Data Logger Setting doubts

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zintonio
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Joined: 14 Oct 2021, 13:53

Data Logger Setting doubts

Post by zintonio »

In datalogger setting, I need to understand what are the follwing parameters:
Publish Interval: what is ? millisecond, apples, bananas, litres?
Keep Alive Count: What is? Count of what? cars, stars, sheep?
Lifetime Count: What is?

Sampling Interval: What is? millisecond, apples, bananas, litres?
Queue Size? size of What? meter, Kilograms?

Thanks in advance for your help

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Support Team
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Joined: 18 Mar 2011, 15:09

Re: Data Logger Setting doubts

Post by Support Team »

Hi,

as always in OPC UA all duartion values are "milliseconds".
And all count/size values are "per piece" numbers.

The DataLogger view is for demonstrating the monitored item and subscription parameters/settings in OPC UA. Whereas sampling is the scan rate on the source, and publish is the rate transfered to the client, and queue is filled when sampling is faster that publish (to not loose data). The keep alive is the number of publish-durations before an empty publish is sent (in case no velue has changes = keep alive) .

The Datalogger creates a subscription on the server and ask for e.g. the list of MonitoredItems to be sampled (checked for change) with "250ms" interval, and queued into a queue of "10" pieces of DataValues, whereas such queues (when containing values) will be published to the Client/DataLogger every "500ms", and if no changes in value (no content in queue) have occured, at least send a keep-alive after "10" counts of publish intervals (10x500ms meaning 5 seconds), which is an "empty" publish to evidence that the connection is still working.

I agree that some tooltip explanation would be helpful here.
Best regards
Unified Automation Support Team

User avatar
Support Team
Hero Member
Hero Member
Posts: 3064
Joined: 18 Mar 2011, 15:09

Re: Data Logger Setting doubts

Post by Support Team »

Hi,

as always in OPC UA all duartion values are "milliseconds".
And all count/size values are "per piece" numbers.

The DataLogger view is for demonstrating the monitored item and subscription parameters/settings in OPC UA. Whereas sampling is the scan rate on the source, and publish is the rate transfered to the client, and queue is filled when sampling is faster that publish (to not loose data). The keep alive is the number of publish-durations before an empty publish is sent (in case no velue has changes = keep alive) .

The Datalogger creates a subscription on the server and ask for e.g. the list of MonitoredItems to be sampled (checked for change) with "250ms" interval, and queued into a queue of "10" pieces of DataValues, whereas such queues (when containing values) will be published to the Client/DataLogger every "500ms", and if no changes in value (no content in queue) have occured, at least send a keep-alive after "10" counts of publish intervals (10x500ms meaning 5 seconds), which is an "empty" publish to evidence that the connection is still working.

I agree that some tooltip explanation would be helpful here.
Best regards
Unified Automation Support Team

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