Table Of Contents

XNET Connect Terminals (G Dataflow)

Version:
    Last Modified: March 13, 2017

    Connects terminals on the XNET interface.

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    session in

    The session to use for the connection. This session is selected from the LabVIEW project or returned from XNET Create Session.

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    source terminal

    The connection source.

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    destination terminal

    The connection destination.

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    error in

    Error conditions that occur before this node runs. The node responds to this input according to standard error behavior.

    Default: No error

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    session out

    A duplicate of session in, provided for simpler wiring.

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    error out

    Error information. The node produces this output according to standard error behavior.

    Description

    This node connects a source terminal to a destination terminal on the interface hardware. The XNET terminal represents an external or internal hardware connection point on a National Instruments XNET hardware product. External terminals include PXI_Trigger lines for a PXI card, RTSI terminals for a PCI card, or the single external terminal for a C Series module. Internal terminals include timebases (clocks) and logical entities such as a start trigger.

    The terminal inputs use the XNET Terminal I/O name, so you can select from possible values using the drop-down list. Typically, one of the pair is an internal and the other an external.

    Valid Combinations of Source/Destination

    The following table lists all valid combinations of source terminal and destination terminal.

    Source Destination
    PXI_Trigx FrontPanel0 FrontPanel1 Start Trigger MasterTimebase Log Trigger
    PXI_Trigx X X
    FrontPanel0 FrontPanel1 X X
    PXI_Star 1 X X X X
    PXI_Clk10 1 X X X X
    StartTrigger X X X
    CommTrigger X X X
    FlexRayStartCycle 2 X X X
    FlexRayMacrotick 2 X X
    1MHzTimebase X X X
    10MHzTimebase X X X X

    1Valid only on PXI hardware.

    2Valid only on FlexRay hardware.

    Source Terminals

    The following table describes the valid source terminals.

    Source Terminal Description
    PXI_Trigx Selects a general-purpose trigger line as the connection source (input), where x is a number from 0 to 7. For PCI cards, these are the RTSI lines. For PXI cards, these are the PXI Trigger lines. For C Series modules in a CompactDAQ chassis, all modules in the chassis automatically share a common timebase. For information about routing the StartTrigger for CompactDAQ, refer to the XNET Session Interface:Source Terminal:Start Trigger property.
    FrontPanel0

    FrontPanel1

    Selects a general-purpose Front Panel Trigger line as the connection source (input).
    PXI_Star

    Selects the PXI star trigger signal.

    Within a PXI chassis, some PXI products can source star trigger from Slot 2 to all higher-numbered slots. PXI_Star enables the PXI XNET hardware to receive the star trigger when it is in Slot 3 or higher.

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    Note  

    You cannot use this terminal with a PCI device.

    PXI_Clk10

    Selects the PXI 10 MHz backplane clock.

    The only valid destination terminal for this source is MasterTimebase. This routes the 10 MHz PXI backplane clock for use as the XNET card timebase. When you use PXI_Clk10 as the XNET card timebase, you also must use PXI_Clk10 as the timebase for other PXI cards to perform synchronized input/output.

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    Note  

    You cannot use this terminal with a PCI device.

    StartTrigger

    Selects the start trigger, which is the event set when the Start Interface transition occurs. The start trigger is the same for all sessions using a given interface.

    You can route the start trigger of this XNET card to the start trigger of other XNET or DAQ cards to ensure that sampling begins at the same time on both cards. For example, you can synchronize two XNET cards by routing StartTrigger as the source terminal on one XNET card and then routing StartTrigger as the destination terminal on the other XNET card, with both cards using the same PXI Trigger line for the connections.

    CommTrigger

    Selects the communicating trigger, which is the event set when the Comm State Communicating transition occurs. The communicating trigger is the same for all sessions using a given interface.

    You can route the communicating trigger of this XNET card to the start trigger of other XNET or DAQ cards to ensure that sampling begins at the same time on both cards.

    The communicating trigger is similar to a start trigger, but is used if your clock source is the FlexRayMacrotick, which is not available until the interface is properly integrated into the bus. Because you cannot generate a start trigger to another interface until the synchronization clock is also available, you can use this trigger to allow for the clock under this special circumstance.

    FlexRayStartCycle

    Selects the FlexRay Start of Cycles as an advanced trigger source.

    This generates a repeating pulse that external hardware can use to synchronize a measurement or other action with each FlexRay cycle.

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    Note  

    You can use this terminal only with a FlexRay device.

    FlexRayMacrotick

    Selects the FlexRay Macrotick as a timing source. The FlexRay Macrotick is the basic unit of time in a FlexRay network.

    You can use this source terminal to synchronize other measurements to the actual time on the FlexRay bus. In this scenario, you would configure the FlexRayMacrotick as the source terminal and route it to a PXI Trigger or front panel terminal. After the interface is communicating to the FlexRay network, the Macrotick signal becomes available.

    You also can connect the FlexRayMacrotick to the MasterTimebase. This configures the counter that timestamps received frames to run synchronized to FlexRay time, and also allows you to read the FlexRay cycle macrotick to do additional synchronization with the FlexRay bus in your application.

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    Note  

    You can use this terminal only with a FlexRay device.

    1MHzTimebase

    Selects the XNET card's local 1 MHz oscillator. The only valid destination terminals for this source are PXI_Trig0–PXI_Trig7.

    This source terminal routes the XNET card local 1 MHz clock so that other NI cards can use it as a timebase. For example, you can synchronize two XNET cards by connecting 1MHzTimebase to PXI_Trigx on one XNET card and then connecting PXI_Trigx to MasterTimebase on the other XNET card.

    10MHzTimebase Selects the XNET card's local 10 MHz oscillator. This routes the XNET card local 10 MHz clock for use as a timebase by other NI cards. For example, you can synchronize two XNET cards by connecting 10MHzTimebase to PXI_Trigx on one XNET card and then connecting PXI_Trigx to MasterTimebase on the other XNET card.

    Destination Terminals

    The following table describes the valid destination terminals.

    Destination Terminal Description
    PXI_Trigx Selects a general-purpose trigger line as the connection destination (output), where x is a number from 0 to 7. For PCI cards, these are the RTSI lines. For PXI cards, these are the PXI Trigger lines. For C Series modules in a CompactDAQ chassis, all modules in the chassis automatically share a common timebase. For information about routing the StartTrigger for CompactDAQ, refer to the XNET Session Interface:Source Terminal:Start Trigger property.
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    Caution  

    NI-XNET does not automatically reserve PXI trigger lines. Driving the same line from two devices may cause hardware damage. Before configuring a PXI trigger line as a destination terminal, reserve it through the PXI chassis properties in NI Measurement & Automation Explorer.

    FrontPanel0

    FrontPanel1

    Selects a general-purpose Front Panel Trigger line as the connection destination (output).
    StartTrigger

    Selects the start trigger, which is the event that allows the interface to begin communication. The start trigger occurs on the first source terminal low-to-high transition. The start trigger is the same for all sessions using a given interface. This causes the Start Interface transition to occur.

    You can route the start trigger of another XNET or DAQ card to ensure that sampling begins at the same time on both cards. For example, you can synchronize with an M-Series DAQ MIO card by routing the AI start trigger of the MIO card to a RTSI line and then routing the same PXI Trigger line with StartTrigger as the destination terminal on the XNET card.

    The default (disconnected) state of this destination means the start trigger occurs when XNET Start is invoked with the scope set to either Normal or Interface Only. Alternately, if Auto Start? is enabled, reading or writing to a session may start the interface.

    MasterTimebase

    MasterTimebase instructs the XNET card to use the connection source terminal as the master timebase. The XNET card uses this master timebase for input sampling (including timestamps of received messages) as well as periodic output sampling.

    Your XNET hardware supports incoming frequencies of 1 MHz, 10 MHz, and 20 MHz, and automatically detects the frequency without any additional configuration.

    For example, you can synchronize a CAN and DAQ M Series MIO card by connecting the 10 MHz oscillator (board clock) of the DAQ card to a PXI_Trig line, and then connecting the same PXI_Trig line as the source terminal.

    For PXI and PXI Express form factor hardware, you also can use PXI_Clk10 as the source terminal. This receives the PXI 10 MHz backplane clock for use as the master timebase.

    MasterTimebase applies separately to each port of a multiport XNET card, meaning you could run each port off of a separate incoming (or onboard) timebase signal.

    If you are using a PCI board, the default connection to the MasterTimebase is the local oscillator. If you are using a PXI or PXI Express board, the default connection to the MasterTimebase is the PXI_Clk10 signal, if it is available. Some chassis allow PXI_Clk10 to be turned off. In this case, the hardware automatically uses the local oscillator as the default MasterTimebase.

    Log Trigger The Log Trigger terminal generates a frame when it detects a rising edge. When connected, this frame is transferred into the Frame Stream Input session's queue if the session is started.

    Where This Node Can Run:

    Desktop OS: Windows

    FPGA: Supported


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