diff --git a/mainwindow.cpp b/mainwindow.cpp
index 0f4225b..a0df9ec 100644
--- a/mainwindow.cpp
+++ b/mainwindow.cpp
@@ -713,16 +713,16 @@ void MainWindow::CloseDigitizers(){
 
   if( digi == NULL) return;
 
-  if(scalar && nDigiConnected > 0 ){ // scalar is child of this
-    scalar->close();
-    CleanUpScalar(); // this use digi->GetNChannels(); 
-  }
-
   if( scope ){
     scope->close();
     delete scope;
     scope = NULL;
   }
+
+  if(scalar && nDigiConnected > 0 ){ // scalar is child of this, This MUST after scope, because scope tell scalar to update ACQ status
+    scalar->close();
+    CleanUpScalar(); // this use digi->GetNChannels(); 
+  }
   
   if( digiSetting ){
     digiSetting->close();
diff --git a/scope.cpp b/scope.cpp
index ba8537f..32e54aa 100644
--- a/scope.cpp
+++ b/scope.cpp
@@ -55,6 +55,7 @@ Scope::Scope(Digitizer2Gen **digi, unsigned int nDigi, ReadDataThread ** readDat
   xaxis->setTitleText("Time [ns]");
 
   updateTraceThread = new TimingThread();
+  updateTraceThread->SetWaitTimeSec(0.2);
   connect(updateTraceThread, &TimingThread::TimeUp, this, &Scope::UpdateScope);
   
   //*================ add Widgets
@@ -322,7 +323,7 @@ Scope::Scope(Digitizer2Gen **digi, unsigned int nDigi, ReadDataThread ** readDat
 }
 
 Scope::~Scope(){
-  //printf("------- %s \n", __func__);
+  printf("------- %s \n", __func__);
   StopScope();
   updateTraceThread->Stop();
   updateTraceThread->quit();
@@ -330,6 +331,7 @@ Scope::~Scope(){
   delete updateTraceThread;
   for( int i = 0; i < 6; i++) delete dataTrace[i];
   delete plot;
+  printf("------- end of %s \n", __func__);
 }
 
 void Scope::ReadScopeSettings(){