Custom Column to calculate Open value (1 min) at 0930

I can't really do anything with your code. It has a degree of complexity that far exceeds the intended task. This makes the code extremely difficult to read. So I would start over from scratch, if I could understand exactly what it is you are trying to accomplish.

One thing about your code I will mention. The following statements are completely unnecessary:

def C_1m = CLOSE(period = AggregationPeriod.MIN);
def O_1m = OPEN(period = AggregationPeriod.MIN);
def H_1m = HIGH(period = AggregationPeriod.MIN);
def L_1m = LOW(period = AggregationPeriod.MIN);
def V_1m = VOLUME(period = AggregationPeriod.MIN);

Why?

Because the only place you can use these statements is on a chart that is set to a 1 min time frame. Understand that? When your code says "period = AggregationPeriod.MIN", this code can only run on the 1 min time frame. Any other time frame applied to the chart will generate errors. In case you are asking why. It is because you cannot read data from a lower time frame than the chart is set to. You can only read data from a higher time frame, or the time frame the chart is set to.

Which means all of those lines I listed above are best written as:

def c_1m = close;
def o_1m = open;
def h_1m = high;
def l_1m = low;
def v_1m = volume;

But that still does nothing to answer your question.

It seems that you are trying to read the opening price of the first candle of the regular trading hours. There is a very simple solution to that. So the complexity of your code leads me to believe you are trying to achieve something entirely different. But I don't know what that is. Perhaps you can clarify things, and provide a screenshot showing what values you are trying to plot on a chart.

If you really are trying to read the value of the first opening bar on the chart. That is very simply done like this:

def regularSessionOpen = open(period = AggregationPeriod.DAY);

This reads the daily data and reports the opening bar of the current day. If the markets have not yet opened for regular session hours, you will get N/A. But you can work around this, depending on what you are doing with this value. Until I know that, I cannot provide any further solution.