Distributed equipment arbitration in a process control system

A distributed arbitration system in a process control system that includes a plurality of process control devices, the distributed arbitration system comprising:

• a plurality of software objects corresponding to the plurality of process control devices, the software objects defining ownership arbitration queues for storing arbitration data associated with the corresponding control devices including a first software object defining a pending acquisitions queue and an owned equipment queue and a second software object defining a pending requests queue and an owned-by queue;
• one or more processors for executing the software objects, the software objects configured such that when executed by the one or more processors the software objects arbitrate ownership requests amongst themselves, the first software object adapted to generate arbitration data in the form of an arbitration token when a first process control device corresponding to the first software object attempts to acquire a second process control device corresponding to the second software object, the first software object adapted to store a copy of the arbitration token in the pending acquisitions queue and adapted to communicate a copy of the arbitration token to the second software object, and the second software object is adapted to receive the copy of the arbitration token and store the copy of the arbitration token in the pending requests queue, wherein the second software object itself determines whether the second process control device may be acquired by the first process control device and, upon making a determination that the second process control device may be acquired by the first process control device, the second software object sending a copy of the arbitration token back to the first software object in a confirmation message indicating that the second software object has allowed the first process control entity to acquire the second process control entity.

A method of arbitrating ownership of a first process control entity over a second process control entity comprising:

• the first process control entity requesting ownership of the second process control entity by sending a first arbitration token to the second process control entity and storing a copy of the first arbitration token in a pending acquisitions queue of the first process control entity;
• the second process control entity storing the first arbitration token in a pending requests queue of the second process control entity and determining whether the second process control entity is available to be acquired by the first process control entity;
• the second process control entity submitting to the acquisition of the second process control entity by the first process control entity by moving the first arbitration token from the pending requests queue of the second process control entity to an owned by queue of the second process control entity when the second process control entity determines that it is available to be acquired by the first process control entity;
• and
• the second process control entity sending a copy of the first arbitration token to the first process control entity in a message indicating that the second process control entity has submitted to the acquisition of the second process control entity by the first process control entity.

A method of implementing a distributed equipment ownership arbitration system in a process control system that includes a plurality of process control devices and in which one or more of the process control devices must exercise ownership over one or more other process control devices to perform one or more process related tasks, the method comprising:

• implementing a plurality of control modules associated with the process control devices, the control modules defining arbitration queues for storing arbitration data relating to ownership of the process control devices with which the control modules are associated;
• generating an arbitration token at a first control module associated with a request by the first control module for a process control device associated with the first control module to acquire a process control device associated with a second control module;
• storing a copy of the arbitration token in a pending acquisitions queue defined by the first control module,
• sending the request to acquire the process control device associated with the second control module from the first control module to the second control module, the request including the arbitration token;
• storing the arbitration token in a pending requests queue defined by the second control module;
• determining whether the process control device associated with the second control module is available to be acquired by the process control device associated with the first control module;
• moving the arbitration token from the pending requests queue defined by the second control module to an owned by queue defined by the second control module indicating that the process control device associated with the second control module has been acquired by the process control device associated with the first control module;
• and
• sending a copy of the arbitration token back to the first control module in a message indicating that the process control device associated with the first control module has acquired the second control module.