diff --git a/src/ATBAPP/DeviceControllerDiag.cpp b/src/ATBAPP/DeviceControllerDiag.cpp
index 4607433..e098b02 100644
--- a/src/ATBAPP/DeviceControllerDiag.cpp
+++ b/src/ATBAPP/DeviceControllerDiag.cpp
@@ -465,7 +465,8 @@ void DeviceControllerDiag::sub_componentAssessment()
     this->isRequestRunning  = false;
     this->flagInterruptDiag = false;
 
-    this->previousMachineEventSet = machineEventSet;
+    this->previousMachineEventSet.unite(machineEventSet);      // add new elements from machineEventSet
+    this->previousMachineEventSet.intersect(machineEventSet);  // remove elements not in machineEventSet
 
     if (this->isDiagBackgroundTask) {
         this->isDiagBackgroundTask = false;