Hi @peter.akester

You can use "CODECR" app (Type in CODECR in Eikon Search to launch it) to check field supported parameters.

Here is a sample code:

dfSP500Smallx, err = ek.get_data(
    instruments = ['0#.SPX'],
    fields = [
        'TR.CommonName',
        'TR.TRBCEconomicSector',
        'TR.TRBCBusinessSector',
        'TR.TRBCIndustryGroup',
        'TR.CompanyMarketCap',
        'TR.PriceOpen',
        'TR.PriceClose',
        'TR.PricePctChg1D',
        'TR.Price52WeekHigh',
        'TR.Price52WeekLow',
        'TR.PriceAvg30D',
        'TR.Price50DayAverage',
        'TR.PriceAvg100D',
        'TR.Price200DayAverage'  
    ],
    parameters = {'SDate':'2021-03-22', 'EDate':'2021-03-24'} #added parameters which applies to all fields
)
display(dfSP500Smallx)

Of all the fields in your request only TR.CompanyMarketCap, TR.PriceOpen and TR.PriceClose are available as timeseries. For the rest of the fields only the most recent value can be retrieved. To retrieve TR.CompanyMarketCap, TR.PriceOpen and TR.PriceClose as of a given historical date add SDate parameter to the request:

ek.get_data(
    instruments = ['0#.SPX'],
    fields = [
        'TR.CommonName',
        'TR.TRBCEconomicSector',
        'TR.TRBCBusinessSector',
        'TR.TRBCIndustryGroup',
        'TR.CompanyMarketCap',
        'TR.PriceOpen',
        'TR.PriceClose',
        'TR.PricePctChg1D',
        'TR.Price52WeekHigh',
        'TR.Price52WeekLow',
        'TR.PriceAvg30D',
        'TR.Price50DayAverage',
        'TR.PriceAvg100D',
        'TR.Price200DayAverage'  
    ],
    parameters = {'SDate':'2021-03-01'}
)

You can use CodeCreator app in Eikon application to explore the metadata for use with Eikon Data APIs including what parameters are available for what fields.