Publication 1756-RM004B-EN-P - October 2000
4-20 CIP Messaging API
rxdata_proc
Syntax:
int rxdata_proc( MVIHANDLE objHandle, MVICIPRECVSTRUC
*sRecv);
Parameters:
objHandle handle of registered object
sRecv pointer to structure of type MVICIPRECVSTRUC
Description:
rxdata_proc
is an optional callback function which may be passed to
the CIP API in the MVIcip_RegisterAssemblyObj call. If the
rxdata_proc
callback has been registered, the CIP API calls it when Class 1
scheduled data is received for the registered object specified by
objHandle
.
sRecv
is a pointer to a structure of type MVICIPRECVSTRUC. This
structure is shown below:
typedef struct tagMVICIPRECVSTRUC
{
DWORD reg_param; // value passed via MVIcip_Register AssemblyObj
MVIHANDLE connHandle; // unique value which identifies this connection
BYTE*‘ rxData; // pointer to buffer of received data
WORD dataSize; // size of received data in bytes
} MVICIPRECVSTRUC;
reg_param
is the value that was passed to
MVIcip_RegisterAssemblyObj. The application may use this to store an
index or pointer. It is not used by the CIP API.
connHandle
is the connection identifier passed to the
connect_proc
callback when this connection was opened.
rxData
is a pointer to a buffer containing the received data. dataSize is
the size of the received data in bytes.
Note:
Use of the
rxdata_proc
callback is not recommended. Registering this
callback increases CPU overhead and reduces overall performance,
especially for relatively small RPI values. It is recommended that this
callback only be used when the RPI is set to 10ms or greater.
This routine is called directly from an interrupt service routine in the
backplane device driver. It should not perform any operating system
calls and should execute as quickly as possible (200us maximum). Its
only function should be to copy the data to a local buffer. The data
must not be processed in the callback routine, or backplane
communications may be disrupted.
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