---
title: Example: Digital Twins
slug: sdk/example-usages/digital-twins
docTags: 
createdAt: 2025-03-20T19:53:00.703Z
---

End-to-end walkthrough: build a Pump digital twin model, attach static and dynamic attributes, create an instance, and query live values.

## Setup

```python
from litmussdk import digital_twins
from litmussdk.devicehub import devices, tags
```

Assumes the default connection is configured; see [Managing Connections](docId\:vwtFo9SXcMRbFX9cAfENw).

## 1. Create a Model

```python
model = digital_twins.create_model(
    name="Pump",
    description="Centrifugal pump - generic template",
)
model_id = model.id
print(f"Created model {model_id}")
```

## 2. Attach Static Attributes

Static attributes don't change at runtime - manufacturer info, location, etc.

```python
digital_twins.create_static_attributes(
    model_id=model_id,
    attributes=[
        {"key": "Manufacturer", "value": "ACME Pumps"},
        {"key": "MaxFlowRate", "value": "200 L/min"},
    ],
)
```

## 3. Attach Dynamic Attributes

Dynamic attributes pull live values from tags or topics. First find a relevant tag from your device:

```python
all_devices = devices.list_devices()
pump_device = next(d for d in all_devices if d.name == "PlantFloor-Pump-01")

device_tags = tags.list_registers_from_single_device(pump_device)
pressure_tag = next(t for t in device_tags if t.tag_name == "Pressure")
```

Then create a dynamic attribute that subscribes to that tag's topic:

```python
digital_twins.create_dynamic_attribute(
    model_id=model_id,
    name="Pressure",
    data_type="Number",
    unit="kPa",
    topic=pressure_tag.topics[0].topic,
)
```

## 4. Create an Instance

The model is a template; instances are concrete twins of real devices.

```python
instance = digital_twins.create_instance(
    model_id=model_id,
    name="PlantFloor-Pump-01",
)

# Set running so the instance starts subscribing to its dynamic attribute topics
digital_twins.set_instance_state(instance.id, state="RUNNING")
```

## 5. Query Live Values

```python
# All instances of this model
all_pumps = digital_twins.get_instance_by_model(model_id)
for inst in all_pumps:
    print(f"{inst.name} - state={inst.state}")
```

## 6. Add a Transformation (Optional)

```python
digital_twins.create_transformations(
    model_id=model_id,
    transformations=[{
        "name": "PressureCategory",
        "formula": 'IF(Pressure > 150, "HIGH", "OK")',
    }],
)
```

## 7. Tear Down

```python
digital_twins.delete_instance(instance.id)
digital_twins.delete_model(model_id)
```

## See Also

- [Digital Twins](docId\:rVI0-UxY2VVGeAzEtbnLu) - full reference
- [Managing Connections](docId\:vwtFo9SXcMRbFX9cAfENw) - LE vs LEM