Make S4A wait until it receives a custom sysex message from Arduino

Hi. I'm using Snap4Arduino to control a drawing robot.

The robot is based on an Arduino Uno, Adafruit motor shield v1 with two 28BYJ-48 steppers.

I'd like the Arduino to report back when the steppers have reached their end positions. I did manage to create some node.js/Firmata.js code that verifies that it does, using a callback function. However, I'm struggling to understand how I can do this from within the javascript code in my Snap! blocks.

Is there any documentation or specific example on how to catch these sysex messages from within Snap4Arduino?



For more info on the project, please have a look at the project Github page: