Minimum config for a chart? (rrd4j)

I have a bunch of numbers, which are pulled via shell script on a RPi2.
The numbers are defined as items, and showing properly on a sitemap.

I want to chart these numbers, have defined the persistence, by simply adding the item to the existing weather* Weather_Chart*, INET_* : strategy = everyMinute, restoreOnStartup … however, the chart is empty.

Sitemap:

Text label="Internet Speed"    icon="gauge" {
  Text item=INET_PING    icon="ping"
  Switch item=INET_Chart label="Chart Period" mappings=[0="Hour", 1="Day", 2="Week"]
  Chart item=INET_PING period=h refresh=300  visibility=[INET_Chart==0]
  Chart item=INET_PING period=D refresh=1800 visibility=[INET_Chart==1, INET_Chart=="Uninitialized"]
  Chart item=INET_PING period=W refresh=3600 visibility=[INET_Chart==2]
}

Items:

Number   INET_PING        "Ping [%.1f ms]"
Number   INET_Chart

Any ideas / hints why the graph does not show?
Could I also only add the chart item in the persist config for rrd4j, rather then INET_*?

(by the way: my weather persistence and graphing is working > ergo sum: I must have done something wrong.)

EDIT: Also checked with URL /chart?items=INET_PING&period=W --> which is empty. So it looks like persistence does not work??

Event log says:

2016-11-04 19:00:47 - INET_PING received command 46.322

Sitemap shows it:

Do you actually have a Group named “INET_”? Or are you assuming that “*” in this context works like a wild card, meaning persist all Items that start with “INET_”?

Unfortunately “*” is not a wild card in this context. It means to persist all members to the preceding Group.

So if you had a Group named gGroup, you would persist all of its members using “gGroup*”. So you should do something like:

Group gINET
Number INET_PING "Ping [%.1f ms]" (gINET)

and persist gINET* in the .persist file.

1 Like

Rich: my saviour!

Yes!

I must have misread the instructions https://github.com/openhab/openhab/wiki/Charts, which said something like:
"To use show multiple items in a chart, they must be in the same group"
Since I had one value recorded / persisted for one chart. I thought it did not apply.

To cut a long story short: I added the group, and the graph appeared in an instant!

Thank you!!