TriggerDelay (Data Acquisition Toolbox)

Specify the delay value for data logging

Description

You can define both pretriggers and postriggers. Pretriggers are specified with a negative TriggerDelay value while postriggers are specified with a positive TriggerDelay value. You can delay a trigger in units of time or samples with the TriggerDelayUnits property. Pretriggers are not defined for hardware triggers or when TriggerType is Immediate.

Pretrigger samples are included as part of the total samples acquired per trigger as specified by the SamplesPerTrigger property. If sample-time pairs are returned to the workspace with the getdata function, then the pretrigger samples are identified with negative time values.

Characteristics

Usage
AI, Common

Access
Read/write

Data type
Double

Read-only when running
Yes

Usage	AI, Common
Access	Read/write
Data type	Double
Read-only when running	Yes

Values

The default value is zero.

Example

Create the analog input object ai and add one channel to it.

ai = analoginput('winsound');
ch = addchannel(ai,1);

Configure ai to acquire 44,100 samples per trigger with 11,025 samples (0.25 seconds) acquired as pretrigger data.

set(ai,'SampleRate',44100)
set(ai,'TriggerType','Manual')
set(ai,'SamplesPerTrigger',44100)
set(ai,'TriggerDelay',-0.25)

See Also

Properties

SamplesPerTrigger, TriggerDelayUnits

TriggerConditionValue TriggerDelayUnits