Signal Routing

DSTs are capable of sending and receiving signals through the front panel connectors and the PXI trigger bus. Signals are routed between a source and destination via a path through the PXI trigger bus; there are two broad categories of routes.

The front panel connectors provide connectivity for input and output signals as well as for the control lines that send and receive clocks. You can use the PXI trigger bus to send and receive events, triggers, and Sample and Reference Clocks.

Note To get triggers and events from the DST to a device located outside of the PXI chassis, use a chassis with the timing and sync option or a Timing and Synchronization module, such as the PXIe-6674T.

Signals can be routed to and from the supported front panel connectors of your instrument. All signal routing operations can be characterized by a source and a destination. The possible signal routes for your instrument depend on the instrument, the PXI chassis, and the occupied PXI chassis slot.

When a signal is exported to a PXI trigger bus line from an instrument, only instruments in the same PXI chassis segment recognize the signal from that PXI trigger bus line. To route the signal to instruments in a different PXI chassis segment, you must establish a dynamic route or static route.

  • Dynamic route—Signal route that is specified by only the route endpoints. The actual route is determined automatically in software and is reserved and unreserved based on the based on the driver session using that route. Closing the driver session using a dynamic route releases that route.

    NI recommends using dynamic reservations and routing whenever possible.

  • Static route—Signal route that you create manually. You can implement static reservation of trigger lines in NI MAX through the Triggers tab.
  • Refer to your chassis documentation to determine the PXI trigger bus segments of your chassis.

    Syntax for Terminal Names

    The syntax for terminal names is a unique identifier that refers to a physical terminal in your system.

    To guarantee the uniqueness of a terminal name across multiple devices, terminal names begin with a forward slash, followed by the name of the device as configured in MAX, such as Dev1. A forward slash and the name of the terminal follow the device identifier, such as PXI_Trig0. For example, the fully qualified terminal name for PXI_Trig0 on Dev1 is /Dev1/PXI_Trig0.

    Use niDSTG Get Trigger Terminal Name VI, niDSTG Get Event Terminal Name VI, niDSTA Get Trigger Terminal Name VI, or niDSTA Get Event Terminal Name VI to obtain the fully qualified terminal name.

    Creating Static and Dynamic Signal Routes

    To establish a dynamic route across segments, you must specify a fully qualified terminal name for the source and destination signal.

    For static routing, complete the following steps.

    1. Launch NI Measurement & Automation Explorer (MAX).
    2. Expand Devices and Interfaces, then expand the Chassis tree.
      Note If you are using a remote RT target, expand Remote Systems, find and expand your remote RT target, and then expand Devices and Interfaces.
    3. Select your chassis.
      The attributes of your chassis are displayed on the right of the MAX window.
    4. Click the Trigger tab below the attributes view.
      A table in the Triggers view shows the PXI trigger bus segments of your chassis.
    5. Configure the static route that you want to make and save the changes.
      Note You may not be able to establish a dynamic route across segments if your application already contains too many static routes between PXI trigger buses of your chassis or if your hardware route segmentation does not support dynamic signal routing. Refer to your chassis documentation to determine the number of allowed static routes between the PXI trigger buses of your chassis and whether your chassis supports dynamic signal routing.