Choosing Continuous Or Finite Data Transfer; Finite Transfers; Continuous Input; Continuous Output - National Instruments 653 Series User Manual

Chapter 2 Using Your NI 653X

Choosing Continuous or Finite Data Transfer

NI 653X User Manual
You can transfer data indefinitely to/from computer memory or finitely by
specifying the number of points you want to transfer.

Finite Transfers

For finite transfers, the NI 653X transfers the specified amount of data
to/from a computer memory buffer and stops the operation.

Continuous Input

For continuous input, the NI 653X transfers input data to the computer
memory buffer continuously. As the device fills the buffer, call the
DIG_DB_Transfer
If at any time the device runs out of space in the buffer, it pauses the
handshaking operation until your program clears more buffer space.
You can allow the device to continue acquiring data when it runs out of
buffer space and overwrite data you have not yet read. You can specify this
through the
oldDataStop
the data overwrite/regen. parameter in the Digital Buffer Control VI
called by the DIO Start VI.

Continuous Output

Similarly, with continuous output, the NI 653X continuously reads data
from computer memory. As the device retrieves data from the buffer, call
the
DIG_DB_Transfer
the buffer. The device pauses the handshaking operation if it runs out of
data to generate. The data transfer resumes once more data is available.
You have the option to allow it to regenerate data that has already been
output. As in continuous input, you specify the device to allow regeneration
though the
oldDataStop
the data overwrite/regen. parameter in the Digital Buffer Control VI,
called by the DIO Start VI.
♦
NI 6534
With the NI 6534, if you want to repeatedly generate the same block of
data, you can load a buffer of data into onboard memory and continuously
loop through this data block. With this option, data is only transferred from
computer memory to the NI 6534 onboard memory once, and the device
generates the same block of data continuously from its onboard memory,
function or the DIO Read VI to retrieve the data.
parameter in the
function or the DIO Write VI to write new data to
parameter in the
2-20
function and
DIG_DB_Config
function and
DIG_DB_Config
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