US 4,057,785 AGranted

Sequence of events recorder and system for transmitting sequence data from a remote station to a master station

AssigneeWestinghouse Electric Corp.

InventorsWilliam E. Furniss, George I. Vancsa, Joseph R. Onufer

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Abstract

Apparatus for detecting and recording status changes of two-state devices in a power network substation, a pipeline substation, or the like. At a substation a remote terminal unit records status changes in its digital memory. When a sequence of status changes occurs, each change is recorded, together with its time of occurrence as measured from the time of occurrence of the first change, thereby reducing the size of memory for recording sequence data. Upon request, data related to a sequence of changes is transmitted to a master station in chronological order of the changes, to simplify processing of such data at the master station. Provision is made to permit the master station to convert elapsed time to real time, and to reduce the time required of the master station to retrieve sequence data from a remote terminal.

Claims22

Dependent claims

System apparatus for detecting and recording a time sequence of status changes of a plurality of two-state devices at each of a plurality of locations, said apparatus comprising:

a remote terminal unit for each of the locations,
means for processing and recording data at a master station in response to data signals received from said remote terminals,
means for transmitting data signals between said remote terminals and said master station under predetermined control conditions,
each of said terminals including first means for periodically detecting the state of each device associated therewith,
second means for comparing the currently detected state of each associated device with the previously detected state of the associated device to detect a difference between such state,
third means for storing the identity and the currently detected state of an associated device when such state differs from the previously detected state, and for storing a representation of the elapsed time at which the difference is detected relative to a reference time point, and
said master station means including means for recording absolute time to enable correlation of transmitted elapsed time data from said remote terminals.

4 more elements

Apparatus for detecting and recording status changes of a plurality of two-state devices, wherein each device is a member of a respective device group having a unique address and including a predetermined number of devices, comprising:

means for periodically detecting the states of the devices of each group, wherein the detected states are represented by a detected status word having a bit corresponding to each device of the group,
storage means for recording a previously detected status word corresponding to each group of devices,
means for comparing each detected status word representing the currently detected states of the devices of a group with the corresponding detected status word in said storage means to detect a difference between such words, and
means for storing the detected status word representing the currently detected status of the devices of a group in storage means when a difference is detected.

1 more element

Dependencies are inferred from the claim text.