<< Click to Display Table of Contents >> Navigation:  NmxDLL Reference Guide > API (programming interface) > Notifications > NMX_RegisterCallback_1

This function is used to register a notification callback function at the DLL.

 

Definition

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NMX_STATUS NMX_RegisterCallback_1(

 NMX_PHANDLE pHandle,

 unsigned long ulNotification,

 NMX_NOTIFICATION_CALLBACK* pCbFunction,

 void* pvContext);

 

Parameter

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pHandle

Connection Handle.

ulNotification

Notification type, e.g. NMXNOTIFY_NEW_STATIC32.

pCbFunction

Pointer to callback function.

pvContext

A caller provided context pointer which is passed unchanged to the callback function.

 

Typical function call (C example)

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RegisterCallback_1(pHandle, NMXNOTIFY_NEW_STATIC32, &Callback_NewStatic32, (void*)&ulCallbackContext);

 

Comments

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If pCbFunction is NULL, a registered callback will be cleared.

 

Callback function

This function is the prototype for a callback notification.

Definition

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void NMX_CALLCONV NMX_NOTIFICATION_CALLBACK(IN void* pvContext);

 

Parameter

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pvContext

This parameter is the same which was passed to the function NMX_RegisterCallback_1. The application can store a context information in this pointer.

 

.Net DLL specific implementation

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NMX_MSTATUS RegisterCallback_1(

                 System::IntPtr pHandle,

                 NMX_NOTIFICATION eNotification,

                 OnNotification^ NotificationDelegate);

NMX_NOTIFICATION is an enum type, which is defined in the .Net - DLL. The available notifications are identical to the standard notifications, except that they don't have a fixed binary representation.

In .Net, delegates are used instead of function pointers. The .Net - DLL calls this delegates in case of a notification.

In C#, an example for a delegate function is:

public void OnNewStaticData(IntPtr pHandle)

{

}

The handle of the calling DLL-instance is provided as a function parameter. If you have only one instance (= 1 connection to a device), don't care about it. This is the most common case.

In case you have multiple instances, the handle can be used to distinquish between multiple connections.

 

An example for registering the delegate is:

cNmx.RegisterCallback_1(pDevice, NMX_NOTIFICATION.NEW_STATIC32, OnNewStaticData);

 

Note: Since the delegate is directly forwarded to the unmanaged DLL, the .Net wrapper fixes the delagte pointer in the garbage collector (gc.Alloc).

 

Comments

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This function is called in a different thread context. The application must handle the synchronisation.