Overview

This page provides general instructions on how to use the eSync 2 for synchronizing external devices.

The eSync 2 is a synchronization hub that allows advanced users to integrate external systems into OptiTrack motion capture systems. With proper sync chain setups, you can have another (parent) system control the mocap system, or have the mocap system control other (child) systems, or both. Note that the setup may change depending on the type and number of the external devices as well as the characteristics of the communicated sync signals. Use this guide for understanding the general idea of how external devices are implemented and apply the knowledge for your needs.

External Device Synchronization

With the eSync 2, Prime series mocap systems can work together with other systems to perform precisely synchronized operations and data collections. This offers benefits in a wide range of applications. Reference video cameras, NI-DAQ devices, Force Plates, and recording triggers are examples of commonly synchronized external devices.

The eSync 2 synchronization hub has multiple sync input and output ports. In general, a parent device connects to the input ports for controlling the mocap system, and the child devices connect to output ports to be controlled by the mocap system. Once the devices are connected to the eSync 2, the input and output signal characteristics need to be specified and configured under the eSync 2's device properties in Motive.

Requirements

• Ethernet Camera System (PrimeX series or SlimX 13)

• The eSync 2

• External Devices (child / parent)

• Sync Cables: BNC or other sync cables with BNC adapters.

The eSync 2

Synchronization Setup

Step 1. Before setting up, draw out the schematic of which devices will be the parent or the child of the synchronization chain in respect to the mocap system.

Step 2. Connect the external devices

• Child Devices (e.g. Force Plates): Connect Output ports of the eSync 2 into sync input ports of the child devices

• Parent Device (e.g. Genlock): Connect the sync output of a parent device into one of the Input ports of the eSync 2. For integrating Genlock, VESA Stereo In, or SMPTE timecode signals, connect them to the corresponding labeled input ports of the eSync 2.

Step 3. Launch Motive. The eSync 2 should get listed under the Devices pane.

Step 4. [Motive] Open the Properties pane and select the eSync 2 in the Devices pane to access its properties.

Step 5. [Motive > Properties: eSync 2] Under the Sync Input Settings: Source section, use the drop-down menu to pick a desired sync source for the camera system to synchronize to. Read more under the Input Source Setup section of this page.

Step 6. [Motive > Properties: eSync 2] Configure the input divider/multiplier settings, and/or the clock frequency settings (for Internal Clock only), to set the camera rate. The final frame rate of the camera system will be displayed next to Camera Rate property or in the Devices pane.

Step 7. [Motive > Properties: eSync 2] Configure the Outputs. Output ports of the eSync 2 are used to tell connected child devices what Motive is doing. Read more under the Output Signal Setup section of this page.

Step 8. [Motive > Properties: eSync 2] If you wish to set up a recording trigger device, connect it to one of the input ports and designate the port under the Recording Trigger section of the eSync 2 properties. Read more under the Recording Trigger Setup section of this page.

Step 9. [Motive > Properties: eSync 2] Lastly, check the Monitor section and make sure all signals are detected properly.

Input Source Setup

Once you have connected the external devices to the eSync 2, the first step is to select and configure the sync source under th eSync 2 properties. The selected source will become the parent sync of both the camera system and other external devices. There are multiple sync source options to choose from under the drop-down menu. Ultimately, only one sync source will be selected and used to synchronize the cameras and subsequent child devices for any particular configuration.

Sync Input: Select the Sync Source

The first step is to define a parent sync source for the camera system. This is configured in the Sync Input → Source entry under the eSync 2 properties:

Internal Free Run

By default, the sync input source is set to Internal Free Run, meaning that the camera system is sampling at a frame rate defined in the Devices pane. In this mode, Prime series cameras are synchronized by communicating the time information with each other through the camera network itself using a high-precision algorithm for timing synchronization. This is the default synchronization protocol for Ethernet camera systems without an eSync 2.

Internal Clock

To use the internal clock of the eSync 2 as the parent sync source for both the camera system and the subsequent child devices, set the sync input source to Internal Clock. When selected, the clock frequency can be adjusted in Sync Input → Clock Freq (Hz) settings.

Input Signal

To use an external sync signal as the parent sync source, set the sync input source to the corresponding input port where the parent device is connected to. See the specifications for more details on each of the input ports.− Input ports (1-3): VIH(max): 3.3V− Isolated Input port: VIH(max): 12V− VESA Stereo Input port: VIH(max): 3.3V− Video Genlock In and SMPTE Timecode

Sync Input: Set the Input Trigger

Once the input source is set, next step is to define an appropriate trigger event. Under the Sync Input → Input Trigger option, pick a signal morphology (Either Edge, Rising Edge, or Falling Edge) for the desired trigger event. Note that the suitable event will vary depending on characteristics of the received signal and how you want the system to synchronize with it. The following diagrams show how the camera system responds to received signal triggers. When configured properly, the camera system will expose in respect to the sync signal from the parent device.

Rising Edge:

Every rising edge of the sync input signal defines either the start or the end of a frame, consecutively.

Falling Edge:

Every falling edge of the sync input signal defines either the start or the end of a frame, consecutively.

Either Edge:

Every rising or falling edge of the sync input signal defines either the start or the end of a frame, consecutively. When using both of the edges as the input trigger, the input signal must have 50% duty cycle for the cameras to synchronize properly.

Set the Input Divider/Multiplier

The frame rate of the camera system gets determined by the selected sync input source. When the frequency of the sync source is higher than the supported frame rate, input dividers and multiplier can be applied to adjust the signal frequency for synchronizing the camera system. The final framerate will be calculated and displayed at the bottom, Sync Input → Final Frame Rate, and you can monitor this rate while you apply the adjustments. When the customized sync configurations are applied at the end of the setup, the cameras will start to capture at this final frame rate.

Set Sync Offset

Advanced: Sync Input Trigger and Exposure Timing

Camera exposures are always positioned at the center of every frame periods, and the precise moment of the camera exposure does not exactly coincide with the trigger event. When synchronizing the camera exposure timing with the sync input signal triggers, make sure this gap is taken into account. To precisely align the input signal trigger with the exposure timing, an offset delay, in microseconds, of half of the frame period plus half of the camera exposure must be applied in the Sync Input → Sync Offset (us). The camera exposure is measured in microseconds on the Ethernet cameras.

Output Source Setup

The eSync 2 has total 4 output ports (3.3 V). If you want to setup the camera system to be a parent of other systems, connect the child devices into the Output ports of the eSync for receiving the reference sync signals. Once the devices are connected, you can configure the output signal source under the eSync 2 properties. Know what type of sync signals are expected by the child devices, and configure the sources accordingly so that appropriate signals are outputted.

The eSync 2 can output the following types of signals:

• Exposure Time

• Recording Gate

• Record Start/Stop Pulse

• Gated Exposure Time

• Gated Internal Clock

• Selected Sync

• Adjusted Sync

• Input signals: Relaying input signals.

  • Selected Sync: Raw input signal.

  • Adjusted Sync: Adjusted (offset, multiplier, and divider) signal.

Gated Output Signal (eSync 2):

The gated (while-recording) output signal from the eSync 2 is frame-synchronous with the recorded mocap data. In the live mode, the cameras are continuously shuttering and capturing frames at a defined frame rate. If the recording trigger is received in the middle of a frame period, the eSync waits until the next frame to start recording and asserting gated output signal. This mechanism ensures that the recorded mocap data and the gated output signals are precisely synchronized.

Exposure Time / Gated Exposure Time

Exposure Time/Gated Exposure Time output signals indicate when the cameras are exposing.

When the Output:Type is set to Exposure Time, a high voltage (3.3V) signal will be outputted from the corresponding output port whenever the camera system is exposing, or shuttering, in the Live Mode. The Gated Exposure Time signal works similarly, but the signal will be sent out only when Motive is recording.

Recording Gate & Recording Start/Stop Pulse

Recording gate/pulse output signals can be used to tell the child device when Motive is recording or not. When configured to Recording Gate, the eSync 2 will output a constant high voltage signal when Motive is recording. When configured to Recording Start/Stop Pulse, the sync hub will output a pulse signal when Motive either starts or stops recording.

Gated Internal Clock

When configured to Gated Internal Clock, the eSync 2 outputs its internal clock signal while Motive is recording. The internal clock signal has a 50% duty cycle with the signal frequency defined under the Sync Input → Clock Freq (Hz) section.

Using Internal Clock Signal to drive both the camera system and external devices

To achieve per-frame synchronization between the camera system and an external device (e.g. force plates, NI-DAQ), the internal clock signal from the eSync 2 can be used to drive both the camera system as well as the external device. This is possible only if the external device has the capability of receiving external clock signal. When the external system runs at a higher sampling rate, a divisor or a multiplier must be applied to the clock signal to achieve the desired framerate on the camera system. Here, please note that depending on the applied divisor/multiplier, the alignment of the outputted signal may vary. The exposure timing of the camera system will always be aligned at the center of the divided or multiplied signal, and whether the exposure timing aligns with the rising edge or falling edge of the output signal may vary depending on the applied divisor. Please see the below image:

Hardware Recording Trigger Setup

With the eSync 2, external triggering devices (e.g. remote start/stop button) can integrate into the camera system and set to trigger the recording start and stop events in Motive. Such devices will connect to input ports of the eSync 2 and configured under the Record Triggering section of the eSync 2 properties.

By default, the remote trigger source is set to Software, which is the record start/stop button click events in Motive. Set the trigger source to the corresponding input port and select an appropriate trigger edge when an external trigger source (Trigger Source → isolated or input) is used. Available trigger options include Rising Edge, Falling Edge, High Gated, or Low Gated. The appropriate trigger option will depend on the signal morphology of the external trigger. After the trigger setting have been defined, press the recording button in advance. It sets Motive into a standby mode until the trigger signal is detected through the eSync 2. When the trigger signal is detected, Motive will start the actual recording. The recording will be stopped and return to the 'armed' state when the second trigger signal, or the falling edge of the gated signal, is detected.

Note: For capturing multiple recordings via recording trigger, only the first TAK will contain the 3D data. For the subsequent TAKs_, the 3D data must be reconstructed through the_ post-processing reconstruction pipeline.

Steps

1. Open the Devices pane and the Properties pane to access the eSync 2 properties.

2. Under the Record Triggering section, set the source to the respective input port where the trigger signal is inputted.

3. Choose an appropriate trigger option, depending on the morphology of the trigger signal.

4. Press the record button in Motive, which prepares Motive for recording. At this stage, Motive awaits for an incoming trigger signal.

5. When the first trigger is detected, Motive starts recording.

6. When the second trigger is detected, Motive stops recording and awaits for next trigger for repeated recordings. For High Gated and Low Gated trigger options, Motive will record during respective gated windows.

7. Once all the recording is finished, press the stop button to disarm Motive.

Troubleshooting

Overview

This page provides general instructions on how to use the OptiHub2 for integrating external devices with Flex series mocap systems. The OptiHub2 not only provides power for the USB cameras, but it also includes external sync in/out ports for integration of external devices. With proper configurations, you can have another device (parent) control the mocap system or have the mocap system control another external device (child), or both. Setup instructions for both child and parent devices will be covered. Note that the sync setup may vary depending on the type of integrated devices as well as the morphology of the communicated sync signals. Use this guide for understanding the general idea of how external devices are implemented, and apply it to your own needs.

External Device Synchronization

On the OptiHub2, there are one External SYNC In and one External SYNC Out ports for connecting external devices. In general, parent devices connect to the input port for controlling the mocap system, and child devices connect to the output port to be triggered by the mocap system. Once the devices are connected, the input and output source needs to be configured under the OptiHub2 properties in Motive.

Additional Notes:

• Unlike the eSync2, the OptiHub2 cannot generate an output signal at a higher frequency than the camera capture rate.

• When using multiple OptiHub2s, input and output ports of only the parent OptiHub2 can be used. The parent OptiHub2 is the first OptiHub2 within the daisy-chained RCA sync chain.

Synchronization Setup

Setting Up a Parent Device

Step 1. [Hardware] Connect a parent device into the External SYNC In port of the parent OptiHub2.

Step 2. [Motive] Launch Motive.

Step 3. [Motive] Open the Devices pane and the Properties pane under the view tab.

Step 4. [Motive] Select the parent OptiHub2 in the Devices pane, then its properties will get listed under the Properties pane.

Step 5. [Motive] Under the Sync Input Settings section, configure the source and the corresponding settings. If you are using an external device connected to the External SYNC In port as the sync source, set the input source to Sync In. See more under the Input Source section of this page.

Step 6. [Motive] Once above is configured, the camera system will capture according to the input signal, and you should be able to see the change in the Devices pane camera frame rate section.

Setting Up a Child Device

Step 1. [Hardware] Connect a child device into the External SYNC Out port of the parent OptiHub2.

Step 2. [Motive] Launch Motive.

Step 3. [Motive] Open the Devices pane and the Properties pane from the view tab.

Step 4. [Motive] Select the parent OptiHub2 in the Devices pane, then its properties will get listed under the Properties pane. By modifying the properties, you can configure the for outputting sync signals to the child devices.

Step 5. [Motive] Under the output section, set the output signal type. This will determine the signal characteristic that the child device will receive. See the Output Source section of this page for details.

Step 6. [Motive] Once this is set, the OptiHub2 will output configured signal through its output ports.

Input Source

The Sync Input configuration determines how the camera system is synchronized. Depending on which input source is configured under the custom sync settings, the cameras will shutter at the corresponding frequency. To configure the sync input signals, first define an input Source and then configure the respective trigger settings. The following input sources can be configured with the OptiHub2:

Internal Sync

(The camera system will be the parent)

When the sync source is set to Internal/Wired the camera system uses the OptiHub2 as the sync source. This is the default configuration, and it uses OptiHub2's sync protocol for synchronizing the cameras. The Parent OptiHub2 will generate an internal sync signal which will be propagated to other (child) OptiHub2(s) via the Hub Sync Out Jack and Hub Sync In Jack, and all of the cameras connected to the OptiHub2s will be synchronized. For V100:R1(legacy) and the Slim 3U cameras, Wired Sync protocol is used. In this mode, the internal sync signal will still be generated but it will be routed directly to the cameras via daisy-chained sync cables.

When the Internal Sync is selected as the sync source, Internal Sync Freq (Hz) can be set under the Synchronization Control section. This setting determines how the OptiHub2 triggers the camera exposures or the camera framerate.

Sync In

(The camera system will be the child)

When synchronizing the camera system to an external device, set the source to Sync In, and the camera system references the external signal through the SYNC In port as the parent sync. In this mode, the Input Trigger event must be defined so that the camera systems respond to the incoming signal as desired; available triggers are Either Edge, Rising Edge, Falling Edge, High Gated, and Low Gated. Note that the suitable event will vary depending on characteristics of the received signal and how you want the system to synchronize with it.

For syncing to input signals with a frequency higher than the supported camera frame rates, the Input Divider can be applied so that the sync source is down-sampled to the supported rate range.

USB Sync

(The camera system will be the child)

This mode is for customers who use the software development kits and would like to have their software trigger the cameras instead. Using the provided API, the OptiHub2 will can receive the trigger signal from the PC via the OptiHub2's USB uplink connection.

Trigger and Camera Exposure

Note that the precise moment of the camera exposure does not exactly coincide with the sync input trigger event. There is a fixed latency between these two events due to specific implementation of the sensors used in the cameras. This delay from the onset of the trigger-event to the start of exposure on the cameras can be calculated as the following:

Flex 3 and Duo/Trio tracking bars

• Camera exposure (measured in scanlines for Flex 3 cameras)

• Imager Scan-Rate: Frame Rate Setting defined under the Devices pane.

Flex 13

Flex 13 cameras have a different trigger-to-exposure latency. From the moment the sync trigger event is received, it takes 480 microseconds for the cameras to synchronize and start exposing. After this delay, the Flex 13 cameras expose for the duration defined under the exposure settings in the Devices pane. The camera exposures are measured in microseconds for Flex 13 cameras.

Output Source

The External SYNC Out port of the OptiHub2 can be used if you want to set up the camera system to be a parent of other systems. The output port sends out the sync signals which can be configured under the External Sync Output section of the OptiHub2 properties. First, understand the characteristic of sync signal that the connected child device is expecting and configure the output source accordingly.

• All output signals can be inverted by setting the Output::Polarity to Inverted.

• For connecting more than one child devices, output signals may be split using a BNC splitter.

• The sync hubs are capable of sending out the following signals:

Exposure Time & Gated Exposure Time

Exposure output signals to inform when the cameras are exposing. When the output type is set to Exposure Time, the sync hub asserts the output signals when the cameras are exposing, or shuttering, in the live mode. When the output is configured to Recording Pulse, the exposure signal is asserted only when Motive is recording.

Recording Gate

The Recording Gate signal can be used to tell the child device when Motive is recording or not. When configured to Recording Gate, the sync hub will output a constant high voltage signal when Motive is recording. Please note that OptiHub2 is not specifically designed for precise synchronization, and there will be a slight delay when it starts outputting the trigger signal. This delay varies on each camera system setup.

Pass-Through

The Pass-through type outputs the signal that is received through the SYNC In port.