Is there a limit on the number of com ports the IDE can display

As the title suggests, I was wanting to work on a "quick project", so I plugged in a new Uno into my PC.
I already had 5 other devices that register as COM ports connected (I will say Serial device from now on). So this new device was the 6th serial device to be connected.

However, the Arduino IDE (1.8.13 on Windows 10) did not show this 6th device in the "tools/port..." menu.

So, is there an upper limit as to the number of devices that the Ardunio IDE will display in the "tools/port..." submenu?

If so, and it appears to be so, why??

Following are some more details.

If I removed one of the other serial devices to "make room" for the new device, the tools/port menu updated to show the 4 serial devices that were connected. If I then plugged in this "new quick project" Uno, then it correctly showed up in the "tools/port..." menu. Thus, it is reasonable to assume that this particular Uno is functional (indeed I could upload the blink program to it and it ran just fine).

Make room (COM14) connected (after COM11 was already connected)
Quick project (COM11) connected
(Sorry, I tried to include 4 images of the combinations of the devices connected/disconnected, but the editor would only permit me to include one)

Note that COM14 does not appear in the above image. However, if I use a python script that enumarates all of the serial ports, you will note that 6 devices are present and that these match what is shown in the Arduino IDE + the missing COM14.

C:\Users\gm310509>python -m -v
    desc: USB Serial Device (COM3)
    hwid: USB VID:PID=15BA:000C SER=OL212AD00002757 LOCATION=1-5.2
    desc: Arduino Mega 2560 (COM7)
    hwid: USB VID:PID=2341:0042 SER=5573530343435110A072 LOCATION=1-2
    desc: Arduino Uno (COM9)
    hwid: USB VID:PID=2341:0043 SER=75736303336351618001 LOCATION=1-5.1
    desc: Arduino Leonardo (COM10)
    hwid: USB VID:PID=2341:8036 SER=8
    desc: Arduino Uno (COM11)
    hwid: USB VID:PID=2341:0043 SER=85035303038351D07140 LOCATION=1-5.4.2:x.0
    desc: Arduino Uno (COM14)
    hwid: USB VID:PID=2341:0043 SER=85035303038351D0C150 LOCATION=1-5.4.1
6 ports found


Again, my question is whether there is some sort of limit that the Arduino applies when listing the COM ports in the tools/port... submenu?
If so, and it appears to be so, why??

I've never heard of such a limit and I regularly have more ports than this on my computer, with never an observation of this issue. There certainly isn't an intentional limit.

However, I have seen some rare reports of a port not appearing in the Arduino IDE's Tools > Port menu even though it is shown elsewhere (i.e., Windows Device Manager). Unfortunately, I don't know what the cause is of that and I also don't know the solution.

I would recommend you to try updating to the latest Arduino IDE 1.8.15 to see if the behavior is different. There was likely some relevant development over the ~year that passed between the 1.8.13 and 1.8.15 releases.

Bingo! I finally got some time (sort of) to get back to this.

I upgraded and as i said, Bingo! 6 devices show up in the ports sub-menu.

It would be kinda nice if the IDE notified us of any updates - rather like it does for boards and libraries.

I'm glad to hear it's working with 1.8.15!

The IDE should notify you that a new version is available. Do you have File > Preferences > Check for updates on startup checked?

I do have that checked. Perhaps the new version of the IDE will also now check for new versions of the IDE (in addition to boards and libraries).


I have switched that off :smiley: Far too annoying and it might break things :wink:

There is that - in my case however, it would have fixed something.

Swings and roundabouts I guess. :slightly_smiling_face:

At least if it notified you, you could ignore it. But I think that implicit in your comment is the thinking that it would be good if there was the option to ignore it (i.e. temporarily disable the notification) until maybe the following release comes out, a couple of weeks or something like that.

I can't believe it. The problem is back - even with version 1.8.15 of the IDE.
I don't know what changed between yesterday and just now, but no matter what, the IDE seems to only want to display the first 5 devices that it sees. Whereas yesterday, it definitely displayed all 6 devices.
Frustrating, but I guess I will have to live with it. :frowning: