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Logo Modbus Big Endian Little Endian

5/5/2023 2:35 PM	Rate (0)
AutoGen_1777689 Joined: 4/25/2023 Last visit: 5/9/2024 Posts: 2 Rating: (0)	I have some new Siemens Logo's and some of the units are giving the data via Modbus as Big Endian and some as Small Endian - I have read that it should just be Big but I seem to be getting this different. Does anyone have any ideas? For example I have a register which is reading 1 on the logo but it is reading 256 if I interpret it as a Big Endian

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5/5/2023 2:38 PM	Rate (0)
ixo65 Grandmaster Joined: 12/18/2014 Last visit: 12/30/2025 Posts: 36385 Rating: (4545)	Siemens works with Big Endian, also by the LOGO!.

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This contribution was helpful to 1 thankful Users LOGO! Support

5/5/2023 3:06 PM	Rate (0)
AutoGen_1777689 Joined: 4/25/2023 Last visit: 5/9/2024 Posts: 2 Rating: (0)	Yes, this is what I thought but it seems to have changed now. I have a register reading 1895 on the logo which should be reading ==0767 but instead, it is reading 6707== which is actually 26375? On the PLC's in the past, they have all been fine but the latest batch seem different as we have not changed anything else?

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5/5/2023 3:12 PM	Rate (0)
ixo65 Grandmaster Joined: 12/18/2014 Last visit: 12/30/2025 Posts: 36385 Rating: (4545)	I am not aware that anything has changed. Makes no sense to me. However, if you still think that something has changed, I can only recommend that you ask Siemens directly. You can do this with a Support Request.

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5/8/2023 7:59 AM	Rate (0)
LOGO! Support Gold Expert Joined: 9/19/2018 Last visit: 12/6/2024 Posts: 399 Rating: (47)	All LOGO! versions use Big Endian. If your communication partner uses Little Endian, you have to swap the bytes.

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