HTTP JSON Sensor Data

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Preface

  • all Sensor data is available in a generic JSON Object, presentes by status.json
  • there are two relevant sub-objects: sensor_values and sensor_descr
  • sensor_descr can tell:
    • what sensor types are actually relevant
    • what is the type-specific sensor-field description
    • how many sensors of each type are actually present
    • what are the names of each of those sensors
  • sensor_values tells you about the sensor values, matching the description explained above
  • it's common practice to get sensor_descr+sensor_values once, and poll sensor_values only subsequently with mich less payload


This empowers you to write small code supporting all products and all sensors in one single future-approach, without the need for sensor specific knowledge. So your software is already prepared for new Gude-Devices, and prepared for new Sensor Add-Ons. As example, this documentation will highly depend on check_gude.py, our HTTP sensor data swiss-knife tool.


Getting Data

  • HTTP-Get status.json?components=8470528
    • here, 8470528 sums up sensor_values (16384 aka 0x10000) plus sensor_descr (65536 aka 0x4000), plus the ‘extended’ marker (0x800000) to get both simple sensors and complex sensor groups
    • 0x4000 + 0x10000 + 0x800000 = 8470528

Example Data

sensor_descr

 [
   {
     "type": 664,
     "num": 2,
     "fields": [
        {"name": "Voltage", "unit": "V", "decPrecision": 3},
        {"name": "Current", "unit": "A", "decPrecision": 1}
     ]
     "properties": [
       { "id": "L1", "name": "Meter1", "state": 1},
       { "id": "L2", "name": "Meter2", "state": 1}
     ]
   },
   {
     "type": 665,
     "num": 1,
     "fields": [
        {"name": "Temperature", "unit": "C", "decPrecision": 1},
        {"name": "Humidity",    "unit": "%", "decPrecision": 1}
     ]
     "properties": [
       { "id": "6102", "name": "Server-Rack", "state": 1}
     ]
   }
 ]

This tells you:

  • there a two Sensors of Type 664, and one of type 665
  • a type-664 sensor has two Fields, Voltage and Ampere
    • Voltage is measured with a decimal precision of 3, Ampere with a decimal precision of 1
  • The two Type-664 sensors (L1 and L2) are named 'Meter1' and 'Meter2'
  • The Type-665 Sensor is named 'Sever-Rack'

sensor_values

 [
   {
     "type": 664,
     "num": 2,
     "values": [
       [{"v": 233.19}, {"v": 3.2}],
       [{"v": 226.2},  {"v": 0.3}]
     ]
   },
   {
     "type": 665,
     "num": 1,
     "values": [
       [{"v": 27.1}, {"v": 40.3}]
     ]
   }
 ]

sensor_desc / sensor_values

bringing together this tells you:

 L1/Meter1 233.19 V (Voltage), 3.2 A (Ampere)
 L2/Meter2 226.20 V (Voltage), 0.3 A (Ampere)
 
 6102/Server-Rack: 27.1 C (Temperature), 40.3 % (Humidity)

Common Sensor Type IDs

  1  Line power meter
  9  Line power meter with residual Current
  7  Digital Inputs
  8  Outlet power meter
 20  System Data (sensor group)
 51  Temperature Sensor
 52  Temperature/Humidity Sensor
 53  Temperature/Humidity/AirPressure Sensor
101  Bank (eFuses Port-groups) Sensor (e.g. used at 8291 PDUs)
102  (DC) Power Sources

check_gude.py in action

  • check_gude.py is a demo code to show how sensor_descr and sensor_values can be assembled generically to make use of all out devices / sensors
  • so when new devices and sensors are coming up, check_gude.py is already prepared to deal with it
  • install python along with requests to run check_gude.py
  • feel free to use check_gude.py as you need it and to rewrite the given code to any language desired

Show all Sensor Data

Here a device with hostname 8041.demo.gude.info is queried to dump all sensor data

Check gude py 1.png

show CGI-Get / JSON Data

when using --verbose check_gude.py will print out the full URL and the JSON return data:

Check gude py 2.png

Sensor Groups