clean up code structure a bit

mission/system/acs/CMakeLists.txt

@@ -9,4 +9,5 @@ target_sources(
           SusAssembly.cpp
           AcsBoardFdir.cpp
           acsModeTree.cpp
-          SusFdir.cpp)
+          SusFdir.cpp
+          StrFdir.cpp)

mission/system/acs/StrFdir.cpp

@@ -0,0 +1,14 @@
+#include "StrFdir.h"
+
+#include "mission/acs/defs.h"
+
+StrFdir::StrFdir(object_id_t strObject)
+    : DeviceHandlerFailureIsolation(strObject, objects::NO_OBJECT) {}
+
+ReturnValue_t StrFdir::eventReceived(EventMessage* event) {
+  if (event->getEvent() == acs::MEKF_INVALID_MODE_VIOLATION) {
+    setFaulty(event->getEvent());
+    return returnvalue::OK;
+  }
+  return DeviceHandlerFailureIsolation::eventReceived(event);
+}

mission/system/acs/StrFdir.h

@@ -0,0 +1,12 @@
+#ifndef MISSION_SYSTEM_FDIR_STRFDIR_H_
+#define MISSION_SYSTEM_FDIR_STRFDIR_H_
+
+#include <fsfw/devicehandlers/DeviceHandlerFailureIsolation.h>
+
+class StrFdir : public DeviceHandlerFailureIsolation {
+ public:
+  StrFdir(object_id_t strObject);
+  ReturnValue_t eventReceived(EventMessage* event) override;
+};
+
+#endif /* MISSION_SYSTEM_FDIR_STRFDIR_H_ */