Thank you for your answers. Unfortunately none of them were helpful. Therefore I will try to describe my whole project. On the website http://esp8266-server.de/Notruftaster.html I have found a WLAN button for the ESP8266, which seems to fit my needs. At the configuration setting I can enter the HTML command I need to trigger a ButtonDevice with the WLAN button.
http://user:pass@192.168.xxx.xxx/api/device/dash-button/buttonPressed?buttonId=dashbutton
The original sketch for the ESP8266 then adds additional parameters (e.g. WachNr, UBatt etc.) to the HTML command. But this does not work with the ButtonDevice of pimatic.
Therefore I omitted these parameters in the URL of the sketch. But now I want to get the value of UBatt displayed in pimatic. Therefore I created a corresponding variable. How can I copy the value of UBatt - which is detected by the sketch - into the variable to display it in pimatic?
As already described, I can use cURL
curl --silent -X PATCH --header "Content-Type:application/json" --user "user:pass" --data '{"type": "value", "valueOrExpression": 3.11, "unit": " Volt"}' http://192.168.69.15/api/variables/batt-06
changes the value manually. But now I want to do that from the sketch (automated).
But NOT as described in the link about a PHP server. Is there a possibility?