UDP Parameter Data Link¶

Listens on a UDP port for datagrams containing Protobuf encoded messages. One datagram is equivalent to a message of type ParameterData.

By enabling the json option, this link can also be switched to accepting the JSON equivalent of a Protobuf ParameterData message.

If more flexibility is needed, this link class can be extended in Java to override the decodeDatagram(byte[] data, int offset, int length) method. Then you can use custom logic to convert the incoming datagram to a message of type ParameterData.

Class Name¶

org.yamcs.tctm.UdpParameterDataLink

Configuration Options¶

stream (string)

Required. The stream where data is emitted

port (integer)

Required. The UDP port to listen on

recordingGroup (string)

Name of the group used for incoming updates. Groups are identifiable in the Archive Browser.

The recording group can also be specified as a property in ParameterData, overriding this configuration setting.

Default: DEFAULT

json (boolean)

If true, decode the incoming message from JSON instead of Protobuf.

Default: false

JSON Example¶

Add UdpParameterDataLink to the list of data links:

etc/yamcs.instance.yaml¶

dataLinks:
  - name: pp-in
    class: org.yamcs.tctm.UdpParameterDataLink
    stream: pp_realtime
    port: 11016
    json: true

Then a Python script like the following updates two parameters at the same time with a single datagram:

import json
import socket
from datetime import datetime, timezone

gentime = datetime.now(timezone.utc).isoformat().replace("+00:00", "Z")

data = json.dumps(
    {
        "parameter": [
            {
                "id": {"name": "/myproject/Battery1_Temp"},
                "generationTime": gentime,
                "engValue": {
                    "type": "FLOAT",
                    "floatValue": 123,
                },
            },
            {
                "id": {"name": "/myproject/ElapsedSeconds"},
                "generationTime": gentime,
                "engValue": {
                    "type": "UINT32",
                    "uint32Value": 123,
                },
            },
        ]
    }
).encode()

with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as s:
    s.sendto(data, ("localhost", 11016))