diff --git a/src/ATBAPP/DeviceControllerDiag.cpp b/src/ATBAPP/DeviceControllerDiag.cpp
index 94ce4c9..bc47ec4 100644
--- a/src/ATBAPP/DeviceControllerDiag.cpp
+++ b/src/ATBAPP/DeviceControllerDiag.cpp
@@ -113,8 +113,10 @@ void DeviceControllerDiag::private_startDiag()
     if (this->flagInterruptDiag) {
         qCritical() << "DeviceControllerDiag::private_startDiag() interrupted!";
         DCMachineEvent E255Event = DCMachineEvent(DeviceController::State::E255);
-        machineEventSet.insert(E255Event);
-        private_sendDiagEvent(E255Event, DeviceController::Action::SET);
+        if (!this->previousMachineEventSet.contains(E255Event)) {
+            machineEventSet.insert(E255Event);
+            private_sendDiagEvent(E255Event, DeviceController::Action::SET);
+        }
         if (this->E255counter > 5) {
             this->restartCArun();
             // try it again, until success:
@@ -174,8 +176,10 @@ void DeviceControllerDiag::sys_superviseSystem()
         qCritical() << "DeviceControllerDiag::sys_superviseSystem() interrupted!";
         // send
         DCMachineEvent E255Event = DCMachineEvent(DeviceController::State::E255);
-        machineEventSet.insert(E255Event);
-        private_sendDiagEvent(E255Event, DeviceController::Action::SET);
+        if (!this->previousMachineEventSet.contains(E255Event)) {
+            machineEventSet.insert(E255Event);
+            private_sendDiagEvent(E255Event, DeviceController::Action::SET);
+        }
         if (this->E255counter > 5) { this->restartCArun(); }
                               else { this->E255counter++; }
         QTimer::singleShot(400, this, &DeviceControllerDiag::diagRequest);