CntGetSamplingWritePointer

Function

Retrieves the transfer position on sampling buffer.

Format

Ret = CntGetSamplingWritePointer ( Id , WritePointer , ScanCount , ScanCarry )

Parameters

Id [ C, C++ : short ] [ Python: ctypes.c_short ]
Specifies the device ID retrieved from CntInit.

WritePointer [ C, C++ : int * ] [ Python: ctypes.POINTER(ctypes.c_int) ]
Specify the address of the variable that stores the returned transfer position.

ScanCount [ C, C++ : int * ] [ Python: ctypes.POINTER(ctypes.c_int) ]
Specify the address of the variable that stores the scan count.

ScanCarry [ C, C++ : int * ] [ Python: ctypes.POINTER(ctypes.c_int) ]
Specify the address of the variable that stores the carry count.

Return Value

Ret [ C, C++ : long ] [ Python: ctypes.c_long ]

The other errors: (See also: Details of Error Code)

Initial Value

None

Remarks

You can know the position where the data is written on the sampling buffer.
When both transfer count number and transfer position are 0, it indicates the state that no data are transferred, therefore, the actual written position is the previous value of the transfer count number retrieved by this function.

And, the sampling count is a 64-bit counter.
You can calculate 64bit value from ScanCount (Second argument) and ScanCarry (Third argument).

ScanCarry is the higher 32-bit, ScanCount is the lower 32-bit.

After starting count, the sampling number will be put into ScanCount.
ScanCarry will be increased (+1) and ScanCount is preset to zero(0) when ScanCount is overflowed.

WritePointer, ScanCount and ScanCarry are reset when you call CntResetDevice or CntSamplingStart.
These are not reset when you call CntInit.

Example