diff --git a/arduino-thorlabs-ledd1b/arduino-thorlabs-ledd1b.ino b/arduino-thorlabs-ledd1b/arduino-thorlabs-ledd1b.ino
new file mode 100644
index 0000000..ab80318
--- /dev/null
+++ b/arduino-thorlabs-ledd1b/arduino-thorlabs-ledd1b.ino
@@ -0,0 +1,72 @@
+/**
+ * Matthias Quintern, 2025
+ * 
+ * Simple Arduino program that listens via serial for single byte commands to control a ThorLabs LEDD1B
+ * Commands:
+ * - 'i': Identify - Prints "Arduino Nano CPD <version>"
+ * - '0': Turn the LED off
+ * - '1': Turn the LED on
+ */
+const int LEDPIN = 11;
+const int VERSION = 1;
+
+void setup() {
+  pinMode(LED_BUILTIN, OUTPUT);
+  digitalWrite(LED_BUILTIN, HIGH);
+  delay(500);
+  Serial.begin(9600, SERIAL_8N1);  			//USB-Prog. Port
+  while (!Serial) {
+    ;  // wait for serial port to connect. Needed for native USB port only
+  }
+  pinMode(LEDPIN, OUTPUT);
+}
+
+void loop() {
+  digitalWrite(LED_BUILTIN, LOW);
+
+  if (Serial.available() <= 0) {
+    return;
+  }
+  char command = Serial.read();
+  digitalWrite(LED_BUILTIN, HIGH);
+  switch (command) {
+    case 'i':
+      identify();
+      break;
+    case '1':
+      Serial.println("LED ON");
+      led_on();
+      break;
+    case '0':
+      Serial.println("LED OFF");
+      led_off();
+      break;
+    case '\n':
+      break;
+    default:
+      blink_internal_led(5);
+      break;
+
+  }
+}
+void blink_internal_led(unsigned N) {
+  unsigned long duration = 100;
+  for (unsigned i = 0; i < N; i++) {
+    digitalWrite(LED_BUILTIN, HIGH);
+    delay(duration);
+    digitalWrite(LED_BUILTIN, LOW);
+    delay(duration);
+  }
+}
+void led_on() {
+  digitalWrite(LEDPIN, HIGH);
+}
+void led_off() {
+  digitalWrite(LEDPIN, LOW);
+}
+
+void identify() {
+    Serial.print("Arduino Nano CPD ");
+    Serial.print(VERSION);
+    Serial.println("");
+}