7681578f22
read_co2() lit IR1..IR4 en une trame (status + CO2) à 9600 8N1, adresse 0xFE 'any address', avec vérification CRC16-Modbus et rejet de la mesure si status non-nul (warm-up ou erreur). CRC requête/réponse validés contre les exemples du datasheet TDE14367. Doc protocole consolidée dans S88/README.md. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
113 lines
2.9 KiB
Python
113 lines
2.9 KiB
Python
'''
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Live read of the Senseair S88 CO2 sensor (used by the web "Get Data" button).
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Prints a JSON object: {"CO2": <int_ppm>} or {"error": "<message>"}.
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Modbus RTU 9600 8N1, reads IR1..IR4 in one frame.
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Usage: /usr/bin/python3 /var/www/nebuleair_pro_4g/S88/get_data.py [port]
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If no port is given, the script reads S88_port from config_table.
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'''
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import json
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import sqlite3
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import sys
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import serial
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DB_PATH = "/var/www/nebuleair_pro_4g/sqlite/sensors.db"
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DEFAULT_PORT = "/dev/ttyAMA5"
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BAUDRATE = 9600
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SLAVE_ADDR = 0xFE
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READ_REQUEST = bytes([SLAVE_ADDR, 0x04, 0x00, 0x00, 0x00, 0x04, 0xE5, 0xC6])
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EXPECTED_RESPONSE_LEN = 13
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def crc16_modbus(data):
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crc = 0xFFFF
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for byte in data:
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crc ^= byte
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for _ in range(8):
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if crc & 1:
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crc = (crc >> 1) ^ 0xA001
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else:
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crc >>= 1
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return crc
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def get_port_from_config():
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try:
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conn = sqlite3.connect(DB_PATH)
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cursor = conn.cursor()
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cursor.execute("SELECT value FROM config_table WHERE key = ?", ("S88_port",))
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row = cursor.fetchone()
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conn.close()
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return row[0] if row else DEFAULT_PORT
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except Exception:
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return DEFAULT_PORT
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def read_co2(ser):
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ser.reset_input_buffer()
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ser.write(READ_REQUEST)
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response = ser.read(EXPECTED_RESPONSE_LEN)
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if len(response) < 5:
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return None, f"short response ({len(response)} bytes)"
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if response[1] & 0x80:
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return None, f"Modbus exception code {response[2]:#04x}"
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if len(response) != EXPECTED_RESPONSE_LEN:
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return None, f"unexpected response length {len(response)}"
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received_crc = response[-2] | (response[-1] << 8)
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if crc16_modbus(response[:-2]) != received_crc:
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return None, "CRC mismatch"
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if response[0] != SLAVE_ADDR or response[1] != 0x04 or response[2] != 0x08:
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return None, f"unexpected header {response[:3].hex()}"
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status = (response[3] << 8) | response[4]
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co2 = (response[9] << 8) | response[10]
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if status != 0:
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return None, f"sensor not ready (status={status:#06x})"
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return co2, None
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def main():
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port = sys.argv[1] if len(sys.argv) > 1 else get_port_from_config()
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try:
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ser = serial.Serial(
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port=port,
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baudrate=BAUDRATE,
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parity=serial.PARITY_NONE,
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stopbits=serial.STOPBITS_ONE,
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bytesize=serial.EIGHTBITS,
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timeout=1,
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)
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except Exception as e:
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print(json.dumps({"error": f"Cannot open {port}: {e}"}))
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return
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try:
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co2, err = read_co2(ser)
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if co2 is None:
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print(json.dumps({"error": err or "No data from S88"}))
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return
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print(json.dumps({"CO2": int(round(co2))}))
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except Exception as e:
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print(json.dumps({"error": f"S88 read error: {e}"}))
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finally:
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try:
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ser.close()
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except Exception:
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pass
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if __name__ == "__main__":
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main()
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