Module Logging

The OMC-045 datalog format is used by a variety of Observator products including OMC-Data-Online. This page documents the API to log data using the OMC-045 Datalog Format. It is not explain the datalog format itself. See the Logger Data Format document for more information about the format itself.

Constructor

class logging.DataLog045(system_id)

Create a OMC045 datalog format object which can be used to log data to a file.

  • system_id is the name of the system/product

  • substation is the name of the substation, which is important when multiple dataloggers are used in the same system/product

Methods

DataLog045.add_sensor(name, unit, tag) → SensorField

Add a sensor to the header of the file. A new sensor can’t be added logging is started(start function is called).

  • name The name of the sensor. Is not allowed to contain \ and ;.

  • unit The data unit in which the data is logged. Is not allowed to contain \ and ;.

  • tag The tag of the sensor, also known as the parameter code, which is an abbreviation of the name. This should be unique and is not allowed to contain \, ; or spaces.

DataLog045.start() → bool

Create a file with the current time in the name and start logging.

Return: True if the file is succesfully created and logging can be started. False if file couldn’t be created.

DataLog045.stop()

Stop logging to the file and close the file currently in use. The logging can be stopped and started again to create a new file with the current timestamp and resume logging.

DataLog045.add_record(sensor: SensorField, value: number, time: datetimetuple)

Add a data record to the file associated to the sensor. When multiple records are received within a second they are logged on the same line.

  • sensor The SensorField associated to this data record.

  • value The data to record, can be a integer or a float.

  • RTC The datetimetuple.

DataLog045.sync()

Synchronise the file by writing all the data in the buffer to the file.

Example

The following code shows an example that logs the internal parameters to a log file, creating a new log file after logging 300 samples.

import logging
import obs
import omc048
from omc048 import RTC

log = logging.DataLog045("SYSTEM")
temp = log.add_sensor_field('Temperature', 'C', 'TPT1')
hum = log.add_sensor_field('Humidity', 'rh', 'HUM')
bat = log.add_sensor_field('Coin cell voltage', 'Volt', 'VBAT')
board = omc048.onboard_sensors()
time = RTC().datetime()
log.start()
index = 0

while True:
    index += 1
    temperature = board.temp()
    humidity = board.hum()
    battery = board.vbat()
    log.add_record(temp, temperature, time)
    log.add_record(hum, humidity, time)
    log.add_record(bat, battery, time)
    obs.delay(1000)
    if index > 300:
        print("Starting new log")
        index = 0
        log.stop()
        log.start()