Arbitrary Waveform:Data Transfer:Advanced:Maximum In-Flight Read Requests Property

NI Signal Generators Help (NI-FGEN 18.1)

Edition Date: April 2018

Part Number: 370524V-01

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Short Name: Maximum In-Flight Read Requests

Property of niFgen

Specifies the maximum number of concurrent PCI Express read requests the signal generator can issue.

When transferring data from computer memory to device onboard memory across the PCI Express bus, the signal generator can issue multiple memory reads at the same time. In general, the larger the number of read requests, the more efficiently the device uses the bus because the multiple read requests keep the data flowing, even in a PCI Express topology that has high latency due to PCI Express switches in the data path. Most NI devices can issue a large number of read requests (typically 8 or 16). By default, this property is set to the highest value the signal generator supports.

If other devices in your system cannot tolerate long data latencies, it may be helpful to decrease the number of in-flight read requests the NI signal generator issues. This change helps to reduce the amount of data the signal generator reads at one time.

Note  You cannot change this property while the device is generating a waveform. If you want to change the device configuration, call the niFgen Abort Generation VI or wait for the generation to complete.

Remarks

The following table lists the characteristics of this property.

Datatype iL
PermissionsRead/Write
High-level VIs N/A
Channel-based No
ResettableYes

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