Device status request count & Throughput

Hi there, If the request count per sec is more than the throughput (1 min), does that mean that the tag update will be slower?

Yes, normally. But your displayed load factor suggests there’s some other optimization impacting your case.

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The throughput suggests your tags subscribed @ 2000ms are updating just a little slower than that.

Load Factor is a strange calculation that I’d like to replace eventually. It’s calculated like this, using the 50th percentile from the histogram:

var loadFactor = Math.round(histogram['p50'] * requestCount / concurrentRequests / rate * 100);

Basically… it’s a crude measurement of the remaining “capacity” of the connection based on the 50th percentile request/response latency. I’m not convinced it’s very useful or accurate any more, and it seems to fall apart when concurrentRequests > 1 and/or there are multiple rate groups.

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It also doesn’t account for writes or out-of-band traffic (system.opc.*).


One more question @pturmel or @Kevin.Herron,
I tried to look at the manual for the meaning of “Tag Count” but couldn’t find it…
Tag Count means the total no. of tags for the Request Count?


Basically, yes. Subscribed items, typically Ignition’s OPC tags. Can also be elements in a SQL Bridge transaction group.

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