Hello,
please see the help for the AsUSB library
B&R Online Help (br-automation.com)
Basically FAT12, 16 and 32 are supported. This Filesystems then also limit the size of the USB Sticks which (If I remember correctly) is 2 Terabyte for FAT32)
Also our PLCs do support hotswap but please note that writing to the stick and disconnecting it will cause damaged files or even a damaged file system on the stick.