This endpoint returns the current status of a single Train Describer area. The returned object consists of:

lastUpdate
The time the last message was received for this describer
heartBeat
The latest time sent in the CT (Heart Beat) message from the describer
berths
An object showing occupied berths. The object's key is the berth name whilst the value is the 4 character train headcode or code describing the status of the berth.
signals
An object consisting of the current signal status received from the S class messages. The keys and values are a single byte represented as a 2 character hexadecimal value. The key is the address in hexadecimal whilst the value (also in hexadecimal) is specific to each individual Train Describer.
$ curl -s http://api.area51.onl/rail/1/td/A2|jq '.'
{
  "lastUpdate": "2016-11-24T14:34:37.595Z",
  "heartBeat": null,
  "berths": {
    "0664": "2A46",
    "0878": "5Z95",
    "0678": "2A44",
    "S315": "7409",
    "S114": "6409",
    "0653": "2R38",
    "0891": "1G38",
    "24": "00000000",
    "28": "00000000",
    "0909": "2R36",
    "ET25": "7405",
    "0646": "2W46"
  },
  "signals": {
    "10": "00",
    "12": "04",
    "1F": "00",
    "08": "00",
    "1B": "00"
  }
}

Berths

You can break the result down to just the berths by appending /berths to the URL

$ curl -s http://api.area51.onl/rail/1/td/A2/berths | jq '.'
{
  "lastUpdate": "2016-11-24T14:34:37.595Z",
  "heartBeat": null,
  "berths": {
    "0664": "2A46",
    "0878": "5Z95",
    "0678": "2A44",
    "S315": "7409",
    "S114": "6409",
    "0653": "2R38",
    "0891": "1G38",
    "24": "00000000",
    "28": "00000000",
    "0909": "2R36",
    "ET25": "7405",
    "0646": "2W46"
  }
}

Signals

You can break the result down to just the signals by appending /signals to the URL

$ curl -s http://api.area51.onl/rail/1/td/A2/signals | jq '.'
{
  "lastUpdate": "2016-11-24T14:34:37.595Z",
  "heartBeat": null,
  "signals": {
    "10": "00",
    "12": "04",
    "1F": "00",
    "08": "00",
    "1B": "00"
  }
}