MeasData Variable's Dictionaries

The MeasData variable is a list of dictionaries where each dictionary describes a FlexDCA measurement. For example,

'MeasData' = [
			{'Name': 'Amplitude', 'Status': 'Correct', 'Source1': 'Channel 1A', 'Result': 0.496241, 'Units':'Volt'},
			{'Name': 'Peak-Peak', 'Status': 'Correct', 'Source2': 'Channel 1B', 'Result': 0.514348, 'Units':'Volt'},
			....]

Dictionary keys return either string values (type unicode in Python 2) or float values. The string values are passed as Unicode. The tables at the end of this topic show example measurement name strings returned for a dictionary's 'Name' key. Use a dictionary's 'Name' key to:

• Identify the measurement that a dictionary describes.
• Learn the status of the found dictionary's measurement result using the 'Status' key.
• Get the found dictionary's measurement result using the 'Result' key.

For example, you could identify a Rise Time and Fall Time measurements using the following code:

For meas in MeasData:  # loop through dictionaries
	if (meas['Name'] == 'Rise Time'):
		RiseTimeMeasurement = meas['Result']
	elif (meas['Name'] == 'Fall Time'):
		FallTimeMeasurement = meas['Result']

How do I handle Unicode symbols (Δ, δ, and μ) in a name string?

In Python 2, strings (the str type) is a sequence of 8-bit values while the unicode type is Unicode characters. Since the measurement string for the Δ Time, DI (δ-δ), and DJ (δ-δ) measurements contain Unicode symbols (chars beyond 255), you must do some extra work when performing comparisons to identify the a measurement dictionary. See also the note above for the situation when a 'μ' symbol can appear in a measurement name.

The following script includes three measurement that include a symbol and a fourth measurement that only includes ASCII (Rise Time). To identify measurement names for these measurements, "string" names of type unicode are used to directly compare with the 'Name' key's Unicode value.

This script:

• Identifies dictionaries for Eye Mode's Rise Time, DJ (δ-δ), Δ Time, and JN measurements. Notice in lines 5, 6, and 7 that the symbols character is represented by Unicode character code shown in this topics sidebar.
• Assigns each measurement's located dictionary to its own variable: RT, DJ, DeltaTime, and J4.
• Returns the Δ Time measurement result to FlexDCA.
• Prints each measurement result to the User Measurement Output dialog.

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def algorithm(variables): 
    Source = variables['Source']      # Source of the input waveform
    MeasData = variables['MeasData']  # A list of measurement dictionaries 
    RISETIME = 'Rise Time'
    DELTAJIT = u'DJ (\u03b4 - \u03b4)'
    DELTATIME = u'\u0394 Time'
    JFOUR = u'J4 (RJ: 1.200\u03bcs)'
    for meas in MeasData:
        if (meas['Source1'] == Source):
            if (meas['Name'] == RISETIME):  # compare Unicode
                RT = meas
                print 'Rise Time Result: ', str(RT['Result'])
            elif (meas['Name'] == DELTAJIT):  # compare Unicode
                DJ = meas
                print 'DJ Result: ', str(DJ['Result'])
            elif meas['Name'] == DELTATIME:  # compare Unicode
                DeltaTime = meas
                print 'Delta Time Result: ', str(DeltaTime['Result'])
            elif meas['Name'] == JFOUR:  # compare Unicode
                J4 = meas
                print 'J4 Result: ', str(J4['Result'])
    return { 'Result': DeltaTime['Result'],
        'Status': 'Correct',
        'Units': 'second',
        'ValueFormat': 'Engineering',
        'Resolution': 0.01e-12,
        'ErrorMsg': ''}

Markers Variable's Dictionaries

The Markers variable is a list of dictionaries where each dictionary describes a waveform marker. For example,

'Markers' = [
			{'Status': 'Correct','Source': 'Channel 1B','Name': 'X1,'Position': 1.01033e-10},
			{'Status': 'Correct','Source': 'Channel 1B','Name': 'X2,'Position': 1.28445e-10},
			....]