BANKNIFTY is positionally bullish. I have drawn a shaded region. If Banknifty goes below the shaded region with volume, it may touch once 40790-40760. After that it should go in upward direction.
If banknifty directly open at 40770-90 region, then you can take long trade with the Stoploss of 50 points. Target 42000 ,42500
But if it sustained below 40780 then it is cautious for bull.