Currently there is little information on the EcoLink.
Is is a standard ISA card that works on older PCs running DOS 3. It appears to have problems on anything later, though I'm not quite sure why.
Because the older PCs were not fully able to keep up with the 2MHz events that the 68B54 generates, and because there doesn't seem to be an awful lot of standardisation to the ISA bus timing, the EcoLink actually contains a 6502 processor on-board which handles the network side of things.
The 6502 places Econet data into part of it's 32K dual-port RAM, for access by the host computer when it is able. The host computer also accesses the RAM in order to download the software for the 6502.