Modbus Data_Type = "BCD"

### Use Case

Hi.
A Modbus device delivers some Registers as data_type = **BCD**.
For example the "Date & Time" information via 3 Bytes (24bit) as BCD.

So far, I did not find a way to decode these registers :-(

Question is:
Is there a way to decode **BCD** coded registers?
or
could this become a **new feature**??

Thanks for your the brillliant "Telegraf"
Cheers
Jurgen

### Expected behavior

Decode for example:
Read 3-bytes and assign 4-bits per digit
and
assign 2 digits to the 1st number ( e.g.: the day)
assign 2 digits to the 2nd number (e.g.: the month)
assign 2 digits to the 3rd number ( e.g. 2 digit year)
etc.

### Actual behavior

??

### Additional info

_No response_

Start by locating Telegraf's Modbus input and its existing register data-type decoding. Review how register values are represented and how other data types are tested, then determine the supported BCD byte and digit layout from the issue's three-byte date example. Done means BCD registers can be decoded with documented behavior and coverage for the requested layout.

Written by the indexing model from the issue text.