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GE Carescape B450 not work on Raspberry Pi Vital Recorder #719

Runyang Fan (2025-09-29 10:05) · 984 view(s) · 2 comment(s)

Hello,
I am trying to use Vital Recorder with a GE Carescape B450 monitor on a Raspberry Pi 5 via an FTDI USB-RS232 adapter. Also I have tried with PL2303 adapter, but the result war similar.

  • On Windows, Vital Recorder connects successfully and starts receiving data from the B450.

  • On Raspberry Pi (Linux), When I run the executable file I installed from your release version,  it repeatedly tried to open the monitor, but always failed. Then I first checked the connection of the port and then try to use sudo cat to read the data from the port. Vital Recorder detects the serial port but never receives any data from the monitor.

So I thought maybe the monitor exepected to recevive something before the streaming began. So I wanted to find out why the windows version worked, so I investigated further with Wireshark on Windows:

  • Vital Recorder sends two initialization frames (0x7E … 0x7E) right after opening the port.

  • Only after these frames does the B450 begin continuous data streaming.

I don't if these functions are also contained in the Raspberry Pi version. Therefore, I would like to ask:

  • Could it be that the Linux build of Vital Recorder does not fully implement the RS232 initialization for GE monitors (RTS/CTS, DTR, or the init packet sequence)?

  • Is there a workaround, or can this handshake be added to the Linux version? 

Thank you for your help.

Yasen (2025-10-18 08:41)
Hello, Runyang Fan. Sorry for off topic, but can you give some hints on how to install VitalRecorder on Raspberry Pi4 or 5? Maybe you can create a new discussion on this topic. I`ve searched for instructions but cant find. VitalRecorder Zero manual lead me to ...Zero :-) . There was a topic on this an year ago, but no progress (Vital Recorder for Raspberry Pi #659)
Thanks in advance
Simon Orlob (2026-09-05 17:57)
We hit the same symptom with a GE Bx50 on x86 Linux (Vital Recorder 1.19.22, AppImage, Ubuntu, ATEN/Prolific PL2303 adapter): fine on Windows, on Linux the device never gets data.
For us the cause was the **port name format**, not the serial layer. Posting in case it is the same thing, and because the failure gives you nothing to go on.

## Could this be your port name?
Vital Recorder expects the port as a bare suffix, with no path and no `tty`:

USB0 opens /dev/ttyUSB0

These all fail for us:

ttyUSB0
/dev/ttyUSB0
/dev/serial/by-path/pci-0000:...-port0

The reason is that vitalrecorder appends the literal `/dev/tty` to whatever you enter.
So `USB0` becomes `/dev/ttyUSB0`, and `/dev/ttyUSB0` becomes `/dev/tty/dev/ttyUSB0`.

Unfortunately we could not find it stated anywhere in the documentation or the UI.

## Request to the developers

Three small changes would have saved this thread and ours:

1. **Truncate or accept a leading path in the port entry.** concatenate `/dev/tty` + name; stripping a leading `/dev/tty`, or accepting an absolute path as-is when
the entry starts with `/`, would make every natural user input work.
2. **Report the failure.** `[dev] open failed` should reach the GUI, with the path that was actually attempted. "off" and a black field is not diagnosable.
3. **Document the format,** or put a placeholder like `USB0` in the Port Name field. The Linux manual only gives `COM1` / `ETH1` examples.