How to convert a piece of data into hex form

How to convert a piece of data to hex form
It's Jiangzi,

This is a blob of data, I now use stream_get_contents to take him out of the image directly into the right ASCII form, but the agreement is not based on ASCII. How can I take or how to convert a string into a hex form?
------Solution--------------------
Let's get something straight.
The ASCII form on the right side of the figure and the HEX form in the middle are all the same thing (we call it a binary string)
Both representations are not used in the actual data communication, while the communication is still using a binary string

$s = ' abcdefghijklmnop ';
Echo Strtoupper (Join (' ', Str_split (Bin2Hex ($s), 4));

4142 4344 4546 4748 494A 4b4c 4d4e 4f50

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