ELM327 OBD2 USB Adapter: FTDI vs CH340, Drivers and Laptop Use

That steadiness matters most when software writes to the car rather than just reading it. Changing module settings in FORScan, running a service procedure or logging a long test drive all go badly if the connection vanishes mid-task.

• Module configuration: FORScan lets a Ford or Mazda owner enable features and run service functions.
• Long logging: a laptop can record live data for a whole drive without a phone going to sleep.
• Older Windows tools: ELMconfig, FoCCCus, FF2 and ScanMaster expect a COM port, which USB provides directly.
• No battery worry: you unplug the cable when you finish, so nothing sits in the port draining power.

The trade-off is plain. A USB cable ties you to a laptop, and most are Windows-only in practice because the software is. Phones need a Bluetooth ELM327 instead: BLE for an iPhone, either type for Android.

Both do the job. The differences show up in driver handling and fine-tuning rather than in which cars you can scan.

• FTDI FT232RL: made by FTDI in Scotland, with drivers that have been stable for many years. Its driver exposes a latency timer, which some FORScan users lower from the default 16 ms for snappier responses.
• WCH CH340: a low-cost Chinese bridge used on budget cables such as the OBDMonster, which asks for the CH340T driver before first use. It works well for reading codes and most configuration jobs.

One warning about FTDI: counterfeit FT232 chips exist. In 2014 an official FTDI driver update disabled many fakes, and FTDI withdrew it after complaints. A cable claiming an FTDI chip at a rock-bottom price may carry a copy.

If a cable names neither chip, you learn which bridge it uses when Windows shows the device name. Most unnamed budget cables turn out to use a CH340.

1. Plug the cable into the laptop only, then open Device Manager.
2. Look under Ports (COM & LPT) for 'USB Serial Port' (FTDI) or 'USB-SERIAL CH340' with a COM number next to it.
3. If you see an unknown device with a yellow warning, install the driver from the chip maker: the FTDI VCP driver, or WCH's CH341SER package for CH340 cables.
4. Unplug, replug and note the COM number.
5. For FTDI cables, open the port's Properties, then Port Settings and Advanced, to change the latency timer if your software suggests it.
6. In FORScan or ELMconfig, choose that COM port or leave it on auto-detect.

Skip driver discs and random download sites. The chip makers' own drivers are current and signed, which newer Windows versions insist on.

Most clone ELM327 cables talk at 38,400 baud by default, and software normally detects the speed on its own. If a program asks, try that first. You can test the link by hand with a few ELM327 AT commands from a terminal.

That leaves Mac owners with a few workable routes, none of them perfect.

• Windows on a spare laptop: the simplest option, and many owners keep an old one for the garage.
• A virtual machine on an Intel Mac: pass the USB device through to Windows and pick its COM port there.
• Apple silicon Macs: Windows for ARM is the only virtual option, and some cable makers state their drivers do not support ARM-based Windows.
• Linux: the kernel's ftdi_sio and ch341 modules handle both chips, and the cable appears as /dev/ttyUSB0 for open-source tools.

The ARM point applies to Windows laptops too. MOCATEC, for one, states its cable is for x86/x64 Windows and not ARM-based Windows, so check the processor in your laptop before buying.

If none of that appeals, a Bluetooth adapter with FORScan Lite on a phone covers much of the same ground. The vLinker FD+ is built for exactly that, though FORScan on Ford and Mazda still needs the full Windows version for some jobs.

• Length: short leads force the laptop against the steering column. The MOCATEC's 4.9 feet reaches the passenger seat.
• Switch type: a toggle works but is easy to leave in the wrong position; auto-switching cables such as the vLinker FS USB and OBDMonster's auto version remove that step.
• Electronic switching: the OBDLink EX reaches all CAN buses at once, which FORScan uses for advanced functions.
• Programming voltage: the vLinker FS USB can supply up to about 18V for ECU programming on select older US vehicles.
• Housing: a solid OBD2 plug with a moulded strain relief outlasts thin, glued shells.

Store the cable loosely coiled, not wrapped tight around the plug. Most failures start where the wire enters the housing.

If the car sits for long spells, unplug the cable after each session. It costs nothing and removes any chance of a slow drain through the port.