Connecting the Tercio FD

The Tercio FD is a standard USB serial device. There is nothing to install: plug it in, and it shows up as a serial port and in the browser.

Your computer

Windows

Windows 10 and 11 load their built-in USB serial driver. The adapter appears in Device Manager under Ports (COM & LPT) as USB Serial Device (COM5), with whatever COM number Windows picks.

macOS

The adapter appears as /dev/cu.usbmodem…. List it with:

ls /dev/cu.usbmodem*

Linux

The adapter appears as /dev/ttyACM0 (or the next free number). Your user needs access to serial ports, which on most distributions means the dialout group:

sudo usermod -aG dialout $USER    # then log out and back in

For a fixed name, add a udev rule:

echo 'SUBSYSTEM=="tty", ATTRS{idVendor}=="1209", ATTRS{idProduct}=="0011", MODE="0660", GROUP="dialout", SYMLINK+="tercio-fd"' \
  | sudo tee /etc/udev/rules.d/99-tercio-fd.rules
sudo udevadm control --reload-rules && sudo udevadm trigger

The adapter is then also /dev/tercio-fd.

The serial settings (baud rate, parity) do not matter: it is a USB device and runs at full USB speed whatever you choose.

One program at a time

Only one program can hold the serial port. Close Tercio Control before running a Python script on the same adapter, and the other way round.

In the browser

Tercio Control talks to the adapter through Web Serial, which Chrome, Edge and other Chromium browsers support on desktop computers. Firefox and Safari do not.

1. Plug in the adapter and open Tercio Control.
2. Select Connect Tercio FD. The browser lists matching devices: choose tercioFD.
3. The page remembers the permission. Next time Reconnect Tercio FD skips the list.

No adapter at hand? Try the demo runs Tercio Control against a simulated adapter with three motors and an IMU.

The bus

Connect the adapter’s JST XH connector (J2) to the first node:

Adapter J2	Signal	S1 J4
1	CAN-H	3
2	CAN-L	4
3	GND	2

• The adapter has a 120 Ω terminator built in, so it must sit at one end of the bus, never in the middle. The node at the other end gets its termination jumper; see Wiring the bus.
• The adapter is powered by USB and does not power the bus. Each S1 needs its own supply.
• Its GND connects to your computer’s ground through USB. Connect it to the drivers’ GND so the bus has a common reference.

Checking the link

With at least one powered S1 on the bus:

• LEDsGreen on; red flickers with telemetry.
• Adapter pageTercio Control shows the bus as Healthy, with frames arriving From the bus.
• MotorsThe driver appears under Motors. If not, see No motor appears.

From Python:

from TercioBridge import Bus

with Bus("/dev/ttyACM0") as bus:
    print(bus.adapter_info())
    for node in bus.discover():
        print(node)