Re: serial from usb port, cu using /dev/cuau0

From: Mark Moellering <markmoellering_at_psyberation.com>
Date: Tue, 18 Apr 2023 15:41:06 UTC
On 4/18/23 08:32, Gary Aitken wrote:
> Connected a USB to serial dongle to a USB port,
> then a straight-through serial cable to my dsl modem.
>
> as root:
>   cu -h -t -s 9600 -l /dev/cuau0
> or maybe cuaU0
>
> Whether anything is connected to the USB port or not,
> when I issue the cu command, I always get a "connected" response.
>
> On one occasion two days ago, I swear the cu connected to the
> usb-serial and I got a login prompt and poked around the modem.
>
> Assuming that actually happened, how does the system know which
> usb / serial port to use?
>
> This mobo has a serial port with a dongle connected.  It appears
> to be activated in BIOS, as when I direct connect the serial cable
> to it I get a connection to the modem.
>
> But I'm confused as to how I got it to work from a usb port.
> Thanks for any insights,
>
> Gary
>

Gary,

I connect via serial to a firewall, and I discovered that it usually 
comes up with a blank screen.

The command I use is:  cu -l cuaU0 -s 115200

If I hit enter, then the login prompt appears but otherwise, I , like 
you, often see "connected", with an otherwise black screen and no 
prompt.  hope this helps.

-- Mark