diff --git a/ModbusThermometer.cpp b/ModbusThermometer.cpp
index e63a819..cf3c48f 100644
--- a/ModbusThermometer.cpp
+++ b/ModbusThermometer.cpp
@@ -1,6 +1,7 @@
 #include "Arduino.h"
 
 #include "Metro.h"
+#include "Streaming.h"
 
 #include "ads1210.h"
 #include "led.h"
@@ -10,6 +11,7 @@
 
 
 
+
 const uint8_t LED_PIN = 8;
 
 const uint8_t ADC_1_CS_PIN = 9;
@@ -39,6 +41,8 @@ uint32_t uptimeSeconds = 0;
 
 typedef enum { e_CAL_IDLE, e_CAL_RUNNING, e_CAL_SET, e_CAL_COMPLETE } tCalibrationState;
 
+bool calibrationOffsetEnabled = false;
+bool calibrationFactorEnabled = false;
 tCalibrationState calibrationState = e_CAL_IDLE;
 uint16_t calibrationCycleCnt = 0;
 float calibrationValueSum[NUM_OF_CHANNELS];
@@ -88,16 +92,29 @@ struct {
 
 
 void setup() {  
+  pinMode(CAL_ENABLE, INPUT_PULLUP);
+  pinMode(CAL_FACTOR_ENABLE, INPUT_PULLUP);
+  pinMode(CAL_OFFSET_ENABLE, INPUT_PULLUP);
+
   delay(100);
+
+  calibrationOffsetEnable = (digitalRead(CAL_ENABLE) == 0) && (digitalRead(CAL_OFFSET_ENABLE) == 0);
+  calibrationFactorEnable = (digitalRead(CAL_ENABLE) == 0) && (digitalRead(CAL_FACTOR_ENABLE) == 0);
+
   bool initializeConfig = Config::initialize();
   led.begin(LED_PIN);
   ads1210[0].begin(ADC_1_CS_PIN, ADC_1_RDY_PIN, initializeConfig, Config::ADC1START);
   ads1210[1].begin(ADC_2_CS_PIN, ADC_2_RDY_PIN, initializeConfig, Config::ADC2START);
   thermometer[0].begin(initializeConfig, Config::THERMO1START);
   thermometer[1].begin(initializeConfig, Config::THERMO2START);
-  modbus_configure(&Serial, MODBUS_BAUD, SERIAL_8N2, MODBUS_ID, MODBUS_TX_ENABLE_PIN,
-                   sizeof(modbusHoldingRegisters), (uint16_t*)(&modbusHoldingRegisters));
 
+  if (calibrationOffsetEnable || calibrationFactor Enable) {
+    Serial.begin(9600);
+  } else {
+    modbus_configure(&Serial, MODBUS_BAUD, SERIAL_8N2, MODBUS_ID, MODBUS_TX_ENABLE_PIN,
+                    sizeof(modbusHoldingRegisters), (uint16_t*)(&modbusHoldingRegisters));
+  }
+  
   for (uint8_t i = 0; i < NUM_OF_CHANNELS; i++) {
     modbusHoldingRegisters.channelVariables[i].calOffset.in = ads1210[i].getCalOffset();
     modbusHoldingRegisters.channelVariables[i].calFactor.in = ads1210[i].getCalFactor();
@@ -105,9 +122,6 @@ void setup() {
     calibrationValueSum[i] = 0.0;
   }
 
-  pinMode(CAL_ENABLE, INPUT_PULLUP);
-  pinMode(CAL_FACTOR_ENABLE, INPUT_PULLUP);
-  pinMode(CAL_OFFSET_ENABLE, INPUT_PULLUP);
 }
 
 void loop() {
@@ -128,13 +142,15 @@ void loop() {
 
 
   if (secondTick.check() == 1) {
-    if ((digitalRead(CAL_ENABLE) == 0) &&
+    if ((calibrationOffsetEnable || calibrationFactorEnable) &&
         (calibrationState != e_CAL_COMPLETE)) {
+      Serial << "Calibration enabled" << endl;
       led.on();
 
 
       switch (calibrationState) {
         case e_CAL_IDLE:
+          Serial << "Calibration state idle" << endl;
           for (uint8_t i = 0; i < NUM_OF_CHANNELS; i++) {
             ads1210[i].setCalOffset(0.0);
             ads1210[i].setCalFactor(1.0);
@@ -142,35 +158,43 @@ void loop() {
           calibrationState = e_CAL_RUNNING;
           break;
         case e_CAL_RUNNING:
+          Serial << "Calibration state running" << endl;
           calibrationCycleCnt++;
+          Serial << "  Cnt: "  << calibrationCycleCnt++ << endl;
           for (uint8_t i = 0; i < NUM_OF_CHANNELS; i++) {
-            calibrationValueSum[i] += ads1210[i].getR();
+            float r = ads1210[i].getR();
+            calibrationValueSum[i] += r;
+            Serial << "  Channel: " << i << ", r: " << r << endl;
           }
           if (calibrationCycleCnt >= CALIBRATION_CYCLES) {
             calibrationState = e_CAL_SET;
           }
           break;
         case e_CAL_SET:
+          Serial << "Calibration state set" << endl;
           // calculate and set according to selected calibration mode
-          if (digitalRead(CAL_OFFSET_ENABLE) == 0) {
+          if (calibrationOffsetEnable) {
             // for offset calibration, the terminals needs to be shorten
             // offset calibration needs to be performed first
             for (uint8_t i = 0; i < NUM_OF_CHANNELS; i++) {
               float offset = calibrationValueSum[i] / ((float)calibrationCycleCnt);
               ads1210[i].setCalOffset(offset);
+              Serial << "Setting offset, Channel: " << i << ", Offset: " << offset << endl;
             }
           }
-          if (digitalRead(CAL_FACTOR_ENABLE) == 0) {
+          if (calibrationFactorEnable) {
             // for factor calibration, a 1000R resistor needs to be connected
             // to the terminals
             for (uint8_t i = 0; i < NUM_OF_CHANNELS; i++) {
               float factor = 1000.0 / (calibrationValueSum[i] / ((float)calibrationCycleCnt));
               ads1210[i].setCalFactor(factor);
+              Serial << "Setting factor, Channel: " << i << ", Factor: " << factor << endl;
             }
           }
           calibrationState = e_CAL_COMPLETE;
           break;
         default:
+          Serial << "Calibration state default" << endl;
           calibrationState = e_CAL_COMPLETE;
           break;
       }
@@ -178,12 +202,11 @@ void loop() {
       led.toggle();
     }
 
-
-
-
     uptimeSeconds++;
     modbusHoldingRegisters.uptimeSeconds.in = uptimeSeconds;
   }
 
-  modbus_update();
+  if (! (calibrationOffsetEnable || calibrationFactorEnable)) {
+    modbus_update();
+  }
 }