diff --git a/companion/src/simulation/debugoutput.cpp b/companion/src/simulation/debugoutput.cpp
index 4f25a228c..03aa757d6 100644
--- a/companion/src/simulation/debugoutput.cpp
+++ b/companion/src/simulation/debugoutput.cpp
@@ -41,5 +41,3 @@ void DebugOutput::traceCallback(const QString & text)
     ui->Output->verticalScrollBar()->triggerAction(QAbstractSlider::SliderToMaximum);
   }
 }
-
-
diff --git a/companion/src/simulation/simulatordialog.cpp b/companion/src/simulation/simulatordialog.cpp
index a072baad2..158a3dc32 100644
--- a/companion/src/simulation/simulatordialog.cpp
+++ b/companion/src/simulation/simulatordialog.cpp
@@ -270,24 +270,45 @@ void SimulatorDialog::onTrimReleased()
 
 void SimulatorDialog::openTelemetrySimulator()
 {
-  TelemetrySimu = new TelemetrySimulator(this, simulator);
-  TelemetrySimu->setAttribute(Qt::WA_DeleteOnClose, true);
-  TelemetrySimu->show();
+  // allow only one instance
+  if (TelemetrySimu == 0) {
+    TelemetrySimu = new TelemetrySimulator(this, simulator);
+    TelemetrySimu->show();
+  }
+  else if (!TelemetrySimu->isVisible()) {
+    TelemetrySimu->show();
+  }
 }
 
 void SimulatorDialog::openTrainerSimulator()
 {
-  TrainerSimu = new TrainerSimulator(this, simulator);
-  TrainerSimu->setAttribute(Qt::WA_DeleteOnClose, true);
-  TrainerSimu->show();
+  // allow only one instance
+  if (TrainerSimu == 0) {
+    TrainerSimu = new TrainerSimulator(this, simulator);
+    TrainerSimu->show();
+  }
+  else if (!TrainerSimu->isVisible()) {
+    TrainerSimu->show();
+  }
 }
 
 void SimulatorDialog::openDebugOutput()
 {
-  DebugOut = new DebugOutput(this);
-  DebugOut->setAttribute(Qt::WA_DeleteOnClose, true);
-  DebugOut->traceCallback(traceBuffer);
-  DebugOut->show();
+  // allow only one instance, but install signal handler to catch dialog destruction just in case
+  if (DebugOut == 0) {
+    DebugOut = new DebugOutput(this);
+    QObject::connect(DebugOut, SIGNAL(destroyed()), this, SLOT(onDebugOutputClose()));
+    DebugOut->traceCallback(traceBuffer);
+    DebugOut->show();
+  }
+  else if (!DebugOut->isVisible()) {
+    DebugOut->show();
+  }
+}
+
+void SimulatorDialog::onDebugOutputClose()
+{
+  DebugOut = 0;
 }
 
 void SimulatorDialog::keyPressEvent (QKeyEvent *event)
diff --git a/companion/src/simulation/simulatordialog.h b/companion/src/simulation/simulatordialog.h
index 1da6e5e3e..40f8a5c2a 100644
--- a/companion/src/simulation/simulatordialog.h
+++ b/companion/src/simulation/simulatordialog.h
@@ -140,6 +140,7 @@ class SimulatorDialog : public QDialog
     void openTelemetrySimulator();
     void openTrainerSimulator();
     void openDebugOutput();
+    void onDebugOutputClose();
 
 #ifdef JOYSTICKS
     void onjoystickAxisValueChanged(int axis, int value);
diff --git a/companion/src/simulation/telemetrysimu.cpp b/companion/src/simulation/telemetrysimu.cpp
index 36e6982ab..150d48d63 100644
--- a/companion/src/simulation/telemetrysimu.cpp
+++ b/companion/src/simulation/telemetrysimu.cpp
@@ -28,6 +28,12 @@ void TelemetrySimulator::onTimerEvent()
   }
 }
 
+void TelemetrySimulator::closeEvent(QCloseEvent *event)
+{
+  ui->Simulate->setChecked(false);
+  event->accept();
+}
+
 void setSportPacketCrc(uint8_t * packet)
 {
   short crc = 0;
diff --git a/companion/src/simulation/telemetrysimu.h b/companion/src/simulation/telemetrysimu.h
index 2d89d9613..22767b026 100644
--- a/companion/src/simulation/telemetrysimu.h
+++ b/companion/src/simulation/telemetrysimu.h
@@ -2,6 +2,7 @@
 #define telemetrysimu_h
 
 
+#include <QCloseEvent>
 #include <QDialog>
 #include <QTimer>
 #include "simulatorinterface.h"
@@ -21,6 +22,7 @@ class TelemetrySimulator : public QDialog
 
 
   protected:
+    virtual void closeEvent(QCloseEvent *event);
 
   private:
     Ui::TelemetrySimulator * ui;
diff --git a/companion/src/simulation/trainersimu.cpp b/companion/src/simulation/trainersimu.cpp
index e96369230..61c2cd407 100644
--- a/companion/src/simulation/trainersimu.cpp
+++ b/companion/src/simulation/trainersimu.cpp
@@ -22,7 +22,6 @@ TrainerSimulator::TrainerSimulator(QWidget * parent, SimulatorInterface * simula
 
   timer = new QTimer(this);
   connect(timer, SIGNAL(timeout()), this, SLOT(onTimerEvent()));
-  timer->start(10);
 }
 
 TrainerSimulator::~TrainerSimulator()
@@ -31,6 +30,18 @@ TrainerSimulator::~TrainerSimulator()
   delete ui;
 }
 
+void TrainerSimulator::showEvent(QShowEvent *event)
+{
+  timer->start(10);
+  event->accept();
+}
+
+void TrainerSimulator::closeEvent(QCloseEvent *event)
+{
+  timer->stop();
+  event->accept();
+}
+
 void TrainerSimulator::centerSticks()
 {
   if (leftStick->scene())
diff --git a/companion/src/simulation/trainersimu.h b/companion/src/simulation/trainersimu.h
index 0bfc646dd..1752c75fd 100644
--- a/companion/src/simulation/trainersimu.h
+++ b/companion/src/simulation/trainersimu.h
@@ -2,6 +2,8 @@
 #define trainersimu_h
 
 
+#include <QShowEvent>
+#include <QCloseEvent>
 #include <QDialog>
 #include <QTimer>
 #include "modeledit/node.h"
@@ -22,6 +24,8 @@ class TrainerSimulator : public QDialog
 
 
   protected:
+    virtual void showEvent(QShowEvent *event);
+    virtual void closeEvent(QCloseEvent *event);
 
   private:
     Ui::TrainerSimulator * ui;
diff --git a/radio/src/opentx.cpp b/radio/src/opentx.cpp
index 12090b09f..61d6c7ac7 100644
--- a/radio/src/opentx.cpp
+++ b/radio/src/opentx.cpp
@@ -206,7 +206,7 @@ void per10ms()
   }
 #endif
 
-#if defined(FRSKY) || defined(JETI)
+#if defined(FRSKY) || defined(JETI) || defined(SIMU)
   if (!IS_DSM2_SERIAL_PROTOCOL(s_current_protocol[0]))
     telemetryInterrupt10ms();
 #endif