You probably also need to provide a link for the sensors, as what these need is often a structured field crammed into a byte.
A byte is just a collection of 8 bits. It can contain anything you want and as the programmer you give it meaning in your code. For example, the bit pattern
0100 0001 (msb first)
can be read a number of ways:
- decimal number 65 (same as hex 0x41)
- ASCII character 'A'
- 2 BCD integers, 4 and 1
- a bit mask for something
but they are all the same value/bit pattern in memory. The context of your code gives it meaning.
The reference you gave is for the standard C/C++ language cast operation that is generally used to convert between different types. For example, taking a 16 bit integer and casting it to byte eliminates the most significant 8 bits from the number. It is not a conversion to/from BCD.