ch

The ch function returns the data of a given channel as a row vector.

The data file is set outside the function. To access the data file the global variable _fi_ncid is used. The function should only be used inside a function for the formula interpreter.

values = ch(ssChannelName)

values = ch(ssChannelName, ssBaseName)

values = ch(ssChannelName, ssBaseName, bSIUnits)

Return Value

Is a row vector with the channel values. For MDF files only the form with two parameters should be invoked. The second parameter specifies the time group the data will be interpolated to.

Parameters

ssChannelName

ssChannelName is a channel name.

ssBaseName

ssBaseName is a channel name. For MDF files the data of ssChannelName is interpolated to the time group of ssBaseName.

If ssBaseName is not specified or an empty string (“”) the data is not interpolated.

bSIUnits

bSIUnits is TRUE (1), if ssChannelName has to be converted to SI units. If bSIUnits is not specified or FALSE (0) the units are not converted.

Example

// Leistung in kW
// M*2*PI*n
// Drehzahl n in 1/min
// Moment m in Nm
def _fi_Power(bInfo)
{
    ssChannels = "n_Motor, Md_Motor";
    if (bInfo) {
        return ["Power"; ..
            "kW"; ..
            "Leistung"; ..
            ssChannels];
    }
    n_Motor = ch("n_Motor");
    Md_Motor = ch("Md_Motor");
    Power = (n_Motor .* Md_Motor) ./ 9549.3;
    set_ch("Power", Power, ssChannels);
}

History

Version	Description
R2013.11	Third parameter.
R2012 (5.40.0)	New documentation.
5.7	New.

See also

Formula Interpreter 1 - Introduction, Unit Converter, OnFormulaStartEval, set_ch, get_ncid,

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