Getting Started

Learn how to configure and use Event Video Playback in your TwinCAT projects

Download as PDF Download Complete Docs

Overview

Event Video Playback is a comprehensive system that consists of three integrated components:

  1. The EventVideoPlayback Service - A Windows service that handles creation of the videos
  2. The Event Video Playback Library - A PLC library that maintains an Image Ring Buffer containing enough images to create videos of configurable length and actively interacts with the EventVideoPlayback Service
  3. The Event Video Playback HMI Control - A modified Logger control that allows associated videos to be played from log entries
Important: Video viewing is only functional in a published, fully deployed project when viewed from a web browser. Videos cannot be viewed via the HMI Live display.

This guide will walk you through configuring each component to work together in your TwinCAT project.

EventVideoPlayback Service Configuration

The EventVideoPlayback Service controls video creation and automatic deletion of video files based on age and folder size limits.

Note: The service reads the configuration file on startup. You must restart the service for any configuration changes to take effect.

To restart the service:

  1. Open the Windows Services window
  2. Right-click the EventVideoPlayback service
  3. Choose Stop or Start

Configuration File Location

The configuration file is located at:

C:\Program Files\Beckhoff USA Community\EventVideoPlayback\Service\EventVideoPlaybackService.config.json

Open the file with Notepad or Visual Studio to edit the following parameters:

{
  "CodecFourCC": "avc1",
  "VideoDeleteTime": 1,
  "AdsPort": 26129,
  "MaxFolderSize": 250
}

CodecFourCC

This is the codec used to create the video from the service. The service supports multiple codecs, but not all are web-compatible. For TwinCAT HMI compatibility, stick with these recommended options:

Codec FourCC Description Web Compatible Recommended
H.264 avc1 Most common, best compatibility ✓ Yes
H.264 avc3 Alternative H.264 variant ✓ Yes
H.265/HEVC hev1 Better compression, newer ✓ Maybe
H.265/HEVC hvc1 Alternative HEVC variant ✓ Maybe
MPEG-4 mp4v Older standard ✓ No
VP9 vp09 Google’s codec ✓ No
AV1 av01 Newest, best compression ⚠ No
Tip: For best results, use avc1 (H.264). It offers the widest compatibility across all web browsers and HMI platforms.

VideoDeleteTime

This setting determines how long video files remain on the system before automatic cleanup.

  • Value type: Floating point
  • Units: Days
  • Example: Use 0.5 for half a day (12 hours)

The service automatically deletes video files older than the specified time.

AdsPort

Warning: Do not change this value. This is the ADS Port that the service is hosting on. This should remain at port 26129 at all times in order for the PLC function blocks to work properly.

MaxFolderSize

This setting limits the total size of the video storage folder.

  • Value type: Integer
  • Units: MB (megabytes)

When a new video is created, the service checks the folder size. If the limit is exceeded, the oldest video will be automatically deleted to free up space.

PLC Function Block Parameters

The FB_ImageToVideo function block maintains an image buffer in Router memory. The memory requirements are directly related to:

  • FramesPerSecond - Higher frame rates require more memory
  • Record time - Longer videos require more memory
  • Image size - Larger images require more memory
  • ReductionFactor - Larger reduction factors (0.1 to 1.0) require more memory
Important: Larger values of these parameters require more Router memory. Plan your Router memory allocation accordingly. 
VAR
    // ImageToVideo Instance
    Playback : FB_ImageToVideo := (CameraName := 'Camera1',
                                   FramesPerSecond := 10,
                                   TimeBeforeEvent := T#3S,
                                   TimeAfterEvent := T#3S,
                                   VideoOutputDirectory := 'C:\EventVideos',
                                   ReductionFactor := 0.25);

    // Event Trigger Boolean
    TriggerEvent1 : BOOL;
    TriggerEvent2 : BOOL;
END_VAR

Parameter Descriptions

CameraName

A unique identifier for each FB_ImageToVideo instance.

  • Examples: Camera1, Infeed_Camera, Arm_Camera
  • Requirement: Must be unique across all instances

FramesPerSecond

The rate at which images are added to the Image Ring Buffer.

  • Value type: Integer
  • Example: 10 frames per second

TimeBeforeEvent and TimeAfterEvent

These times combined determine the total video duration.

  • Value type: TIME (e.g., T#3S)
  • Units: Seconds
  • Total video length: TimeBeforeEvent + TimeAfterEvent

VideoOutputDirectory

The storage location for created videos. Videos are saved in a subfolder named after the CameraName.

  • Example: If set to C:\EventVideos and CameraName is Camera1, videos will be saved to C:\EventVideos\Camera1\

ReductionFactor

Scales down the original image before storing it in the buffer to reduce memory usage.

  • Value type: Decimal
  • Range: 0.1 to 1.0
  • Example: 0.25 = 25% of original size (reduces memory by 75%)

PLC Event Video Playback Library Parameters

These library-level parameters ensure adequate Router Memory is available for your configuration. On startup, the system evaluates available Router Memory. If insufficient memory is detected, a log entry will be generated and Event Video Playback will not function.

Event Video Playback Library Parameters

MAX_NUMBER_IMAGES_2_VIDEO

Defines the maximum number of images in the ring buffer.

Formula: Must be at least 2 greater than: FramesPerSecond × (TimeBeforeEvent + TimeAfterEvent)

Example: For 10 FPS and 6 seconds total time:

  • Minimum required: (10 × 6) + 2 = 62 images

MAX_PERCENT_ROUTER_MEM_FOR_BUFFER

Sets the maximum percentage of Router Memory allowed per FB_ImageToVideo instance.

Single Instance Example:

  • If using one FB_ImageToVideo instance, set this to 60 to allocate up to 60% of Router Memory

Multiple Instance Example:

  • If using three instances and want to allocate 60% total:
    • Set this to 60 / 3 = 20% per instance
    • This ensures all three instances combined use no more than 60% of Router Memory

ADS_PORT_FOR_IMAGE_TO_VIDEO

Warning: Do not change this value. This is the ADS Port that the EventVideoPlayback service is hosting on. This should remain at port 26129 at all times in order for the PLC function blocks to work properly.

LARGE_ROUTER_MEMORY

This parameter specifies the Router Memory size to use for memory checks when the actual value cannot be read programmatically.

Note: In TwinCAT 4026.18, Router Memory larger than 4026 MB cannot be read programmatically. If you have more than 4026 MB of Router Memory, manually set this parameter to your actual Router Memory size.

Add to Existing TwinCAT Vision PLC Project

Prerequisites: Install Event Video Playback XAE and XAR packages using the TwinCAT Package Manager. See the Installation guide for details.

You can easily integrate Event Video Playback with existing TcVision projects by following these steps:

1. Add the Event Video Playback Library to the References

Add the Event Video Playback Library to the References section of the PLC Project.

PLC References

2. Instantiate FB_ImageToVideo and TriggerEvent(s)

VAR
    // ImageToVideo Instance
    EVP1 : FB_ImageToVideo := (CameraName := 'Camera1',
                               FramesPerSecond := 10,
                               TimeBeforeEvent := T#3S,
                               TimeAfterEvent := T#3S,
                               VideoOutputDirectory := 'C:\TcEventVideos',
                               ReductionFactor := 0.25);

    // Event Trigger Boolean
    TriggerEvent1 : BOOL;
    TriggerEvent2 : BOOL;
END_VAR

3. Add a Reset Call to the First Scan

Add a Reset call to the first scan of POU:

EVP1.Reset();

4. Add the CyclicLogic Call

Add the CyclicLogic call to the main body of the POU. This MUST be called cyclically to work.

EVP1.CyclicLogic();

5. Add the AddImage Method

Add the AddImage method to the “new image” section of your program. This will add an image to the buffer of the Playback block.

EVP1.AddImage(ipImageIn := ImageIn);

6. Add the Trigger Logic

Add the trigger logic somewhere in your program. The TriggerAlarmForVideoCapture method only needs to be called once to start Event processing. Multiple event names can be used for events generating a log entry for the same ImageToVideo Instance.

IF TriggerEvent1 THEN
    TriggerEvent1 := FALSE;
    EVP1.TriggerAlarmForVideoCapture(LogEntryName := 'Log Entry Name1');
END_IF

IF TriggerEvent2 THEN
    TriggerEvent2 := FALSE;
    EVP1.TriggerAlarmForVideoCapture(LogEntryName := 'Log Entry Name2');
END_IF

HMI Configuration

Add the EventVision NuGet Package

  1. Open the NuGet Package Manager in your HMI project
  2. Go to the Browse window
  3. Search for and add the EventVision package

HMI NuGet Package

Tip: If the package does not appear, verify that the Package source is set to Beckhoff Offline Packages.

Add the EventVisionControl

Once the package is installed, add the EventVisionControl to your HMI from the Toolbox.

HMI Toolbox EventVisionControl

HMI EventVisionControl Properties

After adding the EventVisionControl, set the properties:

HMI Control Properties

Important: The Virtual drive setting must match that specified in the HMI Publish configuration. The Time Zone Info is required if the viewing browser system time is in a different time zone than the TwinCAT HMI Server.

HMI Publish Configuration

Configure a virtual directory to allow the HMI to access video files stored on the system.

Configure Virtual Directory

  1. In the Solution Explorer, navigate to Server → TcHmiSrv
  2. Add a virtual directory pointing to your video storage location
Important: Be aware of your Publish Configuration. If using a "Remote" Publish Configuration, ensure you add the virtual directory to the corresponding "Remote" configuration via the dropdown menu on the TcHmiSrv page.

HMI Virtual Directory

HMI Publish Connection

HMI Publish Settings

Next Steps

Now that you have configured Event Video Playback, you can:

  • Test video capture by triggering events in your PLC code
  • Review captured videos in your HMI
  • Adjust service configuration parameters as needed
  • Configure additional cameras by creating more FB_ImageToVideo instances

Support

Need help? Here are some resources: