I want to place an MIS order in a 1-min timeframe whenever the LOW of the 1 min candle crosses below the previous 15 min candle with an SL of the previous 15 min HIGH.
Targer - 3:20 Closing.
I was able to do so using 15-min timeframe. Meaning signal and trading candle both are 15 min.
You can write an Algo for the Multi time frame, in a loop call 15min data and 1 min data and continuously check if 1min(low)<15min(low), if this condition satisfies, execute your trade.
The exit you are looking for will not be possible because the Signal/trading candle will now be the 1 min candle that triggered and not the 15min candle. So in order to implement the above scenario, 15min candle would be preferable.
Of course, this is possible by using the candletime or the Nth candle condition.