Adaptive alarm controller changes multiple inputs to industrial controller in order for state word to conform with stored state word

• US 5,089,984 A
• Filed: 05/15/1989
• Issued: 02/18/1992
• Est. Priority Date: 05/15/1989
• Status: Expired due to Term

• Current Assignee: Allen-Bradley Company (Rockwell Automation, Inc.)
• Original Assignee: Allen-Bradley Company (Rockwell Automation, Inc.)
• Inventors: Klimas, Edward J., Struger, Odo J.
• Primary Examiner(s): Lee, Thomas C.
• Assistant Examiner(s): GECKIL, MEHMET B
• Application Number:
  US07/352,189
• Time in Patent Office: 1,009 Days
• Field of Search: 364/200 MS File, 364/900 MS File, 364/185, 364/148
• US Class Current: 700/12
• CPC Class Codes: G05B 19/058 Safety, monitoring
• CPC Class Codes: G05B 2219/14004 On error I-O control state is substituted by actual state to continue
• CPC Class Codes: G05B 2219/14074 Signature analysis, recorded states, zones are compared to actual
• CPC Class Codes: G06F 11/0796 Safety measures, i.e. ensuring safe condition in the event of error, e.g. for controlling element
• CPC Class Codes: G06F 11/28 by checking the correct order of processing G06F11/08 - G06F11/26 take precedence; monitoring patterns of pulse trains H03K5/19

Abstract

An industrial controller monitors its state as comprised of selected inputs and outputs for a present time period and a previous time period. Each current state is compared to a previously acquired list of stored states to detect possible errors in inputs to the industrial controller and to find the closest match of the current state to a previously stored state. This "closest match word" is used to identify erroneous inputs to the industrial controller and to determine whether the controlled process must be halted. The closest match word may be substituted for the current state to permit the controlled process to continue.

Claims

1. A heuristic error correction system for an industrial controller with multiple inputs and outputs for controlling a process having at least one process state comprising:

input means for receiving certain of the multiple inputs and outputs from the industrial controller as status input signals;

a transition detector means coupled to the input means for collecting the status input signal into a state word and for detecting changes in the process state as indicated by changes in the state word;

a content addressable memory receiving the state word from the transition detector and responsive to changes in the state word indicated by the transition detector and, in a learn mode, for storing the state word and, in an alarm mode, for identifying whether the state word has been previously stored and if not for producing a miss signal;

signal means for receiving the miss signal from the content addressable memory and for signalling when the heuristic error correction system is in the alarm mode and the state word cannot be identified as previously stored; and

a correcting means responsive to said signal means for changing the multiple inputs to the industrial controller so that ht estate word conforms to a stored state word.

2. The heuristic error correction system of claim 1 wherein the correcting means change the multiple inputs to conform the state word to that stored state word requiring the fewest changes in the multiple inputs.

3. The heuristic error correction system of claim 1 including a user-defined critical status input table communicating with the correcting means and the industrial controller and identifying the status input signals causing the state word not to match a stored state word and stopping the process if the identified status input signals are in the critical status input table.