Estoy usando la versión de AppInventor online, no aparece en BluetoothClient, when BluetoothClient1.DataReceived do

BluetoothClient

There is no event for that.

You have to pull in a clock component from the sensor drawer in the Designer, and poll with a clock timer.

Here is a simple BlueTooth text receiver sample, for single value per line:
blocks
initialize global message to


Make sure to set toolkit to default in the project properties to get all blocks

Taifun