Location dependent control access in a process control system

An access control system for use in a process environment, the access control system comprising: a computer readable medium; and a first routine stored on the computer readable medium which, when executed by a processor, determines the geographic position of an authorized user operating a portable communicator within the process environment based on data received from one of the portable communicator or electronic location device carried by the authorized user;a second routine stored on the computer readable medium which, when executed by a processor, limits access of the authorized user to data within the process environment based on the determined geographic position of the portable communicator with respect to the plurality of control areas; and a third routine stored on the computer readable medium which, when executed by a processor, receives from a user of a portable communicator data indicative of the authorization level of the user.