Data Acquisition Toolbox

NativeOffset

Indicate the offset to use when converting between the native data format and doubles

Description

NativeOffset, along with NativeScaling, is used to convert data between the native hardware format and doubles.

For analog input objects, you return native data from the engine with the getdata function. Additionally, if you log native data to a .daq file, then you can read back that data using the daqread function. The formula for converting from native data to doubles is

doubles data = (native data)(native scaling) + native offset

For analog output objects, you queue native data in the engine with the putdata function. The formula for converting from doubles to native data is

native data = (doubles data)(native scaling) + native offset

You return the native data type of your hardware device with the daqhwinfo function. Note that the NativeScaling value for a given channel might change if you change its InputRange (AI) or OutputRange (AO) property value.

You might want to return or queue data in native format to conserve memory and to increase data acquisition or data output speed.

Characteristics

Usage	AI, AO, Channel
Access	Read-only
Data type	Double
Read-only when running	N/A

Values

The default value is device-specific.

Example

Create the analog input object ai for a National Instruments board, and add eight channels to it.

• ai = analoginput('nidaq',1);
  addchannel(ai,0:7);
  

Start ai, collect one second of data for each channel, and extract the data from the engine using the native format of the device.

• start(ai)
  nativedata = getdata(ai,1000,'native');
  

You can return the native data type of the board with the daqhwinfo function.

• out = daqhwinfo(ai);
  out.NativeDataType
  ans =
  int16
  

Convert the data to doubles using the NativeScaling and NativeOffset properties.

• scaling = get(ai.Channel(1),'NativeScaling');
  offset = get(ai.Channel(1),'NativeOffset');
  data = double(nativedata)*scaling + offset;
  

See Also

Functions

daqhwinfo, daqread, getdata, putdata

Properties

InputRange, NativeScaling, OutputRange

Name

NativeScaling