The rectangular sequence structure on the left contains things that have to happen first on execution. Variables and property nodes are initialized. Most of the front panel indicator and control terminals are here. Many have no connection here, it just makes them easy to find. The real inputs and outputs occur in local variables scattered through the diagram. The PCI-6534 DIO cards are enumerated, and the names assigned in MAX are read into and array in increasing numeric order. Two arrays are created that disable and gray out DAQ loop controls for which there is no card installed. The device names are inserted in the Clock Source and Physical Channel fields of the DAQ Cfg Prototype, generating the DAQ Cfg Array. One cluster element is indexed out sent to each DAQ loop to service a card. The Modify VetoDAQ Config vi pops up on execution and closes again when terminated.

The event loop at top right responds to the Toggle Mux and Modify Config buttons whenever they are enabled.

The sequence frame below the event loop shows the middle(#1) of three sequence steps. Frame #0 merely configures the Symmetricom card on startup, and frame #2 triggers a strobe pulse on to shut down the muxes when the main vi is terminated. In the middle frame, three identical copies of VetoDAQReadData.vi are called in while loops, checking to see if their respective DAQ Start buttons have been clicked. Values for the front panel controls and indicators are passed in and out of the vis while they are running using control references. These vis and their subvis are reentrant, meaning that each copy maintains separate memory space for it's variables and data, allowing them to run simultaneously without blocking each other. If an individual DAQ loop is stopped using the DAQ Stop button, it will return to polling for DAQ Start. Clicking the red Exit button will pop up a dialog, whicj if confirmed, will shut down all the loops and terminate the main vi.