Table Of Contents

Interface:CAN:Pending Transmit Order

Last Modified: September 16, 2019

Configures how the CAN interface manages the internal queue of frames: As Submitted (0) or By Identifier (1).

As Submitted transmits frames in the order that they were submitted into the queue. By Identifier transmits frames with the highest priority identifier (lower CAN ID value) first.

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Note  

You can modify this property only when the interface is stopped.

Data type: datatype_icon

Long Name: Interface:CAN:Pending Transmit Order

Class: XNET Session

Permissions: Read/Write

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Note  

Setting this property causes the internal queue to be flushed. If you start a session, queue frames, and then stop the session and change this mode, some frames may be lost. Set this property to the desired value once; do not frequently change modes.

NI-XNET stores frames in an internal queue and transmits them onto the CAN bus when the bus is idle. This property modifies how NI-XNET handles this queue of frames.

When you configure this property to be As Submitted, frames are transmitted in the order that they were submitted into the queue. There is no reordering of any frames, and a higher priority frame may be delayed due to the transmission or retransmission of a previously submitted frame. However, this mode has the highest performance.

When you configure this property to be By Identifier, frames with the highest priority identifier (lower CAN ID value) transmit first. The frames are stored in a priority queue sorted by ID. If a frame currently being transmitted requires retransmission (for example, it lost arbitration or failed with a bus error), and a higher priority frame is queued in the meantime, the lower priority frame is not immediately retried, but the higher priority frame is transmitted instead. In this mode, you can emulate multiple ECUs and still see a behavior similar to a real bus in that the highest priority message is transmitted on the bus. This mode may be slower in performance (possible delays between transmissions as the queue is re-evaluated), and lower priority messages may be delayed indefinitely due to frequent high-priority messages.

Where This Property Is Available:

Desktop OS: Windows

FPGA: Not supported

Web Server: Not supported in VIs that run in a web application


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