Unit-level fault codes

Code	Meaning	Likely cause	Action	Status
TODO	TODO	TODO	TODO	Not yet defined

libqynetic / driver-level errors

Code	Meaning
0	Command executed successfully
1	General error (invalid parameters, hardware issue, etc.)

[ERROR: HWDevice_create] Failed to connect to targetted hardware. Check your permissions or make sure the device is on.

Cause: the driver could not open the USB/FTDI connection to the specified serial number.

Action:

Confirm the unit is powered on (Installation & Setup).
Confirm the serial number passed to -s matches the unit.
On Linux, confirm your user is in the dialout group (or run with sufficient permissions) – see qynetic-spi-driver/docs/installation/UDEV.md.
Confirm the USB/host interface cabling is connected.

The driver validates arguments before sending them to hardware, e.g.:

Error: Channel must be between 1-8
Invalid PLL name: invalid_pll
Usage: set_ch_attenuation <channel> <attenuation_db>

Action: correct the argument per the usage message; re-run with -h against the device type for the full action list.

Symptom	Check
No RF output	RF path configuration (Configuration via libqynetic `set_rf_path`); DC power present; RF input drive present and within range
Low/unstable output power	Attenuation and gain settings within Operating Procedures & Safety Precautions limits; input voltage sag under load
Unit runs hot / thermal shutdown suspected	Airflow at or above 20 CFM (Maintenance & Repair); heatsink unobstructed; ambient within spec
Host can't reach the unit over USB-C	Cabling; host driver/enumeration; TODO confirm default discovery behavior (Installation & Setup)
`libqynetic` reports "Failed to connect to targetted hardware"	See above