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>
132 lines
3.6 KiB
Python
132 lines
3.6 KiB
Python
'''
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Script to get CO2 values from Senseair S88 sensor and write to database
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/usr/bin/python3 /var/www/nebuleair_pro_4g/S88/write_data.py
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Modbus RTU 9600 8N1. Reads IR1..IR4 in one frame to get status + CO2.
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If status (IR1) is non-zero the reading is skipped (warm-up or error).
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'''
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import serial
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import sqlite3
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import sys
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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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# Modbus slave address: 0xFE = "any address", any S88 responds regardless of
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# its configured individual address. Fine for single-sensor setups.
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SLAVE_ADDR = 0xFE
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# Read IR1..IR4 in one frame: function 0x04, start 0x0000, qty 0x0004
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READ_REQUEST = bytes([SLAVE_ADDR, 0x04, 0x00, 0x00, 0x00, 0x04, 0xE5, 0xC6])
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EXPECTED_RESPONSE_LEN = 13 # 1 addr + 1 fn + 1 count + 8 data + 2 CRC
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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_config(cursor, key, default):
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cursor.execute("SELECT value FROM config_table WHERE key = ?", (key,))
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row = cursor.fetchone()
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return row[0] if row else default
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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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print(f"S88: short response ({len(response)} bytes)")
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return None
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# Modbus exception response: function code has high bit set (0x84 instead of 0x04)
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if response[1] & 0x80:
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print(f"S88 Modbus exception: code={response[2]:#04x}")
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return None
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if len(response) != EXPECTED_RESPONSE_LEN:
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print(f"S88: unexpected response length {len(response)} (expected {EXPECTED_RESPONSE_LEN})")
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return None
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# Verify CRC (last two bytes, low byte first)
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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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print("S88: CRC mismatch")
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return None
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if response[0] != SLAVE_ADDR or response[1] != 0x04 or response[2] != 0x08:
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print(f"S88: unexpected header {response[:3].hex()}")
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return None
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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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# DI8 = Warm Up (bit 7 of low byte). Other bits = errors.
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print(f"S88: sensor not ready, status={status:#06x}")
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return None
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return co2
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def main():
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conn = sqlite3.connect(DB_PATH)
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cursor = conn.cursor()
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port = get_config(cursor, "S88_port", DEFAULT_PORT)
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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(f"Error opening serial port {port}: {e}")
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conn.close()
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sys.exit(1)
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try:
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co2 = read_co2(ser)
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if co2 is None:
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print("Failed to read CO2 from S88.")
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return
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co2_ppm = int(round(co2))
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cursor.execute("SELECT last_updated FROM timestamp_table LIMIT 1")
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row = cursor.fetchone()
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rtc_time_str = row[0]
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cursor.execute(
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"INSERT INTO data_S88 (timestamp, CO2) VALUES (?, ?)",
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(rtc_time_str, co2_ppm),
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)
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conn.commit()
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print(f"CO2: {co2_ppm} ppm (saved at {rtc_time_str})")
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except Exception as e:
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print(f"S88 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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conn.close()
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if __name__ == "__main__":
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main()
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