Method and Arrangement for Operating Two Redundant Systems

A method for operating an arrangement having two redundant systems each operating in parallel in a cyclic mode, one system of the two systems operating in a productive mode each time and another system of the two systems executing the same task for checking purposes, the method comprising:

• checking reciprocally by the two systems at least one result of a task of a respective other system on a regular basis, each system of the two systems comparing a result of the task of the other system of the two systems with their own result, a detected fault comprising a detected disparity among the results leads to a fault situation being found, with one of the systems being selected or confirmed for the productive mode in the fault situation found;
• picking up at least one respective characteristic variable concerning an operating parameter for each of the systems in multiple or all cycles and using the picked up at least one respective characteristic variable for updating at least one statistical parameter each time;
• correlating a current operating parameter with the associated statistical parameter for each system at least when a disparity between the results of the two systems is found;
• and
• utilizing the system for which the respective current operating parameter differs from the associated statistical parameter less is detected as the correctly operating system as the productive mode.