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How to Read Onboard Memory Size of a Modular Instrument

Hardware: Digital I/O (DIO)>>High-Speed, Signal Sources (AWG/FG/AO)>>Arbitrary Waveform and Function Generators, Modular Instruments>>RF Measurement Devices, Modular Instruments>>High-Speed Digitizers (Scopes)

Problem:
I have a modular instrument (signal source, digitizer, or high-speed digital), but I'm not sure how much memory is on it. How can I find out?

Solution:
The total onboard memory available to any Modular Instrument can be found using a Property Node. The specific location of the property varies among types of devices, so the node must connected to a driver session first. The following picture illustrates each type of property node and the full property name.

Digitizers (NI-SCOPE)
The property is called Memory Size and is located in the Horizontal category. Remember that the total onboard memory is reported, and this is divided between the two channels in your device. So the onboard memory per channel is actually half this value.

High-Speed Digital (NI-HSDIO)
Since the memory banks are not shared, there are two properties: one for acquisition memory, and one for generation memory. They are called Total Acquisition/Generation Memory Size and are located in the Device Characteristics category. Remember that the number of samples that can be acquired is a function of the Data Width and Data Rate. For instance, an NI 6551 acquisition with Data Width = 4 (32 bits per sample) will be able to acquire one fourth as many samples as an acquisition with Data Width = 1 (8 bits per sample).

Arbitrary Waveform Generators (NI-FGEN)
The Memory Size property is found in the Instrument Specific Attributes category

If you do not have LabVIEW installed, you can also check the onboard memory of any Modular Instrument by using the driver API to obtain the memory attribute of the device. The following is a table of functions and attributes that can be used.

Function	Attribute
niScope_GetAttributeViInt32	NISCOPE_ATTR_ONBOARD_MEMORY_SIZE
niHSDIO_GetAttributeViInt32	NIHSDIO_ATTR_TOTAL_ACQUISITION_MEMORY_SIZE
niFgen_GetAttributeViInt32	NIFGEN_ATTR_MEMORY_SIZE

NOTE: If you are trying to find the memory size for an RF Vector Signal Analyzer (RFSA) or RF Vector Signal Generator (RFSG), since these have either a digitizer or a signal generator, respectively, as one of their modules, you can simply reference the digitizer or signal generator portion of the device and follow the same steps as above.

Related Links:
Example Program: Finding Onboard Memory of a Modular Instrument
Product Manuals: NI High-Speed Digitizers Help (June 2008)
Product Manuals: NI Digital Waveform Generator/Analyzer Help (September 2007)
Product Manuals: NI Signal Generators Help (December 2008)

Attachments:


- PropertyNodes.png


Report Date: 09/20/2006
Last Updated: 02/06/2009
Document ID: 41JBNSTT

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