fedefranc [1] filed a request to merge libmodbus-dev [2] into libmodbus [3]:
The two packages provide the same. the libmodbus author (https://github.com/stephane/libmodbus) is now distributing release files via github and no longer distinguish between dev/stable release. [1] https://aur.archlinux.org/account/fedefranc/ [2] https://aur.archlinux.org/pkgbase/libmodbus-dev/ [3] https://aur.archlinux.org/pkgbase/libmodbus/