Sending data from log file to influx with tail plugin

I’m trying to use the tail-plugin in telegraf to read data from a log file and push it into influxdb.
The logfile only contains temperature values that are created by an arduino, and would look like this:
and so on. New measurements are constantly beeing added.

I’m trying this configuration in telegraf.config:


files = [“C:\Program Files\Telegraf\arduino.log”]
from_beginning = false

grok_patterns = ["%{CUSTOM_LOG}"]
grok_custom_patterns = ‘’’
data_format = “grok”

but I’m getting an error : panic: runtime error: index out of range [1] with length 1

Does anyone know how to solve this? Maybe I dont even have to use grok patterns since per line theres the one information that i need?
Forgive me if this is utterly stupid but I’m a complete beginner with this