No you can only know after the new last bar has opened with it's open price.
Not before so even if price goes over or drops below your TP and SL values nothing will happen until the new last bar open price comes in and this is where it differs from ticks.
So your order will be closed, or a new order will be opened only when a new bar opens that breached the values of your triggers.
This depends are you talking about SL and TP levels residing on the trading server side, or are you talking about SL and TP triggers that reside on the trading terminal side ?
These are two different things, of course if your triggers are set on the trading server they will obey every tick, but if you keep your levels hidden from your broker then they will only obey bar open price when it is coded to deal with bar open only.
Now bar open means bar open it does not mean bar close or bar high or bar low so it can not be more then just bar open.
If you run only bar open then thats what it will be so unless you code it to deal with other prices but then it would not be bar open only obviously.
can not determine SL or TP has been triggered.
This depends on :
To determine if anything has been changed, can only be done after a new bar.
It does not rely on OHLC but just O .
In this mode, first, bar is opened (Open = High = Low = Close, Volume=1)
It's the same thing.
Either your EA is coded to only work with open times or your EA is not coded to work with open times but you set strategy tester to open times only.
Even if your EA would rely on anything else then open time it would not be available when run strategy tester open mode only.
Or when your EA IS coded to run open only then you can even set it to on tick it should still results open only but with a lot of wasted time in between for the ticks that are not handled.
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