Main Page → NI-DAQ Setup
OptiTrack motion capture systems support the integration of National Instruments data acquisition (NI-DAQ) devices. Through NI-DAQ devices, signals from various analog devices (e.g. transducers or EMG sensors) can be converted into digital signals at a user-defined sampling frequency, and they can be precisely synchronized with the motion tracking data. This page provides instructions on connecting NI-DAQ devices and acquiring analog signals within Motive.
For a list of supported models, please refer to the Supported NI-DAQ Models section of this page.
For instructions specific to the NI-DAQ devices, please refer to the respective product User Guide or the NI's getting started guide.
Motive supports PCI and USB data acquisition devices from National Instruments, and the NI-DAQmx driver must be installed on the computer in order for Motive to communicate with devices. The setup instructions for the driver will be covered in the software setup section in this page. A list of supported models can be found in the section below.
For general instructions on setting up the mocap system, refer to the Hardware Setup pages.
Hot plugging is not supported with the integration. When a new device is connected to the system, you must re-start Motive to instantiate it.
Below is the list of NI-DAQ device models that are supported with Motive. For best compatibility, use the recommended models or verified models since they are most tested to work with Motive. Unverified models should work as well, but their integration has not been verified yet.
OptiTrack mocap systems use the eSync to provide highly accurate synchronization. When synchronizing the NI-DAQ device through an external clock signal or the reference clock signal, the eSync generates and outputs clock signal to the NI-DAQ device(s), so that it can be used as the master reference clock that the connected devices can synchronize to. This approach is referred to as the reference clock sync, and in this approach, the data samples collected from two systems will be aligned on a per frame basis.
Required for setups using reference clock synchronization
In order to utilize the clock signal, a NI-DAQ device(s) that supports external sample clock input must be used. When using DAQ devices without the sample clock support, they will not be able to reference the clock signal. In this case, the device will have to sync at the start of the recording through the triggered sync and operate in the Free Run mode with independent acquisition rate which may result in synchronization drift over time.
For best results, the reference clock sync approach is recommended to achieve per-sample basis synchronization between two systems; however, there are cases where this is not applicable. For example, you may need to use the clock signal to sync other devices that are sampling at a different rate than the sampling rate of the NI-DAQ device you wish to achieve. In such cases, you can use recording signal to trigger sync both systems at the start of the recording and have them free-run at their own sampling rates. This will align the recorded samples from two systems, but long recordings may be susceptible to phase shift.
For Motive to communicate with NI-DAQ devices, the OptiTrack Peripheral Modules must be installed along with Motive and NI-DAQ device drivers. The OptiTrack Peripherals Module is a software plugin package that installs required drivers and plugin DLLs for integrating external devices, including NI-DAQ devices and force plates (AMTI and Bertec). The following section describes the steps on integrating NI-DAQ device(s) within Motive.
Installation Note: For integration into Motive, the NI-DAQmx 15.1.1 or later runtime driver must be installed. If you are already using an older version of the NI-DAQmx runtime and Motive is having problems recognizing the connected device, update the driver or uninstall and re-install the packaged version of the driver before contacting Support. In Motive, you can inspect device connection status via the Status Log panel which can be accessed under the View tab in Motive.
Once the NI-DAQ device is recognized properly, you will be able to observe the real-time signal on the Graph View pane.
First, make sure the NI-DAQ device and its operating analog input channels are enabled under the Devices pane. Then, open the Graph View pane and create a custom layout for monitoring live-analog data; create a new layout, right-click on the graphs, and select the device channel you wish to plot. Then, open the graph editor () and make sure View Style is set to Live under the Visuals tab. Configured analog channels will be plotted on the graphs.
a. Device Pane: Select a NI-DAQ channel with an active signal.
b. Device Pane: Toggle the NI-DAQ device to begin sampling.
c. Device Pane: Select the active channel.
d. Graph Pane: Show the 'Scope' View.
Now that the device is detected in Motive, you can select and configure settings for the device and its analog channels through Motive. When a data acquisition device or an analog channel is selected in the Devices pane, their respective properties will be displayed on the Properties pane or on a separate pop-up for the analog channels.
Properties of connected NI-DAQ devices get listed in the Properties pane when a device is selected in the Devices pane. These properties need to be configured in order to properly synchronized the data acquisition device and the camera system together. Details about appropriate property settings will be covered in the following section.
For specific details about each properties, visit Properties: NI-DAQ page.
Properties of individual channels can be configured directly from the Devices pane. As shown in the image, you can click on the icon to bring up the settings and make changes.
Depending on the model, NI-DAQ devices may have different sets of allowable input types and voltage ranges for their analog channels. Refer to your NI-DAQ device User's Guide for detailed information about supported signal types and voltage ranges.
The internal clock signal is generated from the eSync and outputted to the NI-DAQ device(s) for precisely synchronizing two systems together. This approach is referred to as the synchronization through reference sample clock signal, and in this setup, all of the data samples will be synchronized per-frame basis.
To configure this, set the Source to Internal Clock in the Sync Input Settings section under the eSync properties. Here, the clock frequency of the internal clock signal will basically set the sampling rate of the NI-DAQ device(s). Then, the input divider/multiplier can be adjusted to achieve desired camera frame rate, and the final camera system framerate will be calculated and indicated under the eSync properties and in the Devices pane. The following steps summarize the reference sample clock sync setup steps:
1. [Hardware]: Connect one of the eSync Output(N) ports into the NI-DAQ digital input terminal.
2. [Motive]: Open the Devices pane and the Properties pane.
3. [Motive: Devices pane]: Select the eSync in the Devices pane and the corresponding properties will be displayed in the Properties pane
4. [Motive: Properties pane (eSync)]: Configure the Sync Source to Internal Clock.
5. [Motive: Properties pane (eSync)] Set the Clock Freq to desired acquisition rate of the NI-DAQ device(s).
6. [Motive: Properties pane (eSync)] Adjust the Input Divider/Multiplier to set the final frame rate for the camera system. In order to accurately sample analog signals, the acquisition rate of the NI-DAQ device(s) should not be greater than X16 of the configured camera frame rate. In other words, the Input Divider should not exceed 16. The final camera system frame rate will always be displayed under the Devices pane and the eSync properties.
7. [Motive: Properties pane (eSync)] For the eSync output ports connected to the NI-DAQ devices, set the Output(N) Type to Gated Internal Clock. Now the internal clock signal is configured to be outputted through the output(N) port into the connected NI-DAQ channel.
8. [Motive: Devices pane] Select the NI-DAQ device in the Devices pane and the corresponding properties will be displayed in the Properties pane.
9. [Motive: Properties pane (NI-DAQ)] Within the NI-DAQ device property, set the Reference Clock Sync to True. At this point, the sampling rate of the NI-DAQ device in the Device Panel should be set to the same frequency as the internal clock signal configured for the eSync.
10. [Motive: Properties pane (NI-DAQ)] Under the NI-DAQ device properties, designate the Reference Clock Terminal to the NI-DAQ digital input terminal connected in Step 1.
11. [Motive: Control Panel] Record. The recorded NI-DAQ device samples will be synchronized with the external clock signal outputted from the eSync.
For best results, use the external clock sync approach to achieve per-sample basis synchronization between two systems. However, there are cases where this is not applicable. For example, you may need to use the external clock signal to sync other devices that are sampling at a different rate than the sampling rate of the NI-DAQ device you wish to achieve.In such cases, you can use recording signal to trigger sync both systems at the start of the recording and have them free-run at their own sampling rates. This will align the recorded samples from two systems, but long recordings may be susceptible to phase shift.
1. [Hardware]: Connect one of the eSync Output(N) ports into the NI-DAQ analog input terminal.
4. [Motive: Properties pane (eSync)]: Configure the Sync Source under the Sync Input Settings. You can set it to either Internal Free Run or Internal Clock.
5. [Motive: Properties pane (eSync)] For the eSync output ports connected to the NI-DAQ devices, set the Output(N) Type to Recording Gate. This will configure the respective output ports to send out a signal into the connected NI-DAQ channel when Motive is recording.
6. [Motive: Devices pane] Select the NI-DAQ device in the Devices pane and the corresponding properties will be displayed in the Properties pane.
7. [Motive: Properties pane (NI-DAQ)] Within the NI-DAQ device property, set the Recording Trigger to Device.
8. [Motive: Properties pane (NI-DAQ)] Within the NI-DAQ device property, set the Reference Clock Sync to False.
9. [Motive: Properties pane (NI-DAQ)] Within the NI-DAQ device property, set a value for the Multiple section. This will set the NI-DAQ to sample at a rate multiple of the master system rate, which was configured in step 4. Since NI-DAQ will be free running after the initial trigger sync, it is important that it samples at a whole multiple of the master rate.
10. [Motive: Properties pane (NI-DAQ)] Under the NI-DAQ device properties, designate the Trigger Terminal to the analog input terminal connected in Step 1.
11. [Motive: Control Deck] Click the record button to initiate the recording, and both the camera system and NI-DAQ will start recording simulatenously using the trigger signal.
The following steps describe a general workflow on collecting signals from connected NI-DAQ channels in Motive. Make sure the camera system is calibrated before recording if you wish to collect tracking data along with the analog signals.
1. [Motive : Device pane] Open the Devices pane and one of the data channels in the data acquisition device. Once it's selected, its properties will be listed out in the Properties pane.
2. [Motive : Device pane] Configure NI-DAQ collection channels properties (terminal type, voltage range) as described in the channel properties section above.
3. [Motive : Device pane] Enable the channels to collect by checking the box next to each channel.
4. [Motive : Properties pane] Now, select the NI-DAQ device in the Devices pane, and configure device properties (Acquisition rate, external clock).
5. [Motive : Devices pane] Make sure the NI-DAQ device enabled by checking the box next to the device.
6. [Motive : Graph View] In Live mode, scope the timeline to verify the recorded channel/terminal signals appear correctly.
7. [Motive : Control Deck] Start Recording.
Captured analog signals are recorded within the Take file and they can be played back in Motive. When in Edit mode, the integrated NI-DAQ device will be shown under the Assets pane, and its Analog measurements can be plotted on the Graph View pane. You will need to create a custom graph layout and enable plotting of analog channels:
Recorded NI-DAQ analog channel data can be exported into C3D and CSV files along with the mocap tracking data. You can just follow the normal the tracking data export steps, and if the analog data exists in the TAK, they will also be exported.
C3D Export: Both mocap data and the analog data will be exported onto a same C3D file. Please note that all of the analog data within the exported C3D files will be logged at the same sampling frequency. If any of the devices are captured at different rates, Motive will automatically resample all of the analog devices to match the sampling rate of the fastest device. More on C3D files: https://www.c3d.org/
CSV Export: When exporting tracking data into CSV, additional CSV files will be exported for each of the NI-DAQ devices in a Take. Each of the exported CSV files will contain basic properties and settings at its header, including device information and sample counts. The voltage amplitude of each analog channel will be listed. Also, mocap frame rate to device sampling ratio is included since analog data is usually sampled at higher sampling rates.
Note that the coordinate system used in Motive (y-up right-handed) may be different from the convention used in the biomechanics analysis software.
Since Motive uses a different coordinate system than the system used in common biomechanics applications, it is necessary to modify the coordinate axis to a compatible convention in the C3D exporter settings. For biomechanics applications using z-up right-handed convention (e.g. Visual3D), the following changes must be made under the custom axis.
This will convert the coordinate axis of the exported data so that the x-axis represents the anteroposterior axis (left/right), the y-axis represents the mediolateral axis (front/back), and the z-axis represents the longitudinal axis (up/down).
Q - Connected NI-DAQ device is not detected in Motive
1) Confirm the NI-DAQ device is detected by the MS Windows system (Devices Manager) and by the NI Device Monitor (task tray) that installs with your NI-DAQ software.
2) If the device is still not detected in Motive even after confirming the connection from the above step, completely uninstall the National Instruments Software drivers and re-install Motive. Make sure to choose 'Yes' to install packaged OptiTrack Peripheral Module and the NI-DAQmx runtime. After installing the drivers, it is essential to restart your computer.
3) After launching Motive, check the Status Log panel (View tab → Status Log) and confirm the following:
4) If the Status Log shows that it failed to load the plugin, make sure the BiomechDevicePlugin.dll is located within the devices folder in Motive's install directory.
Q - I have the NI-DAQmx driver installed for my DAQ device, but they are not the recommended version.
A - This is fine as long as the NI-DAQmx driver version is 15.1.1 or later. If you are experiencing connection difficulties, try uninstalling your current driver and re-installing the driver that ships with Motive.
Q - When installing the device NI-DAQmx driver, I get to a screen that indicates no changes will be made and I can't proceed.
A - This indicates the driver for your device is already installed. Hit cancel to exit the installer, and ensure the driver version is at least 15.1.1 or later. If not, update your driver. You can also re-install the driver that ships with Motive, but make sure the previous install is completely removed before the re-installation.
Q - I can't change the multiplier for my DAQ from the Devices pane in Motive.
A - If the device is configured to use reference clock signals, the option to change the acquisition rate for NI-DAQ devices within Motive will be disabled. Set Reference Clock Sync to False to use the Free Run mode.
Q - Motive warns that the sampling rate is too high for my device.
A - This warning indicates that the sampling may be out of the allowable range for the DAQ device. Some devices share the allowable sample rate across all channels, and each channel takes up a portion of the total allowable sample rate of the device. Other devices have dedicated sample rates for each channel, and the allowable sample rate can be set for each channel in this case. For detailed specification on how your device samples incoming signals, refer to the respective NI-DAQ User's Guide.
Q - The analog input value does not appear to be correct.
A - Ensure that the appropriate channel type is selected. If your signal increases or decreases, with a steady baseline, your ground is not set correctly. See the section on channel types for more information.
Q - In the Device pane, I can't enable my device when checking the box next to it.
A - A device can't be enabled until one of it's channels is made active. Activate at least one channel under the device to enable the device itself. Only the channels that are active, and have the associated device enabled, will be recorded.
Q - No really, my analog input is incorrect.
A - Input channels can be verified using NI's Device Monitor and opening up a configuration session. Within the device monitor, the channel input can be observed. If the observed output is different from what appears in Motive, there may be an issue. This may also be due to aliasing of the sampled signal. Ensure that the signal is captured at the appropriate sampling frequency. A low sampling frequency may inaccurately capture high-frequency signals.
Q - Voltages from one channel seem to affect another channel.
A - Crosstalk or ghosting is a normal occurrence in a digital acquisition device, and can be caused by a variety of sources. For detailed information on crosstalk, and steps you can take to minimize it, please refer to your NI-DAQ documentation. National Instrument also provides some steps on reducing unwanted voltages here: http://digital.ni.com/public.nsf/allkb/B9BCDFD960C06B9186256A37007490CD?OpenDocument
Q - Motive crashes on startup.
A - When you have Peripheral Devices installed along with Motive, the NI services must be running when you first launch Motive. If these sevices from National Instruments are disabled, Motive may crash while attempting to load the peripheral device libraries