Docs / Yamcs Server Manual / Instance Services / Data Link Initialiser

Data Link Initialiser

Manages the various data links and creates needed streams during Yamcs start-up.

Data Links represent data connections to external sources. These connections may represent output flows (TC), input flows (TM, PP) or a combination of these. Data links that read TM and PP data receive telemetry packets or parameters and inject them into the realtime or dump TM or PP streams. Data links that send TC subscribe to a TC stream and send data to external systems.

Note that any Yamcs Service can connect to external sources and inject data in the streams. Data links however, can report on their status using a predefined interface and can also be controlled to connect or disconnect from their data source.

Class Name

org.yamcs.tctm.DataLinkInitialiser

Configuration

This service is defined in etc/yamcs.(instance).yaml. Example from a typical deployment:

yamcs.simulator.yaml 
services:
  - class: org.yamcs.tctm.DataLinkInitialiser

dataLinks:
  - name: tm_realtime
    class: org.yamcs.tctm.TcpTmDataLink
    args:
      stream: tm_realtime
      host: localhost
      port: 10015
  - name: tm_dump
    class: org.yamcs.tctm.TcpTmDataLink
    args:
      stream: tm_dump
      host: localhost
      port: 10115
  - name: udp_realtime
    class: org.yamcs.tctm.UdpTmDataLink
    args: 
      stream: tm_realtime
      port: 5900
      maxLength: 2048
  - name: tc_realtime
    class: org.yamcs.tctm.TcpTcDataLink
    args:
      stream: tc_realtime
      host: localhost
      port: 10025

Each link is defined in terms of an identifying name and a class. There is also a property enabledAtStartup which allows to enable (default) or disable the TM provider for connecting to the external data source at the server start-up.

Specific data links may support additional arbitrary configuration options via the args key.