Tutorial 3. Fridge Monitor#

The System Monitor is a Juice service and dashboard pair for watching your setup’s infrastructure — especially cryogenic equipment — so instruments stay within safe operating conditions. A backend publishes readings (temperatures, pressures, currents, …) from your hardware, and the dashboard turns them into live graphs and controls.

This guide walks you through standing up a System Monitor end to end, from an empty installation to a live dashboard.

We use the built-in mock backend throughout so you can follow along without a fridge attached — everything from configuring the service to setting up the dashboard works the same way once you point it at a real backend instead.

This tutorial exercises the System Monitor service and the cryogenic hardware it talks to — see them highlighted in the architecture overview.

Required privileges

The steps in this guide are performed in the host system terminal by an administrator with sudo privileges, since they edit files under /etc/juice/config.

Starting the System Monitor service#

Add the following to your orchestration.toml configuration, which registers a new service and points it at the mock backend’s entrypoint module:

[services.system-monitor]
entrypoint = "orangeqs.juice.system_monitor._service:SystemMonitorService"

[services.system-monitor.init_kwargs]
init_module = "orangeqs.juice.system_monitor._mock_entrypoint"

[influxdb2.buckets.system_monitor]
name = "system_monitor"

Apply the change and rebuild the service’s environment:

sudo juice install --restart --rebuild

Once this completes, check that the Juice interface shows a running system-monitor service.

The mock backend simulates a small fridge: five thermometers (from 50 K down to the mixing chamber), five heaters, two pulse-tube compressors and a gas handling system, all reporting on a timer. You can tune the simulated readings — or the reporting interval — through mock-system-monitor.toml; the defaults are enough to continue this guide.

Configuring the dashboard#

The dashboard does not automatically know which components to display or what to call them — that mapping is defined in system-monitor-dashboard.toml. Its defaults already match the mock backend’s component IDs, so writing an empty file is enough to get started; the snippet below spells the defaults out explicitly instead, since it doubles as a reference for what each option controls:

mode = "power_user"

[heaters]
heater_50K = "50K Heater"
heater_3K = "3K Heater"
heater_still = "Still Heater"
heater_mc = "Mixing Chamber Heater"
heater_sorb = "Sorb Heater"

thermometry_component_id = "thermometry_unit_1"

[thermometers]
thermometer_1 = "50K"
thermometer_2 = "3K"
thermometer_3 = "Still"
thermometer_4 = "50mK"
thermometer_5 = "Mixing Chamber"

[compressors]
pt_1 = "Compressor Unit 1"
pt_2 = "Compressor Unit 2"

Save this as system-monitor-dashboard.toml in your system configuration location (by default /etc/juice/config), then click the restart button on your dashboard to apply it.

Watching it live#

Open the Fridge Monitor page on the Juice dashboard. The mock thermometers’ temperatures, the compressors’ pressures and currents, and the heaters’ power draw update every few seconds — the same reporting loop that would drive the display for real hardware.

The Fridge Monitor dashboard page showing live mock fridge temperature readings

Next steps#

You now have a full System Monitor running end to end, backed by a mock fridge — the service publishes data, and the dashboard visualizes it.

From here: