diff --git a/.gitignore b/.gitignore
index 2eef895..9aee1f1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -8,6 +8,8 @@ programSettings.txt
 EventKenshikushi
 DataGenerator
 DataReaderScript
+pid.dat
+DAQLock.dat
 
 data
 
diff --git a/FSUDAQ.cpp b/FSUDAQ.cpp
index 93ec271..6a0b0cf 100644
--- a/FSUDAQ.cpp
+++ b/FSUDAQ.cpp
@@ -337,6 +337,9 @@ MainWindow::~MainWindow(){
 
   delete influx;
 
+  printf("-------- remove %s\n", DAQLockFile);
+  remove(DAQLockFile);
+
 }
 
 //***************************************************************
@@ -984,7 +987,7 @@ void MainWindow::StartACQ(){
   if( onlineAnalyzer ) onlineAnalyzer->StartThread();
 
   {//^=== elog and database
-    if( influx && chkSaveData->isChecked() ){
+    if( influx ){
       influx->AddDataPoint("RunID value=" + std::to_string(runID));
       influx->AddDataPoint("SavingData,ExpName=" +  elogName.toStdString() + " value=1");
       influx->WriteData(dataBaseName.toStdString());
@@ -1055,7 +1058,7 @@ void MainWindow::StopACQ(){
   cbAutoRun->setEnabled(true);
 
   {//^=== elog and database
-    if( influx && chkSaveData->isChecked() ){
+    if( influx ){
       influx->AddDataPoint("SavingData,ExpName=" +  elogName.toStdString() + " value=0");
       influx->WriteData(dataBaseName.toStdString());
       influx->ClearDataPointsBuffer();
@@ -1349,9 +1352,13 @@ void MainWindow::OpenScope(){
       if( scope  ) {
         if( onOff ) {
           lbScalarACQStatus->setText("<font style=\"color: green;\"><b>ACQ On</b></font>");
+          influx->AddDataPoint("SavingData,ExpName=" +  elogName.toStdString() + " value=1");
         }else{
           lbScalarACQStatus->setText("<font style=\"color: red;\"><b>ACQ Off</b></font>");
+          influx->AddDataPoint("SavingData,ExpName=" +  elogName.toStdString() + " value=0");
         }
+        influx->WriteData(dataBaseName.toStdString());
+        influx->ClearDataPointsBuffer();
       }
 
       if( canvas ){
diff --git a/macro.h b/macro.h
index 3d18413..4ee75ac 100644
--- a/macro.h
+++ b/macro.h
@@ -15,6 +15,9 @@
 
 #define SETTINGSIZE 2048
 
+#define DAQLockFile "DAQLock.dat"
+#define PIDFile  "pid.dat"
+
 #include <sys/time.h> /** struct timeval, select() */
 
 inline unsigned int get_time(){
diff --git a/main.cpp b/main.cpp
index f57ccdc..2643467 100644
--- a/main.cpp
+++ b/main.cpp
@@ -1,10 +1,55 @@
 #include "FSUDAQ.h"
 
 #include <QApplication>
+#include <QMessageBox>
+#include <QProcess>
+#include <QPushButton>
+#include <QFile>
 
 int main(int argc, char *argv[]){
     QApplication a(argc, argv);
 
+    bool isLock = false;
+    int pid = 0;
+    QFile lockFile(DAQLockFile);
+    if( lockFile.open(QIODevice::Text | QIODevice::ReadOnly) ){
+        QTextStream in(&lockFile);
+        QString line = in.readLine();
+        isLock = line.toInt();
+        lockFile.close();
+    }
+    QFile pidFile(PIDFile);
+    if( pidFile.open(QIODevice::Text | QIODevice::ReadOnly)){
+        QTextStream in(&pidFile);
+        QString line = in.readLine();
+        pid = line.toInt();
+        pidFile.close();
+    }
+    if( isLock ) {
+        qDebug() << "The DAQ program is already opened. PID is " + QString::number(pid) + ", and delete the " + DAQLockFile ;
+        QMessageBox msgBox;
+        msgBox.setWindowTitle("Oopss....");
+        msgBox.setText("The DAQ program is already opened, or crashed perviously. \nPID is " + QString::number(pid) + "\n You can kill the procee by \"kill -9 <pid>\" and delete the " + DAQLockFile + "\n or click the \"Kill\" button");
+        msgBox.setIcon(QMessageBox::Information);
+    
+        QPushButton * kill = msgBox.addButton("Kill and Open New", QMessageBox::AcceptRole);
+        msgBox.setStandardButtons(QMessageBox::Ok);
+        msgBox.setDefaultButton(QMessageBox::Ok);
+        msgBox.exec();
+        if(msgBox.clickedButton() == kill){
+            remove(DAQLockFile);
+            QProcess::execute("kill", QStringList() << "-9" << QString::number(pid));
+        }else{
+            return 0;
+        }
+    }
+    lockFile.open(QIODevice::Text | QIODevice::WriteOnly);
+    lockFile.write( "1" );
+    lockFile.close();
+    pidFile.open(QIODevice::Text | QIODevice::WriteOnly);
+    pidFile.write(  QString::number(QCoreApplication::applicationPid() ).toStdString().c_str() );
+    pidFile.close();
+
     MainWindow w;
     w.show();
     return a.exec();