PXI Platform Services provides an interface to route and reserve triggers so dynamic routing, through drivers such as DAQmx, avoids double-driving and potentially damaging trigger lines. For more information about routing and reserving PXI triggers, refer to ni.com/r/pxitiming.

Each chassis has one or more trigger buses, each with eight lines numbered 0 through 7 that can be reserved and routed statically or dynamically. Static reservation pre-allocates a trigger line to prevent its configuration by a user program. Dynamic reservation/routing/deallocation is on the fly within a user program based on NI APIs such as NI-DAQmx. NI recommends dynamic reservations and routing are used whenever possible. If static reservations are required, static reservation of trigger lines can be implemented by the user in MAX through the Triggers tab. PXI modules dynamically configured by programs such as NI-DAQmx will not use reserved trigger lines. This prevents the instruments from double-driving the trigger lines, possibly damaging devices in the chassis. In the default configuration, trigger lines on each bus are independent. For example, if trigger line 3 is asserted on trigger bus 0, by default it is not asserted automatically on any other trigger bus.

Complete the following steps to reserve these trigger lines in MAX.

  1. In the Configuration tree, click the PXI chassis branch to configure.
  2. In the lower right pane, click the Triggers tab.
  3. Select the trigger lines to statically reserve.
  4. Click the Save button.
    Figure 16. Trigger Configuration in MAX