How to set an output in the template block to send data to MQTT (out)


my goal is to get an request from mqtt to extend the cylinder (created in SVG), in the template block, when the cylinder is extended, it must send a data to MQTT. But I actually don't know how to set an output there.
I tried with $scope.msg.action, $scope.msg.payload, but still, the function block after the template block can't recognize the data I filled in the template.

How template looks like:

What do I need to write here to write stuffs from template into mqtt block?

Thank you!


Bit incomplete but if you are trying to send a msg with $scope.msg.<WhatShouldIdo?> try $scope.send({payload: "HALLO"})