How does 3dslicer read external marker coordinates

How does 3dslicer read external marker coordinates

Slicer communicates with position trackers through the OpenIGTLink communication protocol. You need to install the SlicerOpenIGTLink extension for that. I also recommend installing SlicerIGT extension, if you use real time trackers. There are some useful tutorials on this page: User tutorial | SlicerIGT
Some of them are a bit outdated, but still useful.
PLUS is a great tool to read any tracker and translate the real time information to OpenIGTLink and send in real time to Slicer: https://plustoolkit.github.io/

Thanks your reply, I have installed the OpenIGTLink and communication protocol and PLUS,could you please tell me the examples of read external marker coordinates?

You need to specify which tracker device you are using. Here is a list of devices already supported by PLUS: Plus applications user manual: Device set configuration
Can you find your device in the list?