The hexadecimal, or “hex”, numbering systems is used in PLCs because a “word” of data is made of 16 data bits or two 8-bit bytes.
The hexadecimal system uses 16 as its base. It uses the numerals 0 through 9 and the letters A through F. A through F is used to represent the decimal numbers 10 through 15.
The benefits of using a hexadecimal numbering system are that it allows the status of a large number of binary bits to be represented in a much smaller space – such as on a computer screen or PLC programming device.
The technique used to convert a hexadecimal number to a binary number is the same that we used to convert an octal number to a binary number.
As with all numbering systems, to convert a hexadecimal number to a decimal number, you simply multiply the hexadecimal digits in the columns by a base of 16, depending on digit significance.