Daylight Savings Time (DST) not working correctly  [SOLVED]

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sohryh
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Daylight Savings Time (DST) not working correctly

Postby sohryh » 30 Oct 2015

Hi

I am currently running MultiCharts in Seoul, Korea, where time zone is GMT+9, and we do NOT have Daylight Savings here.
I am using a Crude Oil chart (CL from NYMEX) and an Australian Dollar chart (AD from CME).
Time zones for NYMEX and CME are GMT-5 and GMT-6, respectively.
In the period when Daylight Saving Time is not in effect, the time differences between NYMEX/CME and Seoul are 14/15 hours, respectively. Let’s name this period as Normal period.
In the period when Daylight Saving Time is in effect, the time differences between NYMEX/CME and Seoul are 13/14 hours, respectively, because Seoul is not applying DST rules. Let’s name this period as DST period.
In Normal period, things are ok. But the problems arise when DST period begins.

Please read through both Issue 1 and Issue 2 from the attached file.
Daylight_Savings_Time_Issues.zip
(445.98 KiB) Downloaded 108 times
It has very detailed explanations along with screen captures.

thx for reading

SJ

sohryh
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Re: Daylight Savings Time (DST) not working correctly

Postby sohryh » 10 Nov 2015

Please someone from MultiCharts answer this issue.
TS does NOT have this issue at all.

SJ

eto
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Re: Daylight Savings Time (DST) not working correctly

Postby eto » 13 Nov 2015

maybe u try and check here

viewtopic.php?f=1&t=8437

sohryh
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Re: Daylight Savings Time (DST) not working correctly

Postby sohryh » 16 Nov 2015

Not sure how that solves the DST-related issues I posted.

SJ

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Henry MultiСharts
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Re: Daylight Savings Time (DST) not working correctly

Postby Henry MultiСharts » 17 Nov 2015

Hello sohryh,

When you change the Time Zone from Exchange to Local the exchange time values are converted into the local time values based on the current time zone parameters.
Due to the fact that DST is not applied in your country the session settings conversion to local time are correct at the moment of conversion. Sessions cannot be dynamically adjusted based on the DST. Therefore in your case you need to use the Exchange time zone for sessions configuration to avoid missing data.

sohryh
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Re: Daylight Savings Time (DST) not working correctly

Postby sohryh » 17 Nov 2015

Hello sohryh,

When you change the Time Zone from Exchange to Local the exchange time values are converted into the local time values based on the current time zone parameters.
Due to the fact that DST is not applied in your country the session settings conversion to local time are correct at the moment of conversion. Sessions cannot be dynamically adjusted based on the DST. Therefore in your case you need to use the Exchange time zone for sessions configuration to avoid missing data.
Well, I still need to see the charts plotted using the Local time zone settings because some other local instruments need being plotted too in the same chart. Isn't that the main purpose of the Local Time Zone? Oherwise what's the use of it?

Furthermore, have you read the second issue from the attached file? It differs from the first issue in that MC plots (AD, CME) chart correctly based on dynamically adjusted sessions even though QM wrongly displays the Session Open/Close Times.

After all, there's gotta be a better solution.
For example, one solution is to add a check box for 'Don't apply DST rule' under the session Details from QM's Edit Symbol dialog for QM/MC to calculate the session Open/Close Times correctly in non-DST applying areas.

thx
sohryh

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rrams
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Re: Daylight Savings Time (DST) not working correctly

Postby rrams » 17 Nov 2015

Here in Arizona we do not observe Daylight Saving Time either. I gave up trying to explain the issue a couple years ago and ended up writing work around routines to keep track of session times. It's difficult to reproduce and test fixes because you have to wait eight months for the exchange to switch to DST.

Please forgive me if I don't recall the exact set of conditions. I know that using Symbol Dictionary Sessions will show the correct open and close times in all cases except the day DST goes into effect.

So, if you are displaying your chart instrument in local time, you could code an indicator to help you determine when to shut down and re-open the workspace for MC to re-calculate the correct time like so:

Code: Select all

// Re-adjust for US DST: Begins at 2:00am on 2nd Sunday of March. Ends at 2:00am on the 1st Sunday of November.
if (Month(CurrentDate)=3 and DayOfMonth(CurrentDate)=(14-Mod(Floor(1+YearFromDateTime(ComputerDateTime)*5/4), 7)))
or (Month(CurrentDate)=11 and DayOfMonth(CurrentDate)=(7-Mod(Floor(1+5*YearFromDateTime(ComputerDateTime)/4), 7)))
and CurrentTime<300 then GotOffset=False;
The real problem occurs if you use Custom Sessions and Local Time and your location does not observe DST and DST is in effect. Then either products originating from New York like QM will be off by one hour; or products originating from Chicago like ZS will be off by one hour. I don't remember if it depends on the time zone of the data server or on which chart you load first. But one will not show correctly.

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Re: Daylight Savings Time (DST) not working correctly  [SOLVED]

Postby Henry MultiСharts » 18 Nov 2015

Sohryh, Rrams, you need to have the instrument sessions configured in the Exchange Time Zone in the QuoteManager. On the chart you can select the Local time zone to display the bars with local timestamp. That should not cause you any issues. Sessions are just a filter. The data in the database is stored in GMT timezone.

sohryh
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Re: Daylight Savings Time (DST) not working correctly

Postby sohryh » 18 Nov 2015

Thank you, Henry.

Now, I see why Issue 1 and 2 behaved differently. CL was saved with 'Local', while AD was saved with 'Exchange'.
It's quite confusing, surprising and unexpected that selection of Session time zone affects chart plotting in terms of not simpy timestamp display but also actual chart plotting (missing an hour during DST period).
The safest way is to always save with 'Exchange' before pressing OK.


After all, this confusion better be dealt more intuitively.

For users' perspective, the displayed session Open/Close times should show real/effective values regardless of DST period or Normal period even if Local is selected from QM.

Otherwise, all users from the area where DST is not observed will go through this confusion over and over again wasting huge amount of time to figure out why and eventually will come to Helpdesk or Discussion Forum.

Best
sohryh


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