The specification can be found in https://rainsensors.com/wp-content/uploads/sites/3/2021/03/2020.08.25-rg-9_instructions.pdf. It states the following: All lines are terminated with a carriage return followed by a new line, this is used for all output. But only the new line is required for commands....

I created my own outside sensorbox containing a TSL2591 light sensor and a Hydreon RG-9 RAIN SENSOR. Both are attached to a NodeMCU running ESPEasy. The TSL2591 runs with the TSL2591 plugin. The rain sensor is attached to the RX and TX pins. Until now the rain sensor communication was via the serial...