Apply Precision/Scale/Offset to struct in modbus sensor

[janiversen]

The single values in struct are corrected with presicion, scale and offset,
just as it is done with single values.

Breaking change

Proposed change

the struct configuration e.g.

sensors:
  - name test1
  - data_type = custom
  - count = 8
  - struct = ">4f"

Could result in very long strings being delivered back, due to many decimal digits.

sensors:
  - name test1
  - data_type: custom
  - scale: 1
  - offset: 0
  - precision: 2
  - count: 8
  - struct: ">4f"

will cut the decimals to 2.

Type of change

• Dependency upgrade
• Bugfix (non-breaking change which fixes an issue)
• New integration (thank you!)
• New feature (which adds functionality to an existing integration)
• Breaking change (fix/feature causing existing functionality to break)
• Code quality improvements to existing code or addition of tests

Example entry for configuration.yaml:

# Example configuration.yaml

Additional information

• This PR fixes or closes issue: fixes Modbus TCP - Function code 0x03 (read holding registers) - Cannot use all registers read #44254
• This PR is related to issue:
• Link to documentation pull request:

Checklist

• The code change is tested and works locally.
• Local tests pass. Your PR cannot be merged unless tests pass
• There is no commented out code in this PR.
• I have followed the development checklist
• The code has been formatted using Black (black --fast homeassistant tests)
• Tests have been added to verify that the new code works.

If user exposed functionality or configuration variables are added/changed:

• Documentation added/updated for www.home-assistant.io

If the code communicates with devices, web services, or third-party tools:

• The manifest file has all fields filled out correctly.
  Updated and included derived files by running: python3 -m script.hassfest.
• New or updated dependencies have been added to requirements_all.txt.
  Updated by running python3 -m script.gen_requirements_all.
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[janiversen]

@vzahradnik did you see this PR ?

[vzahradnik]

Not yet. I probably overlooked it. I will check.

[janiversen]

thanks.

[janiversen]

@vzahradnik any comments here ? You wrote in one of your PR´s that you had a comment, and when that was solved you would approve.

It would be nice to get this merged alongside your PR´s so we can get modbus moving.

[janiversen]

@vzahradnik any comments here ? You wrote in one of your PR´s that you had a comment, and when that was solved you would approve.

It would be nice to get this merged alongside your PR´s so we can get modbus moving.

[vzahradnik]

Interesting you don't see that. Let me give you a picture:

[janiversen]

I know why you did not finalize your review :-)

The comment states the value is 1.00e-28 which is a very small number so it converts to 0.00. I did this on purpose to ensure that it worked with very small numbers.

[vzahradnik]

OK, it makes sense now. I will approve. Thanks for clarification.

[janiversen]

@MartinHjelmare you changed the title a while ago, do you have other review comments?

It would be nice to gave this in the next point release.

[MartinHjelmare]

Looks good!