Data Acquisition Toolbox

daqmem

Allocate or display memory resources

Syntax

• out = daqmem
  out = daqmem(obj)
  daqmem(obj,maxmem)
  

Arguments

obj	A device object or array of device objects.
maxmem	The amount of memory to allocate.
out	A structure containing information about memory resources.

Description

out = daqmem returns the structure out, which contains several fields describing the memory resources associated with your platform and the Data Acquisition Toolbox. The fields are described below.

Field	Description
MemoryLoad	Specifies a number between 0 and 100 that gives a general idea of current memory utilization. 0 indicates no memory use and 100 indicates full memory use.
TotalPhys	Indicates the total number of bytes of physical memory.
AvailPhys	Indicates the number of bytes of physical memory available.
TotalPageFile	Indicates the total number of bytes that can be stored in the paging file. Note that this number does not represent the actual physical size of the paging file on disk.
AvailPageFile	Indicates the number of bytes available in the paging file.
TotalVirtual	Indicates the total number of bytes that can be described in the user mode portion of the virtual address space of the calling process.
AvailVirtual	Indicates the number of bytes of unreserved and uncommitted memory in the user mode portion of the virtual address space of the calling process.
UsedDaq	The total memory used by all device objects.

Note that all the above fields, except for UsedDaq, are identical to the fields returned by Windows' MemoryStatus function.

out = daqmem(obj) returns a 1-by-N structure out containing two fields: UsedBytes and MaxBytes for the device object obj. N is the number of device objects specified by obj. UsedBytes returns the number of bytes used by obj. MaxBytes returns the maximum number of bytes that can be used by obj.

daqmem(obj,maxmem) sets the maximum memory that can be allocated for obj to the value specified by maxmem.

Remarks

More About Allocating and Displaying Memory Resources

• For analog output objects, daqmem(obj,maxmem) controls the value of the MaxSamplesQueued property.
• If you manually configure the BufferingConfig property, then this value supersedes the values specified by daqmem(obj,maxmem) and the MaxSamplesQueued property.

Example

Create the analog input object aiwin for a sound card and the analog input object aini for a National Instruments board, and add two channels to each device object.

• aiwin = analoginput('winsound');
  addchannel(aiwin,1:2);
  aini = analoginput('nidaq',1);
  addchannel(aini,0:1);
  

To display the total memory used by all existing device objects:

• out = daqmem;
  out.UsedDaq
  ans =
         69120
  

To configure the maximum memory used by aiwin to 640 KB:

• daqmem(aiwin,640000)
  

To configure the maximum memory used by each device object with one call to daqmem:

• daqmem([aiwin aini],[640000 480000])
  

See Also

Properties

BufferingConfig, MaxSamplesQueued

daqhwinfo

daqpropedit