# DurationInSeconds

Specify duration of acquisition

## Description

When working with the session-based interface, use the `DurationInSeconds` property to change the duration of an acquisition.

When the session contains digital or audio output channels, `DurationInSeconds` becomes a read only property.

If the output channels are analog, digital or audio, the value is determined by $\frac{s.ScansQueued}{s.Rate}$.

If the session contains only counter output channels with PulseGeneration measurement type, then `DurationInSeconds` represents the duration of the pulse train signal generation.

## Values

In a session with only input channels or counter output channels, you can enter a value in seconds for the length of the acquisition. Changing the duration changes the number of scans accordingly. By default, the `DurationInSeconds` is set to 1 second.

## Examples

```s = daq.createSession('ni'); addAnalogInputChannel(s,'cDAQ1Mod1','ai0','voltage'); s.DurationInSeconds = 2 ```
```s = Data acquisition session using National Instruments hardware: Will run for 2 seconds (2000 scans) at 1000 scans/second. Operation starts immediately. Number of channels: 1 index Type Device Channel InputType Range Name ----- ---- --------- ------- --------- ---------------- ---- 1 ai cDAQ1Mod1 ai0 Diff -10 to +10 Volts```

### Functions

`addCounterInputChannel`