Arduino serial data input output
You claim that this code works.  However, since you haven't really specified exactly what the intended behaviour is, I can't verify whether it does what it's supposed to do.  There are some very strong code smells that lead me to suspect that this code is completely broken, or at least doing something silly.


Non-idiomatic loop limits: The idiomatic way to write a loop that does something 14 times, especially when counting from 0, is

for (int i = 0; i &lt; 14; i++) {
    …
}


This tip would be merely a nitpick, except that I suspect you have a bug in setup(): is pin 7 supposed to be in INPUT or OUTPUT mode?
Apparent mismatch of code and comments:  In setup(), you wrote:

//setup digital pins as inputs pin 3 - 13
for (int i = 2; i &lt;= 7; i++) {


What is the relationship between 3-13 and 2-7?  The comment is either erroneous or fails to fully explain the code.
Misuse of String.concat():  dataString, being a String, is immutable.  Therefore, dataString.concat(i) is a no-op, and dataString.concat("," + String(digitalRead(i)) + "/") is a convoluted way of just calling digitalRead(i) and discarding the result.  The final outcome is that Serial.println(dataString) is equivalent to Serial.println("").


In addition, I see some code hygiene issues, such as inconsistent indentation and using Input instead of input for a variable name.