Preselector Support

SCOS Sensor can be configured to support preselectors. This page provides details about preselector support and an example configuration of using a WebRelayPreselectorfrom the NTIA/ITS Preselector API.

Preselector Module and Class

SCOS Sensor's preselector handling is determined by the values of the environment variables PRESELECTOR_MODULE and PRESELECTOR_CLASS. At present, the only supported preselector module is the default, the NTIA/ITS Preselector API. The default preselector class is the WebRelayPreselector, defined in that module. If you wish to replace this with another module, modify the environment variables such that PRESELECTOR_MODULE is the name of a Python module which implements the preselector as a class with the name defined by PRESELECTOR_CLASS.

Preselector Configuration File

To use a preselector with the NTIA/ITS Preselector API, you must create and populate a JSON preselector configuration file. This file defines the various states, sensors, inputs, and control URLs for a given preselector. By default, SCOS Sensor looks in the configs directory for the file preselector_config.json. However, the location of this file is configurable using the PRESELECTOR_CONFIG environment variable. An example is provided below for a WebRelayPreselector.

Example preselector_definition.json

The following example defines a WebRelayPreselector with three controllable relay states and a variety of sensors. Specifically, this preselector includes multiple temperature sensors, a humidity sensor, voltage monitors, and a "door-open" sensor. Digital inputs to the preselector web relay also provide status flags for the onboard Uninterruptible Power Supply (UPS).

{
  "name": "preselector",
  "base_url" : "http://192.168.1.2/state.xml",
  "control_states": {
      "noise_diode_on" : "1State=1,2State=1,3State=0,4State=0",
      "noise_diode_off" : "1State=1,2State=0,3State=0,4State=0",
      "antenna" : "1State=0,2State=0,3State=0,4State=0"
  },
  "status_states": {
    "noise diode powered" : "relay2=1",
    "antenna path enabled": "relay1=0",
    "noise diode path enabled": "relay1=1"
  },
  "sensors": {
    "internal_temp": 1,
    "internal_humidity": 2,
    "tec_intake_temp": 3,
    "tec_exhaust_temp": 4
  },
  "digital_inputs": {
      "ups_power": 1,
      "ups_battery_level": 2,
      "ups_trouble": 3,
      "ups_battery_replace": 4
  },
  "analog_inputs": {
      "door_sensor": 1,
      "5vdc_monitor": 2,
      "28vdc_monitor": 3,
      "15vdc_monitor": 4,
      "24vdc_monitor": 5
  }
}