On a 5 minute candle chart, if at 9:24:59 there were 2 contracts bought at 1070.25, and then at 9:25:00 there were 2 contracts sold at 1070, should the 9:25 candle have an opening at 1070.25, or 1070. Both Esignal and thinkorswim charts say 1070.25, but interactive brokers chart says 1070.
From what you say IB is correct. Does it really matter though? All this revolves around time stamps. How different data providers handle them (including the precision and any rounding) will undoubtedly affect candles. If you are using IB datafeed with external charting package then be aware that no time stamps are sent with the datafeed. Time stamps come from the PC clock. IB sends a synchronization timestamp on API connection so external software may choose to sync their clock to that. However it would be wise to synchronize your PC clock via NTP to a network time server on a regular basis. NTP servers are provided by most ISPs.
It does matter if you're waiting for a signal for fire off. I use E signal and thinkorswim don't accept data feed from IB. E signal manages their own data from the exchange and cost a lot of money. I think E signal should quote accurate candles if they're charging so much for them. The time and sales on E signal is correct, but the candle on their charts is wrong.
Thanks for the reply but I don't agree. I think it's a blatant mistake on E signal's charts. What if the 5 minute candle in question was the 9:30? If at 9:30:00 the very first order is a sell order at 1000, then the open would be 1000. If it 9:29:59 there had been a buy order for 1 at 1000.25, then the open would be 1000 not 1000.25. This has nothing to do with time stamps. This is about the opening time of a candle, which has nothing to do with my computer. Their time and sales also nothing to do with my computer, I can't change exchange data by chaning my clock.
You can configure the desktop to display exchange time zones, GMT or local (under File/Preferences/Date and Time Settings. We pass along the exchange time stamp where it's provided (which is for most US exchanges). To answer your theoretical question, in general, the bar building should match what you see in T&S as they are coming from the same server. Thanks.