Distributed process control system with means and method of automatic data base management of broadcast information

摘要

A distributed process control system is shown in which a number of distributed processing units are connected by means of a cable. Portions of the system data base aretransm- itted repetitively while other data is only transmitted upon request. Each of the processors looks at all of the data messages transmitted over the highway and selects only those for storage which relate to its local operations. However, each message also contains a status word, a bit of which can be set to indicate that, for example, an alarm condition is in effect, so that each of the processors can be alerted to this whether or not they would ordinarily be interested in that specific data point. In this way, flexibility of communication of the system is maintained while each local processor is not required to have enough memory to store all the process variables involved.