US Patent No. 10,924,371

METHOD FOR MONITORING A FIRST NODE IN A COMMUNICATIONS NETWORK AND MONITORING SYSTEM


Patent No. 10,924,371
Issue Date February 16, 2021
Title Method For Monitoring A First Node In A Communications Network And Monitoring System
Inventorship Oliver Ellerbrock, Vlotho (DE)
Jens Sachs, Petershagen (DE)
Robert Zutz, Verl (DE)
Assignee Beckhoff Automation GmbH, Verl (DE)

Claim of US Patent No. 10,924,371

1. A method for monitoring a first node in a fieldbus communications network by a second node,wherein the second node of the fieldbus communications network determines at two consecutive time points first and second time values, which are based on an internal timer of the second node, and sends the first and second time values to the first node via the fieldbus communications network, the first and second time values equaling first and second counter values, respectively, which are incremented or decremented on the basis of the internal timer of the second node, each counter value being inserted into a respective message, the messages being sent successively to the first node in accordance with a transfer cycle, the second node having a dual-channel design comprising two processors which monitor each other for malfunctions, both processors determining the first and second time values,
wherein the first node, in response to receipt of the first and second time values, determines third and fourth time values, which are based on a further internal timer of the first node, the third and fourth time values equaling third and fourth counter values, respectively, which are incremented or decremented on the basis of the further internal timer of the first node,
wherein the first node compares a difference between the first and second time values from the second node with a difference between the third and fourth time values from the first node, and
wherein the first node executes a safety-oriented application on the basis of a clock provided by the further internal timer and goes into an error state if the respective differences differ by a defined threshold value, wherein the threshold value depends on the safety-oriented application and one or more respective parameters selected from transfer rate, transmission path, and jitter, and wherein the error state indicates or signifies that execution of the safety-oriented application in the first node is stopped.