Here’s one way to solve that problem.
By adding some rules to the /etc/udev/rules.d directory, you can force Linux to always use the same
USB serial device which you can refer to by a more meaningful name.
e.g. You have 2 USB-to-RS485 adapters. One is FTDI based, the other CH340 based.
You want to use them both on the same Raspberry Pi to read two modbus instruments.
The problem is sometimes the OS enumerates the adapters in opposite order. i.e. what was
/dev/ttyUSB0 at last boot time is now /dev/ttyUSB1 and vice-versa.
Adding…
NOT saying implementing a backup solution is easy, just addressing the USB drive part of the problem
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