# SimConnect_SubscribeToSystemEvent<no value>
The **SimConnect\_SubscribeToSystemEvent** function is used to request that a specific system event is notified to the client.

 

##### Syntax

``` cpp
HRESULT SimConnect_SubscribeToSystemEvent(
    HANDLE  hSimConnect,
    SIMCONNECT_CLIENT_EVENT_ID  EventID,
    const char*  SystemEventName
    );
```

 

##### Parameters

{{< table-wrapper >}}

| Parameter         | Description                                                                                                                                                                                                                                                                                                                                                                                               | Type    |
|-------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|---------|
| *hSimConnect*     | Handle to a SimConnect object.                                                                                                                                                                                                                                                                                                                                                                            | Integer |
| *EventID*         | Specifies the ID of the client event.                                                                                                                                                                                                                                                                                                                                                                     | Integer |
| *SystemEventName* | The string name for the requested system event, which should be one from the table below (note that the event names are not case-sensitive). Unless otherwise stated in the Description, notifications of the event are returned in a **[SIMCONNECT\_RECV\_EVENT](../structures-and-enumerations/simconnect-recv-event/)** structure (identify the event from the *EventID* given with this function). | String  |

{{< /table-wrapper >}}


 

The following table shows the available *SystemEventName* variables:

<table><thead><tr class="header"><th>System Event Name</th><th>Description</th></tr></thead><tbody><tr class="odd"><td><code>1sec</code></td><td>Request a notification every second.</td></tr><tr class="even"><td><code>4sec</code></td><td>Request a notification every four seconds.</td></tr><tr class="odd"><td><code>6Hz</code></td><td>Request notifications six times per second. This is the same rate that joystick movement events are transmitted.</td></tr><tr class="even"><td><code>AircraftLoaded</code></td><td>Request a notification when the aircraft flight dynamics file is changed. These files have a .AIR extension. The filename is returned in a <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT_FILENAME.htm">SIMCONNECT_RECV_EVENT_FILENAME</a> structure.</td></tr><tr class="odd"><td><code>Crashed</code></td><td>Request a notification if the user aircraft crashes.</td></tr><tr class="even"><td><code>CrashReset</code></td><td>Request a notification when the crash cut-scene has completed.</td></tr><tr class="odd"><td><code>CustomMissionActionExecuted</code> </td><td>Request a notification when a mission action has been executed.</td></tr><tr class="even"><td><code class="inline" data-condition="Product:Development">DialogFrame</code></td><td></td></tr><tr class="odd"><td><code>FlightLoaded</code></td><td>Request a notification when a flight is loaded. Note that when a flight is ended, a default flight is typically loaded, so these events will occur when flights and missions are started and finished. The filename of the flight loaded is returned in a <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT_FILENAME.htm">SIMCONNECT_RECV_EVENT_FILENAME</a> structure.</td></tr><tr class="even"><td><code>FlightSaved</code></td><td>Request a notification when a flight is saved correctly. The filename of the flight saved is returned in a <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT_FILENAME.htm">SIMCONNECT_RECV_EVENT_FILENAME</a> structure.</td></tr><tr class="odd"><td><code>FlightPlanActivated</code></td><td>Request a notification when a new flight plan is activated. The filename of the activated flight plan is returned in a <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT_FILENAME.htm">SIMCONNECT_RECV_EVENT_FILENAME</a> structure.</td></tr><tr class="even"><td><code>FlightPlanDeactivated</code></td><td>Request a notification when the active flight plan is de-activated.</td></tr><tr class="odd"><td><code>Frame</code></td><td>Request notifications every visual frame. Information is returned in a <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT.htm">SIMCONNECT_RECV_EVENT</a> structure.</td></tr><tr class="even"><td><code>MissionCompleted</code></td><td>Request a notification when the user has completed a mission. Refer to the <a href="../Structures_And_Enumerations/SIMCONNECT_MISSION_END.htm">SIMCONNECT_MISSION_END</a> enum for more information.</td></tr><tr class="odd"><td><code>MultiplayerClientStarted</code></td><td>Used by a client to request a notification that they have successfully joined a multiplayer race. The event is returned as a <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT_MULTIPLAYER_CLIENT_STARTED.htm">SIMCONNECT_RECV_EVENT_MULTIPLAYER_CLIENT_STARTED</a> structure. This event is only sent to the client, not the host of the session.</td></tr><tr class="even"><td><code>MultiplayerServerStarted</code></td><td>Used by a host of a multiplayer race to request a notification when the race is open to other players in the lobby. The event is returned in a <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT_MULTIPLAYER_SERVER_STARTED.htm">SIMCONNECT_RECV_EVENT_MULTIPLAYER_SERVER_STARTED</a> structure.</td></tr><tr class="odd"><td><code>MultiplayerSessionEnded</code></td><td>Request a notification when the mutliplayer race session is terminated. The event is returned in a <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT_MULTIPLAYER_SESSION_ENDED.htm">SIMCONNECT_RECV_EVENT_MULTIPLAYER_SESSION_ENDED</a> structure. If a client player leaves a race, this event wil be returned just to the client. If a host leaves or terminates the session, then all players will receive this event. This is the only event that will be broadcast to all players.</td></tr><tr class="even"><td><code>ObjectAdded</code></td><td>Request a notification when an AI object is added to the simulation. Refer also to the <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT_OBJECT_ADDREMOVE.htm">SIMCONNECT_RECV_EVENT_OBJECT_ADDREMOVE</a> structure.</td></tr><tr class="odd"><td><code>ObjectRemoved</code></td><td>Request a notification when an AI object is removed from the simulation. Refer also to the <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT_OBJECT_ADDREMOVE.htm">SIMCONNECT_RECV_EVENT_OBJECT_ADDREMOVE</a> structure.</td></tr><tr class="even"><td><code>Pause</code></td><td>Request notifications when the flight is paused or unpaused, and also immediately returns the current pause state (1 = paused or 0 = unpaused). The state is returned in the dwData parameter.</td></tr><tr class="odd"><td><code>Pause_EX1</code></td><td><p>Request notifications when the flight is paused or unpaused, and also immediately returns the current pause state with more detail than the regular <code>Pause</code> system event. The state is returned in the <code>dwData</code> parameter, and will be a combination (OR) of the following defines:</p><pre class="language-cpp"><code>#define PAUSE_STATE_FLAG_OFF                0    // No Pause
#define PAUSE_STATE_FLAG_PAUSE              1    // &quot;full&quot; Pause (sim + traffic + etc...)
#define PAUSE_STATE_FLAG_PAUSE_WITH_SOUND   2    // FSX Legacy Pause (not used anymore)
#define PAUSE_STATE_FLAG_ACTIVE_PAUSE       4    // Pause was activated using the &quot;Active Pause&quot; Button
#define PAUSE_STATE_FLAG_SIM_PAUSE          8    // Pause the player sim but traffic, multi, etc... will still run</code></pre></td></tr><tr class="even"><td><code>Paused</code></td><td>Request a notification when the flight is paused.</td></tr><tr class="odd"><td><code>PauseFrame</code></td><td>Request notifications for every visual frame that the simulation is paused. Information is returned in a <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT.htm">SIMCONNECT_RECV_EVENT</a> structure.</td></tr><tr class="even"><td><code>PositionChanged</code></td><td>Request a notification when the user changes the position of their aircraft through a dialog.</td></tr><tr class="odd"><td><code>RaceEnd</code></td><td>Request a notification of the race results for each racer. The results will be returned in <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT_RACE_END.htm">SIMCONNECT_RECV_EVENT_RACE_END</a> structures, one for each player.</td></tr><tr class="even"><td><code>RaceLap</code></td><td>Request a notification of the race results for each racer. The results will be returned in <a href="../Structures_And_Enumerations/SIMCONNECT_RECV_EVENT_RACE_LAP.htm">SIMCONNECT_RECV_EVENT_RACE_LAP</a> structures, one for each player.</td></tr><tr class="odd"><td><code>Sim</code></td><td>Request notifications when the flight is running or not, and also immediately returns the current state (1 = running or 0 = not running). The state is returned in the dwData parameter.</td></tr><tr class="even"><td><code>SimStart</code></td><td>The simulator is running. Typically the user is actively controlling the aircraft on the ground or in the air. However, in some cases additional pairs of <code>SimStart</code>/<code>SimStop</code> events are sent. For example, when a flight is reset the events that are sent are <code>SimStop</code>, <code>SimStart</code>, <code>SimStop</code>, <code>SimStart</code>. Also when a flight is started with the <code>SHOW_OPENING_SCREEN</code> value set to zero, then an additional <code>SimStart</code>/<code>SimStop</code> pair are sent before a second <code>SimStart</code> event is sent when the scenery is fully loaded. The opening screen provides the options to change aircraft, departure airport, and so on.</td></tr><tr class="odd"><td><code>SimStop</code></td><td>The simulator is not running. Typically the user is loading a flight, navigating the shell or in a dialog.</td></tr><tr class="even"><td><code>Sound</code></td><td>Requests a notification when the master sound switch is changed. This request will also return the current state of the master sound switch immediately. A flag is returned in the <code>dwData</code> parameter, 0 if the switch is off, <code>SIMCONNECT_SOUND_SYSTEM_EVENT_DATA_MASTER</code> (0x1) if the switch is on.</td></tr><tr class="odd"><td><code>Unpaused</code></td><td>Request a notification when the flight is un-paused.</td></tr><tr class="even"><td><code>View</code></td><td>Requests a notification when the user aircraft view is changed. This request will also return the current view immediately. A flag is returned in the dwData parameter, one of: <code>SIMCONNECT_VIEW_SYSTEM_EVENT_DATA_COCKPIT_2D</code> <code>SIMCONNECT_VIEW_SYSTEM_EVENT_DATA_COCKPIT_VIRTUAL</code> <code>SIMCONNECT_VIEW_SYSTEM_EVENT_DATA_ORTHOGONAL</code> (the map view).</td></tr><tr class="odd"><td><code>WeatherModeChanged</code> </td><td>Request a notification when the weather mode is changed.</td></tr></tbody></table>

 

##### Return Values

The function returns an **HRESULT**. Possible values include, but are not limited to, those in the following table.

{{< table-wrapper >}}

| Return value | Description             |
|--------------|-------------------------|
| S\_OK        | The function succeeded. |
| E\_FAIL      | The function failed.    |

{{< /table-wrapper >}}


 

##### Example

``` cpp
static enum EVENT_ID {
    EVENT_FLIGHT_LOAD,
    EVENT_RECUR_1SEC,
    EVENT_RECUR_FRAME, 
    };
hr = SimConnect_SubscribeToSystemEvent(hSimConnect, EVENT_FLIGHT_LOAD, "FlightLoaded");
hr = SimConnect_SubscribeToSystemEvent(hSimConnect, EVENT_RECUR_1SEC,  "1sec");
hr = SimConnect_SubscribeToSystemEvent(hSimConnect, EVENT_RECUR_FRAME, "frame");
hr = SimConnect_SetSystemEventState(hSimConnect, EVENT_RECUR_FRAME, SIMCONNECT_STATE_OFF);
Working Samples
```

 

##### Remarks

A single call to this function is all that is necessary to receive the notifications. For greatest efficiency use `SimConnect_SetSystemEventState` to turn these requests on and off temporarily, and call [SimConnect\_UnsubscribeFromSystemEvent](simconnect-unsubscribefromsystemevent/) once only to permanently terminate the notifications of these events.