Keyspan USA-19HS driver: why Windows blocks it, and the old copy that keeps it blocked

Same laptop, same SLC, same cable it has used for years. Then Windows updates, and the next time the Keyspan goes in there is a yellow triangle in Device Manager where the COM port used to be. Reinstalling the Keyspan USA-19HS driver doesn't clear it. Sometimes it looks like it made things worse.

Usually the adapter is fine. The current Windows 10/11 package carries a driver that memory integrity, the Windows security feature behind all of this, loads without complaint. What keeps the adapter dead is an older Keyspan driver still parked in the Windows Driver Store, and uninstalling the software doesn't get it out. pnputil does.

Which Keyspan USA-19HS driver goes with which Windows

Keyspan adapters are sold under Eaton's Tripp Lite series now, and the downloads come one package per Windows generation. They don't mix.

Pick the package by Windows version first. Most of the grief starts with an older package left on a newer machine.

The adapter shows up twice in Device Manager, which confuses people. Keyspan USB Serial Adapter sits under Universal Serial Bus controllers, Keyspan USB Serial Port (COMx) under Ports (COM & LPT). Two drivers, and both have to load.

Open either entry, Driver tab. The current Keyspan USA-19HS driver shows a date of 8/16/2024 and a version starting with 17.14.44. Skip the file version in the .sys properties, it reads 3.7 on the 2024 build and tells you nothing. The date does.

Why a fresh Keyspan USA-19HS driver install still shows a yellow triangle

Memory integrity lives in Windows Security under Device security, Core isolation details. With it on, Windows only lets a kernel driver load if that driver is compatible with it. The older Keyspan USA-19HS driver isn't. Since the 2024 build, it is.

So why doesn't installing the 2024 build fix it? Windows keeps a copy of every driver package it has installed in the Driver Store, and removing the Keyspan software from Apps doesn't touch that copy. If the old package is still in there, memory integrity won't let it load, and the adapter stays broken with the new driver sitting right next to it.

The sequence that gets people here is nearly always the same:

1.    The old driver went on at some point.

2.    Memory integrity was off back then.

3.    Somebody installed the new driver.

4.    Memory integrity got turned back on.

What you see after that: the adapter in Device Manager with a yellow exclamation mark, and its properties saying there are no drivers for the device. Other machines report Code 39, "Windows cannot load the device driver for this hardware." And Windows may pop a notification that a driver can't load on this device.

Both packages sit in the Driver Store and the adapter still fails. Take the old one out and the same 2024 Keyspan USA-19HS driver loads normally.

Turning memory integrity back on used to need a person. Not anymore. From October 2026, Windows quality updates start switching memory integrity on by default on eligible machines. Windows checks readiness first, compatibility included, and leaves alone any machine where somebody already turned it off. A fresh Windows 11 install on current hardware has it on from day one anyway. Does that check catch an old Keyspan package sitting in the Driver Store? I wouldn't bet on it.

Pin down which problem you have

Two checks before changing anything. First, is memory integrity actually on? Core isolation details will tell you. Then Event Viewer: Applications and Services Logs, Microsoft, Windows, CodeIntegrity, Operational. Blocked drivers land there, generally as event ID 3087. If usa19hx64.sys shows up in those events, that's your Keyspan USA-19HS driver problem.

Device Manager and the green light on the adapter tell you most of the story before you uninstall anything.

That steady light catches people more than anything else here. A leftover modem utility or an old HMI runtime opens the COM port at boot, and RSLinx gets nothing.

The clean install that actually sticks

The 2024 installer is built to find an old Keyspan USA-19HS driver and remove it on its own, and most of the time it does. Running it a second time sometimes finishes the job. When it doesn't, pnputil does. On a laptop I don't know the history of, I just run the whole sequence. Ten minutes, admin rights needed.

1.    Unplug the adapter.

2.    Open Settings (Windows key + I), then Apps, Installed apps. Search for "USA" and uninstall every Keyspan USA-19HS or Keyspan USA19H Driver entry.

3.    Open Command Prompt with Run as administrator and dump the Driver Store to a file you can search.

pnputil /enum-drivers > C:\drivers.txt

notepad C:\drivers.txt

4.    Search for KSPN. Each Keyspan entry has Original Name 19h.inf or 19hp.inf and Provider Name KSPN. Write down the Published Name of each one, in the form oemNN.inf. Usually at least two, sometimes more.

5.    Delete each package by its own oem number. Every one should answer "Driver package deleted successfully."

pnputil /delete-driver oem53.inf /uninstall

6.    Run USA-19HS Driver Installer.msi from the Windows 10/11 package and accept the UAC prompt.

7.    Plug the adapter in and check the Driver tab for 8/16/2024.

Windows assigns the oem numbers, and they differ on every machine. Use yours, not the 53 above.

Turning memory integrity off works, and it costs you

Yes, switching Memory integrity off in Core isolation details and restarting lets the old driver load. Everybody suggests it first. For the Keyspan USA-19HS driver it's the wrong move now, because a compatible build exists.

Memory integrity keeps untrusted kernel code from loading, so turning it off lowers the bar for every driver on the machine, not just Keyspan's. On a Secured-core PC it also takes the laptop out of Secured-core state. And on a company laptop, IT policy may switch it right back on. I'd save this for an offline bench machine with some other ancient driver that will never get an update.

COM port settings that matter on a PLC laptop

Once the Keyspan USA-19HS driver loads, a few settings decide whether RSLinx finds anything. They live under Keyspan USB Serial Port, Properties, Port Settings, Advanced in Device Manager, and in the Keyspan Serial Assistant that installs with the driver.

COM number. Some older software only lists the low ones. Move the Keyspan to a free number, either in the Advanced window or under Port Mapping in Serial Assistant. Taking a number something else already uses can break whatever owns it.

Port mapping mode. Dynamic, the default, keeps the COM number with the adapter in any USB socket. Geographic ties it to the socket instead, which keeps a bench with several adapters predictable.

Transmit Completion Timing Advance. It makes the adapter report a transmit as finished early to squeeze out throughput, which can upset flow control and any protocol that times from the end of a message. At 57,600 baud and below there is little to gain, so DF1 at 19,200 stays on the default.

RSLinx side. RS-232 DF1 devices driver, the Keyspan's COM port, then Auto-Configure.

What the USA-19HS reaches on Allen-Bradley hardware

All the Keyspan USA-19HS driver gives you is an RS-232 COM port. That covers more of a legacy line than people expect. Less than they hope.

SLC 5/03, 5/04 and 5/05 Channel 0 is RS-232 and ships set to DF1, so a 1747-CP3 or any equivalent 9-pin null-modem cable from the adapter does the job. MicroLogix with the 8-pin mini-DIN port takes a 1761-CBL-PM02 on the end of the adapter. Both work through the RS-232 DF1 driver.

DH-485 is where it ends. That's the DH-485 port on a 5/01, 5/02 or Channel 1 of a 5/03, and it needs an interface converter, usually the 1747-UIC. Rockwell discontinued it on 9/30/2024 with no replacement planned, and you can't connect more than one to a single computer. DH+ on a 5/04 or a PLC-5 is another adapter altogether, the 1784-U2DHP.

The Keyspan USA-19HS driver gives you an RS-232 port and nothing more. DF1 ports work through the right cable, DH-485 and DH+ need their own interface.

Building a cable for a drive or an HMI instead? The adapter is wired as a standard PC port. Pin 3 sends, pin 2 receives, pin 5 is ground.

Male DB9 on the USA-19HS. Directions are as seen from the adapter.

When I stop trying to save the adapter

Three cases. Windows on ARM first: a Snapdragon laptop, or Windows in Parallels on a Mac with Apple silicon. The Keyspan USA-19HS driver is 64-bit x86 only and Windows on ARM can't load an x86 kernel driver, so there's nothing to fix. Then 32-bit Windows 10, since the 2024 package is 64-bit only and no package is listed for it. And anything that isn't RS-232, because the USA-19HS has no RS-485 or RS-422 mode.

Driver versions and dates as of October 2026.

For a plain RS-232 programming lead, a USA-19HS on the 2024 driver is fine and I wouldn't replace one that works. For a bench that talks to drives over RS-485, I'd buy the Moxa.

Frequently asked questions

Does the Keyspan USA-19HS driver work on Windows 11?

Yes, on 64-bit x86 Windows 10 and 11, with the package dated 8/16/2024 and memory integrity on. If it still fails, an older copy is usually left in the Driver Store.

Why does the Keyspan USA-19HS driver give Code 39?

With memory integrity on, it usually means Windows blocked the old Keyspan package. Memory integrity off? Then suspect corrupted files, or a package that was never meant for that version of Windows.

Is there a Keyspan USA-19HS driver for Windows on ARM?

No, it's 64-bit x86 only. On ARM, use an adapter that ships an ARM64 driver.

Do I have to turn off memory integrity for the Keyspan USA-19HS driver?

No. Remove the old packages with pnputil, install the Windows 10/11 package, and leave memory integrity on.

Where the Keyspan can't take you

If the adapter comes back after the clean install, you're done and you don't need anything from us. Where we come in is the ports a Keyspan can't reach. For DH-485 there's the 1747-UIC, the USB converter Rockwell no longer makes. DH+ takes the 1784-U2DHP. For MicroLogix, the 1761-CBL-PM02 plugs straight into any RS-232 adapter, or the 9300-USBCBL-PM02 has the USB end built in. And if you just want a second RS-232 adapter on the bench, there's Rockwell's own 9300-USBS. All of it ships with our 2-year warranty.