Acquire Data from Multiple Channels and Multiple Devices

Create Interface to Acquisition Devices and Add Channels

Create a DataAcquisition object. Add two analog input voltage channels for cDAQ6Mod1 with channel IDs 0 and 1 using the addinput function.

d = daq("ni");
addinput(d,"cDAQ6Mod1",0:1,"Voltage");
d.Channels

    Index   Type      Device      Channel   Measurement Type         Range              Name   
    _____   ____    ___________   _______   ________________   __________________   _______________

      1     "ai"    "cDAQ6Mod1"   "ai0"     "Voltage (Diff)"   "-10 to +10 Volts"   "cDAQ1Mod1_ai0"
      2     "ai"    "cDAQ6Mod1"   "ai1"     "Voltage (Diff)"   "-10 to +10 Volts"   "cDAQ1Mod1_ai1"

Add an additional channel for a separate device, cDAQ6Mod3 with channel ID 0. For NI devices, use either a terminal name, like ai0, or a numeric equivalent like 0. Then view all channels on the DataAcquisition object.

ch = addinput(d,"cDAQ6Mod3","ai0","Voltage");
d.Channels

    Index   Type      Device      Channel   Measurement Type         Range              Name   
    _____   ____    ___________   _______   ________________   __________________   _______________

      1     "ai"    "cDAQ6Mod1"   "ai0"     "Voltage (Diff)"   "-10 to +10 Volts"   "cDAQ1Mod1_ai0"
      2     "ai"    "cDAQ6Mod1"   "ai1"     "Voltage (Diff)"   "-10 to +10 Volts"   "cDAQ1Mod1_ai1"
      3     "ai"    "cDAQ6Mod3"   "ai0"     "Voltage (Diff)"   "-10 to +10 Volts"   "cDAQ1Mod6_ai0"

You can now use d to acquire data from both devices simultaneously, returned as either a matrix or a timetable.

Acquire Data in Matrix Form and Plot Data from All Channels

Acquire data for a duration of one second. Store the acquired data as a matrix, data, in which each column contains the data from one channel. Then, plot all the data acquired from both devices.

data = read(d,seconds(1),OutputFormat="Matrix");
plot(data)
title("Acquired Data from Multiple Channels");
xlabel("Sample Number");
ylabel("Voltage (V)");
legend("ai0 -cDAQ6Mod1","ai1 -cDAQ6Mod1","ai0 -cDAQ6Mod3");

Acquire Data in Timetable Form

When you acquire data in timetable form, the software uses channel property Name to identify channel data in the output. To see this effect, change the name of the channel ai0 on cDAQ6Mod3 and view the channel properties. For more information, see Channel Properties.

ch.TerminalConfig = "SingleEnded";
ch.Name = "Velocity_sensor";
ch

ch = 

 Index   Type     Device      Channel     Measurement Type           Range               Name   
 _____   ____   ___________   _______   ____________________   __________________  _________________

   1     "ai"   "cDAQ6Mod3"   "ai0"     "Voltage (SingleEnd)"  "-10 to +10 Volts"  "Velocity_sensor"

Acquire data for a duration of one second and store it in the variable data as a timetable.

data = read(d,seconds(1));

Plot Data from Each Device Separately

This time, instead of putting all the data from both devices on the same plot, use two subplots: the first plot shows voltage signals from Device 1, and the second plot shows the signal from Device 2. Use the channel name to specify which time series from data to show in each plot.

figure;
tiledlayout(2,1);
nexttile
plot(data.Time,[data.cDAQ6Mod1_ai0 data.cDAQ6Mod1_ai1]);
title("Acquired Data from Device 1");
xlabel("Time (s)");
ylabel("Voltage (V)");
nexttile
plot(data.Time,data.Velocity_sensor);
title("Acquired Data from Device 2");
xlabel("Time (s)");
ylabel("Voltage (V)");