Serial Snatcher

ifoundreverse · 08-12-2021, 03:57 PM

Hi,

I was using bCNC today (but has also happened before whilst using UGS) when my CNC machine froze, so did bCNC. It happened a few times, all at different places in the gcode execution, so I ran bCNC from a terminal, after it froze again and eventually returned output (I didn't copy it, but will next time) it looked like the python script erred out because it lost its handle to the serial device it was using (/dev/usb0). On restarting after a crash, the handle to the device is still there and another device had been used, and so on until after a restart.

- How do I track down what else may be taking over the serial device?
- What logs should I be looking at?

- Do I remember something about being able to assign a priority when starting an application, if so how?

... I'm currently using a Fedora 32 desktop for this task...

Many thanks

business_kid · 08-14-2021, 02:15 PM

Hello, ifoundreverse, & welcome to LQ.

I gather something of yours uses CNC - not much more. Have a read of this:How_To_Ask_a_Question

Post again, give us details of everything. Is this an old Industrial PC or some usb-serial conversion? If a program doesn't exit, it doesn't release the serial port. It may still be running and hogging resources. But I can't see what you have, and I don't know what it is. You have to tell me

TB0ne · 08-14-2021, 02:51 PM

Quote:

Originally Posted by ifoundreverse

Hi,
I was using bCNC today (but has also happened before whilst using UGS) when my CNC machine froze, so did bCNC. It happened a few times, all at different places in the gcode execution, so I ran bCNC from a terminal, after it froze again and eventually returned output (I didn't copy it, but will next time) it looked like the python script erred out because it lost its handle to the serial device it was using (/dev/usb0). On restarting after a crash, the handle to the device is still there and another device had been used, and so on until after a restart.

- How do I track down what else may be taking over the serial device?
- What logs should I be looking at?
- Do I remember something about being able to assign a priority when starting an application, if so how?

... I'm currently using a Fedora 32 desktop for this task...

I would start with looking at the system logs for Fedora when this problem occurs. Running "journalctl -xe" may give you something, but as business_kid says, without an actual error message it's hard to say anything useful. If you suspect something else is grabbing the serial device, you can install and run minicom, and leave that terminal window open for a while, and see if it drops. Is there any pattern to this? Does it happen after xxx minutes every time, or a certain number of instructions?

You also say /dev/usb0....are you using a USB to serial device? If so, check for (and use if present), the /dev/ttyUSB0 device instead. The direct USB device may be getting confused if the USB bus refreshes (new device plugged in? Device removed?), and the USB-to-Serial driver may be more solid.