To double-check, are you sure the problem is not in the Arduino sketch? Python exhibiting the same behavior tips to that IMO. A quick search yields a similar issue due to using an int for larger baud values:

https://arduino.stackexchange.com/questions/67568/serial-port-fails-with-speeds-greater-than-19200

On Jun 27, 2025, at 2:51 AM, Jim Ruxton <jim.ruxton@gmail.com> wrote:


I'm not clear how this works. Because if I change the baud rate it definitely stops any communication between the laptop  and the Arduino so baud rate must have some meaning in this case. I also tried using a python program I wrote and got the same behaviour  of working up to 19200 then stopping so I don't think it's an issue with Pure Data. Maybe a cable issue?

Note that Arduino is usually (or always?) connected through an USB device
which emulates a serial device (hence the comport).

In this case the baud rate has no meaning (the baud rate is only used by
physical UARTs).

Le jeu. 26 juin 2025 à 00:06, Antoine Rousseau <antoine@metalu.net> a
écrit :

> With the latest comport 1.3 (available on Deken) you can set the baud
> rate  up to 4000000, if your system allows it. See
> https://git.iem.at/pd/comport
>
> Le mer. 25 juin 2025 à 22:53, Alexandros Drymonitis <adrcki@gmail.com> a
> écrit :
>
>> How did you find such a limitation? You can use it with a 115,200 baud
>> rate just fine on any OS (including Linux).
>>
>> On 6/25/25 23:50, Jim Ruxton wrote:
>> > I'm using the comport object to speak to an Arduino. I'm finding the
>> > fastest baud rate I could use was 19200.  I'm on Linux. Would anyone
>> > know if this is a limitation of the object in Linux or if there is
>> > something else going on. I'd like to send data faster if possible.
>> >
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--------
Dan Wilcox
danomatika.com
robotcowboy.com