How to plot a machine cycle?

Fluxlang
,
1

Hi Everyone,

We have a requirement wherein we are recording Pressure in our machine to a particular measurement. The Machine starts it Cycle when pressure is > 80 and cycle ends when Pressure < 1. We are using Grafana Timeseries Panel to plot the cycle Graph. I was wondering how can we achieve this? So far I have below query:

from(bucket: "MyBucket")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => r["_measurement"] == "MyTag")
  |> aggregateWindow(every: v.windowPeriod, fn: (column, tables=<-) => tables 
    |> quantile(q: 0.99, column:column), createEmpty: false)
  |> map(fn: (r) => ({ r with _value: (if r["_value"] > 80 then 1 else 0) }))

Problem with above query is that it ends the cycle as soon as pressure < 80 but I need to end the cycle only when it is < 1 and next cycle should start when again pressure > 80.

I think I am missing something trivial here.

Could someone please point me in the right direction here ?

2

Hi. I am trying to envision this in Grafana, and what I would expect is a time series graph going up and down, sort of like this:

image
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Is your goal to have Grafana display ONLY those sections where pressure reaches 80 and then falls below 1? In other words, just the sections like this?

image
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I do not think Grafana (or Influx) can (via a query) filter out only the time slices you wish to view. You can set alerts or colored thresholds to indicate when you exceed 80 and when it falls below 1.

Maybe I am misunderstanding your goal?

3

@grant1 Thanks for responding!!
Not exactly what I am looking for. Let me explain it in different manner.
Consider we have a boolean flag which indicates if machine is ON or OFF. We need to turn it ON when pressure > 80 and OFF when < 1. The current implementation has a problem because when pressure falls below 80 it considers it OFF. So below steps should happen:

  • pressure > 80 → ON
  • Once ON if pressure < 80 but > 1 than still ON
  • pressure < 1 than OFF
  • Once OFF we turn it ON only when pressure > 80

Hope that helps in understanding the issue that I am facing

4

Hi @grant1

I have written another query:

onFlag = false
alertLevel = (v) => {
  level = if float(v:v) >= 80.0 then 1
          else if float(v:v) < 80.0 and float(v:v) > 1 and onFlag == true then 1
          else if float(v:v) < 80.0 and float(v:v) > 1 and onFlag == false then 0
          else 0
  
  onFlag = if level == 1 then true else false

  return level
}

from(bucket: "MyBucket")
  |> range(start: v.timeRangeStart, stop: v.timeRangeStop)
  |> filter(fn: (r) => r["_measurement"] == "MyTag")
  |> aggregateWindow(every: v.windowPeriod, fn: (column, tables=<-) => tables 
    |> quantile(q: 0.99, column:column), createEmpty: false)
  |> map(fn: (r) => ({ r with _valueOld: r["_value"] }))
  |> map(fn: (r) => ({ r with _value: alertLevel(v: r["_value"]) }))
  |> map(fn: (r) => ({ r with _valueFlag: onFlag }))

As you can notice I am trying to manipulate onFlag variable in alertLevel function but somehow it is not working. Can you suggest what is wrong with it?

5

Hi again. Your explanation is now very clear, but unfortunately I do not know of a way to do this using Flux. Maybe someone in this community can offer some advice.