diff --git a/ClassData.h b/ClassData.h
index 46bdc2a..233c9e4 100644
--- a/ClassData.h
+++ b/ClassData.h
@@ -29,12 +29,14 @@ class Data{
     uint32_t AllocatedSize;      
     
     double TriggerRate[MaxNChannels]; /// Hz
+    double NonPileUpRate[MaxNChannels]; /// Hz
     unsigned long TotNumEvents[MaxNChannels];
-    unsigned short NumEventsDecoded[MaxNChannels];
+    unsigned short NumEventsDecoded[MaxNChannels];  /// reset at every decode
+    unsigned short NumNonPileUpDecoded[MaxNChannels]; /// reset at every decode
 
-    /// store a single Raw event
+    /// store data for event building
     bool IsNotRollOverFakeAgg;
-    unsigned short     NumEvents[MaxNChannels];
+    unsigned short     NumEvents[MaxNChannels];  /// max 65535, reset only clear Data
     unsigned long long Timestamp[MaxNChannels][MaxNData]; /// 47 bit
     unsigned short     fineTime[MaxNChannels][MaxNData];  /// 10 bits, in unit of ch2ns / 1000 = ps
     unsigned short     Energy[MaxNChannels][MaxNData];   /// 15 bit
@@ -144,7 +146,9 @@ inline void Data::Allocate80MBMemory(){
 inline void Data::ClearTriggerRate(){ 
   for( int i = 0 ; i < MaxNChannels; i++) {
     TriggerRate[i] = 0.0; 
+    NonPileUpRate[i] = 0.0;
     NumEventsDecoded[i] = 0;
+    NumNonPileUpDecoded[i] = 0;
   }
 }
 
@@ -340,6 +344,7 @@ inline void Data::DecodeBuffer(bool fastDecode, int verbose){
     double sec =  dTime * ch2ns / 1e9;
     if( sec != 0 && NumEventsDecoded[ch] > 1 ){
       TriggerRate[ch] = NumEventsDecoded[ch]/sec;
+      NonPileUpRate[ch] = NumNonPileUpDecoded[ch]/sec;
     }
   }
   
@@ -532,14 +537,21 @@ inline int Data::DecodePHADualChannelBlock(unsigned int ChannelMask, bool fastDe
       printf(" trapezoid sat. : %d \n", ((extra >> 10) & 0x1) );
     }
 
-    if( rollOver == 0 ) {
+
+    if( rollOver == 0 ) { // non-time roll over fake event
       Energy[channel][NumEvents[channel]] = energy;
       Timestamp[channel][NumEvents[channel]] = timeStamp;
       if(extra2Option == 0 || extra2Option == 2 ) fineTime[channel][NumEvents[channel]] = (extra2 & 0x07FF );
       NumEvents[channel] ++; 
       NumEventsDecoded[channel] ++; 
       TotNumEvents[channel] ++;
+
+      if( !pileUp ) {
+        NumNonPileUpDecoded[channel] ++;
+      }
     }
+
+    if( NumEvents[channel] >= MaxNData ) ClearData();
     
     if( verbose >= 1 ) printf("%4d | ch : %2d, PileUp : %d , energy : %5d, rollOver: %d,  timestamp : %10llu, triggerAt : %d, nSample : %d, %f sec\n", 
                                 NumEvents[channel], channel, pileUp, energy, rollOver, timeStamp, triggerAtSample, nSample , timeStamp * 4. / 1e9);
@@ -710,8 +722,11 @@ inline int Data::DecodePSDDualChannelBlock(unsigned int ChannelMask, bool fastDe
       NumEvents[channel] ++; 
       NumEventsDecoded[channel] ++; 
       TotNumEvents[channel] ++;
+
     }
-    
+
+    if( NumEvents[channel] >= MaxNData ) ClearData();
+     
     if( verbose >= 2 ) printf("extra : 0x%08x, Qshort : %d, Qlong : %d \n", extra, Qshort, Qlong);
     
     if( verbose >= 1 ) printf("ch : %2d, Qshort : %d, Qlong : %d, timestamp : %llu\n", 
diff --git a/CustomThreads.h b/CustomThreads.h
index d9cc63c..914d950 100644
--- a/CustomThreads.h
+++ b/CustomThreads.h
@@ -17,8 +17,10 @@ public:
     this->digi = dig;
     this->ID = digiID;
     isSaveData = false;
+    isScope = false;
   }
-  void SetSaveData(bool onOff) {this->isSaveData = onOff;}
+  void SetSaveData(bool onOff)  {this->isSaveData = onOff;}
+  void SetScopeMode(bool onOff) {this->isScope = onOff;}
   void run(){
     clock_gettime(CLOCK_REALTIME, &ta);
     while(true){
@@ -28,15 +30,12 @@ public:
 
       if( ret == CAEN_DGTZ_Success ){
         digiMTX[ID].lock();
-        if( isSaveData ) {
-          digi->GetData()->SaveData();
-        }else{
-          digi->GetData()->DecodeBuffer(false);
-        }
+        digi->GetData()->DecodeBuffer(!isScope);
+        if( isSaveData ) digi->GetData()->SaveData();
         digiMTX[ID].unlock();
 
       }else{
-        printf("%s------------ ret : %d \n", __func__, ret);
+        printf("ReadDataThread::%s------------ ret : %d \n", __func__, ret);
         if( ret == CAEN_DGTZ_WrongAcqMode) break;
       }
 
@@ -72,47 +71,19 @@ private:
   int ID;
   timespec ta, tb;
   bool isSaveData;
+  bool isScope;
 };
 
-//^#===================================================== UpdateTrace Thread
-class UpdateTraceThread : public QThread {
+//^#======================================================= Timing Thread
+class TimingThread : public QThread {
   Q_OBJECT
 public:
-  UpdateTraceThread(QObject * parent = 0) : QThread(parent){
-    waitTime = 2;
-    stop = false;
-  }
-  unsigned int GetWaitTimeSec() const {return waitTime;}
-  void SetWaitTimeSec(unsigned sec) {waitTime = sec;}
-  void Stop() {this->stop = true;}
-  void run(){
-    unsigned int count = 0;
-    stop = false;
-    do{
-      usleep(100000);
-      count ++;
-      if( count % waitTime == 0){
-        emit updateTrace();
-      }
-    }while(!stop);
-  }
-signals:
-  void updateTrace();
-
-private:
-  bool stop;
-  unsigned int waitTime; //100 of milisec
-};
-
-//^#======================================================= Scalar Thread
-class ScalarThread : public QThread {
-  Q_OBJECT
-public:
-  ScalarThread(QObject * parent = 0 ) : QThread(parent){
+  TimingThread(QObject * parent = 0 ) : QThread(parent){
     waitTime = 20; // 10 x 100 milisec
     stop = false;
   }
   void Stop() { this->stop = true;}
+  void SetWaitTimeinSec(float sec) {waitTime = sec * 10 ;}
   unsigned int GetWaitTimeinSec() const {return waitTime/10;}
   void run(){
     unsigned int count  = 0;
diff --git a/FSUDAQ.cpp b/FSUDAQ.cpp
index cbcf68c..b06fdf2 100644
--- a/FSUDAQ.cpp
+++ b/FSUDAQ.cpp
@@ -182,8 +182,8 @@ MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent){
     lbLastUpdateTime = nullptr;
     lbScalarACQStatus = nullptr;
 
-    scalarThread = new ScalarThread();
-    //connect(scalarThread, &ScalarThread::updataScalar, this, &MainWindow::UpdateScalar);
+    scalarThread = new TimingThread();
+    connect(scalarThread, &TimingThread::updataScalar, this, &MainWindow::UpdateScalar);
 
   }
 
@@ -198,6 +198,14 @@ MainWindow::~MainWindow(){
   SaveProgramSettings();
 
   if( scope ) delete scope;
+
+  if( scalar ) {
+    CleanUpScalar();
+    scalarThread->Stop();
+    scalarThread->quit();
+    scalarThread->exit();
+    delete scalarThread;
+  }
   
 
 }
@@ -522,7 +530,18 @@ void MainWindow::OpenScalar(){
 }
 
 void MainWindow::UpdateScalar(){
+  if( digi == nullptr ) return;
+  
+  lbLastUpdateTime->setText("Last update: " + QDateTime::currentDateTime().toString("MM.dd hh:mm:ss"));
 
+  for( unsigned int iDigi = 0; iDigi < nDigi; iDigi++){
+    Data * data = digi[iDigi]->GetData();
+
+    for( int i = 0; i < digi[iDigi]->GetNChannels(); i++){
+      leTrigger[iDigi][i]->setText(QString::number(data->TriggerRate[i]));
+      leAccept[iDigi][i]->setText(QString::number(data->NonPileUpRate[i]));
+    }
+  }
 
 }
 
@@ -532,34 +551,52 @@ void MainWindow::UpdateScalar(){
 void MainWindow::StartACQ(){
   if( digi == nullptr ) return;
 
-  if( CommentDialog(true) == false) return;
+  bool commentResult = true;
+  if( chkSaveData->isChecked() ) commentResult = CommentDialog(true);
+  if( commentResult == false) return;
 
   for( unsigned int i = 0; i < nDigi ; i++){
     digi[i]->GetData()->OpenSaveFile((rawDataPath + "/" + prefix).toStdString());
     digi[i]->StartACQ();
-    readDataThread[i]->SetSaveData(true);
+    readDataThread[i]->SetSaveData(chkSaveData->isChecked());
     readDataThread[i]->start();
   }
+  if( chkSaveData->isChecked() ) SaveLastRunFile();
+  scalarThread->start();
 
-  SaveLastRunFile();
+  if( !scalar->isVisible() ) {
+    scalar->show();
+  }else{
+    scalar->activateWindow();
+  }
+  lbScalarACQStatus->setText("<font style=\"color: green;\"><b>ACQ On</b></font>");
 
 }
 
 void MainWindow::StopACQ(){
   if( digi == nullptr ) return;
 
-  if( CommentDialog(false) == false) return;
+  bool commentResult = true;
+  if( chkSaveData->isChecked() ) commentResult = CommentDialog(true);
+  if( commentResult == false) return;
 
   for( unsigned int i = 0; i < nDigi; i++){
     digi[i]->StopACQ();
-    digi[i]->GetData()->CloseSaveFile();
+    if( chkSaveData->isChecked() ) digi[i]->GetData()->CloseSaveFile();
 
     if( readDataThread[i]->isRunning() ) {
       readDataThread[i]->quit();
       readDataThread[i]->wait();
     }
   }
+
+  if( scalarThread->isRunning()){
+    scalarThread->Stop();
+    scalarThread->quit();
+    scalarThread->wait();
+  }
   
+  lbScalarACQStatus->setText("<font style=\"color: red;\"><b>ACQ Off</b></font>");
 }
 
 void MainWindow::AutoRun(){
diff --git a/FSUDAQ.h b/FSUDAQ.h
index d513aa0..d314f68 100644
--- a/FSUDAQ.h
+++ b/FSUDAQ.h
@@ -92,7 +92,7 @@ private:
   //@----- Scalar
   QMainWindow  * scalar;
   QGridLayout * scalarLayout;
-  ScalarThread * scalarThread;
+  TimingThread * scalarThread;
   QLineEdit  *** leTrigger; // need to delete manually
   QLineEdit  *** leAccept; // need to delete manually
   QLabel * lbLastUpdateTime;
diff --git a/Scope.cpp b/Scope.cpp
index 9a19bf3..b8e4cf2 100644
--- a/Scope.cpp
+++ b/Scope.cpp
@@ -48,7 +48,9 @@ Scope::Scope(Digitizer ** digi, unsigned int nDigi, ReadDataThread ** readDataTh
   xaxis->setLabelFormat("%.0f");
   xaxis->setTitleText("Time [ns]");
 
-  updateTraceThread = new UpdateTraceThread();
+  updateTraceThread = new TimingThread();
+  updateTraceThread->SetWaitTimeinSec(0.5);
+
   //connect(updateTraceThread, &UpdateTraceThread::updateTrace, this, &Scope::UpdateScope);
 
   //*================================== UI
@@ -115,7 +117,7 @@ Scope::Scope(Digitizer ** digi, unsigned int nDigi, ReadDataThread ** readDataTh
   QLabel * lbhints = new QLabel("Type 'r' to restore view, '+/-' Zoom in/out, arrow key to pan.", this);
   layout->addWidget(lbhints, rowID, 0, 1, 4);
   
-  QLabel * lbinfo = new QLabel("Trace update every " + QString::number(updateTraceThread->GetWaitTimeSec()) + " sec.", this);
+  QLabel * lbinfo = new QLabel("Trace update every " + QString::number(updateTraceThread->GetWaitTimeinSec()) + " sec.", this);
   lbinfo->setAlignment(Qt::AlignRight);
   layout->addWidget(lbinfo, rowID, 5);
 
diff --git a/Scope.h b/Scope.h
index 59f909a..e8d6f83 100644
--- a/Scope.h
+++ b/Scope.h
@@ -53,7 +53,7 @@ private:
   int ch2ns;
 
   ReadDataThread ** readDataThread;   
-  UpdateTraceThread * updateTraceThread;
+  TimingThread * updateTraceThread;
 
   bool enableSignalSlot;