VB0？ - ? One byte (8 bits wide); The unsigned range is 0-255 and the signed range is-128-+127;

VW0 -？ One word (16 bits wide); The unsigned range is 0-65535, and the signed range is -32768-+32767.

VD0？ - ? Double words (32 bits wide);

The unsigned range is about 0-4294967295; Signed range-2147483948-2147483947

Real numbers are also 32 bits wide and can be accessed through VD doublewords.

As for when to use the relative variable type, this is also relatively simple, as long as the maximum value of its variable does not overflow. If the maximum value of a variable is 200, it can be stored in byte, word or double word, but it will waste space. For example, a real number must be a 32-bit doubleword type.