Acquiring and Generating Analog Signals Simultaneously

LabVIEW SignalExpress can execute steps in projects simultaneously. For example, if you have two DAQmx Acquire steps in a project, each step runs at its own rate and independently of the other when you run the project. You can use triggers or you can share data between steps to control the order in which steps execute in a project. For example, when you use LabVIEW SignalExpress to generate a stimulus signal and then measure the response from a unit under test, you must make sure that the acquisition does not occur until after the DAQmx Generate step generates the stimulus signal. The following section describes different options for controlling the execution relationship between hardware steps to ensure measurements operate appropriately.

Execution Dependencies in Hardware Steps

If a project contains two DAQmx Acquire steps and you configure the steps to share the same start trigger, LabVIEW SignalExpress executes both steps simultaneously when you run the project. The steps have a trigger dependency.

If a project contains a DAQmx Generate step and a Create Analog Signal step, and the DAQmx Generate step is generating the signal the Create Analog signal step creates, LabVIEW SignalExpress executes the Create Analog Signal step before the DAQmx Generate step because the steps have a data dependency. The generate step cannot execute until the Create Analog Signal steps passes it an output signal.

You can use trigger sharing or the configuration options on the Step Setup tab of a step to configure execution dependencies for common hardware systems, such as a stimulus/response system.