This protocol is implemented in semiconductor chips that work with the microprocessors in a network station. The people buying the factory automation equipment do not have to worry about the details of token-passing protocol built into the station. The network manager has to know the concepts of token rotation time and slot time and how to calculate them, in order to set up the network correctly. The data frames that are to be sent from a given station can be classified by their importance. The important frames can be given priority and sent first.
Priority is an optional feature of any given station.
Four classes of priority frames can be sent. Alarm and error messages could be assigned top priority. When the time expires, then the token must be passed on. For each of the lower-priority classes, a token rotation time is specified by the station management. If the actual token rotation time is less than the specified time, the station is allowed to send a priority message.