# NatNet: Remote Requests/Commands

## Remote Requests/Commands

***

\
The NatNet SDK features methods for sending remote commands and requests from a client application over to a connected server application. The SendMessageAndWait method within a NatNetClient object passes one of the NatNet commands each time it's called. NatNet commands are sent via the UDP connection; 1510 port by default. Once a NatNet server application (e.g. Motive) receives the remote command, corresponding actions will be performed.

For a sample use of NatNet commands, refer to the provided WinFormSample.

<br>

#### NatNetClient::SendMessageAndWait

```
ErrorCode	SendMessageAndWait( const char* szRequest,
				    void** ppServerResponse, 
					int* pResponseSize );
```

```
ErrorCode	SendMessageAndWait( const char* szRequest,
				    int tries, int timeout, 
				    void** ppServerResponse,
				    int* pResponseSize );
```

**Description**

Sends a NatNet command to the NatNet server and waits for a response.

**Input Parameters:**

* szRequest: NatNet command.
* tries: Number of attempts to send the command. Default: 10.
* timeout: Number of milliseconds to wait for a response from the server before the call times out. Default: 20.
* ppServerResponse: Application defined response.
* pResponseSize: Number of bytes in response

**Returns:**

ErrorCode, On success, it returns 0 or ErrorCode\_OK indicating that the remmote message have been successfully delivered.

#### Motive Supported NatNet Commands/Requests

| Command (string)           | Description                                               | Parameters   | Returns                |
| -------------------------- | --------------------------------------------------------- | ------------ | ---------------------- |
| UnitsToMillimeters         | Request current system’s units, in terms of millimeters   | none         | float                  |
| FrameRate                  | Request current system’s tracking framerate               | none         | float                  |
| StartRecording             | Start recording                                           | none         | none                   |
| StopRecording              | Stop recording                                            | none         | none                   |
| LiveMode                   | Switch to Live mode                                       | none         | none                   |
| EditMode                   | Switch to Edit mode                                       | none         | None                   |
| CurrentMode                | Request current mode                                      | none         | int                    |
| TimelinePlay               | Start take playback                                       | none         | none                   |
| TimelineStop               | Stop take playback                                        | none         | none                   |
| SetPlaybackTakeName        | Set playback take                                         | Take name    | None                   |
| SetRecordTakeName          | Set record take name                                      | Take name    | None                   |
| SetCurrentSession          | Set current session                                       | Session name | None                   |
| SetPlaybackStartFrame      | Set start frame                                           | Frame number | None                   |
| SetPlaybackStopFrame       | Set stop frame                                            | Frame number | None                   |
| SetPlaybackCurrentFrame    | Set current frame                                         | Frame number | None                   |
| CurrentTakeLength          | Request length of current take                            | None         | Number of frames (int) |
| AnalogSamplesPerMocapFrame | Request number of analog samples per motion capture frame | None         | int                    |

## Sample Use

***

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Below is a sample use of the NatNet commands from the WinFormsSample application.

```
private void RecordButton_Click(object sender, EventArgs e)
{
	string command = "StartRecording";

	int nBytes = 0;
	byte[] response = new byte[10000];
	int rc = m_NatNet.SendMessageAndWait(command, 3, 100, out response, out nBytes);
	if (rc != 0)
	{
		OutputMessage(command + " not handled by server");
	}
	else
	{
		int opResult = System.BitConverter.ToInt32(response, 0);
		if (opResult == 0)
			OutputMessage(command + " handled and succeeded.");
		else
			OutputMessage(command + " handled but failed.");
	}
}
```