# What is the sample speed of the DAS-TC/B?

### 問題：

What is the sample speed of the DAS-TC/B?

### 答案：

What is the sample speed of the DAS-TC/B?
In contrast to other plug-in board products, the sample rate of the DAS-TC/B is not deterministic and can be affected by many parameters.

The conversion speed specifications are times required for a single measurement into an onboard buffer, however, the board does not transfer data at this rate. Using the DriverLINX driver, the maximum interrupt rate to transfer data from the onboard buffer is 2.1 Hz (475 msec), which limits the effective data rate to application programs.

The DAS-TC/B also supports the averaging of 2 or more individual readings for each measurement value reported to the controlling application software. Each of these individual readings will require one cycle of the specified conversion speed.

Another factor which affects speed is the block transfer size used by the board. The block size is equal to the number of channels in the scan. Suppose 10 channels are in use, but not all channels require the same amount of averaging such that the total number of samples requested is 43. The board will actually acquire 50 samples in five blocks of 10 samples each. These additional samples must also be accounted for in the timing.

The DAS-TC/B does support the use of an internal burst clock to quickly scan channels at rates up to one half of the selected normal mode rejection frequency. (30 Hz for USA 60Hz AC power). But theses data acquired at the burst rate will be transferred to the application program no faster than 2.1 Hz.

See the "Sample Averaging on the DAS-TC/B" section of the Using DriverLINX with Your Hardware guide (\drvlinx4\docs\notes\kdastc.pdf) for more information.