Handling Method of Sampling Buffer

Here, it explains how to use the buffer and functions for typical patterns about input transfer (Sampling).


Pattern 1: Finite data number, retrieve data after sampling

It is the case that transfer data once and retrieve data after sampling.

 
                                                           Handling

In this case, it is necessary to allocate the buffer size more than the size of the number of the data to be retrieved.

Specify "CNTS_WRITE_ONCE" on CntSamplingSetBuffer function for buffer repetition. When the number of input data is decided, specify "CNTS_STOP_NUM" on CntSetSamplingStopTrigger function for stop condition, and use the CntSetSamplingStopNumber function to stop the transfer with specified times.

After transfer started, use Win32API such as Sleep by loop to wait transfer to complete or status bit CNTS_STATUS_BMSTOP to be retrieved by status acquisition function.



Pattern 2: Finite data number, retrieve data while sampling

It is the case that perform transfer once and retrieve data while sampling.

 
 Handling                 Handling                 Handling

In this case, it is necessary to allocate the buffer size more than the size of the number of the data to be retrieved.

Specify "CNTS_WRITE_ONCE" on CntSamplingSetBuffer function for buffer repetition. When the number of input data is decided, specify "CNTS_STOP_NUM" on CntSetSamplingStopTrigger function for stop condition, and use the CntSetSamplingStopNumber function to stop the transfer with specified times.

During transfer, the handling is performed while the data existing position is retrieved in the transfer number acquisition function (CntGetSamplingCount).
Perform the process during transfer, and besides, check the status function and confirm that completion operation does not occur by an error etc.
Use Win32API such as Sleep in loop so as not to overload the system.



Pattern 3: Infinite data number, retrieve all of the data

It is the case that perform transfer infinitely and perform operation such as storing the data into a file at every specified times interval.
For transfer infinitely, you indicate "CNTS_WRITE_RING" on CntSamplingSetBuffer function.

 
 Handling                  Handling               Handling

To confirm the transfer times, use the message of specified time transfer completion, or use transfer time acquisition function (CntGetSamplingCount) with system timer etc.

The application periodically perform processing from read pointer to write pointer according to system timer or event message.

In this case, please note that in user program, it is necessary to handle the read pointer which indicates the position for marking the handled data, and the write pointer which indicates the buffer position into where the data have been written.

The read pointer/write pointer is a counter that will return to 0 when the transfer is up to the buffer size.
Use the CntGetSamplingWritePointer function to retrieve the write pointer.
The read pointer is the write pointer when processing data last time.



Pattern 4: Infinite data number, retrieve arbitrary data number from any part by retrieving write pointer

It is the case that perform transfer infinitely and retrieve arbitrary data number from any part when an arbitrary condition is satisfied.
For transfer infinitely, you indicate "CNTS_WRITE_RING" on CntSamplingSetBuffer function.

In this case, it is also necessary to handle the read pointer and the write pointer.

Please refer to pattern 3.