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Offline Ashish Atre  
#1 Posted : Tuesday, May 28, 2019 1:13:09 AM(UTC)
Ashish Atre

Rank: Newbie

Joined: 10/3/2015(UTC)
Posts: 2

Thanks: 1 times
Hello!

We are using Matrikon ODH for our Reporting project to collect data from Siemens PCS7 system. We have around 500 Tags being logged at 1 Second.

The problem that we are facing is that ODH is missing records while storing the data. This creates errors on Runtime and Counter tags which are reported in our reporting software. The reporting tool (Sytech XLR) connects to ODH over OPC HDA.

For e.g. If we have to log a value "1" for 3600 seconds (1 hour ) the total no. of records stored by ODH should be 3600. However, we find that it sometimes stores only 3490 / 3495 records (< 3600).. Not 3600. This results in calculation errors in our report.

We are using the following settings:
Update Rate : 1000 ms
Tag Lifetime Enabled : Yes
Lifetime Update Rate : 1000ms

Kindly advise on how we can achieve accurate logging in ODH.

Thank you.

Ashish
Offline Roger Fortune  
#2 Posted : Tuesday, May 28, 2019 2:24:12 AM(UTC)
Roger Fortune

Rank: Advanced Member

Joined: 10/21/2014(UTC)
Posts: 102

Was thanked: 12 time(s) in 12 post(s)
Hi Ashish,

I would suggest that you engage Matrikon OPC Support by emailing support@matrikonopc.com as this need more attention than a simple blog reply!

You need to determine where the data is getting lost. For example, is the PCS7 OPC Server changing the values faster than ODH is set to archive them? You have set ODH to be notified by PCS7 if the tag's value or quality changes, but no faster than every 1000mS. You have also enabled lifetime which causes ODH to do a forced read of PCS7 OPC Server every 1000mS. It could be that the two are crossing over / overloading the OPC Server. I would try without the lifetime enabled as this will be forcing 500 reads every second which has the potential to disrupt subscriptions. Try turning lifetime off for all tags for now and see what effect this has. You may find that you need to increase the update rate in ODH to 500mS to ensure all changes in value are captured.



thanks 1 user thanked Roger Fortune for this useful post.
Offline Ashish Atre  
#3 Posted : Thursday, June 6, 2019 3:09:07 AM(UTC)
Ashish Atre

Rank: Newbie

Joined: 10/3/2015(UTC)
Posts: 2

Thanks: 1 times
Hello Roger,

I tried doing what you suggested. Hoewever, my problem seems to be that the value in the tag for Runtime remains "1" as a constant. ODH logs only values which change when the lifetime option is disabled. So I am not able to totalise the value correctly using the archived values. to explain, 1 value of 1 logged for 1 hour at 1 sec should return 3600 samples containing 1. This will result in a totalized value of 3600. I am not able to achieve this value.

Even with the lifetime option on, and with the 500ms update rate, and SYNC reads (as suggested by India support) the problem persists. I never get 3600 values/samples.

I tried reducing (increasing) the lifetime interval to 10sec.. Still i got incorrect results.. Some hours, the samples returned were 356 or 357 or 359. This is very inconsistent.

Is there any other ID for support. The local support team has not been able to provide any solution to this issue.

Kindly advise.

Thank you.
Offline Roger Fortune  
#4 Posted : Tuesday, June 11, 2019 3:36:45 PM(UTC)
Roger Fortune

Rank: Advanced Member

Joined: 10/21/2014(UTC)
Posts: 102

Was thanked: 12 time(s) in 12 post(s)
Hi Ashish,
How many tags are you archiving in ODH? Excessive tag load could cause data to be missed possibly. As the value is not changing, perhaps try setting the update rate to 10 and the lifetime update rate to 999mS. This should force a read every second and ignore any subscription based updates that occur faster than every 10 seconds. Another option you could explore is the lifetime read interface. By default this setting is hidden and is set to ASYNC, as it is the safest option. You could look to change this to SYNC to see if that makes a difference. Please search the MatrikonOPC Desktop Historian User Manual for "Lifetime read interface" for more details. I would also suggest checking the version of ODH you are using. Current version as at June 2019 is 5.1.0. If your version is earlier, I would suggest upgrading to the latest.
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