Four bits and eight bits are rarely heard, and may refer to some special registers or bcd code data, which are rarely used, so don't worry.

16 bits are word data, that is, registers such as D, T, C and RW all belong to this category, and can store the largest positive integer 2 16 or -2 15-2 15.

32 bits refer to double-byte data. In Mitsubishi, two registers are mainly used together. For example, using the DPLSY instruction is to call double-byte data, that is, when you use D 10, the system will use D 1 1 as the high bit by default, and D 10 as the low bit to access and read together! This is mainly to increase the accessible range of data! And when a data is a real number, it must be 32 bits!

The explanation is actually very simple, and there is no need to understand and learn at all. The most important thing to learn PLC is that you have the control object, the object is clear, and the control problems are clear, and then look up the manual according to your needs to see how to use the instructions. Just like when you write an English composition, in order to express a meaning, look up words in the dictionary. It is meaningless and inefficient to just imagine doing the problem. PLC practice is greater than everything!