Smartmeter: Help with custom binary in Node-Red addon

Hello, all!

I’m new to home assistant, and is blown away by everything it can do:) Thanks to everyone who contribute!
My previous system was Homeseer, and I moved because I wanted more flexibility.
I have a Rpi 3b+ with rasbian headless, where I installed docker and then hass.io.

I want to read data from my smart meter with the node red addon, and then send it to Homeassistant with mqtt. It’s a binary that runs file outside of the docker container that node-red run’s. The challange is: how can I run the same binary from within node-red docker?

I’ve tried to docker cp it to the container.
The log reads:4 Sep 07:57:25 - [info] [exec:AMS] error:Error: Command failed: /opt/ams-han/test_rx -n -d /dev/modbus
/bin/sh: /opt/ams-han/test_rx: not found

Can any of you point me in the right direction?