@mikeyh RexArc command line utility is installed along with the REXYGEN Development Tools (see the installation folder - default: C:\Program Files\REX Controls\REXYGEN 18.104.22.16862\Bin\RexArc.exe)
one more thing - did you try to use ARS function block? https://www.rexygen.com/doc/ENGLISH/MANUALS/BRef/ARS.html
It might help you.
@kotrbus Hi Pavel, there is just RexArc for now. We are aware that it does not have that much publicity - we would like to improve it in next release.