Logging Measurements & Debug Messages¶

This page contains all you need to know about how to log measurements and debug messages in your scripts. It follows the life of a measurement from when you first take it using the equipment get methods to when you store it in your log file.

Note

Typically, logging debug messages is unnecessary unless you are developing low-level functions or need low-level information about equipment state.

Hint

For an example of typical measurement logging, jump to Log Class.

Measurement Object¶

The output of an equipment get measurement method should always be a Python dictionary. The measurement object stores the measurement value itself along with context about how the measurement was taken.

Attributes:

Equipment ID
Transponder tuning parameters
Measurement ID, e.g. snr, pwr, etc.
Measurement value

Here is an example measurement object:

{
    "timestamp": "2016-09-26T14:30:04",
    "equip_id": "fsw-1",
    "txpdr": {
        "id": "txpdr-1",
        "mode": {
            "bcstd": "DVB-S2",
            "mod": "8psk",
            "fec": "6/7"
        },
        "freq": 974,
        "symb": 20000,
        "roll": 20,
        "scramb": 1000,
        "pilot": "True",
        "pol": "None",
        "LO": "None"
    },
    "meas_id": "snr",
    "meas_val": 9.5
}

Log Class¶

The Log Class is an object used to configure what data to store and how to format the output.

Here is an example of typical configuration and use of the Log Class.

snr_log = Log(filename='FSW_SNR', format='csv')
measurement = fsw.getMeas()
snr_meas = measurement['snr']
snr_log.push(snr_meas)

Hint

Try creating a Log object specific to each equipment, and push measurements of that equipment to its individual Log. That way, you can save different equipment measurements to different files.

There are 2 possible formats for the output log file: CSV and JSON. If csv is selected, then a list of measurement values and time stamps are stored and written to separate column in a CSV file. If json is selected, then a list of Measurement Object s with time stamps are stored in the JSON file format.

Note

JSON stands for JavaScript Object Notation. It uses JavaScript syntax, but the format is text only. So, it can be read and used as a data format by any programming language. Python dictionaries lend themselves to JSON formatting due to structure similarities.

Attributes¶

Each Log includes a timestamp for each measurement object.

List of time stamp
List of corresponding measurement objects

Methods¶

Constructor

Description: Configures where the measurements will be written to and what format. If no filename is specified, samples are not written to a file. If a filename is specified and the format is csv, then only the measurement value and timestamp will be written to a CSV file. If a filename is specified and the format is json, then the timestamp will be included in the Measurement Object and written to a JSON file.

Inputs: filename and format

Outputs: instance of the Log Class

Push(sample)

Description: pushes measurement to the list of samples and writes sample to output file

Inputs: instance of Measurement Object

Outputs: Success/ Failure

Class Definition¶

class Log(object):

    def __init__(self, filename=None, format=None):
        """Constructor.

        ~~~~~ Possibilities ~~~~~
        filename: string with no '.'
        format: 'csv', 'json'

        """
        self.filename = filename
        self.format = format
        self.sample = []
        self.time_stamp = []

Debug Messages¶

Error Codes

Debug Class (Parent of all classes to set debug flag and print debug messages)