National Instruments 653X Manuale Utente

You have the option to allow it to regenerate data that has already been 
outputted. As in continuous input, you specify the device to allow 
regeneration though the oldDataStop parameter in the 

DIG_DB_Config

 

function and the Data Overwrite/Regenerate parameter in the Digital 
Buffer Control VI, called by the DIO Start VI.

With 6534 devices, if you want to output the same block of data repeatedly, 
you have the option of loading a buffer of data into on-board memory and 
looping through this data block continuously. With this option, data is only 
transferred from computer memory to the device on-board memory once, 
and the device outputs the same block of data continuously from its 
on-board memory. This allows the device to output data at higher rates 
because it is not limited by the PCI bus bandwidth. To enable onboard 
memory looping:

•

NI-DAQ C interface—Set the 

ND_PATTERN_GENERATION_LOOP_ENABLED 

to ND_ON in the 

Set_DAQ_Device_Info

 function.

•

LabVIEW—Set the Pattern Generation Loop Enable attribute to ON in 
the DIO Parameter VI.

When using DMA (by default), the 6534 device transfers data in 32-byte 
blocks and the 6533 device transfers data in 4-byte blocks. Therefore, at 
any time during a continuous operation, there may be up to 31 bytes (or 
3 bytes for 6533 devices) of data in an internal device FIFO. You can use 
interrupt driven transfers if you need to retrieve data immediately as it is 
acquired. Interrupt driven transfers are slower and take more processing 
time from the computer than DMA driven transfers.

1.

Connect the digital input signals to the I/O connector using the pinout 
diagrams, Figure C-1, 

.

2.

Connect the ACK pin of the 653X device to the 653X-ready line of the 
peripheral device.

3.

Connect the REQ pin of the 653X device to the peripheral-ready line 
of the peripheral device.