Method for Synchronous Execution of Programs in a Redundant Automation System

• US 20130185726A1
• Filed: 01/11/2013
• Published: 07/18/2013
• Est. Priority Date: 01/12/2012
• Status: Abandoned Application

• Current Assignee: Siemens AG
• Original Assignee: Siemens AG
• Inventors: HARMS, Fritz, VEITH, Christian
• Application Number:
  US13/739,571
• Publication Number:
  US 20130185726A1
• Time in Patent Office: Days
• US Class Current: 718/102
• CPC Class Codes: G05B 19/0426 Programming the control sequence
• CPC Class Codes: G05B 19/41865 characterised by job scheduling, process planning, material flow
• CPC Class Codes: G05B 9/03 with multiple-channel loop, i.e. redundant control systems
• CPC Class Codes: G06F 9/52 Program synchronisation; Mutual exclusion, e.g. by means of semaphores
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A method for synchronous execution of programs in a redundant automation system comprising at least two subsystems, wherein at least one request for execution of one of the programs is taken as a basis for starting a scheduling pass, and during this scheduling pass a decision is taken as to whether this one program is executed on each of the subsystems. Suitable measures are proposed which allow all programs a fair and deterministic share of the program execution based on their priorities.

Claims

1. A method for synchronous execution of computer programs in a redundant automation system comprising a plurality of subsystems, wherein at least one request for execution of one computer program of the computer programs forms a basis for starting a scheduling pass during which a decision is performed to determine whether the one computer program of the computer programs is executed in sync on each of the plurality of subsystems, the method comprising the steps of:

recording, by each of the plurality of subsystems, for each of the computer programs, a local execution time which has already accrued, the local execution time indicating for how long a respective computer program of the computer programs has already been executed on a respective subsystem of the plurality of subsystems; and

performing the decision during the scheduling pass based on a respective recorded accrued local execution time and one of a respective prescribable and prescribed maximum execution time for the requested one computer program of the plurality of computer programs, the requested computer program being unexecuted on the plurality of subsystems if an accrued local execution time one of reaches a respective maximum execution time and exceeds the respective maximum execution time.

2. The method as claimed in claim 1, further comprising the steps of:

a) interchanging by the plurality of subsystems, during the scheduling pass, information which comprises the respective accrued local execution time for the requested one computer program of the plurality of computer programs on the respective subsystem;

b) suspending the requested one computer program on each subsystem of the plurality of subsystems if the respective accrued local execution time of the requested one computer program of the plurality of computer programs has exceeded a respective provided maximum execution time for the requested one computer program of the plurality of computer programs in one subsystem of the plurality of subsystems;

c) resetting accrued local execution times in each subsystem of the plurality of subsystems if there is no further program request for a prescribed period of time after the scheduling pass, the suspension of the requested one computer program of the plurality of computer programs in each subsystem of the plurality of subsystems being re-lifted and steps a) and b) being repeated for the request for the one computer program of the plurality of computer programs during a further scheduling pass; and

d) repeating steps a) and b) for the request for the further computer program of the plurality of computer programs during a further scheduling pass if there is a further request for the execution of the further computer program of the plurality of computer programs for a prescribed period of time after the scheduling pass.

3. The method as claimed in claim 2, wherein if there is a request on one of the subsystems of the plurality of subsystems, then the subsystem with the request is used to transmit to another subsystem a message which indicates to the other subsystem the accrued local execution time for the requested one computer program on the one subsystem of the plurality of subsystems, and the already accrued local execution time for the requested one program from the other subsystem is transmitted to said one subsystem from said other subsystem.

4. An automation system configured for synchronous execution of programs comprising:

a plurality of subsystems; and

a scheduler which takes at least one request for execution of a program as a basis for starting a scheduling pass and, during this scheduling pass, decides whether the program is executed on each of the plurality of subsystems;

wherein the automation system is configured to;

use each of the at plurality of subsystems to record, for each of the programs, a local execution time that has already accrued, which indicates for how long a respective program has already been executed on a respective subsystem of the plurality of subsystems; and

perform the decision during the scheduling pass based on a respective recorded accrued local execution time and one of a respective prescribable and prescribed maximum execution time for the requested program, the requested program being unexecuted on the plurality of subsystems if one accrued local execution time one of reaches a respective maximum execution time and exceeds the respective maximum execution time.

5. The automation system as claimed in claim 4, wherein the automation system is configured to implement the steps of:

a) interchanging by the plurality of subsystems, during the scheduling pass, information which comprises the respective accrued local execution time for the requested one computer program of the plurality of computer programs on the respective subsystem;

b) suspending the requested one computer program on each subsystem of the plurality of subsystems if the respective accrued local execution time of the requested one computer program of the plurality of computer programs has exceeded a respective provided maximum execution time for the requested one computer program of the plurality of computer programs in one subsystem of the plurality of subsystems;

c) resetting accrued local execution times in each subsystem of the plurality of subsystems if there is no further program request for a prescribed period of time after the scheduling pass, the suspension of the requested one computer program of the plurality of computer programs in each subsystem of the plurality of subsystems being re-lifted and steps a) and b) being repeated for the request for the one computer program of the plurality of computer programs during a further scheduling pass; and

d) repeating steps a) and b) for the request for the further computer program of the plurality of computer programs during a further scheduling pass if there is a further request for the execution of the further computer program of the plurality of computer programs for a prescribed period of time after the scheduling pass.

6. The automation system as claimed in claim 5, wherein the automation system is further configured such that if there is a request on one subsystem of the plurality of subsystems then the subsystem with the request transmits to another subsystem a message which indicates to the other subsystem an accrued local execution time for the requested program on the subsystem of the plurality of subsystems, and the other subsystem transmits an already accrued local execution time for the requested program from the other subsystem to the subsystem of the plurality of subsystems.