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Send readings from a Python script

Send readings from your own Python code, such as a bench script or a sensor with no connector. They show as live channels.

Before you start

  • Python 3 on the same computer as Phloem. No extra packages needed.
  • The push address from Send your own data.

Steps

  1. Open Inputs and press Add input.

  2. Choose Push endpoint.

  3. Set Codec to batch.

  4. Press Add & start.

  5. Save this script as send_readings.py:

    import json, math, sys, time, urllib.request

URL = sys.argv[1]  # the push address, with batch as the codec

for i in range(600):
    t_us = time.time_ns() // 1000
    body = [
        {"path": "/bench/temp_c",
         "samples": [{"t_us": t_us, "value": {"f64": 21.5 + math.sin(i / 10)}}]},
        {"path": "/bench/step",
         "samples": [{"t_us": t_us, "value": {"i64": i}}]},
    ]
    req = urllib.request.Request(
        URL, data=json.dumps(body).encode(),
        headers={"Content-Type": "application/json"})
    with urllib.request.urlopen(req) as r:
        print(r.read().decode())
    time.sleep(0.1)

  6. Run it with the push address, <codec> replaced by batch:

    python3 send_readings.py <push address>

Check it worked

Each POST prints {"codec":"batch","batches":2,"samples":2}. On Inputs, the Push endpoint row counts samples. On Live, /bench/temp_c and /bench/step appear in the channel list.

The script printsDo
HTTP Error 403no Push endpoint input is open for batch — steps 1–4
Connection refusedPhloem is not running on this computer
HTTP Error 400the body is not valid batch — compare with the script above
Tip

Ran the script before adding the input? Inputs lists it under Sending to this device. Press Enable instead of steps 1–4.

Send your own dataEvery codec, body format and response codeName channels and unitsName a signal, set its unitVerify that your data is arrivingRead an input's row when nothing shows

Updated