Best way to build a scanner

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Posts: 5
Joined: 05 Aug 2017 08:00

Best way to build a scanner

Post by herals20 »


I am trying to build a scanner as follow:

1. I created a screener for Equities Deutschland (124), and for started with the Study "WHS Flap Pattern"
2. Once the screener is completed, I create a new QuoteBoard, add the column "Study" and then I dragged and dropped the whole list from the screener to new QuoteBoard - in total 124 stocks.
3. The appplication NanoTrader full chrashed.

4. I repeated above steps, but instead of copying all stocks in only one QuoteBoard then I divided in two QuoteBoard. However when both tables are open the application crashes again.

Above steps I repeat several times - and the result was the same.

I am running NanoTrader Full in a VirtualMachine with 2-cores and 4 GB RAM.


a) is there a limit in the amuount of stocks in one QuoteBoard table with study.?

b) What is the best way to do a scanner?

My goal is to make a scanner with the 124 stocks using a specific study, in the example above the WHS Flag Pattern.



WHS Support
Posts: 2364
Joined: 14 Feb 2013 10:27

Re: Best way to build a scanner

Post by WHS Support »

When you are using a scanner, your platform is actually applying a strategy. This means that it will calculate the strategy at each tick entering. If you add 124 stocks to your quote board, then your computer has to calculate the strategy at each tick for those 124 stocks. That is quite a challenge.

Scanners are used on limited selections of instruments as they use PCs more intensively. They tend to be used by traders who trade on small timeframes (15’ or less). These traders need instant notification of signals to quickly open their position. Screeners are launched once per day or per (half) hour. They are applied to larger selections of instruments.

Taking this into account, it might be better for you to use the screener option.

Kind regards


Posts: 1
Joined: 10 Feb 2018 11:13

Re: Best way to build a scanner

Post by EricRes »

This explanation makes a lot of sense for this situation. Is there a cut-off number so to speak for when the screener option becomes better than the other one as a general rule of thumb?

WHS Support
Posts: 2364
Joined: 14 Feb 2013 10:27

Re: Best way to build a scanner

Post by WHS Support »


it all depends on the time frame and the number of instruments. How often do you want to (re-) run a screener per day? Normally you do not want to run a screener several times and only do it once per day (after market close or before market open). That's then normally in the daily chart aggregation. Personally I could imagine do to it 2-3 times per day with a 60-minute chart if my list of instruments is too big but I would never do a smaller timeframe with a screener and rather prefer to run a scanner / LiveTable.
Here on the other hand it depends mainly on the number of instruments. If this number gets too big the scanner might need too much computation time to work efficient. I would use a screener on any time frame between 1 minute and 60 minute and for not more than 40-50 instruments.

Please note that this is also a bit personal preference and might be slightly different from user to user.

Hope this helps.

Kind regards,

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