Data Acquisition Toolbox

Configuring Analog Input Triggers

An analog input trigger is defined as an event that initiates data logging. You can log data to the engine (memory) and to a disk file. As shown in the figure below, when a trigger occurs, the Logging property is automatically set On and data is stored in the specified target.

When defining a trigger, you must specify the trigger type. Additionally, you might need to specify one or more of these parameters:

• A trigger condition and trigger condition value
• The number of times to repeat the trigger
• A trigger delay
• A callback function to execute when the trigger event occurs

Properties associated with analog input triggers are given below.

Table 5-6: Analog Input Trigger Properties  

Property Name	Description
InitialTriggerTime	Indicate the absolute time of the first trigger.
ManualTriggerHwOn	Specify that the hardware device starts when a manual trigger is issued.
TriggerFcn	Specify the M-file callback function to execute when a trigger occurs.
TriggerChannel	Specify the channel serving as the trigger source.
TriggerCondition	Specify the condition that must be satisfied before a trigger executes.
TriggerCondition Value	Specify one or more voltage values that must be satisfied before a trigger executes.
TriggerDelay	Specify the delay value for data logging.
TriggerDelayUnits	Specify the units in which trigger delay data is measured.
TriggerRepeat	Specify the number of additional times the trigger executes.
TriggersExecuted	Indicate the number of triggers that execute.
TriggerType	Specify the type of trigger to execute.

Except for TriggerFcn, these trigger-related properties are discussed in the following sections. TriggerFcn is discussed in Events and Callbacks.

Returning Time Information

Defining a Trigger: Trigger Types and Conditions