This is the logic card for the Preferred Access Expander.

This card has the optical isolators, drivers, and other logic required to perform preferred access functions on the Data Hiway.

This card uses a fixed priority approach to granting access to the Hiway. The most recent PAE logic card, 51304207-100, can use either this fixed priority arrangement or a round-robin approach. For heavily loaded Hiways on a Hiway Gateway, the original fixed priority scheme resulted in poor performance, as some preferred device access requests were delayed. The round-robin option of the newer logic card eliminates this problem on heavily loaded Hiways.