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ZeroTrace Companion

Connecting Devices

How Companion finds, identifies, and connects to ZeroTrace hardware over USB.

Companion talks to your ZeroTrace devices over USB serial. When you plug a device in, the operating system exposes it as a virtual COM port; Companion enumerates the ports, probes each one to figure out what's on the other side, and presents the result in the device picker.

This section covers the connection layer, how it works, how to handle multiple devices, and how to add custom firmware that does not match the standard signatures.

What's in this section

PageWhat it covers
Serial portsWhat a COM port is, how to find one on each operating system, and what permissions you need
Auto-detectionHow Companion figures out which ZeroTrace device is on which port
Multiple devicesWorking with two or more ZeroTrace devices plugged in simultaneously
Custom firmwareConfiguring Companion to recognise a custom-firmware device that does not match the standard handshake

The connection lifecycle in 30 seconds

  1. Plug in a device. OS recognises it as a USB serial device.
  2. Open Companion. The device picker (top-left) lists every detected port.
  3. Companion probes each port, sends a quick handshake, listens for a response.
  4. Each port is labelled with what Companion found: HID, AirLeak, BLE Logger, unknown, busy, or empty.
  5. Pick a device and click Connect. Companion opens the connection at the right baud rate for that device type.
  6. The workspace switches to match the connected device, HID dashboard, AirLeak workspace, or generic terminal for unknown devices.

Companion remembers the last connected device. If you plug the same device into the same port, Companion can auto-reconnect on launch, toggle this in Settings → Connection.

What happens when you disconnect

Pulling the USB cable, putting the device to sleep, or clicking Disconnect:

  • The port closes cleanly.
  • The connected workspace shows a "device disconnected" banner.
  • Any unsaved capture data is preserved in memory until you explicitly discard it.
  • The picker re-scans and updates.

For unexpected disconnects (cable knocked loose, device crashed), Companion attempts a single auto-reconnect by default. If that fails, you can re-connect manually.

When something goes wrong

The fastest first checks:

  1. Re-scan ports, Companion's picker has a refresh button, or Ctrl+R.
  2. Try a different USB cable. Cheap charge-only cables are a common cause of "device not detected."
  3. Try a different USB port. USB hubs occasionally cause issues; direct connection usually fixes them.
  4. Check device drivers, see serial ports for the per-OS driver guidance.
  5. Check for permission errors, Linux users need dialout group membership.

For deeper troubleshooting see the troubleshooting page.