Switch management OpenHab - Arduino

Hello to all,
forgive the banality of my question , but just now I’m approaching with these arguments .
As a first experience I would simply turn on an LED on Arduino via openhab .

For now using windows but acquired the necessary knowledge I would spend all of raspberry .
I opehab configured with a simple switch .
I defined the following item :

Switch Luce1 “Luce 1” (gSolaio, gLuci)
String Node5 “Nodo 1” (All) { serial=“COM4”, autoupdate=“false” }

I called these RULE:

rule “accensione luce”
Item Luce1 changed
sendCommand(Node1, “1”)

This however is the sketch of Arduino:

void setup() {
// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);
void loop() {
int ser=0;
if (Serial.available() )
{ ser=Serial.read();
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
else if (ser== ‘2’)
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW

unfortunately I can not make it work .
Noting also the serial monitor when I turn the switch on openhab not written anything .
I think the problem is due to the serial communication .
What’s wrong ?
I hope I was clear and I thank you in advance

I don’t know Arduino yet but I notice that you define a String Item named Node5 but are trying to send a command to an Item named Node5.

Beyond that I don’t know enough to comment.