Core Concepts

Understanding the fundamental concepts behind SimFusion's visual programming model.

The Block Paradigm

SimFusion uses a dataflow programming model where computation is represented as a directed graph of connected blocks.

Types of Blocks

Source Blocks

Generate or import data into the system:

• Signal generators (sine, square, noise)
• File readers (CSV, JSON, Excel)
• Live data streams (MQTT, IoT feeds)
• Database connectors

Processing Blocks

Transform and analyze data:

• Mathematical operations (add, multiply, FFT)
• Filters (low-pass, high-pass, Butterworth)
• Statistical analysis (mean, variance, correlation)
• Machine learning inference

Sink Blocks

Output or visualize results:

• Real-time plots and charts
• File writers
• Live data streams
• Cloud exporters

Signals and Data

NDArray-First Design

SimFusion is built around N-dimensional arrays (tensors) as the primary data type:

# Example: 3-channel audio signal
shape: (3, 1024)  # (channels, samples)
dtype: float64

Data Types

Data Flow

Execution Model

1. Discrete-time: Models advance sample by sample on a simulation clock
2. Push-based: Data flows from sources to sinks
3. Vectorized: Operations apply to entire arrays

Sample Rate and Timing

• Each signal carries a sample rate metadata
• Blocks can upsample, downsample, or resample
• Real-time execution maintains timing constraints

Projects and Workspaces

Project Structure

MyProject/
├── model.sdl           # Main model file
├── blocks/
│   ├── custom_block.py
│   └── helpers.cpp
├── data/
│   └── input.csv
└── config.yaml

Project History

• Track changes to models and custom blocks
• Restore earlier snapshots of your project

Execution Modes

Simulation Mode

• Run discrete-time simulations on virtual time
• Fast-forward, pause, rewind
• Ideal for development and testing

Debugging a Simulation

• Set breakpoints at a time (in seconds) or at an exact sample
• Inspect any block's buffers at the paused point
• Every block is well documented — check its docs right from the project workspace

Further Reading

• Block System — Detailed block documentation
• API Reference — Programmatic access