Absolute Values in Graphs

How do I have to set up Grafana to get absolute values of my mixed positive and negative data set from InfluxDB?

Grafana visualizes what is returned by the query. So correct question will be how to return absolute values from my query? Use ABS function in your query https://docs.influxdata.com/influxdb/v1.8/query_language/functions/#abs

Exactly. But is the query not done in grafana? My example shows
“SELECT last(“value”) FROM …”
What I need is “SELECT ABS(“value”) FROM…”
I can’t find the selector “ABS” or something similar.

Don’t use UI query editor mode. Toogle it to the text edit mode and write whole query manually. You will be able to write whatever you want.