Why can I not access all channels of my MOTU 24ai audio device when using the Data Acquisition Toolbox?

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I am trying to read data from my MOTU 24ai audio DAQ using the session-based interface in the Data Acquisition Toolbox. "daq.getDevices" shows that my device is recognized:
 
>> daq.getDevices
index Vendor Device ID Description
----- ----------- --------- ------------------------------------------------------------------
4 directsound Audio2 DirectSound Ligne (MOTU AVB USB Audio)
Also, I am able to successfully add audio input channels for all 24 channels, as indicated about the output of session variable:
 
Data acquisition session using DirectSound hardware:
Will run continuously at 44100 scans/second until stopped.
Number of channels: 24
index Type Device Channel MeasurementType Range Name
----- ---- ------ ------- --------------- ------------- -------------
1 audi Audio2 1 Audio -1.0 to +1.0 My Channel 1
2 audi Audio2 2 Audio -1.0 to +1.0 My Channel 2
3 audi Audio2 3 Audio -1.0 to +1.0 My Channel 3
4 audi Audio2 4 Audio -1.0 to +1.0 My Channel 4
5 audi Audio2 5 Audio -1.0 to +1.0 My Channel 5
6 audi Audio2 6 Audio -1.0 to +1.0 My Channel 6
7 audi Audio2 7 Audio -1.0 to +1.0 My Channel 7
8 audi Audio2 8 Audio -1.0 to +1.0 My Channel 8
9 audi Audio2 9 Audio -1.0 to +1.0 My Channel 9
10 audi Audio2 10 Audio -1.0 to +1.0 My Channel 10
11 audi Audio2 11 Audio -1.0 to +1.0 My Channel 11
12 audi Audio2 12 Audio -1.0 to +1.0 My Channel 12
13 audi Audio2 13 Audio -1.0 to +1.0 My Channel 13
14 audi Audio2 14 Audio -1.0 to +1.0 My Channel 14
15 audi Audio2 15 Audio -1.0 to +1.0 My Channel 15
16 audi Audio2 16 Audio -1.0 to +1.0 My Channel 16
17 audi Audio2 17 Audio -1.0 to +1.0 My Channel 17
18 audi Audio2 18 Audio -1.0 to +1.0 My Channel 18
19 audi Audio2 19 Audio -1.0 to +1.0 My Channel 19
20 audi Audio2 20 Audio -1.0 to +1.0 My Channel 20
21 audi Audio2 21 Audio -1.0 to +1.0 My Channel 21
22 audi Audio2 22 Audio -1.0 to +1.0 My Channel 22
23 audi Audio2 23 Audio -1.0 to +1.0 My Channel 23
24 audi Audio2 24 Audio -1.0 to +1.0 My Channel 24
However, I can only access the first 2 channels. When I try to read from channels 3 through 24, the reading is just 0. How can I read all 24 channels?

Accepted Answer

MathWorks Support Team
MathWorks Support Team on 23 May 2016
The Data Acquisition Toolbox Session interface uses DirectSound drivers to communicate with audio devices. The behavior you are experiencing might be due to an issue with the manufacturer-provided DirectSound drivers. The manufacturer (MOTU) recommends using ASIO drivers to take advantage of all the MOTU 24ai input and output channels.
MOTU also provides ASIO drivers for interfacing with the MOTU 24ai device. However, the Data Acquisition Toolbox Session interface does not support ASIO drivers. A possible alternative would be to use DSP System Toolbox or Audio System Toolbox, which provide support for devices with ASIO drivers.

More Answers (2)

Gloria Helena Munera
Gloria Helena Munera on 16 Feb 2017
How to send an audio file to different channels of an audio interface Motu ultralite mk3 in matlab 2016a on windows
I used this code
X = uigetfile; [Aw, fs] = audioread (x); Player = audioplayer (aw, fs, 24); Play (player)
Every time you play audioplayer (aw, fs, 24, id);
Error using audioplayer (line 223) Could not find the specified device
Error in pru (line 10) Player = audioplayer (aw, fs, 24.2);
Use info = dspAudioDeviceInfo to know my card ID
Please help! With examples

Patrick Johan Ngontie Ngounou
Hello, I would like to connect my MOTU 24i to MATLAB for data analysis with Data Acquisition Toolbox. I connected the MOTU 24i to my PC via USB. Matlab does not detect MOTU 24i when I use the '' daq.getDevices '' function.

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