A long-haul process control plant includes a process control system which controls industrial processes running within the plant, and a safety instrumented system, servicing the process control system, which detects safety-related problems within the plant and communicates safety messages within and between portions of the process plant, e.g., to effect a trip or other mitigating action. To transmit safety messages between remotely located portions of the process plant via a low-bandwidth long-haul link, a safety data concentrator combines individual safety messages generated by the safety logic solvers disposed at one portion of the plant into a concentrated safety message, and transmits the concentrated safety message to a safety data de-concentrator in the remote portion of the plant. The safety data de-concentrator recovers the individual safety messages from the concentrated safety message and communicates the recovered safety messages to recipient safety logic solvers disposed at the remote portion of the plant.