To look like Ethernet I/O like the GS1/GS2/GS3, you need to have a GSEDRV100 module. It knows how to talk "Ethernet I/O" protocol with Do-more. The native GS4 does not.
If you want to do everything raw (where there is no Do-more Ethernet I/O driver for the GS4, no GSDrive structure, no GSREGRD/GSREGWR instruction support), then you must do everything by hand using MRX/MWX.
GSEDRV100 makes it easy (but added cost).