Subsurface not communicating with computer

[tool man]

when i try to import my dives from my Ratio IX3M dive computer I get "unable to open Com6" I checked my device manage and the is the right COM Port. when i check the log file i see "ERROR: Access is denied (5) [in src/serial_win32.c:325 (dc_serial_open)]"

i tried 2 different USB cables, pausing my anti virus, turning off bluetooth, 

the computer shows it is charging, but no data transfer.

how do i fix this?

[Michael Keller]

Hi Tool.

What version of Subsurface are you using?


What version of the operating system (presumably Windows) are you using?


How is your dive computer connected to your computer?


Ngā mihi

  Michael Keller

[tool man]

I'm using Subsurface 6.0.5504

Windows 11

Connected via USB cable

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[Jason Bramwell]

How have you verified that the com port is correct? If you unplug the cable does that com port disappear but it reappears when you plug the cable back in? I think that’s pretty normal behaviour with some cables that dive computers use.

I’m just wondering if you are seeing a com port that’s something else unrelated.

Jason

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On 7 Feb 2026, at 22:46, tool man <toolm...@gmail.com> wrote:



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[Jason Bramwell]

Another thing, are you in PC mode on the dive computer? There is no mention of this in your original post.

Also, have you tried to see if this working in the Divelogger software too? Might be worth trying that too to see if this could be a computer or cable issue rather than a Subsurface issue.

Jason 

Sent from my iPhone

On 7 Feb 2026, at 23:22, Jason Bramwell <jb2...@gmail.com> wrote:

How have you verified that the com port is correct? If you unplug the cable does that com port disappear but it reappears when you plug the cable back in? I think that’s pretty normal behaviour with some cables that dive computers use.

[tool man]

i check device manager and see what com port is being used, unplug the cable, it disappears, plug it back in and it reappears. I havent tried another program as i don't have another one installed. I will try that

[Jason Bramwell]

Ok that sounds right for identifying the correct COM port, that is what I would expect.

Are you entering the dive computer into PC Mode? You need to tell it to listen for a computer.

Jason

Sent from my iPhone

On 8 Feb 2026, at 04:06, tool man <toolm...@gmail.com> wrote:

i check device manager and see what com port is being used, unplug the cable, it disappears, plug it back in and it reappears. I havent tried another program as i don't have another one installed. I will try that

To view this discussion visit https://groups.google.com/d/msgid/subsurface-divelog/e24ad45a-2128-4038-90a2-67c72a930e14n%40googlegroups.com.

[Jef Driesen]

The most common reason for the access denied error is when another application
has already opened the serial port (due to exclusive access). Some applications
(not only dive computer applications) try to open serial ports immediately when
they appear on the system in order to detect their own devices. If you have such
an application running, you have to exit it first, or wait long enough to let it
realize it's not the device it is looking for and release the serial port again.

For the ix3m dive computers, the serial port appears as soon as the USB cable is
connected, but you can only communicate with it after enabling PC mode (System
-> PC mode menu). If you forget to enable PC mode, opening the serial port
should work fine, but you won't get any response from the dive computer.
Certainly not the access denied error you reported.

Jef

[tool man]

It is in PC Mode. I'm thinking its a busy serial port, just trying to figure out what is using it. I installed Divelogger4 and it has the same issue. its NOT just Subsurface. Thanks for ther help.