For those who have multiple serial to USB devices that they need to connect to, INDI serial driver has an Auto Search feature that tries to connect to each system port available, initiates a handshake to check if there is proper communication, and if not it moves on to the next port in the list.

The problem with this is that multiple driver would try to access the same ports at the same time. For example, suppose we have a mount, focuser, and auxiliary drivers and we have system ports /dev/ttyUSB0, /dev/ttyUSB1, /dev/ttyUSB2, so each driver would try /dev/ttyUSB0 and you can have multiple drivers connecting to the same port at the same time. You can see how this can lead to collision of the traffic data getting exchanged.

To resolve this issue, INDI now locks the port when it is open by a process. This would make the port appear BUSY when another driver tries to access it, so the driver can wait a bit to retry connection, or moves on to the next port in the list. If the handshake is successful, the driver keeps the port to itself. Otherwise, it closes the port and releases it so that other drivers can access it.

This change can affect numerous drivers and therefore testing is necessary. Please share your experiences. So far, I've seen one report about connecting to [url=https://indilib.org/forum/mounts/4624-now-celestron-gps-not-connect.html=Celestron driver[/url].

Ok so it turns out I indeed introduced a very stupid omission in the code that is fixed now. Please please either test nightly later today or compile from git master.