You cannot import a DLL into the MC4N-ECAT. It has a BASIC compiler and IEC-61131-3 Compiler. The Operating System is a special Trio designed OS with large motion library. If you connect a PC to the MC4N-ECAT using Ethernet, then you can install a DLL in the PC that will communicate with the MC4N.

Download the TrioPC Motion DLL from the Trio Website here: TrioPC Motion