CA2764203A1 - Control system including soe device - Google Patents
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Abstract
A control system comprises a computing device, an input/output device, and an SOE device which are connected through a shared communication line. The input/output device transmits a status signal inputted from a control target to the computing device and outputs a control signal transmitted from the computing device to the control target, and the SOE
device imports the control signal or the status signal to record a predetermined change thereof as event data, wherein the SOE device has a communication control portion which receives a read request from the computing device with a predetermined reception cycle, and transmits the event data to the computing device with a predetermined transmission cycle in response to the read request.
device imports the control signal or the status signal to record a predetermined change thereof as event data, wherein the SOE device has a communication control portion which receives a read request from the computing device with a predetermined reception cycle, and transmits the event data to the computing device with a predetermined transmission cycle in response to the read request.
Description
CONTROL SYSTEM INCLUDING SOE DEVICE
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to a control system and an SOE device.
Description of the Related Art Data handled by a general plant control system includes control data processed by a computing device constantly to monitor and control a control target, and event data processed by the computing device temporarily to analyze the behavior of the control target when there occurs an abnormal event.
As a method for collecting and managing such event data, for example, JP-A-2000-10604 has disclosed a method in which an event input module including an event collecting function is placed in the same hierarchy as a plurality of process input/output devices in order to collect event data.
For example, in a control system for a power plant, control data is required to have immediacy and constant periodicity. It is therefore desired to perform periodical memory transfer for quantitative and continuous data transmission between a computing device and a process input/output device. On the other hand, event data must be transmitted between the computing device and an event data collecting device (hereinafter referred to as "SOE device") temporarily by interrupt processing or the like only when the SOE device detects and records a defined event.
When the technique disclosed in JP-A-2000-10604 is, for example, applied to the SOE device, the transmission required between the SOE device and the computing device when the SOE device detects an event has to be performed using the same communication line as a communication line the input/output device is connected to. Therefore, there arises a problem that the transmission performed between the SOE device and the computing device affects the periodical transmission between the input/output device and the computing device so as to spoil the constant periodicity of the control data. In addition, when the control system is constructed with different lines for the control data and the event data in order to secure the constant periodicity of the control data, there arises a problem that the system as a whole becomes large in scale.
SUMMARY OF THE INVENTION
BACKGROUND OF THE INVENTION
Field of the Invention The present invention relates to a control system and an SOE device.
Description of the Related Art Data handled by a general plant control system includes control data processed by a computing device constantly to monitor and control a control target, and event data processed by the computing device temporarily to analyze the behavior of the control target when there occurs an abnormal event.
As a method for collecting and managing such event data, for example, JP-A-2000-10604 has disclosed a method in which an event input module including an event collecting function is placed in the same hierarchy as a plurality of process input/output devices in order to collect event data.
For example, in a control system for a power plant, control data is required to have immediacy and constant periodicity. It is therefore desired to perform periodical memory transfer for quantitative and continuous data transmission between a computing device and a process input/output device. On the other hand, event data must be transmitted between the computing device and an event data collecting device (hereinafter referred to as "SOE device") temporarily by interrupt processing or the like only when the SOE device detects and records a defined event.
When the technique disclosed in JP-A-2000-10604 is, for example, applied to the SOE device, the transmission required between the SOE device and the computing device when the SOE device detects an event has to be performed using the same communication line as a communication line the input/output device is connected to. Therefore, there arises a problem that the transmission performed between the SOE device and the computing device affects the periodical transmission between the input/output device and the computing device so as to spoil the constant periodicity of the control data. In addition, when the control system is constructed with different lines for the control data and the event data in order to secure the constant periodicity of the control data, there arises a problem that the system as a whole becomes large in scale.
SUMMARY OF THE INVENTION
In consideration of the aforementioned problem, an object of the present invention is to provide a control system in which process input/output devices and an SOE
device are connected through a shared communication line while the constant periodicity of control data can be secured.
In order to solve the aforementioned problem, for example, configurations stated in the scope of claims are used.
The invention includes a plurality of means to solve the foregoing problem.
For example, one of the means is a control system including a computing device which monitors and controls a control target, an input/output device which is connected to the control target, transmits a status signal inputted from the control target to the computing device, and outputs a control signal transmitted from the computing device to the control target, and an SOE device which imports the control signal or the status signal to detect a predetermined change thereof as an event, and records the control signal or the status signal as event data when the event is detected, wherein the computing device, the input/output device and the SOE
device are connected through one and the same transmission line, the SOE device is provided with a communication control portion which receives a read request for the event data from the computing device with a predetermined reception cycle, and transmits the event data stored in the SOE device, to the computing device with a predetermined transmission cycle in response to the read request.
According to the invention, in a control system in which a process input/output device and an SOE device are connected through a shared communication line, data transmission can be performed without spoiling the constant periodicity of control data.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a configuration diagram of a control system;
Fig. 2 is a diagram showing constantly periodical control based on memory transfer;
Fig. 3 is a flow chart of an operation in which an SOE device collects event data;
Fig. 4 is a diagram of an event data collecting block of the SOE device;
Fig. 5 is a timing chart of an operation in which the SOE device imports an initial status signal;
Fig. 6 is a timing chart of an event detecting operation of the SOE device (absence of event);
Fig. 7 is a timing chart of an event detecting operation of the SOE device (presence of event);
Fig. 8 is a view showing a format of event data;
Fig. 9 is a view showing event write performed by the SOE device and a write pointer thereof;
Fig. 10 is a flow chart showing an input memory transfer operation of the SOE
device;
Fig. 11 is a diagram showing an input memory transfer block of the SOE device;
Figs. 12A-12B are views showing formats of communication frames in the input memory transfer;
Fig. 13 is a view showing event read performed by the SOE device and a read pointer thereof;
Fig. 14 is a view showing a method by which the SOE device administers an event data buffer;
Fig. 15 is a view showing a part of the SOE device for determining whether event data is empty or not;
Fig. 16 is a view showing an initial state of the event data buffer in the SOE
device;
Fig. 17 is a view showing a pattern with which the SOE device carries out an event read response (Pattern 1);
Fig. 18 is a view showing a pattern with which the SOE device carries out an event read response (Pattern 2); and Fig. 19 is a view showing a pattern with which the SOE device carries out an event read response (Pattern 3).
DETAILED DESCRIPTION OF THE INVENTION
A mode for carrying out the invention will be described with reference to the drawings.
[Embodiment]
Fig. 1 is a configuration diagram of a control system showing an embodiment of the invention. In the control system for controlling a turbine in a power plant or the like, configuration is made as follows. A control target 6, a computing device 1, at least one process input device 2, at least one process output device 3, and at least one event data collecting device (hereinafter referred to as "SOE device") 7 are connected through a communication line 4 which is a line for serial communication based on RS-485. The control target 6 includes a turbine, sensors and auxiliary machines. The computing device 1 always monitors the status of the control target 6 and performs optimum feedback control on the control target 6. The process input device 2 converts a signal showing the status of the control target 6, into data to be transmitted to the computing device 1. The process output device 3 converts feedback data transmitted from the computing device 1, into a signal to be transmitted to the control target 6.
When the control target 6 indicates a specific control status, the SOE device 7 records the status and an occurrence time thereof. The process input and output devices 2 and 3 are connected to the control target 6 through a control signal line 5 having a signal which indicates the status of the control target 6 and a signal with which the feedback data is transmitted to the control target 6.
In addition, the SOE device 7 has a reception buffer 79 and a transmission buffer 83 as buffers for memory transfer. Though not shown, the computing device 1, the process input device 2 and the process output device 3 also have reception buffers, transmission buffers and communication control functions respectively. The memory transfer using the reception buffer 79 and the transmission buffer 83 will be described briefly below.
Transmission data received periodically from the computing device 1, the process input device 2 and the process output device 3 through the communication line 4 is stored in the reception buffer 79 by a communication control function 78. The SOE device 7 determines whether data stored in the reception buffer 79 is addressed to the SOE device 7 itself or not.
When the data is addressed to the SOE device 7 itself, the SOE device 7 then executes a process requested by the data, and stores response data addressed to a request source device into the transmission buffer 83. The data stored in the transmission buffer 83 is transmitted to the computing device 1, the process input device 2 and the process output device 3 simultaneously with a predetermined cycle by the communication control function 78, and stored in the reception buffers of the respective devices. The request source device determines whether the stored response data is addressed to the device itself or not, and recognizes that the request of the device itself has been executed.
Such a process is performed in the process input device 2 and the process output device 3 in the same manner. In this embodiment, the device transmitting requests to the process input device 2, the process output device 3 and the SOE device 7 is mainly the computing device 1.
Next, description will be made on the SOE device 7 processing a status signal 51.
The SOE device 7 uses a signal import function 71 to import at least one status signal 51 indicating the control status of the control target 6. An imported value of the status signal 51 is held as a current value 72 and a previous value 73 only for the first time. In and after the second time, data held in the current value 72 is held as the previous value 73, and the imported value is held as the current value 72. A comparison function 74 compares the held previous value 73 with the held current value 72 and outputs a comparison result signal 741 to an event detection function 75. Based on the comparison result signal 741, the event detection function 75 determines "presence of event" when the value of the status signal 51 has changed into a specific status, and determines "absence of event" when the value of the status signal 51 has not changed into the specific status.
When "presence of event" is determined, the event detection function 75 outputs an event detection signal 751 to an event write command function 76. The event write command function 76 outputs information about the change of the status signal 51 (hereinafter referred to as "event data") as an event write command signal 761 to an event data buffer control function 81. On this occasion, a current time acquired from a current time count signal 771 outputted from a current time counter 77 is added to the event data. The event data buffer control function 81 receiving the input of the event write command signal 761 records the event data into an event data buffer 82.
Here, while the event data is recorded into the event data buffer 82, a pointer indicating the address of the event data buffer 82 where the event data should be recorded is controlled by a write pointer control function 84 and an event data buffer administration function 88. On receiving a command signal 762 from the event write command function 76, the write pointer control function 84 outputs a write pointer signal 841 to the event data buffer administration function 88 and the event data buffer control function 81. The write pointer signal 841 indicates that the address where the event data should be recorded into the event data buffer 82 should be updated. Thus, every time when an event is detected, the write pointer signal 841 is outputted to update the address of the event data buffer 82 where the event data should be recorded. In this manner, event data can be stored into the event data buffer 82 every time when an event is detected.
The event data buffer administration function 88 administers the storage status and the pointer position of event data in the event data buffer 82, and outputs the status of the event data buffer 82 as an event data buffer status signal 881 to the event data buffer control function 81. Assume here that no more event data can be written in the event data buffer 82, for example, because the event data buffer 82 is full of event data which has not yet been read.
In such a case, the event data buffer control function 81 recognizes the status of the event data buffer 82 based on the event data buffer status signal 881, and suspends writing into the event data buffer 82. In this manner, the event data which has not yet been read can be prevented from being overwritten and the continuity of the event data can be prevented from being lost.
On the other hand, the SOE device 7 receives a communication frame from the communication line 4 with a constant cycle as described previously. A memory transfer block of the SOE device 7 is constituted by the communication control function 78 which receives a communication frame flowing in the communication line 4 and sends out a communication frame into the communication line 4, the reception buffer 79 which holds the communication frame received by the communication control function 78, a reception determination function 86 which determines the contents of the communication frame in the reception buffer 79, an event read command function 80 which issues a command to read event data when the contents of the communication frame indicate an "event read request", a read pointer command function 87 which issues a read pointer command to a read pointer control function 85, the read pointer control function 85 which indicates the address of the event data buffer 82 where event data should be read, the event data buffer administration function 88 which determines whether event data is contained in the event data buffer 82 or not, the event data buffer control function 81 which reads event data from the event data buffer 82 in accordance with an event read command signal 801 and a read pointer signal 851, the event data buffer 82 which can record or read event data in accordance with a command from the event data buffer control function 81, the transmission buffer 83 which holds the event data read from the event data buffer 82, and a dummy response function 810 which stores dummy event data into the transmission buffer 83 when event data is not contained in the event data buffer 82. Using the memory transfer block configured thus, the SOE device 7 receives and transmits an event data read request and an event data read response from and to the computing device I periodically.
Fig. 2 shows constantly periodical control based on the memory transfer performed by the computing device 1. In the steady state of the system, the computing device 1 always repeats the control with a constant cycle. In addition, as shown in Fig. 2, each control cycle is constituted by input memory transfer in which the computing device I
performs data transmission with the process input device 2 and the SOE device 7 to acquire data therefrom, computing in which the computing device 1 computes optimum feedback data for the control target 6 from the acquired data, and output memory transfer in which the computing device I
transmits the computed feedback data to the process output device 3.
Further, during every input memory transfer, transmission of data read requests having a fixed size and reception of data read responses having a fixed size to and from the process input device 2 and the SOE device 7 are performed. That is, the computing device 1 transmits a data read request to the process input device 2 and receives a data read response, to which data responding to the request has been added, from the process input device 2. Next, the computing device 1 transmits a data read request to the SOE device 7 and receives a data read response, to which data responding to the request has been added, from the SOE device 7.
On the other hand, during every output memory transfer, the computing device 1 transmits a data output request to the process output device 3 and receives a data output response, which indicates a data output has been executed, from the process output device 3.
According to the embodiment, in this manner, data transmission and reception between the computing device I and the SOE device 7 is incorporated in the control cycle of memory transfer performed with the process input device 2 and the process output device 3 by the computing device 1 to secure the constant periodicity of control data.
Thus, data transmission can be performed without spoiling the constant periodicity of the control data even in the control system in which the SOE device 7 is connected to the process input device 2 and the process output device 3 through one and the same communication line.
Fig. 3 shows the flow of an operation in which the SOE device 7 collects event data. The signal import function 71 imports at least one status signal 51 indicating the control status of the control target 6 (S30). The current value holding function 72 and the previous value holding function 73 hold the imported value of the status signal 51 as a current value and a previous value only for the first time (S3 1). As for the status signal 51 imported in and after the second time (S32), the current value is held as a previous value and the imported value is held as a current value (S33). The comparison function 74 compares the held current value with the held current value (S34). The event detection function detects whether the value of the status signal 51 has changed into a specific status or not based on the comparison result (S35). The event detection function determines "presence of event" when the value of the status signal 51 has changed into the specific status, and determines "absence of event" when the value of the status signal 51 has not changed into the specific status (S36). When "absence of event" is determined, the SOE device 7 returns to the import of the status signal 51.
When "presence of event" is determined, the SOE device 7 uses the event data buffer control function 81 to record event data into the event data buffer 82 (S37). Recording the event data into the event data buffer 82 is repeated till all entries of the detected event data have been recorded (S38).
Fig. 4 shows a diagram of an event data collecting block of the SOE device 7.
The event collecting block of the SOE device 7 is constituted by the signal import function 71 which imports the status signal 51, the current value holding function 72 which holds an imported value of the status signal 51 as a current value, the previous value holding function 73 which holds the imported value or the current value of the status signal 51 as a previous value, the comparison function 74 which compares the current value with the previous value, the event detection function 75 which determines "presence of event" or "absence of event" based on the comparison result, the current time counter 77 which keeps on counting a current time, and the event write command function 76 which records event data into the event data buffer 82 when "presence of event" is determined.
Next, event detection based on import of the status signal 51 will be described with reference to Figs. 5 to 7. Fig. 5 shows the operation in which the SOE
device 7 imports the status signal 51 for the first time. The signal import function 71 imports the status signal 51 with a predetermined cycle. When the status signal 51 is imported for the first time, the imported value is merely held as a current value and a previous value, and the status signal 51 is imported for the next time. That is, in status signal import (1), channels chO
to ch3 as the status signal 51 indicate "1, 0, 1, 0" respectively, and the values of the channels are therefore held as a current value and a previous value.
Fig. 6 shows the event detection operation in which the SOE device imports the status signal 51 in and after the second time when there occurs no event. The SOE device 7 imports the status signal 51 in status signal import (2), and holds the current value as a previous value and the imported value as a current value. The SOC device 7 uses the comparison function 74 to compare the values of the channels chO to ch3 in the held prevent value with those in the held previous value respectively. The comparison is, for example, performed by exclusive OR between the current value and the previous value. On this occasion, the channels chO to ch3 remain "1, 0, 1, 0" respectively, and there is no difference in each channel chO to ch3 between the previous value and the current value. Therefore, the SOE device 7 determines "absence of event". After "absence of event" is determined, the SOE device 7 imports the status signal 51 for the next time.
Fig. 7 shows the event detection operation in which the SOE device 7 imports the status signal 51 in and after the second time when there occurs an event. The SOE device 7 imports the status signal 51 in status signal import (3), and holds the current value as a previous value and the imported value as a current value, in the same manner as in the event detection operation shown in Fig. 6. The SOC device 7 uses the comparison function 74 to compare the values of the channels chO to ch3 in the imported current value with those in the previous value respectively. In this example, the channels chO to ch3 designate "1, 1, 0, 0"
respectively. That is, the channel chl has changed from the previous value "0" to the current value "1" and the channel ch 2 has changed from the previous value "I" to the current value "0".
Therefore, the SOE device 7 determines "presence of event" in the channel chi and ch2 two times in total.
After "presence of event" is determined, the SOE device 7 records event data of the channels chl and ch2 into the event data buffer 82. In addition, the change of the channel ch3 from "0" to "1" thereafter as shown in Fig. 7 is detected as an event when the status signal 51 is imported for the next time.
Thus, when the channel ch3 of the status signal is, for example, a signal indicating the existence of some warning, how the warning has occurred after the change of the status signal 51 indicated by the channels chO to ch2 can be analyzed. Although the change of a digital signal is monitored to detect an event in the embodiment as shown in Figs. 5 to 7, configuration may be made in such a manner that an analog signal as the status signal 51 is monitored so that an event can be detected when a difference between a current value and a previous value exceeds a predetermined threshold.
Fig. 8 shows a format of event data. Each entry of event data is constituted by the ch number of a channel which is determined to have "presence of event" in the aforementioned event detection, the current value of the channel in the status signal 51, and the event detection time which is a value indicated by the current time counter 77 at the point of time when "presence of event" is determined in the aforementioned event detection.
In the embodiment, assume that the current time counter 77 indicates "Oxl 1" at the point of time when "presence of event" is determined. In this case, the ch number, the current value and the event detection time in the event data of the channel chl are "l/l/Oxl l"
respectively. In the same manner, the event data of the channel ch2 has values of "2/0/Ox 11 ".
Fig. 9 shows the state of event write and write pointer control in the SOE
device 7. When event data is recorded into the event data buffer 82 (hereinafter referred to as "event write"), the event write is performed in accordance with the write pointer signal 841 by the write pointer control function 84. The write pointer signal 841 indicates the address of the event data buffer 82 where event data should be recorded. The write pointer signal 841 is updated whenever the event write command signal 761 is inputted. Thus, the write pointer signal 841 always indicates the address of the event data buffer 82 where event data should be recorded next time. When there are two or more entries of event data, the event write command function 76 and the write pointer signal 841 are updated repeatedly as many times as the number of the entries of event data.
In the embodiment, by event write of two entries for the channels ch l and ch2, event data is stored in addresses "3" and "4" of the event data buffer 82, and the write pointer signal 841 is updated from "4" to "5" and from "5" to "6". Here, for example, assume that the event data buffer 82 is constituted by a ring buffer. When the write pointer reaches the end of addresses of the event data buffer 82, the write pointer is updated to the address " 1 " again.
However, when the address is updated, there may be a case where event data which has not yet been read has to be overwritten. In this case, the event data buffer control function 81 recognizes such a state based on the event data buffer status signal 881 from the event data buffer administration function 88 and suspends writing into the event data buffer 82. Thus, the event data which has not yet been read can be prevented from being overwritten and the continuity of the event data can be prevented from being lost.
Fig. 10 shows the flow of operation of the input memory transfer of the SOE
device 7. The SOE device 7 always uses the communication control function 78 to receive a communication frame from the communication line 4 and stores the communication frame into the reception buffer 79 (S 100). On receiving the communication frame from the computing device 1, the reception determination function 86 determines the contents of the received communication frame (S101). Further, the reception determination function 86 determines whether the received communication frame is "addressed to its own node" or not (S102), When it is concluded as the determination result that the received communication frame is "addressed to another node", the SOE device 7 abandons or ignores the communication frame, and returns to S 100. When it is concluded as the determination result that the received communication frame is "addressed to its own node", the reception determination function 86 determines whether the received communication frame is an "event read request" or not (S 103). When the communication frame is not an "event read request", the SOE device 7 executes processing other than event read requested by the communication frame and returns to S100. When the communication frame is an "event read request", the SOE device 7 reads event data from the event data buffer 82 repeatedly until all the entries of the event data are read (S 105). When all the entries of the event data have been read, a communication frame including the event data read from the event data buffer 82 is transmitted as an event read response addressed to the computing device I (S 106). After transmitting the event read response, the SOE device 7 waits for reception of a communication frame from the computing device I again.
Fig. 11 shows the memory transfer block of the SOE device 7. The communication control function 78 always receives a communication frame from the communication line 4 and stores the communication frame into the reception buffer 79 through a reception path 781. Every time when a communication frame is stored into the reception buffer, the reception determination function 86 determines whether the communication frame is "addressed to its own node" or not and whether the communication frame is an "event read request" or not. When the contents of the communication frame are "addressed to its own node" and an "event read request", the reception determination function 86 outputs a reception determination result signal 861 to the read pointer command function 87 and the event read command function 80. The event read command function 80 receiving the reception determination result signal 861 outputs an event read command signal 801 to the read pointer control function 85 and the event data buffer control function 81. The event data buffer control function 81 receiving the event read command signal 801 reads event data from the event data buffer 82 and stores the event data into the transmission buffer 83.
Here, when event data is read from the event data buffer 82, pointer control at the address of the event data buffer 82 where the event data should be read is performed by the read pointer control function 85 and the event data buffer administration function 88. On receiving the event read command signal 801 from the event read command function 80, the read pointer control function 85 outputs a read pointer signal 851, which indicates that the address where the event data should be read from the event data buffer 82 should be updated, to the event data buffer administration function 88 and the event data buffer control function 81. That is, whenever the SOE device 7 receives an "event read request", the read pointer control function 85 outputs a read pointer signal 851 to update the address of the event data buffer 82 where event data should be read.
For example, assume that the computing device 1 fails to receive event data.
In such a case, the read pointer command function 87 outputs a read pointer command signal 871 to the read pointer control function 85 so as to read again the event data which has been already read. That is, when the contents of an "event read request" from the computing device I are a request to read again the event data which has been already read, the read pointer command function 87 outputs the read pointer command signal 871 to the read pointer control function 85 so as to set the read pointer at the address where the event data has been read, and to suspend updating the read address. Thus, it is possible to deal with a failure in transmitting or receiving event data, or the like, in the process in which the address where the event data should be read is updated every time when an "event read request" is received.
The event data buffer administration function 88 administers the storage status and the pointer position of event data in the event data buffer 82, and outputs the status of the event data buffer 82 as an event data buffer status signal 881 to the event data buffer control function 81. Here, assume that the event data buffer status signal 881 indicates that the read pointer and the write pointer indicate one and the same address. In this case, it is understood that event data which has not yet been read will not be contained even if the address is further updated. Therefore, the event data buffer administration function 88 does not update the read address but uses the dummy response function 810 in the event data buffer administration function 88 to store dummy event data into the transmission buffer 83. The dummy event data stored in the transmission buffer 83 is transmitted to the computing device 1 at the timing when the SOE device 7 performs transfer. When the computing device 1 makes determination that the received event data is dummy, the computing device I recognizes that the event data which has not yet been read is not contained.
As described previously, the computing device 1 performs communication with the process input device 2 and so on through memory transfer. Communication with the SOE
device 7 is also defined in a predetermined control cycle of the computing device 1. Here, when the event data which has not yet been read is not contained as described above, the dummy event data is transmitted so that the control system can be constructed without disturbing the periodical transmission with the computing device 1.
Figs. 12A-12B show formats of communication frames in the input memory transfer. The upper stage of Fig. 12A shows a format of a communication frame when the communication frame is stored in the reception buffer 79 in the input memory transfer from the computing device 1. The type of a communication frame addressed to the SOE
device 7 from the computing device 1 in the input memory transfer is an event read request, which is determined in accordance with the contents of each area of "request/response", "read/write", "destination node address" and "event read size". In the embodiment, "request/response"
consists of one bit indicating whether the communication frame is a request "1" or a response "0"
from the computing device 1; "read/write" consists of one bit indicating whether the communication frame is read "1" or write "0" from the computing device 1; and "destination node address" consists of ten bits indicating which node address 0 to 1023 is a destination of the communication frame. In addition, "event read size" consists of five bits by which the data size of the request from the computing device 1 can be set from 1 event to 32 events. The "event read size" is set at the time of system construction. In the embodiment, description will be made below on the assumption that the read size has been set at four.
For example, assume that an event read request frame as shown in the lower stage of Fig. 12A is received. In this case, the reception determination function 86 determines whether the value of the "request/response" area in the communication frame in the reception buffer 79 is "1" (request) or not, whether the value of the "read/write" area are is "1" (read) or not and whether the value of the "destination node address" area coincides with the node address of the SOE device 7 itself or not. Thus, the reception determination function 86 judges that the received communication frame is an "event read request" addressed to its own node.
When the reception determination function 86 judges that the communication frame is an "event read request" addressed to its own node, the event read command function 80 outputs the event read command signal 801 to the event data buffer control function 81 to read event data from the event data buffer 82. In accordance with the event read command signal 801, the event data buffer control function 81 reads, from an area of the event data buffer 82 indicated by the read pointer signal 851, one entry of event data which has not yet been read, and stores the read event data into the transmission buffer 83.
The event read command function 80 reads event data from the event data buffer 82 in accordance with the event read command signal 801 repeatedly as many times as the request data size of the aforementioned "read size" area, and stores the event data corresponding to the request data size into the transmission buffer 83.
Here, the upper stage of Fig. 12B shows a format of a communication frame for an event read response.
The type of a communication frame addressed to the computing device 1 from the SOE device 7 in the input memory transfer is an event read response, which is determined in accordance with the contents of each area of "request/response", "read/write", "destination node address" and "event read size". In the embodiment, an event read response frame as shown in the lower stage of Fig. 12B is stored in the transmission buffer 83. When event data corresponding to the request data size is stored into the transmission buffer 83, the communication control function 78 transmits the event data in the transmission buffer as an "event read response" to the computing device 1.
Fig. 13 shows the operation of the event data buffer 82 and the read pointer control function 85 in the event read of the SOE device 7. The read pointer indicates the address where event data to be read in response to a next request has been stored in the event data buffer. When there comes a read request, the read pointer is updated after event data is read. The event data buffer administration function 88 and the event data buffer control function 81 repeats the cycle as many times as the number of requested entries of event data. In the embodiment, the event read size is four. Accordingly, the read cycle is repeated four times, and the read pointer is updated by four as illustrated in Fig. 13.
Fig. 14 shows a method for administering the event data buffer. The read pointer and the write pointer indicate the addresses where event data should be read or written in response to a next read request or a next write request. Accordingly, when the read pointer and the write pointer indicate one and the same address, it is understood that the "address where event data should be read next time" coincides with the "address where event data should be written next time (currently empty). This means that event data which has not yet been read is not contained in the event data buffer (event data is empty).
Fig. 15 shows a method for determining whether the event data is empty or not.
As described above, event data is empty when the address indicated by the read pointer coincides with the address indicated by the write pointer. Accordingly, those addresses are compared with each other by a pointer address comparator 9 so as to determine whether event data is empty or not. The pointer address comparator 9 may be provided in the event data buffer administration function 88 or provided in the event data buffer control function 81.
Fig. 16 shows an initial status of the event data buffer. Immediately after the event data buffer 82 is reset, the event data buffer 82 is empty with no data.
Accordingly, the event data buffer 82 is in the event data empty state where the read pointer and the write pointer indicate one and the same address.
Fig. 17 shows a read response of the SOE device 7 when event data which has not yet been read is contained in the event data buffer 82 and has a size not smaller than the read size. When event data which has not yet been read is contained in the event data buffer 82 and has a size not smaller than the read size, a response is made while event data is stored into all data areas of an event read response frame. That is, in the embodiment, the read size is four while the number of entries of event data which has not yet been read is five.
Therefore, the event data is stored into all the four data areas of the event read response frame. The remaining one entry of the event data which has not yet been read will be transmitted in response to a next event read request.
Fig. 18 shows a read response of the SOE device 7 when event data which has not yet been read is not contained in the event data buffer 82 (event data is empty). In this case, the event data buffer administration function 88 uses the event data buffer status signal 881 to inform the event data buffer control function 81 of the fact that the read pointer and the write pointer indicate one and the same address, that is, the fact that event data which has not yet been read is not contained. In this manner, the event data buffer administration function 88 does not update the read address but stores dummy response data (stores an invalid value into the event detection time area of event data but does not care the area of the ch number where an event has been detected and the area of the current value of the status signal) in all the data areas of the event read response frame. Thus, the SOE device 7 makes a response.
Fig. 19 shows a read response of the SOE device 7 when at least one entry of event data which has not yet been read is contained in the event data buffer 82 and has a size smaller than the read size. When at least one entry of event data which has not yet been read is contained in the event data buffer 82 and has a size smaller than the read size, the event data buffer administration function 88 stores dummy response data (stores an invalid value into the event detection time area of event data but does not care the other areas) into a part of the data areas of the read response frame. Thus, the SOE device 7 makes a response. In the embodiment, the read size is four, and the size of event data which has not yet been read is two.
Therefore, two entries of event data and two entries of dummy response data are stored in the transmission buffer 83.
As described above, the read pointer is controlled as shown in Figs. 18 and 19, so as to prevent the address of the read pointer from being updated earlier than the address of the write pointer. Thus, it is possible to prevent an omission in reading event data which has not yet been read. In addition, when event data which has not yet been read is not contained, dummy event data is transmitted. Thus, it is possible to construct the control system without disturbing periodical transmission with the computing device 1.
According to the invention which has been described above, in a control system in which process input and output devices and an SOE device are connected through one and the same communication line, a computing device performs memory transfer with a predetermined control cycle so as to perform transmission of control data with the process input and output devices periodically. A period of data transmission/reception with the SOE
device 7 required only when a proper predetermined event is detected is defined within the control cycle of the computing device 1. Thus, it is possible to perform event data transmission without spoiling the constant periodicity of the control data.
In addition, when event data to be transmitted is not contained, the SOE
device transmits dummy response data. In this manner, periodical transmission with the computing device I can be kept. Thus, it is possible to construct the system without disturbing the control cycle of the computing device.
In addition, the constant periodicity of the control data can be secured without arranging a communication path for the control data and a communication path for event data as different lines. Accordingly, it is possible to miniaturize the system while functions as a general plant control system are provided.
The invention is not limited to the aforementioned embodiment, but various modifications are included in the invention. For example, the aforementioned embodiment has been described in detail for the purpose of giving explanation to understand the invention easily.
However, the invention does not have to be always limited to the embodiment provided with the whole configuration described above. In addition, a part of the configuration of one embodiment may be replaced by a part of the configuration of another embodiment, or the configuration of another embodiment may be added to the configuration of one embodiment.
In addition, a part of the configuration of each embodiment may be added to another configuration, deleted or replaced. In addition, as for each configuration, function, processing portion, processing means, etc. as described above, a part or all of those may be designed for example, into an integrated circuit so as to be implemented as hardware. In addition, each configuration, function, etc. as described above may be implemented as software by a processor which interprets a program implementing the function and executes the program.
In addition, control lines or information lines are illustrated and regarded as necessary for the sake of explanation, but all the control lines or information lines in a product are not always illustrated. In practice, almost all the constituents may be regarded as connected mutually.
device are connected through a shared communication line while the constant periodicity of control data can be secured.
In order to solve the aforementioned problem, for example, configurations stated in the scope of claims are used.
The invention includes a plurality of means to solve the foregoing problem.
For example, one of the means is a control system including a computing device which monitors and controls a control target, an input/output device which is connected to the control target, transmits a status signal inputted from the control target to the computing device, and outputs a control signal transmitted from the computing device to the control target, and an SOE device which imports the control signal or the status signal to detect a predetermined change thereof as an event, and records the control signal or the status signal as event data when the event is detected, wherein the computing device, the input/output device and the SOE
device are connected through one and the same transmission line, the SOE device is provided with a communication control portion which receives a read request for the event data from the computing device with a predetermined reception cycle, and transmits the event data stored in the SOE device, to the computing device with a predetermined transmission cycle in response to the read request.
According to the invention, in a control system in which a process input/output device and an SOE device are connected through a shared communication line, data transmission can be performed without spoiling the constant periodicity of control data.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a configuration diagram of a control system;
Fig. 2 is a diagram showing constantly periodical control based on memory transfer;
Fig. 3 is a flow chart of an operation in which an SOE device collects event data;
Fig. 4 is a diagram of an event data collecting block of the SOE device;
Fig. 5 is a timing chart of an operation in which the SOE device imports an initial status signal;
Fig. 6 is a timing chart of an event detecting operation of the SOE device (absence of event);
Fig. 7 is a timing chart of an event detecting operation of the SOE device (presence of event);
Fig. 8 is a view showing a format of event data;
Fig. 9 is a view showing event write performed by the SOE device and a write pointer thereof;
Fig. 10 is a flow chart showing an input memory transfer operation of the SOE
device;
Fig. 11 is a diagram showing an input memory transfer block of the SOE device;
Figs. 12A-12B are views showing formats of communication frames in the input memory transfer;
Fig. 13 is a view showing event read performed by the SOE device and a read pointer thereof;
Fig. 14 is a view showing a method by which the SOE device administers an event data buffer;
Fig. 15 is a view showing a part of the SOE device for determining whether event data is empty or not;
Fig. 16 is a view showing an initial state of the event data buffer in the SOE
device;
Fig. 17 is a view showing a pattern with which the SOE device carries out an event read response (Pattern 1);
Fig. 18 is a view showing a pattern with which the SOE device carries out an event read response (Pattern 2); and Fig. 19 is a view showing a pattern with which the SOE device carries out an event read response (Pattern 3).
DETAILED DESCRIPTION OF THE INVENTION
A mode for carrying out the invention will be described with reference to the drawings.
[Embodiment]
Fig. 1 is a configuration diagram of a control system showing an embodiment of the invention. In the control system for controlling a turbine in a power plant or the like, configuration is made as follows. A control target 6, a computing device 1, at least one process input device 2, at least one process output device 3, and at least one event data collecting device (hereinafter referred to as "SOE device") 7 are connected through a communication line 4 which is a line for serial communication based on RS-485. The control target 6 includes a turbine, sensors and auxiliary machines. The computing device 1 always monitors the status of the control target 6 and performs optimum feedback control on the control target 6. The process input device 2 converts a signal showing the status of the control target 6, into data to be transmitted to the computing device 1. The process output device 3 converts feedback data transmitted from the computing device 1, into a signal to be transmitted to the control target 6.
When the control target 6 indicates a specific control status, the SOE device 7 records the status and an occurrence time thereof. The process input and output devices 2 and 3 are connected to the control target 6 through a control signal line 5 having a signal which indicates the status of the control target 6 and a signal with which the feedback data is transmitted to the control target 6.
In addition, the SOE device 7 has a reception buffer 79 and a transmission buffer 83 as buffers for memory transfer. Though not shown, the computing device 1, the process input device 2 and the process output device 3 also have reception buffers, transmission buffers and communication control functions respectively. The memory transfer using the reception buffer 79 and the transmission buffer 83 will be described briefly below.
Transmission data received periodically from the computing device 1, the process input device 2 and the process output device 3 through the communication line 4 is stored in the reception buffer 79 by a communication control function 78. The SOE device 7 determines whether data stored in the reception buffer 79 is addressed to the SOE device 7 itself or not.
When the data is addressed to the SOE device 7 itself, the SOE device 7 then executes a process requested by the data, and stores response data addressed to a request source device into the transmission buffer 83. The data stored in the transmission buffer 83 is transmitted to the computing device 1, the process input device 2 and the process output device 3 simultaneously with a predetermined cycle by the communication control function 78, and stored in the reception buffers of the respective devices. The request source device determines whether the stored response data is addressed to the device itself or not, and recognizes that the request of the device itself has been executed.
Such a process is performed in the process input device 2 and the process output device 3 in the same manner. In this embodiment, the device transmitting requests to the process input device 2, the process output device 3 and the SOE device 7 is mainly the computing device 1.
Next, description will be made on the SOE device 7 processing a status signal 51.
The SOE device 7 uses a signal import function 71 to import at least one status signal 51 indicating the control status of the control target 6. An imported value of the status signal 51 is held as a current value 72 and a previous value 73 only for the first time. In and after the second time, data held in the current value 72 is held as the previous value 73, and the imported value is held as the current value 72. A comparison function 74 compares the held previous value 73 with the held current value 72 and outputs a comparison result signal 741 to an event detection function 75. Based on the comparison result signal 741, the event detection function 75 determines "presence of event" when the value of the status signal 51 has changed into a specific status, and determines "absence of event" when the value of the status signal 51 has not changed into the specific status.
When "presence of event" is determined, the event detection function 75 outputs an event detection signal 751 to an event write command function 76. The event write command function 76 outputs information about the change of the status signal 51 (hereinafter referred to as "event data") as an event write command signal 761 to an event data buffer control function 81. On this occasion, a current time acquired from a current time count signal 771 outputted from a current time counter 77 is added to the event data. The event data buffer control function 81 receiving the input of the event write command signal 761 records the event data into an event data buffer 82.
Here, while the event data is recorded into the event data buffer 82, a pointer indicating the address of the event data buffer 82 where the event data should be recorded is controlled by a write pointer control function 84 and an event data buffer administration function 88. On receiving a command signal 762 from the event write command function 76, the write pointer control function 84 outputs a write pointer signal 841 to the event data buffer administration function 88 and the event data buffer control function 81. The write pointer signal 841 indicates that the address where the event data should be recorded into the event data buffer 82 should be updated. Thus, every time when an event is detected, the write pointer signal 841 is outputted to update the address of the event data buffer 82 where the event data should be recorded. In this manner, event data can be stored into the event data buffer 82 every time when an event is detected.
The event data buffer administration function 88 administers the storage status and the pointer position of event data in the event data buffer 82, and outputs the status of the event data buffer 82 as an event data buffer status signal 881 to the event data buffer control function 81. Assume here that no more event data can be written in the event data buffer 82, for example, because the event data buffer 82 is full of event data which has not yet been read.
In such a case, the event data buffer control function 81 recognizes the status of the event data buffer 82 based on the event data buffer status signal 881, and suspends writing into the event data buffer 82. In this manner, the event data which has not yet been read can be prevented from being overwritten and the continuity of the event data can be prevented from being lost.
On the other hand, the SOE device 7 receives a communication frame from the communication line 4 with a constant cycle as described previously. A memory transfer block of the SOE device 7 is constituted by the communication control function 78 which receives a communication frame flowing in the communication line 4 and sends out a communication frame into the communication line 4, the reception buffer 79 which holds the communication frame received by the communication control function 78, a reception determination function 86 which determines the contents of the communication frame in the reception buffer 79, an event read command function 80 which issues a command to read event data when the contents of the communication frame indicate an "event read request", a read pointer command function 87 which issues a read pointer command to a read pointer control function 85, the read pointer control function 85 which indicates the address of the event data buffer 82 where event data should be read, the event data buffer administration function 88 which determines whether event data is contained in the event data buffer 82 or not, the event data buffer control function 81 which reads event data from the event data buffer 82 in accordance with an event read command signal 801 and a read pointer signal 851, the event data buffer 82 which can record or read event data in accordance with a command from the event data buffer control function 81, the transmission buffer 83 which holds the event data read from the event data buffer 82, and a dummy response function 810 which stores dummy event data into the transmission buffer 83 when event data is not contained in the event data buffer 82. Using the memory transfer block configured thus, the SOE device 7 receives and transmits an event data read request and an event data read response from and to the computing device I periodically.
Fig. 2 shows constantly periodical control based on the memory transfer performed by the computing device 1. In the steady state of the system, the computing device 1 always repeats the control with a constant cycle. In addition, as shown in Fig. 2, each control cycle is constituted by input memory transfer in which the computing device I
performs data transmission with the process input device 2 and the SOE device 7 to acquire data therefrom, computing in which the computing device 1 computes optimum feedback data for the control target 6 from the acquired data, and output memory transfer in which the computing device I
transmits the computed feedback data to the process output device 3.
Further, during every input memory transfer, transmission of data read requests having a fixed size and reception of data read responses having a fixed size to and from the process input device 2 and the SOE device 7 are performed. That is, the computing device 1 transmits a data read request to the process input device 2 and receives a data read response, to which data responding to the request has been added, from the process input device 2. Next, the computing device 1 transmits a data read request to the SOE device 7 and receives a data read response, to which data responding to the request has been added, from the SOE device 7.
On the other hand, during every output memory transfer, the computing device 1 transmits a data output request to the process output device 3 and receives a data output response, which indicates a data output has been executed, from the process output device 3.
According to the embodiment, in this manner, data transmission and reception between the computing device I and the SOE device 7 is incorporated in the control cycle of memory transfer performed with the process input device 2 and the process output device 3 by the computing device 1 to secure the constant periodicity of control data.
Thus, data transmission can be performed without spoiling the constant periodicity of the control data even in the control system in which the SOE device 7 is connected to the process input device 2 and the process output device 3 through one and the same communication line.
Fig. 3 shows the flow of an operation in which the SOE device 7 collects event data. The signal import function 71 imports at least one status signal 51 indicating the control status of the control target 6 (S30). The current value holding function 72 and the previous value holding function 73 hold the imported value of the status signal 51 as a current value and a previous value only for the first time (S3 1). As for the status signal 51 imported in and after the second time (S32), the current value is held as a previous value and the imported value is held as a current value (S33). The comparison function 74 compares the held current value with the held current value (S34). The event detection function detects whether the value of the status signal 51 has changed into a specific status or not based on the comparison result (S35). The event detection function determines "presence of event" when the value of the status signal 51 has changed into the specific status, and determines "absence of event" when the value of the status signal 51 has not changed into the specific status (S36). When "absence of event" is determined, the SOE device 7 returns to the import of the status signal 51.
When "presence of event" is determined, the SOE device 7 uses the event data buffer control function 81 to record event data into the event data buffer 82 (S37). Recording the event data into the event data buffer 82 is repeated till all entries of the detected event data have been recorded (S38).
Fig. 4 shows a diagram of an event data collecting block of the SOE device 7.
The event collecting block of the SOE device 7 is constituted by the signal import function 71 which imports the status signal 51, the current value holding function 72 which holds an imported value of the status signal 51 as a current value, the previous value holding function 73 which holds the imported value or the current value of the status signal 51 as a previous value, the comparison function 74 which compares the current value with the previous value, the event detection function 75 which determines "presence of event" or "absence of event" based on the comparison result, the current time counter 77 which keeps on counting a current time, and the event write command function 76 which records event data into the event data buffer 82 when "presence of event" is determined.
Next, event detection based on import of the status signal 51 will be described with reference to Figs. 5 to 7. Fig. 5 shows the operation in which the SOE
device 7 imports the status signal 51 for the first time. The signal import function 71 imports the status signal 51 with a predetermined cycle. When the status signal 51 is imported for the first time, the imported value is merely held as a current value and a previous value, and the status signal 51 is imported for the next time. That is, in status signal import (1), channels chO
to ch3 as the status signal 51 indicate "1, 0, 1, 0" respectively, and the values of the channels are therefore held as a current value and a previous value.
Fig. 6 shows the event detection operation in which the SOE device imports the status signal 51 in and after the second time when there occurs no event. The SOE device 7 imports the status signal 51 in status signal import (2), and holds the current value as a previous value and the imported value as a current value. The SOC device 7 uses the comparison function 74 to compare the values of the channels chO to ch3 in the held prevent value with those in the held previous value respectively. The comparison is, for example, performed by exclusive OR between the current value and the previous value. On this occasion, the channels chO to ch3 remain "1, 0, 1, 0" respectively, and there is no difference in each channel chO to ch3 between the previous value and the current value. Therefore, the SOE device 7 determines "absence of event". After "absence of event" is determined, the SOE device 7 imports the status signal 51 for the next time.
Fig. 7 shows the event detection operation in which the SOE device 7 imports the status signal 51 in and after the second time when there occurs an event. The SOE device 7 imports the status signal 51 in status signal import (3), and holds the current value as a previous value and the imported value as a current value, in the same manner as in the event detection operation shown in Fig. 6. The SOC device 7 uses the comparison function 74 to compare the values of the channels chO to ch3 in the imported current value with those in the previous value respectively. In this example, the channels chO to ch3 designate "1, 1, 0, 0"
respectively. That is, the channel chl has changed from the previous value "0" to the current value "1" and the channel ch 2 has changed from the previous value "I" to the current value "0".
Therefore, the SOE device 7 determines "presence of event" in the channel chi and ch2 two times in total.
After "presence of event" is determined, the SOE device 7 records event data of the channels chl and ch2 into the event data buffer 82. In addition, the change of the channel ch3 from "0" to "1" thereafter as shown in Fig. 7 is detected as an event when the status signal 51 is imported for the next time.
Thus, when the channel ch3 of the status signal is, for example, a signal indicating the existence of some warning, how the warning has occurred after the change of the status signal 51 indicated by the channels chO to ch2 can be analyzed. Although the change of a digital signal is monitored to detect an event in the embodiment as shown in Figs. 5 to 7, configuration may be made in such a manner that an analog signal as the status signal 51 is monitored so that an event can be detected when a difference between a current value and a previous value exceeds a predetermined threshold.
Fig. 8 shows a format of event data. Each entry of event data is constituted by the ch number of a channel which is determined to have "presence of event" in the aforementioned event detection, the current value of the channel in the status signal 51, and the event detection time which is a value indicated by the current time counter 77 at the point of time when "presence of event" is determined in the aforementioned event detection.
In the embodiment, assume that the current time counter 77 indicates "Oxl 1" at the point of time when "presence of event" is determined. In this case, the ch number, the current value and the event detection time in the event data of the channel chl are "l/l/Oxl l"
respectively. In the same manner, the event data of the channel ch2 has values of "2/0/Ox 11 ".
Fig. 9 shows the state of event write and write pointer control in the SOE
device 7. When event data is recorded into the event data buffer 82 (hereinafter referred to as "event write"), the event write is performed in accordance with the write pointer signal 841 by the write pointer control function 84. The write pointer signal 841 indicates the address of the event data buffer 82 where event data should be recorded. The write pointer signal 841 is updated whenever the event write command signal 761 is inputted. Thus, the write pointer signal 841 always indicates the address of the event data buffer 82 where event data should be recorded next time. When there are two or more entries of event data, the event write command function 76 and the write pointer signal 841 are updated repeatedly as many times as the number of the entries of event data.
In the embodiment, by event write of two entries for the channels ch l and ch2, event data is stored in addresses "3" and "4" of the event data buffer 82, and the write pointer signal 841 is updated from "4" to "5" and from "5" to "6". Here, for example, assume that the event data buffer 82 is constituted by a ring buffer. When the write pointer reaches the end of addresses of the event data buffer 82, the write pointer is updated to the address " 1 " again.
However, when the address is updated, there may be a case where event data which has not yet been read has to be overwritten. In this case, the event data buffer control function 81 recognizes such a state based on the event data buffer status signal 881 from the event data buffer administration function 88 and suspends writing into the event data buffer 82. Thus, the event data which has not yet been read can be prevented from being overwritten and the continuity of the event data can be prevented from being lost.
Fig. 10 shows the flow of operation of the input memory transfer of the SOE
device 7. The SOE device 7 always uses the communication control function 78 to receive a communication frame from the communication line 4 and stores the communication frame into the reception buffer 79 (S 100). On receiving the communication frame from the computing device 1, the reception determination function 86 determines the contents of the received communication frame (S101). Further, the reception determination function 86 determines whether the received communication frame is "addressed to its own node" or not (S102), When it is concluded as the determination result that the received communication frame is "addressed to another node", the SOE device 7 abandons or ignores the communication frame, and returns to S 100. When it is concluded as the determination result that the received communication frame is "addressed to its own node", the reception determination function 86 determines whether the received communication frame is an "event read request" or not (S 103). When the communication frame is not an "event read request", the SOE device 7 executes processing other than event read requested by the communication frame and returns to S100. When the communication frame is an "event read request", the SOE device 7 reads event data from the event data buffer 82 repeatedly until all the entries of the event data are read (S 105). When all the entries of the event data have been read, a communication frame including the event data read from the event data buffer 82 is transmitted as an event read response addressed to the computing device I (S 106). After transmitting the event read response, the SOE device 7 waits for reception of a communication frame from the computing device I again.
Fig. 11 shows the memory transfer block of the SOE device 7. The communication control function 78 always receives a communication frame from the communication line 4 and stores the communication frame into the reception buffer 79 through a reception path 781. Every time when a communication frame is stored into the reception buffer, the reception determination function 86 determines whether the communication frame is "addressed to its own node" or not and whether the communication frame is an "event read request" or not. When the contents of the communication frame are "addressed to its own node" and an "event read request", the reception determination function 86 outputs a reception determination result signal 861 to the read pointer command function 87 and the event read command function 80. The event read command function 80 receiving the reception determination result signal 861 outputs an event read command signal 801 to the read pointer control function 85 and the event data buffer control function 81. The event data buffer control function 81 receiving the event read command signal 801 reads event data from the event data buffer 82 and stores the event data into the transmission buffer 83.
Here, when event data is read from the event data buffer 82, pointer control at the address of the event data buffer 82 where the event data should be read is performed by the read pointer control function 85 and the event data buffer administration function 88. On receiving the event read command signal 801 from the event read command function 80, the read pointer control function 85 outputs a read pointer signal 851, which indicates that the address where the event data should be read from the event data buffer 82 should be updated, to the event data buffer administration function 88 and the event data buffer control function 81. That is, whenever the SOE device 7 receives an "event read request", the read pointer control function 85 outputs a read pointer signal 851 to update the address of the event data buffer 82 where event data should be read.
For example, assume that the computing device 1 fails to receive event data.
In such a case, the read pointer command function 87 outputs a read pointer command signal 871 to the read pointer control function 85 so as to read again the event data which has been already read. That is, when the contents of an "event read request" from the computing device I are a request to read again the event data which has been already read, the read pointer command function 87 outputs the read pointer command signal 871 to the read pointer control function 85 so as to set the read pointer at the address where the event data has been read, and to suspend updating the read address. Thus, it is possible to deal with a failure in transmitting or receiving event data, or the like, in the process in which the address where the event data should be read is updated every time when an "event read request" is received.
The event data buffer administration function 88 administers the storage status and the pointer position of event data in the event data buffer 82, and outputs the status of the event data buffer 82 as an event data buffer status signal 881 to the event data buffer control function 81. Here, assume that the event data buffer status signal 881 indicates that the read pointer and the write pointer indicate one and the same address. In this case, it is understood that event data which has not yet been read will not be contained even if the address is further updated. Therefore, the event data buffer administration function 88 does not update the read address but uses the dummy response function 810 in the event data buffer administration function 88 to store dummy event data into the transmission buffer 83. The dummy event data stored in the transmission buffer 83 is transmitted to the computing device 1 at the timing when the SOE device 7 performs transfer. When the computing device 1 makes determination that the received event data is dummy, the computing device I recognizes that the event data which has not yet been read is not contained.
As described previously, the computing device 1 performs communication with the process input device 2 and so on through memory transfer. Communication with the SOE
device 7 is also defined in a predetermined control cycle of the computing device 1. Here, when the event data which has not yet been read is not contained as described above, the dummy event data is transmitted so that the control system can be constructed without disturbing the periodical transmission with the computing device 1.
Figs. 12A-12B show formats of communication frames in the input memory transfer. The upper stage of Fig. 12A shows a format of a communication frame when the communication frame is stored in the reception buffer 79 in the input memory transfer from the computing device 1. The type of a communication frame addressed to the SOE
device 7 from the computing device 1 in the input memory transfer is an event read request, which is determined in accordance with the contents of each area of "request/response", "read/write", "destination node address" and "event read size". In the embodiment, "request/response"
consists of one bit indicating whether the communication frame is a request "1" or a response "0"
from the computing device 1; "read/write" consists of one bit indicating whether the communication frame is read "1" or write "0" from the computing device 1; and "destination node address" consists of ten bits indicating which node address 0 to 1023 is a destination of the communication frame. In addition, "event read size" consists of five bits by which the data size of the request from the computing device 1 can be set from 1 event to 32 events. The "event read size" is set at the time of system construction. In the embodiment, description will be made below on the assumption that the read size has been set at four.
For example, assume that an event read request frame as shown in the lower stage of Fig. 12A is received. In this case, the reception determination function 86 determines whether the value of the "request/response" area in the communication frame in the reception buffer 79 is "1" (request) or not, whether the value of the "read/write" area are is "1" (read) or not and whether the value of the "destination node address" area coincides with the node address of the SOE device 7 itself or not. Thus, the reception determination function 86 judges that the received communication frame is an "event read request" addressed to its own node.
When the reception determination function 86 judges that the communication frame is an "event read request" addressed to its own node, the event read command function 80 outputs the event read command signal 801 to the event data buffer control function 81 to read event data from the event data buffer 82. In accordance with the event read command signal 801, the event data buffer control function 81 reads, from an area of the event data buffer 82 indicated by the read pointer signal 851, one entry of event data which has not yet been read, and stores the read event data into the transmission buffer 83.
The event read command function 80 reads event data from the event data buffer 82 in accordance with the event read command signal 801 repeatedly as many times as the request data size of the aforementioned "read size" area, and stores the event data corresponding to the request data size into the transmission buffer 83.
Here, the upper stage of Fig. 12B shows a format of a communication frame for an event read response.
The type of a communication frame addressed to the computing device 1 from the SOE device 7 in the input memory transfer is an event read response, which is determined in accordance with the contents of each area of "request/response", "read/write", "destination node address" and "event read size". In the embodiment, an event read response frame as shown in the lower stage of Fig. 12B is stored in the transmission buffer 83. When event data corresponding to the request data size is stored into the transmission buffer 83, the communication control function 78 transmits the event data in the transmission buffer as an "event read response" to the computing device 1.
Fig. 13 shows the operation of the event data buffer 82 and the read pointer control function 85 in the event read of the SOE device 7. The read pointer indicates the address where event data to be read in response to a next request has been stored in the event data buffer. When there comes a read request, the read pointer is updated after event data is read. The event data buffer administration function 88 and the event data buffer control function 81 repeats the cycle as many times as the number of requested entries of event data. In the embodiment, the event read size is four. Accordingly, the read cycle is repeated four times, and the read pointer is updated by four as illustrated in Fig. 13.
Fig. 14 shows a method for administering the event data buffer. The read pointer and the write pointer indicate the addresses where event data should be read or written in response to a next read request or a next write request. Accordingly, when the read pointer and the write pointer indicate one and the same address, it is understood that the "address where event data should be read next time" coincides with the "address where event data should be written next time (currently empty). This means that event data which has not yet been read is not contained in the event data buffer (event data is empty).
Fig. 15 shows a method for determining whether the event data is empty or not.
As described above, event data is empty when the address indicated by the read pointer coincides with the address indicated by the write pointer. Accordingly, those addresses are compared with each other by a pointer address comparator 9 so as to determine whether event data is empty or not. The pointer address comparator 9 may be provided in the event data buffer administration function 88 or provided in the event data buffer control function 81.
Fig. 16 shows an initial status of the event data buffer. Immediately after the event data buffer 82 is reset, the event data buffer 82 is empty with no data.
Accordingly, the event data buffer 82 is in the event data empty state where the read pointer and the write pointer indicate one and the same address.
Fig. 17 shows a read response of the SOE device 7 when event data which has not yet been read is contained in the event data buffer 82 and has a size not smaller than the read size. When event data which has not yet been read is contained in the event data buffer 82 and has a size not smaller than the read size, a response is made while event data is stored into all data areas of an event read response frame. That is, in the embodiment, the read size is four while the number of entries of event data which has not yet been read is five.
Therefore, the event data is stored into all the four data areas of the event read response frame. The remaining one entry of the event data which has not yet been read will be transmitted in response to a next event read request.
Fig. 18 shows a read response of the SOE device 7 when event data which has not yet been read is not contained in the event data buffer 82 (event data is empty). In this case, the event data buffer administration function 88 uses the event data buffer status signal 881 to inform the event data buffer control function 81 of the fact that the read pointer and the write pointer indicate one and the same address, that is, the fact that event data which has not yet been read is not contained. In this manner, the event data buffer administration function 88 does not update the read address but stores dummy response data (stores an invalid value into the event detection time area of event data but does not care the area of the ch number where an event has been detected and the area of the current value of the status signal) in all the data areas of the event read response frame. Thus, the SOE device 7 makes a response.
Fig. 19 shows a read response of the SOE device 7 when at least one entry of event data which has not yet been read is contained in the event data buffer 82 and has a size smaller than the read size. When at least one entry of event data which has not yet been read is contained in the event data buffer 82 and has a size smaller than the read size, the event data buffer administration function 88 stores dummy response data (stores an invalid value into the event detection time area of event data but does not care the other areas) into a part of the data areas of the read response frame. Thus, the SOE device 7 makes a response. In the embodiment, the read size is four, and the size of event data which has not yet been read is two.
Therefore, two entries of event data and two entries of dummy response data are stored in the transmission buffer 83.
As described above, the read pointer is controlled as shown in Figs. 18 and 19, so as to prevent the address of the read pointer from being updated earlier than the address of the write pointer. Thus, it is possible to prevent an omission in reading event data which has not yet been read. In addition, when event data which has not yet been read is not contained, dummy event data is transmitted. Thus, it is possible to construct the control system without disturbing periodical transmission with the computing device 1.
According to the invention which has been described above, in a control system in which process input and output devices and an SOE device are connected through one and the same communication line, a computing device performs memory transfer with a predetermined control cycle so as to perform transmission of control data with the process input and output devices periodically. A period of data transmission/reception with the SOE
device 7 required only when a proper predetermined event is detected is defined within the control cycle of the computing device 1. Thus, it is possible to perform event data transmission without spoiling the constant periodicity of the control data.
In addition, when event data to be transmitted is not contained, the SOE
device transmits dummy response data. In this manner, periodical transmission with the computing device I can be kept. Thus, it is possible to construct the system without disturbing the control cycle of the computing device.
In addition, the constant periodicity of the control data can be secured without arranging a communication path for the control data and a communication path for event data as different lines. Accordingly, it is possible to miniaturize the system while functions as a general plant control system are provided.
The invention is not limited to the aforementioned embodiment, but various modifications are included in the invention. For example, the aforementioned embodiment has been described in detail for the purpose of giving explanation to understand the invention easily.
However, the invention does not have to be always limited to the embodiment provided with the whole configuration described above. In addition, a part of the configuration of one embodiment may be replaced by a part of the configuration of another embodiment, or the configuration of another embodiment may be added to the configuration of one embodiment.
In addition, a part of the configuration of each embodiment may be added to another configuration, deleted or replaced. In addition, as for each configuration, function, processing portion, processing means, etc. as described above, a part or all of those may be designed for example, into an integrated circuit so as to be implemented as hardware. In addition, each configuration, function, etc. as described above may be implemented as software by a processor which interprets a program implementing the function and executes the program.
In addition, control lines or information lines are illustrated and regarded as necessary for the sake of explanation, but all the control lines or information lines in a product are not always illustrated. In practice, almost all the constituents may be regarded as connected mutually.
Claims (9)
1. A control system comprising:
a computing device which monitors and controls a control target;
an input/output device which is connected to the control target transmits a status signal inputted from the control target to the computing device and outputs a control signal transmitted from the computing device to the control target; and an SOE device which imports the control signal or the status signal to detect a predetermined change thereof as an event, and records the control signal or the status signal as event data when the event is detected, so that the computing device, wherein:
the input/output device and the SOE device are connected through a shared transmission line; the SOE device is provided with a communication control portion which receives a read request for the event data from the computing device with a predetermined reception cycle, and transmits the event data stored in the SOE device, to the computing device with a predetermined transmission cycle in response to the read request.
a computing device which monitors and controls a control target;
an input/output device which is connected to the control target transmits a status signal inputted from the control target to the computing device and outputs a control signal transmitted from the computing device to the control target; and an SOE device which imports the control signal or the status signal to detect a predetermined change thereof as an event, and records the control signal or the status signal as event data when the event is detected, so that the computing device, wherein:
the input/output device and the SOE device are connected through a shared transmission line; the SOE device is provided with a communication control portion which receives a read request for the event data from the computing device with a predetermined reception cycle, and transmits the event data stored in the SOE device, to the computing device with a predetermined transmission cycle in response to the read request.
2. The control system according to Claim 1, wherein:
the SOE device further includes an event data buffer which stores the event data, and an event data buffer control portion which writes the event data into the event data buffer when the event is detected, and reads the event data from the event data buffer when the read request is received;
the event data buffer control portion reads dummy data, which indicates that the event data which has not yet been transmitted is not contained, when the event data which has not yet been transmitted is not contained in the event data buffer; and the communication control portion transmits the dummy data to the computing device at a timing of transmission defined by the transmission cycle.
the SOE device further includes an event data buffer which stores the event data, and an event data buffer control portion which writes the event data into the event data buffer when the event is detected, and reads the event data from the event data buffer when the read request is received;
the event data buffer control portion reads dummy data, which indicates that the event data which has not yet been transmitted is not contained, when the event data which has not yet been transmitted is not contained in the event data buffer; and the communication control portion transmits the dummy data to the computing device at a timing of transmission defined by the transmission cycle.
3. The control system according to Claim 2, wherein:
the SOE device further includes a write pointer control portion which updates a write address in the event data buffer every time when the event is detected, and a read pointer control portion which updates a read address from the event data buffer every time when the read request is received; and the event data buffer control portion makes determination that the event data which has not yet been transmitted is not contained when the write address indicated by the write pointer control portion is identical to the read address indicated by the read pointer control portion.
the SOE device further includes a write pointer control portion which updates a write address in the event data buffer every time when the event is detected, and a read pointer control portion which updates a read address from the event data buffer every time when the read request is received; and the event data buffer control portion makes determination that the event data which has not yet been transmitted is not contained when the write address indicated by the write pointer control portion is identical to the read address indicated by the read pointer control portion.
4. The control system according to Claim 1, wherein:
the SOE device further includes:
a comparison portion which compares the imported control signal or the imported status signal with the control signal or the status signal imported before the imported control signal or the imported status signal is imported;
an event detection portion which detects the event when a result of comparison by the comparison portion indicates a predetermined change; and an event write command portion which gives a command to the event data control portion to write the event data when the event is detected.
the SOE device further includes:
a comparison portion which compares the imported control signal or the imported status signal with the control signal or the status signal imported before the imported control signal or the imported status signal is imported;
an event detection portion which detects the event when a result of comparison by the comparison portion indicates a predetermined change; and an event write command portion which gives a command to the event data control portion to write the event data when the event is detected.
5. The control system according to Claim 4, wherein:
the SOE device further includes:
a reception determination portion which determines whether data transmitted to a reception storage portion of the SOE device from another device is a transmission request to transmit the event data or not; and an event read command portion which gives a command to the event data control portion to read the event data when the reception determination portion determines that the data is the transmission request.
the SOE device further includes:
a reception determination portion which determines whether data transmitted to a reception storage portion of the SOE device from another device is a transmission request to transmit the event data or not; and an event read command portion which gives a command to the event data control portion to read the event data when the reception determination portion determines that the data is the transmission request.
6. A control system comprising:
a computing device which monitors and controls a control target;
an input/output device which is connected to the control target, transmits a status signal inputted from the control target to the computing device and outputs a control signal transmitted from the computing device to the control target; and an SOE device which imports the control signal or the status signal and stores the imported signal as event data, wherein:
the computing device performs transmission with the input/output device and the SOE device with a predetermined control cycle; and the predetermined control cycle includes a period in which a read request to read the status signal is transmitted to the input/output device, a period in which a read response of the status signal is received from the input/output device, a period in which a read request to read the event data is transmitted to the SOE device, and a period in which a read response of the event data is received from the SOE device.
a computing device which monitors and controls a control target;
an input/output device which is connected to the control target, transmits a status signal inputted from the control target to the computing device and outputs a control signal transmitted from the computing device to the control target; and an SOE device which imports the control signal or the status signal and stores the imported signal as event data, wherein:
the computing device performs transmission with the input/output device and the SOE device with a predetermined control cycle; and the predetermined control cycle includes a period in which a read request to read the status signal is transmitted to the input/output device, a period in which a read response of the status signal is received from the input/output device, a period in which a read request to read the event data is transmitted to the SOE device, and a period in which a read response of the event data is received from the SOE device.
7. The control system according to Claim 6, wherein:
when the event data which has not yet been transmitted is not contained, the SOE
device which has received the read request for the event data from the computing device transmits dummy data, which indicates that the event data which has not yet been transmitted is not contained, to the computing device in the period in which the read request to read the event data is transmitted.
when the event data which has not yet been transmitted is not contained, the SOE
device which has received the read request for the event data from the computing device transmits dummy data, which indicates that the event data which has not yet been transmitted is not contained, to the computing device in the period in which the read request to read the event data is transmitted.
8. An SOE device which periodically imports a status signal inputted/outputted to/from a control target, and detects a predetermined change thereof as an event, the SOE device comprising:
a transmission storage portion which stores data transmitted to a computing device which monitors and controls the control target;
a reception storage portion which stores data received from the computing device;
an event data control portion which writes the status signal as event data into an event storage portion when the event is detected, and which reads the event data written in the event storage portion and stores the event data into the transmission storage portion; and a communication control unit which receives a read request for the event data from the computing device with a predetermined reception cycle to store the read request into the reception storage portion, and which transmits the event data read and stored in the transmission storage portion, to the computing device with a predetermined transmission cycle in response to the read request.
a transmission storage portion which stores data transmitted to a computing device which monitors and controls the control target;
a reception storage portion which stores data received from the computing device;
an event data control portion which writes the status signal as event data into an event storage portion when the event is detected, and which reads the event data written in the event storage portion and stores the event data into the transmission storage portion; and a communication control unit which receives a read request for the event data from the computing device with a predetermined reception cycle to store the read request into the reception storage portion, and which transmits the event data read and stored in the transmission storage portion, to the computing device with a predetermined transmission cycle in response to the read request.
9. The SOE device according to Claim 8, wherein:
when the event data which has not yet been transmitted is not contained in the event storage portion, the event data control portion stores dummy data, which indicates that the event data which has not yet been transmitted is not contained, into the transmission storage portion; and the communication control portion transmits the dummy data to the computing device at a transmission timing defined by the predetermined transmission cycle.
when the event data which has not yet been transmitted is not contained in the event storage portion, the event data control portion stores dummy data, which indicates that the event data which has not yet been transmitted is not contained, into the transmission storage portion; and the communication control portion transmits the dummy data to the computing device at a transmission timing defined by the predetermined transmission cycle.
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| JP2011008373A JP5401479B2 (en) | 2011-01-19 | 2011-01-19 | Control system and SOE device |
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| CN103293981B (en) * | 2013-05-31 | 2016-03-02 | 京东方科技集团股份有限公司 | The managing and control system of the monitoring method of sheet material quantity and device, drying oven in drying oven |
| CN104598388A (en) * | 2015-01-06 | 2015-05-06 | 青岛龙庆达电气有限公司 | Flash-based SOE (Sequence of Event) storing and sending method |
| KR102522154B1 (en) * | 2016-03-15 | 2023-04-17 | 에스케이하이닉스 주식회사 | Controller of semiconductor memory device and operating method thereof |
| JP6649415B2 (en) * | 2018-01-29 | 2020-02-19 | ファナック株式会社 | Control system |
| KR102427946B1 (en) * | 2018-04-20 | 2022-08-01 | 엘에스일렉트릭(주) | Master Module Device for SOE Interface |
| JP2021144651A (en) * | 2020-03-13 | 2021-09-24 | 株式会社安川電機 | Production system, data transmission method, and program |
| JP7126712B2 (en) * | 2020-05-12 | 2022-08-29 | ラトナ株式会社 | Data processing device, method, computer program, and recording medium |
| JP7110472B1 (en) * | 2021-12-24 | 2022-08-01 | 岩井ファルマテック株式会社 | management system |
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| JPH0437398A (en) * | 1990-06-01 | 1992-02-07 | Toshiba Corp | Remote monitor control system |
| JP2000010604A (en) * | 1998-06-25 | 2000-01-14 | Mitsubishi Heavy Ind Ltd | Digital controller in plant control system |
| JP2004199624A (en) * | 2002-12-20 | 2004-07-15 | Mitsubishi Electric Corp | Plant monitoring control system |
| JP3863119B2 (en) * | 2003-03-11 | 2006-12-27 | 株式会社東芝 | Substation monitoring and control system |
| CN100414466C (en) * | 2005-11-14 | 2008-08-27 | 杨卫民 | Multi-event sequential recording and testing system |
| CN201191370Y (en) * | 2007-10-26 | 2009-02-04 | 内蒙古天野化工(集团)有限责任公司 | Event sequence recording SOE system based on PLC |
| CN201383106Y (en) * | 2009-03-04 | 2010-01-13 | 福州福大自动化科技有限公司 | Novel control system |
| CN101694579B (en) * | 2009-10-22 | 2011-05-11 | 南京科远自动化集团股份有限公司 | Soe intelligent module |
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| JP2012150621A (en) | 2012-08-09 |
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| CN102608923B (en) | 2015-04-22 |
| CN102608923A (en) | 2012-07-25 |
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