinum Expert Joined: 1/21/2013 Last visit: 1/14/2026 Posts: 4400 Rating: (653)	Hi I am not quite sure what your question is. Your picture shows a symbolic name for the double word address %DB2.DBD0. If you address a single bit - as in your case %DB2.DBX0.0 - from this variable, your input will be highlighted in orange as a warning that you are using an address without a symbolic name. This is a system behavior of STEP 7 TIA Portal and can be very useful. In your case, you will run into trouble when you add a new variable to DB2 at the top. In this case, the address of the variable you are using (currently %DB2.DBD0) changes, while %DB2.DBX0.0 remains untouched. So you are accessing the wrong bit in this case. There may be a solution without such a warning, but to provide you with such a solution, we volunteers need to know your system (PLC family) and your goal. Kind regards Stefan

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9/12/2023 10:13 AM	Rate (0)
qwazee Platinum Expert Joined: 3/30/2020 Last visit: 12/11/2025 Posts: 5656 Rating: (1083)	Structure of DWORD / WORD / BYTE as used by S7 PLCs is shown in the attached text file. Assume %MD10 == 1, then the following is also true: + %MW10 == 0 and %MW11 == 1 + %MB10 == 0 and %MB11 == 0 and %MB12 == 0 and %MB13 == 1 + %M13.0 == TRUE and other bits in %MD10 is FALSE Attachment dword-word-bytes-bits.txt (216 Downloads)
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