Patent Application
20170364424
This disclosure relates generally to the use of redundant devices in industrial process control and automation systems and other systems. More specifically, this disclosure relates to hardware assist mechanisms for alive detection of redundant devices.
Industrial process control and automation systems are often used to automate large and complex industrial processes. These types of systems routinely include sensors, actuators, and controllers. Some of the controllers receive measurements from the sensors and generate control signals for the actuators. Other controllers perform higher-level functions, such as planning, scheduling, and optimization operations.
Equipment redundancy and fault tolerance are often desired in an industrial process control and automation system. For example, controllers that receive sensor measurements and generate actuator control signals are often arranged in redundant pairs. One controller in a redundant pair typically operates in a primary mode and actively controls an industrial process (or portion thereof). Another controller in the redundant pair typically operates in a backup or secondary mode and, upon a fault or other problem with the primary controller, transitions to the primary mode.
This disclosure provides hardware assist mechanisms for alive detection of redundant devices.
In a first embodiment, an apparatus includes a first hardware assist device and at least one processing device. The first hardware assist device includes at least one transmitter configured to transmit at least one first signal to a second hardware assist device of a redundant second apparatus. The at least one first signal indicates to the second hardware assist device that the apparatus is functional. The first hardware assist device also includes at least one receiver configured to receive at least one second signal from the second hardware assist device. The at least one second signal indicates to the first hardware assist device that the second apparatus is functional. The first hardware assist device further includes a timer configured to control a driver in order to block transmission of the at least one first signal in response to a fault associated with the apparatus. The at least one processing device is configured to perform one or more actions in response to a loss of the at least one second signal from the second apparatus.
In a second embodiment, a system includes first and second devices forming at least part of a redundant set of devices. The first device includes a first hardware assist device and at least one processing device. The first hardware assist device includes at least one transmitter configured to transmit at least one first signal to a second hardware assist device of the second device. The at least one first signal indicates to the second hardware assist device that the first device is functional. The first hardware assist device also includes at least one receiver configured to receive at least one second signal from the second hardware assist device. The at least one second signal indicates to the first hardware assist device that the second device is functional. The first hardware assist device further includes a timer configured to control a driver in order to block transmission of the at least one first signal in response to a fault associated with the first device. The at least one processing device configured to perform one or more actions in response to a loss of the at least one second signal from the second device.
In particular embodiments, the second device includes the second hardware assist device and at least one second processing device. The second hardware assist device includes at least one second transmitter configured to transmit the at least one second signal to the first hardware assist device. The second hardware assist device also includes at least one second receiver configured to receive the at least one first signal from the first hardware assist device. The second hardware assist device further includes a second timer configured to control a second driver in order to block transmission of the at least one second signal in response to a fault associated with the second device. The at least one second processing device is configured to perform one or more actions in response to a loss of the at least one first signal from the first device.
In a third embodiment, a method includes, at a first hardware assist device associated with a first apparatus, transmitting at least one first signal to a second hardware assist device of a redundant second apparatus. The at least one first signal indicates to the second hardware assist device that the first apparatus is functional. The method also includes, at the first hardware assist device associated with the first apparatus, receiving at least one second signal from the second hardware assist device. The at least one second signal indicates to the first hardware assist device that the second apparatus is functional. The method further includes, at the first hardware assist device associated with the first apparatus, controlling a driver in order to block transmission of the at least one first signal in response to a fault associated with the first apparatus. In addition, the method includes performing one or more first actions in response to a loss of the at least one second signal from the second apparatus.
In particular embodiments, the method also includes, at the second hardware assist device, transmitting the at least one second signal to the first hardware assist device, receiving the at least one first signal from the first hardware assist device, and controlling a second driver in order to block transmission of the at least one second signal in response to a fault associated with the second apparatus. The method further includes performing one or more second actions in response to a loss of the at least one first signal from the first apparatus.
Other technical features may be readily apparent to one skilled in the art from the following figures, descriptions, and claims.
For a more complete understanding of this disclosure, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
It is often necessary or desirable to provide redundant components in an industrial process control and automation system or other system. For example, pairs of redundant process controllers could be used in an industrial process control and automation system to provide more reliable process control operations in the system. In some instances, it may be necessary or desirable for each device in a redundant pair to detect if the other device in the redundant pair is active and functioning correctly. This allows a device functioning in a backup or secondary mode to transition into a primary mode under appropriate circumstances. This also allows a device functioning in the primary mode to identify a fault or other problem with a device operating in the secondary mode and to generate a warning that redundancy is no longer available.
The ability of one device to detect if another device is available may be referred to as “alive detection.” Each device in a redundant pair could perform alive detection to verify whether the other device in the redundant pair is active and available. In some conventional approaches, each device relies on a communication timeout to detect the absence of a redundant device. Communication timeouts typically occur after a prolonged period without communication from a redundant device, such as about 500 or 600 milliseconds. This may not be suitable for industrial process control and automation systems or other systems where redundant devices need to assume a primary mode more quickly, such as within about 10 or 20 milliseconds.
Also, in some conventional approaches, it is difficult to distinguish between a fault in a communication path between redundant devices and an absence of a redundant device due to a fault with the redundant device. The absence of a redundant device could be due to a number of reasons, such as user removal of the redundant device from service, a hardware fault, or a power loss. If a primary device becomes absent, a secondary device should transition into the primary mode in order to compensate for the loss of the primary device. However, when a fault in a communication path between redundant devices occurs, signals cannot be transported between the redundant devices. The primary device may still be operating correctly, but the secondary device may be unable to determine if the primary device is active. In those cases, it may not be desirable to have the secondary device transition into the primary mode since there would then be two devices operating in the primary mode. If that occurs with process controllers, for example, the process controllers could interfere with each other's operations.
This disclosure provides various hardware assist mechanisms for alive detection of redundant devices. The hardware assist mechanisms facilitate faster detection of a missing or unavailable redundant device. Among other things, this allows a secondary device to transition into a primary mode more quickly. Moreover, the hardware assist mechanisms could provide support for redundant signaling between redundant devices, reducing the likelihood that a single communication path fault will prevent the redundant devices from detecting one another.
In
At least one network 104 is coupled to the sensors 102a and actuators 102b. The network 104 facilitates interaction with the sensors 102a and actuators 102b. For example, the network 104 could transport measurement data from the sensors 102a and provide control signals to the actuators 102b. The network 104 could represent any suitable network or combination of networks. As particular examples, the network 104 could represent an Ethernet network, an electrical signal network (such as a HART or FOUNDATION FIELDBUS network), a pneumatic control signal network, or any other or additional type(s) of network(s).
In the Purdue model, “Level 1” may include controllers 106a-106b, which are coupled to the network 104. Among other things, each of the controllers 106a-106b may use the measurements from one or more sensors 102a to control the operation of one or more actuators 102b. For example, each controller 106a-106b could receive measurement data from one or more sensors 102a and use the measurement data to generate control signals for one or more actuators 102b. Each controller 106a-106b includes any suitable structure for interacting with one or more sensors 102a and controlling one or more actuators 102b. Each controller 106a-106b could, for example, represent a multivariable controller, such as a Robust Multivariable Predictive Control Technology (RMPCT) controller or other type of controller implementing model predictive control (MPC) or other advanced predictive control (APC). As a particular example, each controller 106a-106b could represent a computing device running a real-time operating system.
Two networks 108 are coupled to the controllers 106a-106b. The networks 108 facilitate interaction with the controllers 106a-106b, such as by transporting data to and from the controllers 106a-106b. The networks 108 could represent any suitable networks or combination of networks. As particular examples, the networks 108 could represent a pair of Ethernet networks or a redundant pair of Ethernet networks, such as a FAULT TOLERANT ETHERNET (FTE) network from HONEYWELL INTERNATIONAL INC.
At least one switch/firewall 110 couples the networks 108 to two networks 112. The switch/firewall 110 may transport traffic from one network to another. The switch/firewall 110 may also block traffic on one network from reaching another network. The switch/firewall 110 includes any suitable structure for providing communication between networks, such as a HONEYWELL CONTROL FIREWALL (CF9) device. The networks 112 could represent any suitable networks, such as a pair of Ethernet networks or an FTE network.
In the Purdue model, “Level 2” may include one or more machine-level controllers 114 coupled to the networks 112. The machine-level controllers 114 perform various functions to support the operation and control of the controllers 106a-106b, sensors 102a, and actuators 102b, which could be associated with a particular piece of industrial equipment (such as a boiler or other machine). For example, the machine-level controllers 114 could log information collected or generated by the controllers 106a-106b, such as measurement data from the sensors 102a or control signals for the actuators 102b. The machine-level controllers 114 could also execute applications that control the operation of the controllers 106a-106b, thereby controlling the operation of the actuators 102b. In addition, the machine-level controllers 114 could provide secure access to the controllers 106a-106b. Each of the machine-level controllers 114 includes any suitable structure for providing access to, control of, or operations related to a machine or other individual piece of equipment. Each of the machine-level controllers 114 could, for example, represent a server computing device running a MICROSOFT WINDOWS operating system. Although not shown, different machine-level controllers 114 could be used to control different pieces of equipment in a process system (where each piece of equipment is associated with one or more controllers 106a-106b, sensors 102a, and actuators 102b).
One or more operator stations 116 are coupled to the networks 112. The operator stations 116 represent computing or communication devices providing user access to the machine-level controllers 114, which could then provide user access to the controllers 106a-106b (and possibly the sensors 102a and actuators 102b). As particular examples, the operator stations 116 could allow users to review the operational history of the sensors 102a and actuators 102b using information collected by the controllers 106a-106b and/or the machine-level controllers 114. The operator stations 116 could also allow the users to adjust the operation of the sensors 102a, actuators 102b, controllers 106a-106b, or machine-level controllers 114. In addition, the operator stations 116 could receive and display warnings, alerts, or other messages or displays generated by the controllers 106a-106b or the machine-level controllers 114. Each of the operator stations 116 includes any suitable structure for supporting user access and control of one or more components in the system 100. Each of the operator stations 116 could, for example, represent a computing device running a MICROSOFT WINDOWS operating system.
At least one switch/firewall 118 couples the networks 112 to two networks 120. The switch/firewall 118 includes any suitable structure for providing communication between networks, such as a secure switch or combination switch/firewall. The networks 120 could represent any suitable networks, such as a pair of Ethernet networks or an FTE network.
In the Purdue model, “Level 3” may include one or more unit-level controllers 122 coupled to the networks 120. Each unit-level controller 122 is typically associated with a unit in a process system, which represents a collection of different machines operating together to implement at least part of a process. The unit-level controllers 122 perform various functions to support the operation and control of components in the lower levels. For example, the unit-level controllers 122 could log information collected or generated by the components in the lower levels, execute applications that control the components in the lower levels, and provide secure access to the components in the lower levels. Each of the unit-level controllers 122 includes any suitable structure for providing access to, control of, or operations related to one or more machines or other pieces of equipment in a process unit. Each of the unit-level controllers 122 could, for example, represent a server computing device running a MICROSOFT WINDOWS operating system. Although not shown, different unit-level controllers 122 could be used to control different units in a process system (where each unit is associated with one or more machine-level controllers 114, controllers 106a-106b, sensors 102a, and actuators 102b).
Access to the unit-level controllers 122 may be provided by one or more operator stations 124. Each of the operator stations 124 includes any suitable structure for supporting user access and control of one or more components in the system 100. Each of the operator stations 124 could, for example, represent a computing device running a MICROSOFT WINDOWS operating system.
At least one router/firewall 126 couples the networks 120 to two networks 128. The router/firewall 126 includes any suitable structure for providing communication between networks, such as a secure router or combination router/firewall. The networks 128 could represent any suitable networks, such as a pair of Ethernet networks or an FTE network.
In the Purdue model, “Level 4” may include one or more plant-level controllers 130 coupled to the networks 128. Each plant-level controller 130 is typically associated with one of the plants 101a-101n, which may include one or more process units that implement the same, similar, or different processes. The plant-level controllers 130 perform various functions to support the operation and control of components in the lower levels. As particular examples, the plant-level controller 130 could execute one or more manufacturing execution system (MES) applications, scheduling applications, or other or additional plant or process control applications. Each of the plant-level controllers 130 includes any suitable structure for providing access to, control of, or operations related to one or more process units in a process plant. Each of the plant-level controllers 130 could, for example, represent a server computing device running a MICROSOFT WINDOWS operating system.
Access to the plant-level controllers 130 may be provided by one or more operator stations 132. Each of the operator stations 132 includes any suitable structure for supporting user access and control of one or more components in the system 100. Each of the operator stations 132 could, for example, represent a computing device running a MICROSOFT WINDOWS operating system.
At least one router/firewall 134 couples the networks 128 to one or more networks 136. The router/firewall 134 includes any suitable structure for providing communication between networks, such as a secure router or combination router/firewall. The network 136 could represent any suitable network, such as an enterprise-wide Ethernet or other network or all or a portion of a larger network (such as the Internet).
In the Purdue model, “Level 5” may include one or more enterprise-level controllers 138 coupled to the network 136. Each enterprise-level controller 138 is typically able to perform planning operations for multiple plants 101a-101n and to control various aspects of the plants 101a-101n. The enterprise-level controllers 138 can also perform various functions to support the operation and control of components in the plants 101a-101n. As particular examples, the enterprise-level controller 138 could execute one or more order processing applications, enterprise resource planning (ERP) applications, advanced planning and scheduling (APS) applications, or any other or additional enterprise control applications. Each of the enterprise-level controllers 138 includes any suitable structure for providing access to, control of, or operations related to the control of one or more plants. Each of the enterprise-level controllers 138 could, for example, represent a server computing device running a MICROSOFT WINDOWS operating system. In this document, the term “enterprise” refers to an organization having one or more plants or other processing facilities to be managed. Note that if a single plant 101a is to be managed, the functionality of the enterprise-level controller 138 could be incorporated into the plant-level controller 130.
Access to the enterprise-level controllers 138 may be provided by one or more operator stations 140. Each of the operator stations 140 includes any suitable structure for supporting user access and control of one or more components in the system 100. Each of the operator stations 140 could, for example, represent a computing device running a MICROSOFT WINDOWS operating system.
Various levels of the Purdue model can include other components, such as one or more databases. The database(s) associated with each level could store any suitable information associated with that level or one or more other levels of the system 100. For example, a historian 142 can be coupled to the network 136. The historian 142 could represent a component that stores various information about the system 100. The historian 142 could, for instance, store information used during production scheduling and optimization. The historian 142 represents any suitable structure for storing and facilitating retrieval of information. Although shown as a single centralized component coupled to the network 136, the historian 142 could be located elsewhere in the system 100, or multiple historians could be distributed in different locations in the system 100.
In particular embodiments, the various controllers and operator stations in
Various components in the system 100 could be arranged in a redundant configuration. For example, the controllers 106a-106b could operate in a redundant configuration, such as when one controller 106a operates as a primary controller while another controller 106b operates as a backup controller. The backup controller can synchronize with the primary controller and can take over for the primary controller in the event of a fault or other problem with the primary controller. To support alive detection for redundant devices, each of the controllers 106a-106b could include a hardware assist device 144, which can be used at each controller 106a-106b to detect the presence of the other controller 106a-106b. Different implementations of the hardware assist device 144 are described below. Note that while shown here as being used in redundant process controllers, hardware assist devices 144 could be used in any other suitable redundant devices, and those redundant devices need not be used for process control or automation.
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Each device 202a-202b includes one or more communication interfaces 206a-206b, respectively. The communication interfaces 206a-206b support communications with one or more external devices or systems. For example, the communication interfaces 206a-206b could allow the devices 202a-202b to transmit or receive data over one or more external networks or communication links. Each communication interface 206a-206b includes any suitable structure configured to transmit or receive information, such as a 10/100/1000 Ethernet interface. While four communication interfaces 206a-206b are shown in each device 202a-202b, each device 202a-202b could include any suitable number of communication interfaces 206a-206b.
Each device 202a-202b also includes an additional communication interface 208a-208b, respectively. The communication interfaces 208a-208b support the transport of data between the devices 202a-202b, such as data used to synchronize one device in the secondary mode with another device in the primary mode. Each communication interface 208a-208b includes any suitable structure configured to transmit or receive information, such as a 10/100/1000 Ethernet interface. While a single communication interface 208a-208b is shown in each device 202a-202b, each device 202a-202b could include any suitable number of communication interfaces 208a-208b. At least one communication link 210 couples the communication interfaces 208a-208b. The communication link 210 denotes any suitable communication medium, such as a communication link embedded within the backplane 204.
Each device 202a-202b further includes a hardware assist device 212a-212b, respectively. The hardware assist devices 212a-212b denote hardware components used to facilitate faster identification of the loss of a redundant device. For example, as described in more detail below, the hardware assist devices 212a-212b can transmit signals to one another during normal operation. Upon a fault or other problem with a first device 202a-202b, the hardware assist device 212a-212b in a second device 202a-202b can detect the lack of signals from the hardware assist device in the first device. This can occur very quickly, typically much faster than waiting for a communication timeout associated with the communication interfaces 208a-208b.
The hardware assist device 212a includes one or more “alive” transmitters 214a-214b and one or more “alive” receivers 216a-216b. Similarly, the hardware assist device 212b includes one or more “alive” transmitters 218a-218b and one or more “alive” receivers 220a-220b. Each transmitter 214a-214b, 218a-218b in one device 202a-202b can transmit one or more signals to a corresponding receiver 216a-216b, 220a-220b in the other device 202a-202b. The presence of these signals can be used by each device 202a-202b as an indication that the other device 202a-202b is active and operating as expected. The absence of these signals can be used by each device 202a-202b as an indication that the other device 202a-202b has experienced some type of problem.
Each transmitter 214a-214b, 218a-218b includes any suitable structure for transmitting one or more signals. Each receiver 216a-216b, 220a-220b includes any suitable structure for receiving one or more signals. In some embodiments, a transmitter and a receiver could be combined into a single transceiver. In particular embodiments, each transmitter-receiver pair in a hardware assist device 212a-212b could be implemented using a Universal Asynchronous Receiver/Transmitter (UART) engine.
In this example, there is redundancy in the communications between the hardware assist devices 212a-212b. Namely, there are two transmitters and two receivers in each hardware assist device 212a-212b. The transmitters 214a, 218a and the receivers 216a, 220a communicate over one or more first communication links 222, and the transmitters 214b, 218b and the receivers 216b, 220b communicate over one or more second communication links 224. Each of the communication links 222-224 denotes any suitable communication medium. In some embodiments, the communication links 222-224 could be embedded within the backplane 204. However, there need not be redundancy in the communications between the hardware assist devices 212a-212b, and each hardware assist device 212a-212b could include a single alive transmitter and a single alive receiver.
It is also possible to include one or more additional interfaces between the redundant devices 202a-202b.
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In particular embodiments, the signaling pattern shown in
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Each signal 352-358 also conveys additional information, such as the mode of operation in which each device 202a-202b would like to operate or is operating. For example, a pattern 360 could be used by a device 202a-202b to indicate that the device is preparing to enter the primary mode, while a pattern 362 could be used by a device 202a-202b to indicate that the device is operating in the primary mode. Similarly, a pattern 364 could be used by a device 202a-202b to indicate that the device is preparing to enter the secondary mode, while a pattern 366 could be used by a device 202a-202b to indicate that the device is operating in the secondary mode.
In some embodiments, the signaling pattern shown in
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Each hardware assist device 212a-212b includes a memory, such as in the form of a register set 402a-402b. The register sets 402a-402b are accessible by central processing units (CPUs) or other processing devices 404a-404b, respectively. The processing devices 404a-404b could denote processing devices used to execute software or firmware instructions of the devices 202a-202b to perform some desired functionality. Each processing device 404a-404b denotes any suitable processing or computing device(s), such as one or more microprocessors, microcontrollers, digital signal processors, application specific integrated circuits, field programmable gate arrays, or discrete logic devices.
Each register set 402a-402b here stores a “local role” value that defines the role (primary or secondary) of the redundant device 202a-202b associated with the register set 402a-402b. The “local role” values in the register sets 402a and 402b can be used to define or control the alive signals transmitted by the transmitters 214a and 218a, respectively. Each register set 402a-402b also stores a “partner role” value that identifies the role (primary or secondary) of the other device 202a-202b. The “partner role” values in the register sets 402a and 402b can be based on the signals received by the receivers 216a and 220a, respectively.
Interfaces 405a-405b can be used to support access to and from the register sets 402a-402b by the processing devices 404a-404b. Any suitable interfaces 405a-405b can be used in the hardware assist devices 212a-212b. For example, the interfaces 405a-405b could denote interfaces supporting an Advanced eXtensible Interface (AXI) protocol.
Interrupt signals 406a-406b can be generated when the associated “partner role” values in the register sets 402a-402b change, thereby letting the associated processing devices 404a-404b know of the status changes. As a result, each processing device 404a-404b could determine whether to initiate a mode change of the associated device 202a-202b, such as when a secondary device is transitioned to the primary mode in response to detecting a loss of a primary device. Each processing device 404a-404b could also determine whether to generate a notification, such as when a primary device initiates a warning or alarm in response to detecting a loss of a secondary device. The interrupt signals 406a-406b could be generated by logic 407a-407b, which may denote one or more logic gates, program code, or other functionality implemented within the hardware assist devices 212a-212b.
Each register set 402a-402b further stores a watchdog timer input value (WDT_IN), which is used to control a watchdog timer 408a-408b, respectively. The watchdog timers 408a-408b control the operations of drivers 410a-410b, respectively. The drivers 410a-410b can selectively block transmissions from the transmitters 214a, 218a over the communication links 222. For example, each watchdog timer 408a-408b could be regularly reset by the associated processing device 404a-404b (such as by the processing device 404a-404b writing a value to the associated WDT_IN register). As long as each processing device 404a-404b resets its associated watchdog timer 408a-408b, the watchdog timers 408a-408b allow signals from the transmitters 214a, 218a to flow over the communication links 222 through the drivers 410a-410b. If one of the processing devices 404a-404b fails, the processing device stops resetting its watchdog timer 408a or 408b, which then times out and causes the driver 410a or 410b to block signals from the associated transmitter 214a or 218a from flowing over the communication links 222. This allows the watchdog timers 408a-408b to block the transmissions of alive signals when their associated processing devices 404a-404b fail. Moreover, this can be done quickly, such as within about 10 milliseconds in some embodiments.
Note that the watchdog timers 408a-408b could also be controlled in other ways. For example, firmware or software instructions could alter the watchdog timer input values stored in the register sets 402a-402b to disable the transmissions of the alive signals. This could occur, for instance, during an intention shutdown or reboot of a device.
In particular embodiments, each hardware assist device 212a-212b can be implemented using an FPGA, possibly with an associated processing device 404a-404b formed on an integrated circuit chip. For example, devices such as the ZYNQ-7000 family of devices from XILINX INC. can include a programmable FPGA used in conjunction with a multipoint control unit (MCU) or other processing device.
In
The register sets 402a-402b in
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In some embodiments, testing the hardware assist devices 212a-212b can occur, such as at a specified interval or at other times. For example, one of the hardware assist devices 212a-212b could intentionally disable its alive transmission over one of the communication links 222 and 224. The other hardware assist device 212a-212b could then determine whether the loss of the alive signal on that communication link is detected (such as by verifying whether one “partner role” value changes while the other “partner role” value does not change). This may allow, for example, verification that each hardware assist device 212a-212b is operating correctly and that the communication links 222-224 are not shorted together. This type of test could occur in one or both directions on each communication link 222-224.
In this way, the hardware assist devices 212a-212b can use the transmitters 214a-214b, 218a-218b to generate alive signals (possibly continuously) in order to indicate to one another that the devices 202a-202b are active and available. In response to a fault or other problem, one or more transmitters 214a-214b or 218a-218b cease to generate alive signals, rapidly providing an immediate and explicit notification that one of the redundant devices 202a-202b has faulted or powered-off. The transmitted alive signals can be dynamic in nature to be immune from short or open faults on the signal paths, and the alive signals can be periodically and individually tested to ensure that there are no latent faults (such as a short across redundant signal paths). As can be seen above, the hardware assist devices 212a-212b can employ “negative logic” in that the transmitted signals may be continuously sent unless and until there is a fault, at which point the transmission(s) can stop.
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As noted above, in some embodiments, signals sent between the hardware assist devices 212a-212b could define four patterns. Those patterns could identify whether a device is preparing to enter the primary mode, in the primary mode, preparing to enter the secondary mode, or in the secondary mode. These four patterns can be defined using different bit patterns within the payload 604 of the repeating pattern frame. In particular embodiments, the different bit patterns that could be sent within the payload 604 could be defined as follows.
The payload 604 in two consecutive frames can be received and compared to identify a change in the status of a partner device. A change in payload values could cause an interrupt 406a-406b to be asserted. Also, a lack of a signal or the receipt of one or more bad frames could cause the interrupt 406a-406b to be asserted.
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Alive signals are generated and transmitted between hardware assist devices of the redundant devices at step 704. This could include, for example, one or more transmitters 214a-214b, 218a-218b in each of the hardware assist devices 212a-212b transmitting one or more alive signals over one or more communication links 222 and 224. This could also include the watchdog timers 408a-408b being reset periodically in order to allow the drivers 410a-410b (or 410a-410d) to pass the alive signals over the communication links 222 and 224. One or more alive signals are received and monitored at each device at step 706. This could include, for example, one or more receivers 216a-216b, 220a-220b in each of the hardware assist devices 212a-212b receiving one or more alive signals over one or more communication links 222 and 224.
A determination is made at each device whether the received alive signal or signals are lost or otherwise negated at step 708. This could include, for example, an FPGA in each hardware assist device 212a-212b determining whether one or more alive signals are no longer being received or contain invalid values or bad frames. This could occur repeatedly at a defined interval (such as every 10 milliseconds) or at any other suitable times. If the received alive signals are lost or otherwise negated at one device, it may be indicative of the other device suffering from a fault or otherwise becoming absent. In that case, a determination is made whether the device that is absent is in the primary mode at step 710.
If the absent device is a primary device, a redundancy role change occurs in the secondary device at step 712. This could include, for example, the processing device 404a or 404b in the secondary device causing the secondary device to enter the primary mode. If the device represents a process controller, the mode change could cause a secondary process controller to enter the primary mode and begin actively controlling one or more industrial processes. This could also include the secondary device blindly sending a role change command to the other device in step 712. If the loss of the alive signal(s) is due to a communication fault between the devices 202a-202b and not due to a fault in the absent device, the absent device may still be functioning, and the role change command can cause the absent device to switch to the secondary mode.
If the absent device is not a primary device and is therefore a secondary device, synchronization with the absent device stops at step 714. This could include, for example, the processing device 404a or 404b in the primary device causing the primary device to stop sending synchronization information to the absent secondary device. This could also include the primary device sending at least one alarm, warning, or other notification in step 714. The notification(s) could inform appropriate personnel, a maintenance system, or other destination(s) that redundancy is no longer available with the primary device.
At specified intervals (such as every five minutes) or at other times, testing of the hardware assist devices is initiated and occurs at step 716. This could include, for example, the hardware assist device 212a-212b of one device 202a-202b intentionally stopping the transmission of the alive signal(s) to the hardware assist device 212a-212b of the other device 202a-202b on one (but not all) communication links 222-224. This could also include the other device 202a-202b determining whether the hardware assist device 212a-212b of the other device 202a-202b accurately detects the lack of the alive signal(s). This could further include the other device 202a-202b determining whether the hardware assist device 212a-212b of the other device 202a-202b continues to accurately detect the alive signal(s) sent over other communication link(s). If a problem is detected in the test at step 718, a notification identifying the problem is generated at step 720. This could include, for example, the device 202a-202b at which the error is noted sending at least one alarm, warning, or other notification. The notification(s) could inform appropriate personnel, a maintenance system, or other destination(s) that accurate alive detection may no longer be possible with the redundant devices.
Although
In some embodiments, various functions described in this patent document are implemented or supported by a computer program that is formed from computer readable program code and that is embodied in a computer readable medium. The phrase “computer readable program code” includes any type of computer code, including source code, object code, and executable code. The phrase “computer readable medium” includes any type of medium capable of being accessed by a computer, such as read only memory (ROM), random access memory (RAM), a hard disk drive, a compact disc (CD), a digital video disc (DVD), or any other type of memory. A “non-transitory” computer readable medium excludes wired, wireless, optical, or other communication links that transport transitory electrical or other signals. A non-transitory computer readable medium includes media where data can be permanently stored and media where data can be stored and later overwritten, such as a rewritable optical disc or an erasable storage device.
It may be advantageous to set forth definitions of certain words and phrases used throughout this patent document. The terms “application” and “program” refer to one or more computer programs, software components, sets of instructions, procedures, functions, objects, classes, instances, related data, or a portion thereof adapted for implementation in a suitable computer code (including source code, object code, or executable code). The term “communicate,” as well as derivatives thereof, encompasses both direct and indirect communication. The terms “include” and “comprise,” as well as derivatives thereof, mean inclusion without limitation. The term “or” is inclusive, meaning and/or. The phrase “associated with,” as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, have a relationship to or with, or the like. The phrase “at least one of,” when used with a list of items, means that different combinations of one or more of the listed items may be used, and only one item in the list may be needed. For example, “at least one of: A, B, and C” includes any of the following combinations: A, B, C, A and B, A and C, B and C, and A and B and C.
The description in the present application should not be read as implying that any particular element, step, or function is an essential or critical element that must be included in the claim scope. The scope of patented subject matter is defined only by the allowed claims. Moreover, none of the claims invokes 35 U.S.C. §112(f) with respect to any of the appended claims or claim elements unless the exact words “means for” or “step for” are explicitly used in the particular claim, followed by a participle phrase identifying a function. Use of terms such as (but not limited to) “mechanism,” “module,” “device,” “unit,” “component,” “element,” “member,” “apparatus,” “machine,” “system,” “processor,” or “controller” within a claim is understood and intended to refer to structures known to those skilled in the relevant art, as further modified or enhanced by the features of the claims themselves, and is not intended to invoke 35 U.S.C. §112(f).
While this disclosure has described certain embodiments and generally associated methods, alterations and permutations of these embodiments and methods will be apparent to those skilled in the art. Accordingly, the above description of example embodiments does not define or constrain this disclosure. Other changes, substitutions, and alterations are also possible without departing from the spirit and scope of this disclosure, as defined by the following claims.
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/CN2016/086021 | Jun 2016 | US |
| Child | 15594857 | US |
