The 7 Best USB To CAN Adapters
Updated by · How we research
Seven USB-to-CAN adapters compared on CAN FD support, isolation and software, from open boards to PEAK interfaces. Our pick: the Grid Connect GC-CAN-USB-ISO. When users buy our independently chosen editorial recommendations, we may earn commissions to help fund the Wiki.
Newer car controllers and robot motor drives increasingly talk CAN FD, a faster version of the CAN bus that many popular adapters can't read at all. Check your network before you buy. These USB dongles let a laptop watch, log and send traffic on a vehicle or machine network, and this list covers engineers, technicians and hobbyists, from shop benches to robot builds.
From the manual
- Install PEAK's driver before plugging the adapter in, and skip USB extension cables, which PEAK says break the USB specification. pp. 14-15
- The 120-ohm terminator is off at delivery and is set with solder bridges inside the case; units below serial number 200000 have none. pp. 12, 17
- The optional 5-volt output for bus accessories is limited to 50 mA on this isolated model and is also set by solder bridge. p. 8
- On Linux the kernel driver shows it as a standard CAN port, but PEAK's own programming library needs PEAK's separate driver package. pp. 30, 39
Why the Grid Connect GC-CAN-USB-ISO is our top pick
Our pick is the safer dongle to hang off a running truck or machine, and it comes with fuller software and documentation than the runner-up; it gives up CAN FD to get there. Grid Connect sells it as PEAK-System's opto-decoupled PCAN-USB,2,3 whose bus side is isolated from the computer up to 500 volts.1 Our runner-up, the DSD TECH SH-C31A, has no isolation at all,4 so a ground fault on the bus can reach your laptop.
Software is the other half. PEAK ships its PCAN-View monitor and PCAN-Basic programming library with the adapter,1 and one PCAN-Basic library drives every PEAK interface,1 so scripts carry over to bigger PEAK boxes. Many Linux kernels already include the driver and list it as a standard network-style CAN port.1 The runner-up shows up on Linux natively too, but its maker warns that python-can, when it talks to the adapter directly over USB rather than through Linux, opens it only at 500 kbit/s or 1 Mbit/s.4
The runner-up wins on speed and convenience. It carries CAN FD frames on current firmware, measured by its maker to a 5 Mbit/s data rate,5 while our pick stops at classic CAN's 1 Mbit/s.1 Its terminator is a built-in switch;6 ours is a solder jumper inside, off at delivery, and early units have none.1 If your bus runs CAN FD, the runner-up or PEAK's own FD models are the better buy.
| Grid Connect GC-CAN-USB-ISO | DSD TECH SH-C31A | |
|---|---|---|
| Galvanic isolation | Up to 500 V | None |
| CAN FD | No; classic CAN to 1 Mbit/s | Yes, to 5 Mbit/s data rate |
| Maker's software | PCAN-View, PCAN-Basic library | DSD's diCAN app (Windows, macOS) |
| Built-in terminator | Solder jumper, off at delivery | Built-in switch |
| Documentation | 40-page PDF manual | GitHub pages |
Sources
- PEAK-System PCAN-USB 1User manual 3.2.0 (PDF), pp. 5, 6, 12, 17, 30, 39 2Grid Connect comparison chart 3Grid Connect product page
- DSD TECH SH-C31A 4Documentation (GitHub) 5Firmware page (GitHub) 6Product page 7diCAN software (GitHub)
From the manual
- Older stock may carry the original upstream firmware, which has no CAN FD at all; DSD's free update adds it and can be undone. firmware page
- Switch the terminator off on a car or any existing bus; turn it on only when the adapter ends a short bench cable. termination guide
- python-can's direct USB backend opens it only at 500 kbit/s or 1 Mbit/s; through Linux's built-in CAN support, 10 kbit/s to 1 Mbit/s all work. README
- The green lights stay dark until software opens the channel, which DSD says is normal. README
Compare the specs
Swipe the table sideways to see every column.
| Product | CAN FD | CAN channels (count) | Isolation (V) | Fastest data rate (Mbit/s) | Built-in terminator (120 ohm) | Computers (per maker) |
|---|---|---|---|---|---|---|
| 1. Grid Connect GC-CAN-USB-ISO | No | 1 | 500 | 1 | Solder jumper, off | Windows, Linux |
| 2. DSD TECH SH-C31A | Yes | 1 | None | 5 | Switch | Windows, macOS, Linux |
| 3. Jhoinrch RH-02 Pro | — | — | — | — | — | — |
| 4. Grid Connect PCAN-USB Pro FD | Yes | 2, plus 2 LIN | 500 per channel | 12 | Solder jumpers, off | Windows, Linux |
| 5. Pibiger SavvyCAN-FD-C | Yes | 1 | 2,500 | 12 | On; set in software | Windows, macOS, Linux |
| 6. Kvaser Leaf Light v2 | No | 1 | Yes, no rating given | 1 | None | Windows, Linux |
| 7. Waveshare USB-CAN-FD | Yes | 2 | 3,000 | 5 | 2 switches per channel | Windows (Linux on -B) |
Figures are the makers' own. Jhoinrch publishes no spec sheet, so its row is blank; its seller claims CAN FD and isolation. DSD TECH's 5 Mbit/s is its own measurement on current firmware; older units may lack CAN FD. Waveshare's plain USB-CAN-FD runs on Windows only; the -B version adds Linux.
Sources
- PEAK-System PCAN-USB User manual 3.2.0 (PDF) Grid Connect product page
- DSD TECH SH-C31A Documentation (GitHub) Firmware page (GitHub) Product page diCAN software (GitHub)
- PEAK-System PCAN-USB Pro FD User manual 2.1.0 (PDF)
- Pibiger SavvyCAN-FD-C Series user manual V1.1 (PDF)
- Kvaser Leaf Light v2 User's guide (PDF) Data sheet (PDF)
- Waveshare USB-CAN-FD Product page Wiki
From the manual
- LIN needs its own 8 to 18 volt supply on pin 9 of each connector; USB power doesn't run the LIN side. pp. 7, 16
- Each CAN channel is isolated up to 500 volts, but the two LIN channels share a ground and aren't isolated from each other. pp. 16, 45
- Termination is off at delivery and is set per channel with solder bridges inside the aluminum case. p. 13
- CAN FD's faster data phase doesn't buy longer cables; bus length still follows the nominal rate, about 110 meters at 500 kbit/s. p. 18
From the manual
- Its 120-ohm terminator ships switched on, so turn it off before tapping a bus that's already terminated, such as a car's. pp. 20, 24
- It ships set up for Windows; for Linux or macOS you change its device ID first, then unplug and replug it. pp. 24-25
- On Windows, Pibiger supplies its own CAN FD build of SavvyCAN; Linux and macOS use the open-source version. pp. 25-26
- Pibiger rates the isolation at 2,500 volts for both signal and power. p. 11
From the manual
- There's no built-in terminator at all, so a bench setup with one module needs external 120-ohm resistors. p. 15
- It has no silent, listen-only mode and can't generate error frames for testing. p. 12
- Install Kvaser's driver first; firmware updates then come from Kvaser's download page. p. 7
- Kvaser's data sheet lists a two-year warranty and free support. data sheet, p. 1
From the manual
- The plain USB-CAN-FD runs on Windows only; Waveshare's USB-CAN-FD-B version adds Linux, Raspberry Pi included. product page
- Each port has two 120-ohm resistors on switches, and Waveshare's first fix for abnormal communication is switching them on. wiki
- For a self-test, wire port one to port two with both terminators on; with them off, frames sent aren't received. wiki
Editor's Notes
November 5, 2026, by Ezvid Wiki Editors:
We read the PEAK, Kvaser and Pibiger manuals plus the DSD TECH and Waveshare documentation, added a spec table, a section on why the top pick leads, and notes from each manual. We corrected two older notes: PEAK-System's name, and the 11- and 29-bit figures, which describe identifiers, not messages. The guide no longer credits a short forum thread with praise for PEAK and Kvaser that it never gave.
October 23, 2026, by Ezvid Wiki Editors:
The new top pick, the Grid Connect GC-CAN-USB-ISO, turns out to be PEAK-System's isolated PCAN-USB under a reseller's label, and the Grid Connect PCAN-USB Pro FD is PEAK hardware too. PEAK's drivers and free tools are what most CAN software expects, so that's where the list starts.
Cheap boards built on the open CANable design have changed this category, so the DSD TECH SH-C31A, the Jhoinrch RH-02 Pro and the Pibiger SavvyCAN-FD-C join, along with the two-port Waveshare USB-CAN-FD. Kvaser now lists the Kvaser Leaf Light v2 as end of life; it stays for shops already running Kvaser software.
The Utek UT-8251, ViewTool VTG203B and Innomaker module are no longer sold, and Kvaser has retired the Leaf Pro HS v2. The Drew Tech Mongoose Pro is gone as well, and it was a pass-thru reflashing tool rather than a plain adapter. Nobody publishes lab tests of these dongles, so we leaned on PEAK and Kvaser data sheets, the open firmware projects, the Linux kernel's CAN documentation and an engineers' forum thread.
Earlier notes
February 23, 2021, by Kaivaan Kermani:
To reiterate the previous editor’s note, these devices are used in a fairly specialized context, and there aren’t a whole lot of manufacturers on the market, so, by extension, there is a limited number of decent models. With that being said, I’ve left all of the models in from the previous update, as they’re all still decent, and I could find few others without issues that made me even want to consider including them on our list. I have however added the Grid Connect Pro FD, which supports the CAN FD or (CAN Flexible Data-Rate) protocol that builds on classical CAN. Although Grid Connect does have its own models, I do believe that they’re also a distributor or reseller of many of the adapters and other hardware components from Peak View, which is not necessarily a bad thing, because Peak View makes some of the best adapters and hardware interfaces for CAN. [2026 update: the maker is PEAK-System; PCAN-View is the name of its monitor software.]
Since CAN is a data bus, like USB, and not an actual hardware interface, it can use a variety of different connector types, which is why we’ve included options like the Drew Tech Mongoose Pro for OBD-2 ports, as well as the Utek UT-8251 ; many systems, however, will employ a 9-pin, d-subminiature connector, or a DE-9. Likewise, not all DE-9-to-USB adapters won’t meet the requirements needed to support or facilitate high-speed CAN connections. Quickly on the note of connectors, the DE-9 connector is often mislabeled and sold as a DB-9 connector, which is a mistake that stems from the fact that DB-25 connectors were replaced with DE-9 connectors on laptops, and most sellers simply carried the ‘B’ over without thinking twice about what it represented – which is the shell size, and should be represented with an ‘E’ in the case of the 9-pin d-sub. Unfortunately, the ‘B’ is still used, so don’t be confused.
June 7, 2019, by Kevin Flores:
These devices are often used in a very specialized context and their descriptions involve a lot of jargon, so let's break down some of the main features so you can better understand which interface is best suited for you.
First let's talk data throughput speed. Data travels across CAN networks in packages called messages, of which frames are the most common. Some manufacturers use frames to measure the speed of their interfaces, such as the ViewTool VTG203B, which moves data at 8,000 frames per second. Others are measured using bits, like the Grid Connect GC-CAN-USB-ISO, rated at 1 megabit per second. A more technical term for this is the baud rate.
Messages can be different data sizes, depending on the CAN protocol. CAN2.0A and CAN2.0B are the most common, with 11-bit and 29-bit messages, respectively. [2026 update: the 11 and 29 bits are the length of each message's identifier, not of the message; a classic CAN frame carries up to 8 data bytes.] Models like the Utek UT-8251 work with both, and this something that should be taken into careful consideration before making a purchase.
Special Honors
Kvaser Leaf v3 And U100 Kvaser's replacement for the Leaf Light v2 is the Leaf v3, and its U100 is a rugged single-channel CAN FD interface with reinforced isolation. Both are sold through Kvaser and its distributors, and they use the same free CanKing software and drivers. kvaser.com
PEAK-System PCAN-USB FD PEAK's single-channel CAN FD adapter sits between its classic PCAN-USB and the two-channel Pro FD. It handles data bit rates up to 12 Mbit/s, has isolation up to 500 volts and one-microsecond timestamps, and runs the same drivers and PCAN-View monitor. peak-system.com
Classic CAN Or CAN FD
If you work on newer vehicles, motor controllers or robotics gear, check the controller's data sheet first.
Classic CAN (CAN 2.0A and 2.0B) carries up to 8 data bytes per frame at up to 1 Mbit/s, and a car's OBD-II diagnostic bus usually runs at 500 kbit/s. That's all the PEAK PCAN-USB and the Kvaser Leaf Light v2 handle. CAN FD keeps the same wiring but sends up to 64 data bytes per frame and speeds up the data phase; PEAK rates its PCAN-USB FD for data bit rates up to 12 Mbit/s.
A classic-only adapter can't decode FD frames, and on a mixed bus it sees them as errors. If you work on newer vehicles, motor controllers or robotics gear, check the controller's data sheet first. If the bus is classic and always will be, an FD adapter costs little extra but buys nothing.
Channel count is the other split. One channel covers almost every job. Two channels let you watch both sides of a gateway, or bridge two networks, which is why the two-channel PEAK and Waveshare boxes exist.
Isolation, Termination And Wiring Traps
Galvanic isolation separates the adapter's bus side from your laptop's ground. On a running vehicle or an industrial machine, the two grounds can sit at different voltages, and a fault can travel up the USB cable. PEAK sells the PCAN-USB with or without isolation (up to 500 V on the IPEH-002022 version, per PEAK), while Kvaser builds isolation into the Leaf Light v2. Budget boards vary: some isolate, many don't. Isolation protects the computer, not the bus, so it won't save the car from a wiring mistake.
A CAN bus needs a 120-ohm resistor at each of its two ends and nowhere else. A bench setup with just the adapter and one module usually needs the adapter's resistor switched on; a car's network already has its own. Missing termination, the wrong bit rate and swapped CAN high and low wires cause most "it doesn't work" reports. Kent Lennartsson, a Kvaser founder who has designed CAN interfaces since 1990, gave a simple check on Kvaser's developer blog in December 2019: with the nodes powered down, unplug the adapter and measure between pins 2 and 7 of its cable's connector; about 60 ohms means both terminators are in place. Some adapters ship with their own resistor switched on, Pibiger's among them, so check before tapping a car. PEAK's adapters set termination and an optional 5 V supply on pin 1 with solder jumpers, according to PEAK's specifications.
Reading a car's bus through the OBD-II port is common and fairly safe. Sending frames into a live vehicle is not: brakes, airbags and steering can share that network. Reflashing an engine computer is a job for a J2534 pass-thru tool and the automaker's software, not a plain CAN adapter. Grid Connect's setup guide walks through a first connection.
Software Is What You're Paying For
The hardware inside a cheap board and a professional dongle is not so different; the software is. PEAK ships PCAN-View and the PCAN-Basic programming library, and Kvaser ships CanKing and its CANlib library, with drivers for Windows and Linux. Both makers also keep one programming library across their range, so code written for one of their interfaces runs on the others.
Budget boards based on the CANable design run open firmware. With candleLight firmware they appear on Linux as a native SocketCAN port (see the kernel's CAN documentation), and you bring them up like a network card. The free SavvyCAN program and python-can, which supports PEAK, Kvaser, candleLight and serial-line (slcan) adapters, cover logging, replay and scripting. On Windows, expect more setup.
Serial-line firmware is simpler but slower: in an EEVblog thread, one member called a serial-type dongle's bandwidth severely limited and said its Linux support doesn't work great. If you need to log a heavily loaded network or hand scripts to coworkers, the pro drivers earn their price.
How we researched this
We compared 17 USB-to-CAN adapters and read PEAK-System's PCAN-USB and PCAN-USB Pro FD user manuals, Kvaser's Leaf Light v2 user's guide and data sheet, Pibiger's SavvyCAN-FD series manual, DSD TECH's SH-C31A documentation on GitHub and Waveshare's USB-CAN-FD wiki; Jhoinrch publishes no manual, so its pick rests on seller specs. Grid Connect's comparison chart tied its part numbers to PEAK's, and the Linux kernel, candleLight and python-can documentation showed which boards need extra drivers. A search of the CPSC recall database on November 5, 2026 found no recalls for any of the seven brands.
Sources (18)
- PEAK-System: PCAN-USB
- PEAK-System: PCAN-USB FD
- Kvaser: Leaf Light v2
- Grid Connect: CAN USB adapters
- python-can: interface list
- Linux kernel: SocketCAN documentation
- candleLight firmware (GitHub)
- SavvyCAN (GitHub)
- EEVblog forum: CAN bus converter thread
- PEAK-System: PCAN-USB user manual 3.2.0 (PDF)
- PEAK-System: PCAN-USB Pro FD user manual 2.1.0 (PDF)
- Grid Connect: USB-to-CAN adapter comparison chart
- Kvaser: Leaf Light v2 user's guide (PDF)
- DSD TECH: SH-C31A documentation (GitHub)
- Pibiger: SavvyCAN-FD series user manual (PDF)
- Waveshare: USB-CAN-FD wiki
- Kvaser developer blog: testing CAN termination
- U.S. CPSC SaferProducts.gov
Frequently asked questions
What is a CAN bus?
It's a two-wire network that lets the controllers in a car, truck, boat or machine share messages. Each module can talk and listen on the same pair of wires, and a USB-to-CAN adapter lets a computer join in.
Do I need a CAN FD adapter?
Only if your network uses CAN FD, which is common in newer vehicles, motor drives and robotics. A CAN FD adapter also reads classic CAN, but a classic-only adapter can't read CAN FD frames.
Do I need galvanic isolation?
It's worth having whenever the bus belongs to a vehicle or machine with its own power supply, because the grounds may not match your laptop's. On a bench with a USB-powered board, a non-isolated adapter is usually fine.
Is the Grid Connect adapter the same as a PEAK PCAN-USB?
Yes. Grid Connect resells PEAK-System's PCAN-USB, PCAN-USB opto-decoupled and PCAN-USB Pro FD, and the hardware carries PEAK branding. It uses PEAK's drivers and software.
Can a USB-to-CAN adapter reflash my car's computer?
Not by itself. Shops use a J2534 pass-thru tool with the automaker's software for that. Holley EFI owners should use Holley's own CAN-to-USB cable, which works with Holley's tuning software.
Do the cheap adapters work on Windows?
Yes, with tools such as Cangaroo, SavvyCAN or python-can, but setup takes more steps than on Linux, where candleLight-based boards show up as native CAN ports.
