When the device is not there
“The software cannot see it” is one sentence covering four unrelated faults. They are cheap to eliminate in the right order and expensive in the wrong one, and the wrong one is the order people reach for: reinstalling an application to fix a charge-only cable.
Four links, cheapest first
Between the box on your desk and a trace on your screen there are four things, and each of them can be the one that is broken:
The order in the drawing is the order to check them, and it is not arbitrary — it is sorted by how long each takes to eliminate. A cable swap is fifteen seconds. A driver is five minutes. Reinstalling an application is twenty and almost never the answer.
The cable
Start here every time. Both cables in the box are data cables, but everybody has a drawer of micro-USB leads that came with something that only ever needed charging, and a charge-only cable produces exactly this symptom: no device, no error, no clue.
If a cable swap fixes it, mark the bad one and throw it out. You will otherwise diagnose it again in six months.
The port
Directly into the machine. Not the hub, not the dock, not the monitor's downstream port.
Hubs fail here in two ways. They share a power budget, so an analyzer next to a phone on charge can brown out; and they share a controller, so an analyzer next to the target board's serial connection is competing for the bandwidth it does not have to spare.
The driver
This is the only step where the answer depends on the platform, and it is the step people skip.
Windows. Logic 2's installer sets up its own driver. PulseView needs WinUSB, which the sigrok Windows installer arranges through Zadig. There is one driver slot for one device, so installing the second takes the device away from the first — and going back means running Zadig again. That is not a bug and there is no configuration that avoids it. If you want both applications on one Windows machine, expect to swap.
macOS. Neither application needs a driver. If the device is not appearing here, the fault is above or below this step rather than in it.
Linux. No driver either, but PulseView needs permission to open a USB device
and a normal user does not have it by default. The fix is a udev rule granting
access to the device, which sigrok packages ship and a manual build does not.
Running the application with sudo proves the diagnosis and is not the fix.
The application
Last, and mostly one check: is something else already holding the device open.
Two applications cannot share it. The second one to ask does not get an error saying "in use" — it gets an empty device list, which looks identical to a device that is not plugged in. So before reinstalling anything, quit the other application properly, including from the menu bar or the tray where it may still be running with no window.
When all four are good and the trace is still wrong
Then the chain is whole and the problem has moved: it is a question about channels, about the sample rate, or about ground. Those are the previous four chapters, and ground is the one to check first, because it is the one that produces a trace rather than an absence.
When it does not work
Swap the cable first. Both cables in the box carry data, but a micro-USB out of a drawer is a coin flip, and a charge-only one is indistinguishable from the outside. Then try a port directly on the machine rather than through a hub or a dock. Those two checks take a minute and cover most of these.
That is the driver, and it is the only step with a different answer per platform. Windows: Logic 2 installs its own, PulseView wants WinUSB through Zadig, and each displaces the other. macOS: neither needs one. Linux: neither needs a driver, but PulseView needs permission to open the device, which is a udev rule rather than running it as root.
Check nothing else has it open. Two applications cannot share the device, and the second one to ask gets an empty list rather than an error explaining why. A Logic 2 still running in the menu bar or the tray after its window was closed is the usual answer.
That is usually power or the bus rather than the device. A hub that is sharing its budget with a phone charging on the next port will brown the analyzer out, and a controller that is saturated will stall it. Move it to a port of its own and drop the sample rate.
Two channels, a sketch that generates traffic, and the ninth clock that tells you whether a sensor is on the bus at all.
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