JPH0432941A - Method of controlling update of data base of redundant processor in process control system - Google Patents

Abstract

PURPOSE: To hold the data base of a redundant controller at a process control system by updating the data base related with a 1st-order controller and simultaneously transferring prescribed information stored in a 1st-order data base to a 2nd-order controller. CONSTITUTION: A 1st-order controller 30 executes the defined control function of a process control system 10. This function also contains the update of the data base related with the 1st-order controller 30 after the execution of the defined control function, and the change due to that update is utilized for updating the data base related with a 2nd-order controller 40. Then, the predetermined information stored in the 1st-order data base is collected simultaneously with the update of the data base. After the execution of the control function is completed, the predetermined information is transferred to the 2nd-order controller 40 and the data base of the 2nd-order controller is updated. Thus, the data base of a redundant controller 20 at the system 10 can be held.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a method for maintaining consistency between a primary database and a secondary image of a database of a redundant processor in a process control system. The present invention relates to a method for tracking changes to a database, making changes to a secondary database, and updating only predetermined areas that have changed, thereby increasing the efficiency of the update function.

U.S. RI 1% Permit No. 4.133.027 issued to J.A. Hogan on February 2, 1979 and 2/1979.
U.S. Patent No. 4 issued to Y, Ks11es on May 20th.
The backup process controller described in No. 141.066 includes a process control system that includes dedicated random access memory (RAM) and dedicated read-only storage (ROM). The backup controller may be essentially unused or perform background tasks that are not directly related to process control functions. If any of the primary process controllers fails, the data stored in the failed controller's RAM is immediately transferred to the backup controller's RA in order to activate the primary controller.
Must be forwarded to M. These systems exhibit a 1:N redundancy scheme.

The present invention provides a method in a one-to-one redundancy scheme whereby the database of a secondary device (i.e., a secondary or backup controller) is periodically updated and the update process is (Basically) Transparent to functionality, does not prevent the CPU or processor from executing (9 is a penalty), and minimizes usage time. The method of the present invention updates only the information that has changed, makes more efficient use of the CPU or microprocessor, allows the update process to be performed more frequently at a real-time pace, and allows the control register to have up to 7 failovers. (fai-1over)
Make it practical to track large amounts of data without being affected by it. In this way, if a failover situation occurs, the time it takes to bring a secondary controller into service in place of a failed primary controller is substantially reduced; Reduce the impact.

Therefore, the present invention includes maintenance of databases in redundant controllers of process control systems (
In other words, a method for controlling the update) is provided. The process control system includes first and second controllers, the former as a primary controller and the latter as a secondary controller. Each controller has an image of the database; the primary controller operates on and updates the database, and the secondary controller maintains an equivalent image of the database. The primary controller performs the defined control functions of the flow control system. It also includes updating the database associated with the primary controller after performing the L1 defined side control functions. The method of the present invention for updating a database associated with a primary controller comprises means for performing this control function.

The resulting changes are used to update the database related to el-1 (secondary control).

At the same time as the database is updated, predetermined information stored in the primary database is collected. After the execution of the control function is completed, predetermined information is transferred to the secondary controller and the database of the secondary controller is updated.

Therefore, the object of this invention is to provide a process controller.

- To provide a method for maintaining a database of redundant controllers in a system.

Another object of the invention is to provide a method for maintaining a database of redundant controllers that is updated only with predetermined changes.

It is a further object of the present invention to provide a method for maintaining a database of redundant controllers in a process control system without significantly impacting the CPU microprocessor.

These and other objects of the invention will become more apparent from the following description and accompanying drawings. Like characters in the drawings indicate like parts, and the drawings are part of this application.

FIG. 1 will be explained. It shows a block diagram of a process control system 10 having redundant controllers using the method of the present invention.
More specifically, a functional block diagram of a redundant process controller 20 is shown, which includes a primary controller 30 and a secondary controller 4°. The controllers are the primary controller 30 and the secondary controller 40.
However, the controller is bidirectional with respect to redundancy, with either the redundant (or sometimes referred to as secondary) controller being the primary or secondary controller. This means that it can operate satisfactorily. The numbers identified herein as primary and secondary are strictly for identification and description purposes.

Process control system 10 includes a plant control network 11 to which is connected a data highway 12 that allows multiple process controllers to be attached to data highway 12 . The primary controller 30 includes a primary processor 31.1.
There is a secondary memory 32 and a primary tracking device [33]. The secondary controller 40 includes a secondary processor 41 and a secondary memory 42.
and a secondary tracking device 43. The primary processor 31 and the secondary processor 41 are each connected to the data highway 12. The primary processor 31 is connected to a primary memory 32 and its primary tracking device 33 . Secondary processor 41 is connected to its secondary memory 42 and its secondary tracking device 43. Various inputs and outputs are connected to the process controller 20, including an analog input (A/I), an analog output (A10), a digital input (D/I), and a digital output (Dlo).

These inputs and outputs display current information or status and are also connected to various valves, pressure switches, pressure gauges, thermocouples, etc. used to control the process in a process control system. There is.

Plant control network 11 may be of the type described in U.S. Pat. You can also. Although not shown here, various analog and digital inputs and outputs
It is also known to be connected to the secondary processor 31 and the secondary processor 41 via suitable interface devices.

In process controller 2G, controller 30.4
The decision as to which controller of 0 is the primary or secondary controller is made by the download control personality (i.e., operating software and database information) from the plant control network 11. At that time, the first loaded controller among the controllers 30 and 40 becomes the primary controller, and the other one plays the role of the secondary controller. Controller 30.40 of process controller 20 is shown in FIG. 1 for purposes of illustration and example.
controller 30 is already the primary controller,
Although controller 40 is identified as a secondary controller, it is also well known that controller 40 is the primary controller and controller 30 is the secondary controller. In this way, the controller 30°4
Since the basic/secondary side of 0 is set, the primary controller 30 executes the control processing algorithm (algorithm) 1, which requires reading input data from valves, pressure gauges, etc. Contains routine calculation execution and output of results. Data is also stored in base memory 32. There is an area of primary memory 32 designated as trace memory (also referred to as trace RAM). This write to the tracking RAM is shadowed by the primary tracker 33. The primary tracking device 33 stores additional data in advance in a set format shown as a packet in an internal storage device (not shown) at the same time as writing into the tracking RAM i.

After completing its processing function for a predetermined time, the primary processor 3
1 sends a control signal to the primary tracking device 33 to begin transferring the data stored in the primary tracking device 33 to the secondary tracking device 43. Control information such as head information, byte count, data type, etc. is also reliably transferred to the primary processor 31. The secondary processor 41 then controls the secondary tracking device 43.
The data stored in the secondary tracking device 43 is retrieved and
Create the necessary information from the information packets stored in the. Secondary processor 41 accepts this packet, performs an integrity test, communicates the test results to primary processor 31, retrieves the data value, and then stores it in secondary memory 42.
Compute an address that stores the data value of the address identified in the information packet of. By updating the secondary memory in this manner, the execution penalty for the primary processor 31 is significantly reduced, while the control processing capacity (sometimes referred to herein as bandwidth) of the primary processor 31 is increased. Another advantage of this method is that all control data is automatically tracked, making control more reliable and significantly reducing software errors. CPU used in the processor 31-41 in the preferred embodiment
is of type Motorola 68000.

FIG. 2 will be explained. It shows the distribution of time used by the primary processor 31.

In a preferred embodiment of this invention, the cycle is
It is defined as a length of time of one second, and is divided into eight subcycles. In each subcycle, the processor executes a predetermined algorithm (referred to as point processing in FIG. 2).

The time required for point processing is less than the subcycle time. Before starting point processing, primary processor 31 begins to transfer tracking data to secondary controller 4D (denoted as DBA data transfer in the figure). From this time frame diagram, the secondary controller 40
It can be readily seen that the data contained in the database of the primary controller 30 is one means (ie, a subcycle) after the data contained in the database of the primary controller 30. Therefore, while the primary controller is performing the control operation (i.e. point processing) of subcycle n, the 2
The next controller updates its database as changes occur in subcycle N-1. (In a system where each write to primary memory results in a write to secondary memory, the primary and secondary controllers maintain the same database. However, errors, i.e. failures during transmission of partial bytes, If both the primary and secondary controllers have partial byte data,
In other words, they will have the same incomplete data. ) In this invention, although the aforementioned secondary database has complete data, the primary controller is also one of the latter means. Other functions can be performed within the time of the subcycle. In the preferred embodiment, external data storage from other nodes of the network is also performed, but it does not form part of this invention and will not be described here.

@3 will be explained. It shows a partial memory map of primary memory 32. Contains scan data containing actual values of Ilo throughout, read from valves, pressure gauges, etc. The configuration data marked sections contain information that indicates which options are selected, how points are configured, what algorithms are operating, etc. The section indicating the process data to be backed up contains the results of the algorithm.

Also included is information indicating the operation of various functions, such as various timers that have been set and various alarm devices that have been set.

The memory mark DBA data area is "tracking memory"
This is an area of primary memory 32 (ie, RAM) called RAM. Writing to this area of the primary memory 32 is
The information is collected by the primary tracking device 33 (referred to as shadowing or capture (collection)). The data collected by the primary tracking device 33 is formatted in defined packets.

FIG. 4 will be explained. It shows the format of the packets produced by the primary tracking device 33 in the preferred embodiment of the invention.

The upper and lower data strobe values indicate the lowest 7 address bit values and also indicate that the most significant 5 address bits are 0 trace memory packets that can be assumed (i.e. implicitly known) depending on the layout of the trace memory. but,
Created on every write (byte or word) to trace memory, but only if memory trace is requested. An important feature of primary tracker 330, as discussed above, is that there is essentially no execution penalty when writing to track memory.

The tracking data packets are stored in the memory storage (not shown) of the primary tracking operation s3 in three word packets, not sequentially but in a column format. The primary tracker is stored packets based on a counter (not shown) of the primary tracker 33.

The counter is 1 whenever a packet is stored.
Increased by increments. This counter can be read by the primary processor 31 to ascertain the amount of data to be transferred. The primary tracking device 33Fi is described in detail in co-pending application no. Note that this document was filed at the same time as the application for this invention, and was created in the same eyelid application as this invention.

FIG. 5 will be explained. It includes a primary controller 30 and a secondary controller 4 that implement the method of this invention.
70-diagram of both software. Immediately upon the start of its software operation, each processor performs the necessary initializations, which may include diagnostic tests, self-tests, zeroing of various buffers and memory locations, etc. (block 100). can. Each processor determines whether it is operating as a primary processor or a secondary processor. This determination is made when the controller's personality image is being downloaded. The decision is 1
Based on whether the next controller (block 1o5) is present. When determining whether a processor operates as a primary processor, this controller periodically determines whether a secondary controller is operationally rotated as part of the basic normal function (block 110). to test. Once the secondary controller is detected, the entire database is transferred to the secondary processor (block 115) and the primary processor 31 begins executing control operations (block 120). The execution control function includes all control functions, that is, everything related to control. This includes obtaining input, performing output functions, performing point processing, processing changes from Data Highway 12, and Data Highway 12.
2t- Output of necessary predetermined information to the plant control network 11 via
11Of-database updates, etc. are included. The execution control function is displayed as the point processing described above with reference to FIG. 2 and executed during the nine subcycle.

After finishing the execution control function, database changes are transferred to the secondary controller. The change data is predetermined and is called DBA data (block 125). In addition to performing other functions to indicate to the primary controller that the secondary controller is currently operating, in the protocol of the present invention, the secondary controller indicates that all data has been received and no errors have been detected. Respond to basic controllers. This function is subject to a determination whether the secondary controller is operating properly (block 130). If the secondary controller is performing properly without errors, the process will perform the control functions performed (
Return to block 120). If there are no errors and there is a normal situation where the secondary controller is operational, block 1
A loop consisting of 20.125 and 130 is running continuously for each subcycle. Primary Controller f) If an error is detected by the secondary controller, a failover condition occurs, but the secondary controller 40 becomes the primary controller and the primary controller 30 goes offline. Processing of secondary controller 40 (now the primary controller) executes control function block 135 and returns to block 110. Previous 1
If the next controller 30 is still offline, the response to the determination at block 110 as to whether there is a secondary controller has no effect, and the loop consisting of blocks 135 and 110 is executed continuously until it becomes operational. Since either controller 30 or 40 can operate as the primary controller, a switch pack to the previous primary controller once restored is neither necessary nor desirable in the preferred embodiment of the invention.

After initial startup and initialization, the controller determines to operate as a secondary controller (block 105);
The secondary controller is connected to the primary controller (block 14
Set to receive all data blocks transferred from 0). The entire data block contains scan data and configuration data that includes a personality image defined by the plant control network 11. To effectuate failover, the secondary controller tests whether the primary controller is operational (block 145).

If the primary controller is inoperable, the secondary controller returns to the primary state or mode (block 150'').
If no primary controller is selected, processing continues at block 110. If the primary controller is operational, the controller acting as the secondary controller transfers changes (block 155) to the primary controller (block 155).
block 125) configuring to receive database changes transferred to the primary controller as a result of the function;
I will receive it again. After receiving the changes, the processor acting as a secondary processor interprets the data packet with a secondary tracking device and writes the new value contained in this packet to the secondary memory 42, i.e. the secondary database. It serves to store the data received in the database of the secondary processor. After the secondary processor has processed all data packets (e.g. setting a flag)
, are displayed to the primary processor by the secondary processor. The primary processor tests the flag to determine whether the secondary controller has completed its processing. If a new transfer is requested while previously transferred data is still being stored by the secondary controller, the secondary controller can respond by requesting the primary controller to pause its request. Therefore, as mentioned above, the subcycle N received from the primary processing
A secondary processor interpreting and storing -1 data packets occurs in subcycle N while the primary controller is executing segment N. That is, data stored in the database of the secondary processor lags data into the database of the primary processor by one subcycle, as described above. The secondary processor is configured to receive data. The secondary processor is essentially in standby mode, ie performing various background tasks such as its own speed monitor diagnostics.

The primary controller 30 and the secondary controller 40 are
3 media, i.e. data file 1 12. link 13 between primary tracking device 33 and secondary tracking device 43;
10 Link (not shown) - This link is A/
I, &, Φ, primary processor 31 and secondary processor 4 to interface with D/I and Dlo.
1 and 1 can be communicated to each other through the bus. These communication buses ensure that the primary controller 30
A secondary controller 40 may be present and operable, and the secondary controller may be configured to determine when it (i.e., the controller designated as the secondary controller) is in the primary state (or mode). The primary controller can be tested to see if it is operational.

While there has been shown what is considered to be a preferred embodiment of the invention, it will be obvious that the invention may be practiced with various modifications without departing from the essential spirit and scope of the invention. All modifications that come within the true scope of this invention are therefore intended to be included in the accompanying frames.

[Brief explanation of the drawing]

FIG. 1 shows a block diagram of a process control system with redundant controllers, FIG. 2 shows the time allocation that defines the controller cycles, and FIG.
4 is a partial memory map of the primary memory of the controller in a preferred embodiment of the present invention, FIG. 4 is a packet format of collected data in a preferred embodiment of the present invention, and FIG. 5 is a method of the present invention. 1 is a flow diagram of the software for both the primary and secondary controllers implementing the . 11...-Plant control network, 12
-...Datano Iway, 20-.O.Process Controller, 30...Fist Primary Controller, 31...
・・Primary processor, 32・e・・Primary memory, 33・
...Primary tracking device, 40...Secondary controller,
41--Secondary processor, 42-Secondary memory, 43-φ Secondary tracking device. Engraving of drawings (no changes to content)

Claims (3)

[Claims] (1) having a process controller including a first controller being a primary controller and a second controller being a secondary controller, each controller having a corresponding image of a database; A process control system in which a controller updates a database by performing predetermined functions of the process controller, including updating a database associated with the primary controller, comprising: a) performing a control function; b) a second database; updating a database associated with the primary controller; c) collecting predetermined information stored in the primary database simultaneously with said updating means; and d) upon completion of the performance of the control function and the database updating means, predetermined information. A method for updating a database associated with a secondary controller, the method comprising the steps of transferring the data to a secondary controller. (2) a process controller including a first controller that is a primary controller and a second controller that is a secondary controller, each controller having a corresponding image of a database; In a process control system adapted to perform its predetermined functions, a) performing a predetermined control function; b) updating a database associated with a primary controller by performing said predetermined control function; updating; c) capturing predetermined information stored in a first time database simultaneously with said updating means; d) repeating said means a) to e) until all said predetermined control functions have been performed; e) A method for updating a database associated with a secondary controller, comprising the steps of: transmitting the predetermined information captured by means e) to the secondary controller. (3) Where each of the operational controller and the backup controller has an image of a database, a) performing predetermined control functions, including performing calculations and algorithms by the operational controller; b) performing in a) above; c) collecting predetermined information stored in the database of the operable controller simultaneously with the updating means and enabling the controller to be actuated thereby; d) the transfer of said information to said backup controller in standby mode for receiving the predetermined information collected in step c) after the completion of the means of execution; A method of updating a database that cooperates with the backup controller described above.