Time-critical data transmission in the Foundation Fieldbus

The data link layer (DLL) of Foundation Fieldbus (FF) includes both token-passing and scheduling services. Periodic data are transmitted via the scheduling service, while time-critical and time-available data are transmitted via the token-passing service. This study develops an analytical model of the token-passing service. The analytical model is used to determine which network parameters will satisfy the delay requirement of time-critical data within pre-specified design constraints.