From Technologic Systems Manuals

Depending on which baseboard the TS-4900 is used with, the OTG port may be usable as host, or it may be brought out to a MicroAB port allowing it to be host or device. Several devices are compiled into the default kernel. Additional devices can be compiled into the kernel by following the section here.

USB Serial

modprobe g_serial use_acm=1

This will create a /dev/ttyGS0. See the kernel documentation for more information:

USB Ethernet

modprobe g_ether

This provides a usb0 network interface which simulates an ethernet network connection between the host pc and the i.MX6.