Hi there,
We have a Securitas Direct's home alarm system in our house.

It's brand name is Verisure and is available in several countries in Europe (UK, Belgium, France, The Netherlands, Denmark, Finland, Norway). Since long I have interfaced this system with Node-RED via "My Pages". What I have done so far is just to monitor the system arm state. It can have three different states; armed_home, armed_away and unarmed. I am using those states to control lights, other stuff and scenarios in our house automation. The house automation in itself is completely managed by Node-RED.
Yesterday was a breakthrough! Finally I succeeded also to send commands to the system. Since the Verisure system supports so called Smart Plugs for controlling the power on/off for connected devices, I have been looking for a way to command these from "outside". And yesterday I found out how.
The benefit with those Smart Plugs are that they have 2-way communication. Like z-wave, zig-bee, BLE and others. This provides a more reliable communication than what you get with normal RF devices and you will know the actual state of the device. Besides they are cheaper than z-wave, at least here in Sweden. I just ordered a set of 3 since they have a campaign right now (3 for approx 83 €).

Principle for the solution is as follows: I have a python script running in a RPi that checks the arm state at a configurable interval (in my case every ten second). The script is started at reboot. It publishes the arm state to a MQTT broker so the current state can be used in the automation system. The python script is running threads and one is listening to incoming events (since yesterday also commands to turn Smart Plugs on/off). Besides this, the script is self-monitoring and logs on again if necessary.

If there is any interest, I can publish my solution and a guide?