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

Choosing Continuous or Finite Data Transfer

© National Instruments Corporation
You can transfer data continuously into or from computer memory or
specify the number of points you want to transfer.

Finite Transfers

For finite transfers, the NI 653X transfers the specified amount of data
to/from computer memory 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
function or the DIO Read VI to retrieve the data. If at
DIG_DB_Transfer
any time the device runs out of space in the buffer, it stops the operation
and NI-DAQ returns an error.
You can allow the device to continue acquiring 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,
which is 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 device stops and returns an error if it runs out of data to generate, but
you can allow it to regenerate data that has already been generated. As in
continuous input, you configure the device to allow regeneration with the
parameter in the
oldDataStop
overwrite/regen. parameter in the Digital Buffer Control VI, which is
called by the DIO Start VI.
parameter in the
function or the DIO Write VI to write the data.
DIG_DB_Config
2-11
Chapter 2 Using Your NI 653X
function and
DIG_DB_Config
function and the data
NI 653X User Manual