I started working on the sensors.I am able to read the data on the serial . that reading I am not able to make a the graph? for these I wrote some configuration on the site map as below

Chart item=Temperature period=h refresh=6000 service=“rrd4j”.

It shown the graph but nothing came on it.

Please help me?

Do you have persistence set up on those Items? Since you are using rrd4j, do you save the value every minute?

yes, I am able to see that values, I am print it also

How is the item Temperature defined, it should be a number type strings can’t be persisted by rrd4j!
You are printing the values? Are you printing the actual ones or really the persisted ones?

i am hard coated some of the values. randomly i am printing that values.

you have any example to see the gragh or chat please share me.

The definition of the graph looks OK to me, hence my questions. Please show your item definition. And also the definition of your persistence.


I am taking string as data from serial and converting to float sending to Temperature item.
Here are my declarations item,persistance,rule, sitemap.

item :-

String MySerialDevice “Temperature [%s]” { serial="/dev/ttyUSB1@115200" }
Number Temperature “Temperature [%.1f °C]”

persistance :-

Strategies {
everyMinute:"0 * * * * ?"
everyHour : "0 0 * * * ?"
everyDay : "0 0 0 * * ?"
default = everyChange

Items {

   Temparature : strategy = everyUpdate, everyMinute


rule :-
import org.openhab.core.library.types.*
import java.util.List

rule “Data"
Item MySerialDevice received update
var List items = MySerialDevice.state.toString().trim().split(” ")
var Number value
value = Float.parseFloat(items.get(0))


sitemap default label=“Phytec” {
Frame label=“Demo” {
Text item=Temperature label=“Temperature [%.1f °C]” icon=“temperature”
Frame label=“Graph” {
Chart item=Temperature period=h refresh=600 service=“rrd4j”


Looks OK to me as well.
Did you have a look into the values persisted using the REST API? That way you could ensure that values are persisted, limiting the area where the problem is.

Sorry for the typos, it is a bit early in here.

this is my screen shot.

The Screenshot shows what you have told before.
Are you familiar with the REST API?

I am not familiar with RESET API.can you just help me.

If you haven’t done already, then install REST DOCS via PaperUI.

After installing start the REST API via:

Then go to the “persistence” page , on this page hit the GET BUTTON next to “persistence/items/{itemname}”

In here put in “rrd4j” as the SERVICEID and the itemname and hit try it out.
You should get displayed a JSON like output with several values.

These are the screen shots .

That’s what I was thinking, your persistence isn’t setup correctly.
Did you install rrd4j persistence at all?

Yes, I have installed rrd4j.

Is anything else I want to do .

In this case I’d check the logs for a hint.You might need the set the logging level for rrd4j to DEBUG.
On the karaf console use this command to set the debug level

log:set DEBUG org.openhab.persistence.rrd4j

And use “log:tail” to show a actual log entries as they are written.

yesterday working fine, I sea the graph but today I got one error as below

2017-10-12 16:50:08.708 [WARN ] [thome.ui.internal.chart.ChartServlet] - Illegal argument in chart: Persistence service not found ‘rrd4j’.

please help me.