Main Page → NI-DAQ Setup
National Instruments data acquisition (NI-DAQ) devices can be integrated with OptiTrack motion capture systems. Through NI-DAQ devices, analog signals from various 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 tracking data in Motive. This page provides instructions on connecting NI-DAQ devices and acquiring analog signals within Motive. Please refer to the Supported NI-DAQ Models section of this page for a list of supported models.
For instructions specific to the NI-DAQ devices, please refer to the respective product User Guide or the NI's getting started guide.
Integration of NI-DAQ device(s) uses the Peripheral Device module to register, initialize, and record using the connected DAQ device(s). When properly configured, voltage signals of up to 32 analog channels per each connected NI-DAQ device can be sampled along with the tracking data. Recorded analog data can be saved into the Take (.TAK) file and the data can be exported into C3D and CSV files for further analysis.
The eSync synchronization hub must be used for precisely aligning recorded signals with tracking data. NI-DAQ device(s) synchronizes with a camera system by syncing with the internal clock signal outputted from the eSync. For this reason, NI-DAQ device(s) must support the sample clock signal input and connect to the camera system through the eSync.
For general instructions on setting up the mocap system, refer to the Hardware Setup pages.
Motive supports PCI and USB data acquisition devices from National Instruments. A list of supported models can be found in the supported devices section.
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.
The following diagrams show hardware setups for connecting and synchronizing USB NI-DAQ devices with Prime series motion capture systems:
OptiTrack mocap systems use the eSync to provide highly accurate synchronization. In Motive, the eSync will be configured to output internal clock signals and used as the master reference clock which other devices can synchronize to. 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 and operate in the Free Run mode with independent acquisition rate which may result in synchronization drift over time.
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 and approved to work with Motive. Unverified models should work as well, but their integration has not beenbeen verified yet.
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 bundles and 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 to integrate 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 live sampled 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. Timeline Pane: Show the 'Scope' View.
Now that the device is recognized by Motive, you can select and configure the device and its channels under the Devices pane. Analog channels of each device will be listed. For better identification of the channels, you can also rename them in the Devices panel to more descriptive names; such as the signal types or name of the connected device.
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.
In order to precisely synchronize the motion capture system with NI-DAQ devices, the eSync must be used. Particularly, the internal clock signal from the eSync is delivered into the NI-DAQ devices and referenced as the external sample clock. To accomplish this, set the Sync Input to Internal Clock under the Custom Synchronization settings. Here, the clock frequency of the internal clock signal can be adjusted for controlling the sampling rates of the NI-DAQ device(s). Then, the input divider/multiplier can be adjusted to set the camera frame rate. The Final Frame Rate of the internal clock signal will set the frame rate of the camera system.
Synchronized with the eSync as the master clock, the internal clock rate from the eSync will determine the acquisition rate of the NI-DAQ device. The following steps summarize the external 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 Synchronization Pane and the Devices pane.
3. [Motive: Synchronization Pane]: Select Custom Synchronization from the dropdown menu.
4. [Motive: Synchronization Pane]: Configure the Sync Source to Internal Clock.
6. [Motive: Synchronization Pane: Sync Input (Internal Clock)] Set the Clock Freq to desired acquisition rate of the NI-DAQ device(s).
7. [Motive: Synchronization Pane: Sync Input (Internal Clock)] Adjust the Input Divider to configure the resulting Final Frame Rate which will be used to synchronize the cameras within the 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.
8. [Motive: Synchronization Pane] 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.
9. [Motive: Devices Pane] Within the NI-DAQ device property, set the Use External Clock to True. The NI-DAQ sampling rate in the Device Panel should now display the eSync Internal Clock rate.
10. [Motive: Devices Pane] Under the NI-DAQ device properties, designate the NI-DAQ External Clock Channel to the NI-DAQ digital input terminal connected in Step 1.
11. [Motive: Timeline Pane] Record. The recorded NI-DAQ device samples will be synchronized with the external clock signal.
The OptiHub is not supported for synchronization at this time. The OptiHub does not feature clock signals, and for this reason, precise synchronization of NI-DAQ devices cannot be achieved.
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 Panel] Configure NI-DAQ collection channels properties (terminal type, voltage range).
2. [Motive : Device Panel] Enable the channels to collect by checking the box next to each channel.
3. [Motive : Device Panel] Configure NI-DAQ device properties (Acquisition rate, external clock). Set the Use External Clock to true for synchronization through the eSync.
4. [Motive : Device Panel] Enable the NI-DAQ device by checking the box next to the device.
5. [Motive : Timeline] In Live mode, scope the timeline to verify the recorded channel/terminal signals appear correctly.
6. [Motive : Timeline] 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 chanel data can be exported into C3D and CSV files along with the mocap tracking data.
All of the 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.
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).
For more information, refer to the Data Export page or https://www.c3d.org/.
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 external clock signals, the option to change the acquisition rate for NI-DAQ devices within Motive will be disabled. Set UseExternalClock 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