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()