US 12,355,553 B2
Diagnostic system and method for network synchronized time in safety applications
Yanbin Zhang, Shanghai (CN); Xiaobo Peng, Shanghai (CN); Sikai Zhang, Shanghai (CN); Steven T. Seidlitz, Eagle, WI (US); and Arun K. Guru, Brookfield, WI (US)
Assigned to Rockwell Automation Technologies, Inc., Mayfield Heights, OH (US)
Filed by Rockwell Automation Technologies, Inc., Mayfield Heights, OH (US)
Filed on Mar. 30, 2022, as Appl. No. 17/709,341.
Prior Publication US 2023/0318728 A1, Oct. 5, 2023
This patent is subject to a terminal disclaimer.
Int. Cl. H04J 3/06 (2006.01)
CPC H04J 3/0661 (2013.01) [H04J 3/062 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of monitoring clock circuits for use in a safety rated application, the method comprising the steps of:
synchronizing a first clock in a first node with a second clock in a second node;
transmitting a first diagnostic message from the first node to the second node at a first time based on the first clock;
transmitting a second diagnostic message from the second node to the first node at the first time based on the second clock;
generating a first diagnostic timestamp in the first node corresponding to receipt of the second diagnostic message;
generating a second diagnostic timestamp in the second node corresponding to receipt of the first diagnostic message;
transmitting the first diagnostic timestamp from the first node to the second node;
transmitting the second diagnostic timestamp from the second node to the first node;
storing a diagnostic value in a buffer for either the first node or the second node, wherein the diagnostic value is determined as a function of the first diagnostic timestamp and the second diagnostic timestamp; and
determining a clock skew between the first clock and the second clock as a function of the diagnostic value in either the first node or the second node.