Sequence of events detection in a process control system

A sequence of events detection system comprising:

• a database;
• a master clock;
• one or more primary devices communicatively coupled to the master clock, each primary device including a first counter and a secondary clock time synchronized to the master clock;
• and
• a plurality of secondary devices each communicatively coupled to one of the primary devices, each secondary device including an event buffer, a second counter, and a processor programmed to, upon the detection of an event, store an indication of the event in the event buffer and store the value of the second counter at the time of the detection of the event as an event counter value in the event buffer and further programmed to send an event message to an associated one of the first devices, the event message including the indication of the event and an indication of the event counter value for the event;
• wherein at least one of the first devices further includes a processor programmed to use the first counter, the secondary clock and the indication of the event counter value within the event message to assign an absolute time to the detection of the event.

A sequence of events detection system for use in a process control system having a database, a master clock, a primary device communicatively coupled to the master clock and including a first processor, a first memory, a first counter and a secondary clock time synchronized to the master clock, and a secondary device communicatively coupled the primary device and including a second processor, a second memory, an event buffer and a second counter, the sequence of events detection system comprising:

• a first routine stored in the first memory and adapted to be executed on the first processor;
• and
• a second routine stored in the second memory and adapted to be executed on the second processor which, upon the detection of an event by the secondary device, stores an indication of the event in the event buffer and stores the value of the second counter at the time of the detection of the event as an event counter value in the event buffer and which further sends an event message to the first device, the event message including the indication of the event and an indiction of the event counter value for the event;
• wherein the first routine is adapted to use the first counter, the secondary clock and the indication of the event counter value to assign an absolute time to the detection of the event.

A method of detecting events within a process control system having a database, a master clock, a first device communicatively coupled to the master clock and including a first processor, a first memory, a first counter and a secondary clock and a second device communicatively coupled the primary device and including a second processor, a second memory, an event buffer and a second counter, the method comprising the steps:

• time synchronizing the secondary clock to the master clock;
• storing an indication of an event in the event buffer and storing the value of the second counter upon detection of the event as an event counter value in the event buffer;
• sending an event message from the second device to the first device including the indication of the event and an indication of the event counter value;
• and
• using the first counter, the secondary clock and the indication of the event counter value to assign an absolute time to the detection of the event.