Serch string

hello, I am sending a string for a serial port which consists of 32 bytes and is like this:

xxx, 1111111,2222222,3333333,

byte 5 to 12 are the one
byte 14 to 21 are the two
byte 23 to 30 are the three
 
my question is how can I separate the string into three substrings?

string 1: 1111111
string 2: 2222222
chain 3: 3333333