logging vlaues of a property

[Sruthi]

I have a property whose values are coming from kepserver(datas are simulated with sine function). I want to log those data for every one second. How to do this?

I have checked in the logged check box in properties, and in advanced settings, i have given Always as a data change type. Bu,t when i execute the "query named property history" service for last one minute it is taking 5 minutes delay to give the result and it is showing the values logged in milliseconds instead of seconds. 

[raluca_edu]

Hi,

But how often the data are coming from Kepserver?

Regards,

Raluca Edu

[PaiChung · Accepted solution]

In your situation the best way to get a recording very second is to set that on the Kepware side.

The channel should feature a 'scan rate' which you can set to I think 1000 (milliseconds)

If you are transmitting every millisecond right now, then you are probably overloading the platform which might be causing the slow response.

[Sruthi]

yes, the  scan rate of the tag was in 100. I changed it to 1000. Thanks for the reply

[Sruthi]

I deleted all the data's stored in the value stream using purge service. Now i need to check whether all the data's got purged or not. So i executed "query property history service". but service execution takes a long time. am i doing it in the right way? or what is the solution to check my value stream is data free?

[PaiChung]

The best way is to be in the back end.

But else running that query should work, or if you specifically purged for a property you can query for that property specifically.

Someone else actually posted some info on this: https://community.ptc.com/t5/IoT-Tech-Tips/Purging-ValueStream-entries-from-Deleted-Things/td-p/646440

[Sruthi]

ok will try like this

[Sruthi]

I have a property called power for which the data is coming from kepserver for every second. now my requirement is, for every one min i need to check the aggregated value of the power against threshold. what is the best way to do this?

[PaiChung]

What is the actual aggregation that you are doing?

Are you doing a historical calculation 'total power consumed' or a comparison 'power consumption before vs. now' or just a direct comparison 'current power consumption > xyz'

What is the exact definition of the aggregation and what you are trying to check?

FYI: In the future it is better to start a new topic with a question  like this because it isn't necessarily related to your initial question.

[Sruthi]

Aggregation in the sense sum.

I need to check,

historical calculation 'total power consumed'  > threshold value ?

[PaiChung]

I would probably use a subscription to a datachange which then per value change increases a sum property.

if you need to do more in depth analysis over time, then you may want to look into maintaining aggregates by hour or day etc to more quickly handle large amounts of data vs. just applying a date time filter and pulling all records over a period.