diff --git a/firmware/weather_station_MK2_sensor_temperature/weather_station_MK2_sensor_temperature.ino b/firmware/weather_station_MK2_sensor_temperature/weather_station_MK2_sensor_temperature.ino
new file mode 100644
index 0000000..62421ad
--- /dev/null
+++ b/firmware/weather_station_MK2_sensor_temperature/weather_station_MK2_sensor_temperature.ino
@@ -0,0 +1,238 @@
+/*********************************************************************************
+ *
+ *  A temperature sensor which can be connected to an RS-485 ModBus interface. 
+ *
+ *  LED on Arduino gives status:
+ *
+ *       ON    : Booting
+ *       BLINK : I2C ERROR
+ *       FLASH : Heartbeat
+ *
+ * Copyright (C) 2025 M.T. Konstapel https://meezenest.nl/mees
+ *
+ * This file is part of weather_station_MK2_sensor_temperature
+ *
+ *    weather_station_MK2_sensor_temperature is free software: you can redistribute it and/or modify
+ *    it under the terms of the GNU General Public License as published by
+ *    the Free Software Foundation, either version 3 of the License, or
+ *    (at your option) any later version.
+ *
+ *    weather_station_MK2_sensor_temperature is distributed in the hope that it will be useful,
+ *    but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *    GNU General Public License for more details.
+ *
+ *    You should have received a copy of the GNU General Public License
+ *    along with weather_station_MK2_sensor_temperature. If not, see <https://www.gnu.org/licenses/>.
+ *
+ * See CHANGELOG.md
+ *
+ **********************************************************************************/
+
+// When set to 1 debug messages are send to the serial port, set it to 0 for production code!
+#define _DEBUG_ 0
+
+#include <ModbusSerial.h>
+#include "SparkFun_Weather_Meter_Kit_Arduino_Library.h"
+
+/**************************/
+/* Configurable variables */
+/**************************/
+// RS485 driver
+#define RS485_RE 11            // Tight to RS485_DE and must be configured as an input to prevent a short circuit
+#define RS485_DE 12
+// Used Pins
+const uint16_t TxenPin = RS485_DE; // -1 disables the feature, change that if you are using an RS485 driver, this pin would be connected to the DE and /RE pins of the driver.
+// ModBus address
+const uint8_t SlaveId = 14;
+/* Modbus Input Registers
+ *
+ * 0-3  : DefineSensorSerial (unique value): 0x4D45 followed by index. The index starts at 0x0 0x0 0x0 and is incremented for every unique device.
+ * 4    : Sensor Type (specifies sensor type): 0x01 for this temperature sensor
+ * 5    : Sensor Version (specifies sensor version)
+ * 6-30 : Human readable description of sensor: Every register holds two ASCII values, one in the MSB and the other in the LSB for a total of 60 characters. "Temparature sensor with two sensors"
+ * 31   : Number of available input registers
+ *
+ * 40   : Temperature reading sensor 1
+ * 41   : Temperature reading sensor 2 (if available)
+ * 42   : Minimum temperature reading sensor 1 since last reset
+ * 43   : Minimum temperature reading sensor 2 since last reset (if available)
+ * 44   : Maximum temperature reading sensor 1 since last reset
+ * 45   : Maximum temperature reading sensor 2 since last reset (if available)
+ */
+// Pre-defined register values
+const uint16_t DefineSensorSerial[4]        = {0x4D45,0x00,0x00,0x01};
+const uint16_t DefineSensorType             = 0x01;
+const uint16_t DefineSensorVersion          = 0x01;
+const uint8_t DefineSensorTypeString[]      = "Dual temperature sensor"; // Make sure the string is not longer than 60 charaters
+const uint16_t DefineNumberOfInputRegisters = 6;
+const uint16_t DefineNumberOfHoldingRegisters     = 0;
+const uint16_t DefineNumberOfCoilRegisters        = 0;
+const uint16_t DefineNumberOfContactRegisters     = 0;
+
+// Registers
+const uint16_t SensorID[4]              = {0,1,2,3};
+const uint16_t SensorType               = 4;
+const uint16_t SensorVersion            = 5;
+const uint16_t SensorTypeString[30]     = {6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35};
+const uint16_t NumberOfInputRegisters   = 36;
+const uint16_t NumberOfHoldingRegisters = 37;
+const uint16_t NumberOfCoilRegisters    = 38;
+const uint16_t NumberOfContactRegisters = 39;
+
+const uint16_t SensorTemperature[2]    = {40,41};
+const uint16_t SensorTemperatureMin[2] = {42,43};
+const uint16_t SensorTemperatureMax[2] = {44,45};
+
+/* Modbus Coil Registers
+ * 0: ResetMinMax (Reset Min/Max values)
+ */
+const uint16_t ResetMinMax                 = 0;
+
+// RS-485 serial port 
+#define MySerial Serial // define serial port used, Serial most of the time, or Serial1, Serial2 ... if available
+const uint32_t Baudrate = 9600;
+/******************************/
+/* END Configurable variables */
+/******************************/
+
+// ModbusSerial object
+ModbusSerial mb (MySerial, SlaveId, TxenPin);
+
+uint32_t ts;
+
+struct MeasuredData {
+  float Temperature01;
+  float Temperature02;
+
+  float MinTemperature01;
+  float MinTemperature02;  
+
+  float MaxTemperature01;
+  float MaxTemperature02;  
+
+} MeasuredData;
+
+void setup() {
+
+  uint16_t RegisterIndex;
+
+  MySerial.begin (Baudrate); // works on all boards but the configuration is 8N1 which is incompatible with the MODBUS standard
+  // prefer the line below instead if possible
+  // MySerial.begin (Baudrate, MB_PARITY_EVEN);
+
+  // initialize digital pin LED_BUILTIN as an output and turn it on.
+  pinMode(LED_BUILTIN, OUTPUT);
+  digitalWrite(LED_BUILTIN, HIGH);
+
+  //Setup control lines for RS485 driver
+  pinMode(RS485_RE,INPUT);        // In hardware connected to RS485_DE. Should be input to prevent a short circuit!
+  pinMode(RS485_DE,OUTPUT);
+  digitalWrite(RS485_DE,LOW);
+
+  mb.config (Baudrate);
+  mb.setAdditionalServerData ("TEMP_SENSOR"); // for Report Server ID function (0x11)
+  
+  // Add SensorID to ModBus
+  for (RegisterIndex = 0; RegisterIndex < 4; RegisterIndex++) {
+    mb.addIreg (SensorID[RegisterIndex]);
+    mb.Ireg (SensorID[RegisterIndex], DefineSensorSerial[RegisterIndex]);
+  }
+ 
+  // Add SensorType to ModBus
+  mb.addIreg (SensorType);
+
+  mb.addIreg (SensorTemperature[0]);
+  mb.addIreg (SensorTemperature[1]);
+  mb.addIreg (SensorTemperatureMin[0]);
+  mb.addIreg (SensorTemperatureMin[1]);
+  mb.addIreg (SensorTemperatureMax[0]);
+  mb.addIreg (SensorTemperatureMax[1]);  
+  // Add HeaterCoil register
+  mb.addCoil (ResetMinMax);
+    
+  // Set Weather station ID (ModBus)
+  mb.Ireg (SensorType, DefineSensorType);
+
+  // Fill SensorTypeString (ModBus)
+  uint16_t SensorTypeCharacter;
+  uint16_t LastRegister;
+  
+  // Get length of pre defined description string
+  LastRegister = strlen(DefineSensorTypeString);
+  
+  // Add SensorTypeString to ModBus
+  for (RegisterIndex = 0; RegisterIndex < 30; RegisterIndex++) {
+    
+    mb.addIreg (SensorTypeString[RegisterIndex]);
+
+    // Fill MSB of SensorTypeString with character from pre defined string until we reach the end of the description string
+    if (2*RegisterIndex < LastRegister) {
+      SensorTypeCharacter = DefineSensorTypeString[2*RegisterIndex] << 8;
+    // ...otherwise fill with a space
+    } else {
+      SensorTypeCharacter = ' ' << 8;
+    }
+    // Fill LSB of SensorTypeString with character from pre defined string until we reach the end of the description string
+    if ((2*RegisterIndex)+1 < LastRegister) {
+      SensorTypeCharacter += DefineSensorTypeString[(2*RegisterIndex)+1];
+    // ...otherwise fill with a space
+    } else {
+      SensorTypeCharacter += ' ';
+    }
+    mb.Ireg (SensorTypeString[RegisterIndex], SensorTypeCharacter);
+
+  }
+  
+  mb.addIreg (NumberOfInputRegisters);
+  mb.Ireg (NumberOfInputRegisters, DefineNumberOfInputRegisters);
+
+  mb.addIreg (NumberOfHoldingRegisters);
+  mb.Ireg (NumberOfHoldingRegisters, DefineNumberOfHoldingRegisters);
+
+  mb.addIreg (NumberOfCoilRegisters);
+  mb.Ireg (NumberOfCoilRegisters, DefineNumberOfCoilRegisters);
+
+  mb.addIreg (NumberOfContactRegisters);
+  mb.Ireg (NumberOfContactRegisters, DefineNumberOfContactRegisters);
+
+  Serial.println(F("weather_station_MK2_sensor_temperature v0.1"));
+  Serial.println(F("(C) 2025 M.T. Konstapel"));
+  Serial.println(F("This project is free and open source (GPL-3.0)"));
+  Serial.println(F("More details: https://meezenest.nl/mees/"));
+
+  ts = millis();
+}
+
+void loop() {
+
+  // Call once inside loop() - all magic here
+  mb.task();
+  
+  // Read each two seconds
+  if ( ( millis() - ts) >= 2000) {
+    
+    ts = millis();
+
+    digitalWrite(LED_BUILTIN, HIGH);  // LED as heartbeat
+
+    // Fill input registers
+    mb.Ireg (SensorTemperature[0], 20);
+    mb.Ireg (SensorTemperature[1], 21);
+    mb.Ireg (SensorTemperatureMin[0], 22);
+    mb.Ireg (SensorTemperatureMax[0], 23);
+    mb.Ireg (SensorTemperatureMin[1], 24);
+    mb.Ireg (SensorTemperatureMax[1], 25);
+    
+    // reset min/max temperatures
+    if (mb.Coil (ResetMinMax)) {
+      // reset min/max temperatures
+    } else {
+      // do something
+    }
+
+    digitalWrite(LED_BUILTIN, LOW);  // LED as heartbeat
+
+
+    }
+}
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