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Investor/RT
Tip of the Day
Living With Symbol Limits
Also See: Q&A:
Scanning Multiple Periodicities (see bottom of page)
The
symbol limit imposed by any realtime data service refers to the number of symbols that can be
"watched" real-time at any one point in time. You can have a
much larger universe of stocks defined to Investor/RT but you must take
care not to activate more than your symbol limit at any one time. A few rules:
- Any instrument marked "intra-day" (see
Setup: Instruments) is actively watched all the time you are
connected to myTrack.
- Other instruments are actively watched only when
they are active in a quote page, a chart, a ticker tape, a quick quote
window, a portfolio window, etc.
- An instrument can be active in any number of
charts, quote pages, etc. and only counts as 1 debit against the
symbol limit.
- When you close a window, all instruments in the
window that are not marked intra-day and are not still active in some
other window are removed from the watch list.
- If you accidentally open windows that bring your
watch count above limit, the data service will send data on only the first
X (with X being the symbol limit). A
warning message usually appears.
- Finally, don't cut it too close, keep the watch
count below limit by 2 or so, since Investor/RT may need a couple of
"slots" to perform historical and other download requests. This
does vary somewhat between data services.
- It IS NOT required to have the quotepage open on
which you are either downloading data, running a scan, or running a
backtest. If you're using eSignal, and your symbol limit is 500,
but you want to download intraday (1-minute) data on 1000 symbols and
backtest those symbols, you can do so. However, you shouldn't open
up that 1,000 symbol quotepage WITH the date feed active. Start
the feed, then start the intraday download on the 1,000 symbol quotepage
(with the quotepage closed). When the download is completed, you
could stop the feed and do what you want as far as opening the quotepage
or running scans and backtests.
You can view the watch list count at any time in the
feed status window.
You can view the instruments that are currently marked for intra-day by
opening the system quote page named ".Intra-day".
You can view the instruments that are currently being watched by opening
the system quote page named ".Watched"
Investor/RT myTrack users have full access to Dial/Data for end-of-day
updating of closing prices. Use the Data Download window, setting the
server to Dial/Data, after market hours to request "current
quotes" on the entire ".Stocks" quote page, for example.
Those track more than say 3000 stocks should consider using the Dial/Data
"Bulk Download". Read more about this in the Help topic titled
"Dial/Data".
These same concepts apply to all internet based feeds supported by
Investor/RT. Limits vary by data service and account type. Check with data
vendors regarding symbol limit levels. Our web page www.linnsoft.com/datafeed
has additional information. Quote.com is an
exception, there are no symbol limits per se, however, my understanding is
that quote.com somehow manages (limits) bandwidth for each client
connection at the server level. I do not know the details, but the idea is
that a client tracking a few hundred symbols gets more frequent price
updates than a client who is watching thousands. Server demand and trading
levels in the markets on any given day is a factor also.
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