CANsub.4: 4 x CAN Bus Interface (USB + Ethernet)

In short? Because it is the best value/cost CAN bus interface you can get.

The combination of below factors makes the CANsub unique vs. other CAN interfaces:

• Instant CAN access: The LCD display + webCAN + bit-rate auto-detection enables out-the-box CAN access in <30 seconds
• Pro specs: 4 x CAN FD, galvanic isolation, 20K+ frames/second, 1 µs timestamps, error frames, silent mode and even edge-based transmit sequences - the CANsub is on par with (or exceeding) best-in-class pro specs CAN interfaces
• 50% lower cost; 50% smaller: Despite the top-tier specs, the CANsub offers a radically lower cost & size vs comparable devices
• 100% free software: webCAN offers functionality matching 1000+ EUR CAN software tools - but it is free
• USB and Ethernet: In contrast to most CAN interfaces, the CANsub also enables streaming via Ethernet - which stacks uniquely with the webCAN GUI to allow any device (PC, tablet, phone) on the network to stream CAN data via LAN, WiFi or LTE
• LCD display: This offers rich real-time device/CAN insights (bit-rate, frames/second, busload) - far beyond classic LEDs
• Open API: The modern REST/WebSocket API is perfect for building 3rd party apps/integrations via Python, Qt - or even pure web

Getting started with the CANsub is a simple 4-step process:

1. Connect to CAN: Connect your CAN bus to the CANsub (optionally using the plug & play adapter cables)
2. Connect via USB: Plug the CANsub into your PC with our USB-C cable - it powers up and shows its URL on the LCD display
3. Open webCAN: Enter the URL in your browser - webCAN loads instantly with zero installation needed
4. Configure and stream: Set bit-rates (or auto-detect), optionally assign DBC files - and click connect to start streaming CAN data

You can of course also use the CANsub with other tools like Python, SavvyCAN and more.

In addition to USB, the CANsub has an RJ45 Ethernet port for network-based access. Connect the device to a router or switch (using a separate USB power source or a Power-over-Ethernet adapter for power) and it will display an Ethernet URL/IP on its LCD. Any PC, tablet or phone on the same network can then open webCAN in its browser to start streaming.

This opens up workflows that USB alone cannot support:

• Share a single CANsub across a team of engineers on the same LAN
• Connect wirelessly via a WiFi router - e.g. for hard-to-reach installations or vehicles/machines with a WiFi router installed
• Reach the device remotely over the internet via VPN - e.g. for field assets equipped with an LTE router

webCAN is the primary software tool for the CANsub - and it runs directly on the device itself. Unlike traditional CAN interfaces that require you to install proprietary software and drivers on your PC, webCAN requires zero installation. Simply connect the CANsub, find the URL on the display and enter it in your browser - webCAN opens immediately with a full-featured CAN interface including DBC decoding, real-time plots, transmit lists and more. The tool is 100% free - with no license fees or subscriptions.

Because webCAN is served by the device, it requires no internet access and is fully self-contained. It also means that any authorized user on the same network can access the device from their own browser - whether via USB, LAN or WiFi/LTE routers. This is especially powerful for team setups where multiple engineers need to access the same device without installing anything on their PCs.

Yes. webCAN runs 100% offline and entirely client-side in your browser, no internet access is required/relevant at any point. Specifically:

• The full webCAN app is served by the CANsub itself, not from any external website or CDN
• No external libraries, fonts or scripts are loaded at runtime
• No communication with CSS Electronics servers, cloud services or third-parties
• All decoding, plotting and export processing happens locally in your browser
• DBC files persist in browser storage (cookies / local storage), nothing leaves your device

This means webCAN works on air-gapped networks, in vehicles without LTE coverage, behind corporate firewalls and in regulated environments where outbound internet is blocked. The only network link required is the direct connection between your computer/tablet and the CANsub itself, over USB or Ethernet.

The webCAN code is embedded in the CANsub firmware and served by the device when you open its URL/IP in your browser. Since it is delivered as a standard web application over HTTPS, it runs on anything with a modern browser - Windows, macOS, Linux, iOS or Android - across laptops, tablets and phones. There are no drivers, no installers and no OS-specific builds to maintain.

webCAN is optimized for performance and can fully leverage the pro specs of the CANsub, including sustained busloads of 20,000+ frames/second. For such high throughput, the consuming device needs appropriate specs. As an example, webCAN has been validated at 20,000+ frames/second on a Lenovo ThinkPad with an AMD Ryzen AI 7 PRO 350 (2.00 GHz, x64) and 32 GB RAM running Windows.

webCAN also runs on lightweight platforms such as the Raspberry Pi 5. On performance-constrained devices, very high busloads are not practical in the GUI - but this is easily addressed by configuring hardware filters on the CANsub itself, so only the relevant CAN frames are streamed to the webCAN frontend.

The CANsub comes with a number of plug & play software/API tools that help you get started immediately. All tools for the CANsub are 100% free with no subscription fees:

• webCAN: Runs on the device. Configure, stream, DBC decode and visualize CAN data in your browser
• SavvyCAN: Open source GUI for streaming raw / DBC decoded data - ideal for reverse engineering
• Python API: Open source python-can API for scripted data streaming and automation
• JS/TS libraries: Build custom CANsub web apps

Generally, the CANsub is designed for interoperability and custom integrations, allowing you to easily integrate it with custom tools in addition to the above. In particular, the CANsub provides a REST-based configuration interface (OpenAPI) and websocket-based data streaming for easy integration with custom tools.

No. The CANsub's primary tool, webCAN, runs directly on the device and is accessed via your browser - no drivers, no software installation and no internet required. Simply connect the device, find the URL on the display and enter it in your browser.

For specialized use cases, you can optionally use SavvyCAN or the Python API (python-can) - but webCAN alone provides a complete CAN interface experience with zero installation.

The CANsub uses HTTPS with self-signed TLS certificates to encrypt all communication between the device and your browser. On first use, you install the CANsub root certificate in your browser or OS - this is a one-time step that enables seamless HTTPS access going forward.

If the certificate is not installed, your browser will show a security warning that you can accept to proceed. In rare cases, corporate IT policies may restrict access to websites using self-signed certificates or block installation of such certificates. If this applies to your organization, contact your IT department to whitelist the device URL or certificate.

The Ethernet interface provides the same access experience as USB - but over a network. Connect the CANsub to a router or switch via the RJ45 Ethernet port. The device obtains an IP via DHCP and displays it on the screen. Note that the device still requires power from a USB power supply or via a PoE adapter if the router supports Power-over-Ethernet.

Since the IP is assigned via DHCP, it may change over time. However, the device is also accessible via its hostname: https://deviceid-usb.local for USB access or https://deviceid-eth.local via Ethernet - providing a stable address you can bookmark.

LAN access: The most common use of Ethernet is simple LAN access. Any authorized user on the same local network can open the device URL in their browser to use webCAN - no installation required on any of their PCs. Users can of course also connect via other software/API tools.

WiFi access: If the CANsub is connected to a WiFi-capable router, users can access the device wirelessly from laptops or tablets on the same WiFi network. This is useful in offices/test labs - but especially for hard-to-reach installations, or mobile assets like trucks, tractors or construction equipment that have a WiFi router installed. The latter setup allows field technicians to connect to the device from outside the vehicle without physically plugging in.

Remote internet access via VPN: For remote access over the internet - e.g. to a CANsub installed on a mobile asset in the field via an LTE-capable router - a VPN is the recommended approach. The LTE router connects outbound to a VPN server, and remote users join the same VPN network to access the device securely. This approach works regardless of carrier NAT restrictions (which can prevent traditional port forwarding) and ensures only authenticated VPN members can reach the device. Modern VPN solutions make this straightforward to configure on most routers. As a simpler alternative, port forwarding can be used if the router has a public IP - but a VPN is recommended for production setups as it provides stronger access control.

The CANsub.4 uses a DB25 connector for the 4 x CAN channels. We recommend adding the DB25-4xDB9 adapter cable which splits the DB25 into 4 x standard DB9 connectors.

From there, you can use our standard DB9 adapter cables to connect to your specific CAN bus connector - e.g. the OBD2-DB9, J1939-DB9 or other adapters from the adapter cable range. The DB25 pinout matches the CANmod.router, so the same DB25-4xDB9 adapter cable can be used.

The CANsub operates at the lower CAN layer - it sends and receives raw CAN frames without assuming anything about the higher-layer protocol. This means it works with any CAN-based protocol, including J1939, CANopen, NMEA 2000, OBD2, UDS, CCP/XCP and more.

Protocol-specific decoding is handled via DBC files in webCAN (or via SavvyCAN/Python API). webCAN supports advanced DBC features including extended multiplexing (required for OBD2/UDS) and PGN decoding (required for J1939, ISOBUS, NMEA 2000).

The device supports both Classical CAN (5K to 1 Mbit/s) and CAN FD (1M, 2M, 4M, 5M) across all 4 channels.

Yes. webCAN runs in any Linux browser via USB or Ethernet - with zero installation, drivers or internet access required.

The Python API (python-can) and SavvyCAN also run on Linux, giving you multiple options for CAN data streaming and processing.

Yes. Since webCAN runs in your browser, it works on Mac just like on any other platform - simply enter the device URL and start streaming. The Python API (python-can) is also supported on Mac for scripted data streaming and automation.

The CANsub features a 160 x 80 px built-in LCD display on the backside. The display has two states:

• Boot state: Shows the device URL/IP that you enter in your browser to open webCAN - making it easy to connect to the device
• Connected state: Shows CAN channel status with bit-rates, errors, busloads and frames/second

The display replaces the basic LEDs used by traditional CAN interfaces - giving you rich device status information at a glance.

The CANsub.2 and CANsub.4 share the same core features and only differ in channel count and connector:

• CANsub.2: 2 x CAN channels via 2 x standard DB9 connectors
• CANsub.4: 4 x CAN channels via 1 x DB25 connector (use the optional DB25-4xDB9 adapter cable)

The CANsub and CANedge series serve two distinct use cases - and many users benefit from both in parallel:

• CANsub: Real-time streaming of CAN data via USB/Ethernet to a client device (e.g. laptop) running webCAN, SavvyCAN, Python or a custom app. Ideal for live diagnostics, test benches and sniffing.
• CANedge: Standalone CAN/LIN data loggers that record to an SD card for long-duration field deployments (days, weeks or months) with no PC connected. Ideal for fleet analytics, R&D campaigns and predictive maintenance.

For remote CAN data access the right choice depends on whether you need a push or pull model:

• The CANedge2/3 pushes log files via WiFi/LTE to your own S3 server - ideal for automated data collection at scale
• The CANsub can be accessed remotely via the Ethernet interface and LAN/WiFi/LTE routers, but uses a pull model: A client device (e.g. a laptop) connects to the CANsub to stream data, i.e. the device does not push data standalone to e.g. cloud storage

For near real-time remote workflows, the CANedge2/3 can be configured with short file splits (down to 10 seconds) combined with our automation work flows - enabling end-to-end latencies of 20-60 seconds when the device is in coverage. The CANsub achieves closer-to-true real-time remote streaming, limited mainly by WiFi/LTE round-trip latency, but requires an active client connection.

Several of our products support USB streaming of CAN data - but the CANsub is by far our most capable streaming interface. The others support streaming as a side feature to their primary purpose:

• CANsub (recommended): Dedicated CAN FD streaming interface via USB/Ethernet. Zero-install webCAN app, 20,000+ frames/sec, 1 µs timestamp resolution, built-in LCD, and native support for SavvyCAN, Python and custom web apps
• CANmod.router: Primarily a 4 x CAN FD router/gateway for merging, splitting and filtering CAN buses. Can also be used as a USB streaming interface via SavvyCAN/Python - but it is not streaming-first and lacks webCAN, Ethernet and the LCD, and timestamps at 1000 µs (1 ms) resolution vs. 1 µs on the CANsub. We recommend the CANmod.router when you primarily need routing/gateway functionality, with USB streaming as a secondary capability
• CL1000/CL2000 (legacy): 1 x CAN data loggers (classical CAN only) that support ad-hoc USB streaming in SavvyCAN/Python at max ~1,000 frames/sec with 1000 µs (1 ms) timestamp resolution. Their primary purpose is standalone SD logging - we recommend the CANsub for any modern streaming use case

If live CAN streaming is your primary goal, the CANsub.4 is the right choice.