diff --git a/linux/devices/startracker/StarTrackerHandler.cpp b/linux/devices/startracker/StarTrackerHandler.cpp
index 7cf857d7..caf9ebdc 100644
--- a/linux/devices/startracker/StarTrackerHandler.cpp
+++ b/linux/devices/startracker/StarTrackerHandler.cpp
@@ -713,6 +713,30 @@ void StarTrackerHandler::fillCommandAndReplyMap() {
                                    startracker::MAX_FRAME_SIZE * 2 + 2);
 }
 
+ReturnValue_t StarTrackerHandler::isModeCombinationValid(Mode_t mode, Submode_t submode) {
+  if (this->mode == MODE_NORMAL && mode == MODE_ON) {
+    return TRANS_NOT_ALLOWED;
+  }
+  switch (mode) {
+    case MODE_OFF:
+    case MODE_NORMAL:
+    case MODE_RAW:
+      if (submode == SUBMODE_NONE) {
+        return RETURN_OK;
+      } else {
+        return INVALID_SUBMODE;
+      }
+    case MODE_ON:
+      if (submode == SUBMODE_BOOTLOADER || submode == SUBMODE_FIRMWARE || submode == SUBMODE_NONE) {
+        return RETURN_OK;
+      } else {
+        return INVALID_SUBMODE;
+      }
+    default:
+      return HasModesIF::INVALID_MODE;
+  }
+}
+
 ReturnValue_t StarTrackerHandler::scanForReply(const uint8_t* start, size_t remainingSize,
                                                DeviceCommandId_t* foundId, size_t* foundLen) {
   ReturnValue_t result = RETURN_OK;
diff --git a/linux/devices/startracker/StarTrackerHandler.h b/linux/devices/startracker/StarTrackerHandler.h
index 3a078b51..691237a4 100644
--- a/linux/devices/startracker/StarTrackerHandler.h
+++ b/linux/devices/startracker/StarTrackerHandler.h
@@ -48,8 +48,8 @@ class StarTrackerHandler : public DeviceHandlerBase {
 
   void performOperationHook() override;
 
-  static const Submode_t SUBMODE_BOOTLOADER = 0;
-  static const Submode_t SUBMODE_FIRMWARE = 1;
+  static const Submode_t SUBMODE_BOOTLOADER = 1;
+  static const Submode_t SUBMODE_FIRMWARE = 2;
 
  protected:
   void doStartUp() override;
@@ -60,6 +60,7 @@ class StarTrackerHandler : public DeviceHandlerBase {
   void fillCommandAndReplyMap() override;
   ReturnValue_t buildCommandFromCommand(DeviceCommandId_t deviceCommand, const uint8_t* commandData,
                                         size_t commandDataLen) override;
+  ReturnValue_t isModeCombinationValid(Mode_t mode, Submode_t submode) override;
   ReturnValue_t scanForReply(const uint8_t* start, size_t remainingSize, DeviceCommandId_t* foundId,
                              size_t* foundLen) override;
   ReturnValue_t interpretDeviceReply(DeviceCommandId_t id, const uint8_t* packet) override;