# Plus Server error when connecting NDI Aurora tracker to Slicer

**URL:** <https://discourse.slicer.org/t/plus-server-error-when-connecting-ndi-aurora-tracker-to-slicer/27729>\
**Category:** Support\
**Tags:** plus, openigtlink\
**Created:** [February 9, 2023, 7:18pm UTC](https://discourse.slicer.org/t/plus-server-error-when-connecting-ndi-aurora-tracker-to-slicer/27729 "2023-02-09T19:18:14Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![sm-philips](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/sm-philips/32/18269_2.png) [@sm-philips](https://discourse.slicer.org/u/sm-philips)\
**Post date:** [February 9, 2023, 7:18pm UTC](https://discourse.slicer.org/t/plus-server-error-when-connecting-ndi-aurora-tracker-to-slicer/27729/1 "2023-02-09T19:18:14Z")

</div>

Hi,

I have been trying to connect a NDI Aurora tracker to Slicer. Initially I just want to visualize the points coming in from the tracker in 3D space. I have couple of issues I am running into.

1. The Plus Server launched and the connection was successful. But the indicator did not turn green. Upon inspection of the log file (attached), I found the error:` |ERROR|008.162000| Unable to start data sending. OutputChannelId not found: TrackerStream| in E:\D\PSNP64b\PlusLib\src\PlusServer\vtkPlusOpenIGTLinkServer.cxx(328)`

The OutputChanneld used in the config file was taken from example config files. I did not find documentation to what OutputChannelIds can be used.

1. In OpenIGTLinkIF, after adding a connector and changing status to Active, Status changes to ON. But in I/O configuration I do not see a visualize option for IN. Also I do not see any transforms. Could anyone advice on what I might be doing wrong? I am following the instruction to visualize tracked tools [here](http://perk-software.cs.queensu.ca/plus/doc/nightly/user/ProcedureStreamingToSlicer.html)

I am guessing 2 might be related to the error in 1. But cannot figure out where things are going wrong.

Config File:

```auto
<PlusConfiguration version="2.1">
  <DataCollection StartupDelaySec="1.0">
    <DeviceSet 
      Name="PlusServer: NDI Aurora"
      Description="Broadcasting tool tracking data through OpenIGTLink
      Tracking a single EM pointer and an optical pointer and reference." />
    <Device
      Id="EmTracker" 
      Type="AuroraTracker"
      SerialPort="3"
      BaudRate="115200"
      AcquisitionRate="20"
      LocalTimeOffsetSec="0.0"
      ToolReferenceFrame="EmTracker" >
      <DataSources>
        <DataSource Type="Tool" Id="Pointer" PortName="0" />
      </DataSources>
      <OutputChannels>
        <OutputChannel Id="EmTrackerStream">
          <DataSource Id="Pointer" />
        </OutputChannel>
      </OutputChannels>
    </Device>
    
  </DataCollection>
  <PlusOpenIGTLinkServer 
    MaxNumberOfIgtlMessagesToSend="1" 
    MaxTimeSpentWithProcessingMs="50" 
    ListeningPort="18944" 
    SendValidTransformsOnly="TRUE" 
    OutputChannelId="TrackerStream" > 
    <DefaultClientInfo> 
      <MessageTypes> 
        <Message Type="TRANSFORM" />
      </MessageTypes>
      <TransformNames> 
        <Transform Name="StylusToReference" />
        <!-- <Transform Name="ReferenceToOpticalTracker" />
        <Transform Name="StylusToOpticalTracker" />
        <Transform Name="PointerToEmTracker" /> -->
      </TransformNames>
    </DefaultClientInfo>
  </PlusOpenIGTLinkServer>
  
</PlusConfiguration>

```

---

<div class="post-metadata">

**Author:** ![Sunderlandkyl](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/sunderlandkyl/32/79987_2.png) [@Sunderlandkyl](https://discourse.slicer.org/u/Sunderlandkyl)\
**Post date:** [February 9, 2023, 7:53pm UTC](https://discourse.slicer.org/t/plus-server-error-when-connecting-ndi-aurora-tracker-to-slicer/27729/2 "2023-02-09T19:53:37Z")

</div>

The output channel in the AuroraTracker device is EmTrackerStream, not TrackerStream.

So in PlusOpenIGTLinkServer:

```auto
OutputChannelId="TrackerStream"

```

should be

```auto
OutputChannelId="EmTrackerStream"

```