> For the complete documentation index, see [llms.txt](https://developer.magtek.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://developer.magtek.com/hardware/oem-readers-and-components/oem-readers/odynamo/documentation/programmers-manuals/common-message-structure-mtcms-programmers-reference-manual-c++/mtdevice-events.md). # MTDevice Events #### OnDeviceList The library will call this function when device information is available. ``` typedef void ( stdcall * OnDeviceListEvent)( void* sender, MTConnectionType connectionType, int deviceCount, MTDeviceInformation* deviceList); ```


Parameter	Description
sender	Object representing the publisher of the event.
connectionType	MTConnectionType value: MTConnectionType.USB, MTConnectionType.IP, MTConnectionType.Serial
deviceCount	Number of devices in deviceList.
deviceList	A list of MTDeviceInformation objects.

Return Value: None #### OnDeviceConnectionStateChanged This event occurs when the connection state of the device is changed. ``` typedef void ( stdcall * OnDeviceConnectionStateChangedEvent)( void* sender, MTConnectionState state); ```


Parameter	Description
sender	Object representing the publisher of the event.
state	MTConnectionState value indicating the state of the device: MTConnectionState.Disconnected MTConnectionState.Connecting MTConnectionState.Error MTConnectionState.Connected MTConnectionState.Disconnecting

#### OnDeviceDataString This event occurs when a response is received from the device. ``` typedef void ( stdcall * OnDeviceDataStringEvent)( void* sender, const char* dataString); ```


Parameter	Description
sender	Object representing the publisher of the event.
dataString	String representing data received.

Return Value: None #### OnDeviceResponseMessage This event occurs when a response is received from the device. ``` typedef void ( stdcall * OnDeviceResponseMessageEvent)( void* sender, const MTCMSMessage* response); ```


Parameter	Description
sender	Object representing the publisher of the event.
response	MTCMSMessage representing data received.

#### OnDeviceNotificationMessage This event occurs when a response is received from the device. ``` typedef void ( stdcall * OnDeviceNotificationMessageEvent)( void* sender, const MTCMSMessage* notification); ```


Parameter	Description
sender	Object representing the publisher of the event.
notification	MTCMSMessage representing data received.

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