Data Acquisition Toolbox

NativeOffset

Indicate the offset to use when converting data from native format to doubles

Description

NativeOffset, along with NativeScaling, is used to convert data from your hardware's native format to doubles using the formula

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

For analog input objects, you return data from the engine in native format using the getdata function. Additionally, if you log native data to a .daq file, then you can read back that data using the daqread function. For analog output objects, you queue native data in the engine using the putdata function. You may want to return or queue data in native format to conserve memory and to increase speed.

The NativeOffset value for a given channel may change if you change the UnitsRange, SensorRange, or InputRange property values for that channel.

You can return the native data type of your hardware device with the daqhwinfo function.

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, SensorRange, UnitsRange

Name

NativeScaling