diff --git a/src/main.cpp b/src/main.cpp
index da761d0..2de1678 100644
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -121,6 +121,63 @@ uint8_t fReadInputRegister(uint8_t fc, uint16_t address, uint16_t length) {
     return STATUS_OK;
 }
 
+// Write function for holding registers
+uint8_t fWriteHoldingRegister(uint8_t fc, uint16_t address, uint16_t length) {
+    if (address >= sizeof(HoldingRegister) / sizeof(HoldingRegister[0]) || (address + length) > sizeof(HoldingRegister) / sizeof(HoldingRegister[0])) {
+        return STATUS_ILLEGAL_DATA_ADDRESS;
+    }
+
+    for (uint16_t i = 0; i < length; i++) {
+        int value = slave.readRegisterFromBuffer(i);
+        HoldingRegister[address + i] = value;
+
+        // Use switch-case for specific register addresses
+        switch (address + i) {
+            case 0:
+                modbusConfig.SetModbusID(value);  // Update Modbus ID in EEPROM
+                break;
+            case 1:
+                modbusConfig.SetModbusID(value);  // Update Modbus ID in EEPROM
+                break;
+            case 2:
+                modbusConfig.SetBaudRate(value);  // Update Baud rate in EEPROM
+                break;
+            default:
+                // No specific action for other addresses
+                break;
+        }
+    }
+
+    return STATUS_OK;
+}
+
+// Optional: Read function for holding registers
+uint8_t fReadHoldingRegister(uint8_t fc, uint16_t address, uint16_t length) {
+    if (address >= sizeof(HoldingRegister) / sizeof(HoldingRegister[0]) || (address + length) > sizeof(HoldingRegister) / sizeof(HoldingRegister[0])) {
+        return STATUS_ILLEGAL_DATA_ADDRESS;
+    }
+
+    for (uint16_t i = 0; i < length; i++) {
+        // Add specific data to holding registers
+        switch (address + i) {
+            case 0:  // Modbus ID
+                slave.writeRegisterToBuffer(i, modbusConfig.GetModbusID());
+                break;
+            case 1:  // Modbus ID
+                slave.writeRegisterToBuffer(i, modbusConfig.GetModbusID());
+                break;
+            case 2:  // Baud rate
+                slave.writeRegisterToBuffer(i, modbusConfig.GetBaudRate());
+                break;
+            default:  // Other data from HoldingRegister array
+                slave.writeRegisterToBuffer(i, HoldingRegister[address + i]);
+                break;
+        }
+    }
+
+    return STATUS_OK;
+}
+
 void setup() {
     pinMode(RS485_CTRL_PIN, OUTPUT);
     digitalWrite(RS485_CTRL_PIN, LOW);  // RS485-Empfang aktivieren
@@ -132,7 +189,8 @@ void setup() {
     slave.cbVector[CB_WRITE_COILS] = writeDigitalOut;
     slave.cbVector[CB_READ_DISCRETE_INPUTS] = fReadCoilRegister;
     slave.cbVector[CB_READ_INPUT_REGISTERS] = fReadInputRegister;
-    //slave.cbVector[CB_WRITE_INPUT_REGISTERS] = fWriteInputRegister;  // Registrierung der Schreib-Funktion
+    slave.cbVector[CB_WRITE_HOLDING_REGISTERS] = fWriteHoldingRegister;
+    slave.cbVector[CB_READ_HOLDING_REGISTERS] = fReadHoldingRegister;//slave.cbVector[CB_WRITE_INPUT_REGISTERS] = fWriteInputRegister;  // Registrierung der Schreib-Funktion
 
     pinMode(OutPutPin, OUTPUT);
     digitalWrite(OutPutPin, LOW);