reading I2C ADC converters can be done using Rexlang function block. I recommend you to have a look at example group called "0502 Generic I2C Communication" - you can modify 0502-02 example in order to communicate with ADS1115.

As for PWM output - have a look at PWM function block. Idea about it's usage can be found in 0303-10 example.

Hope it helps.

Regards, Tomas