JPH0431424B2 - - Google Patents

Description

[Detailed description of the invention] [Technical field to which the invention pertains]

This invention provides a plurality of terminal devices (also abbreviated as terminals),
The present invention relates to a data transmission system composed of a center device and a host computer, in which the host computer and the center device are provided with means for detecting changes in terminal data. Note that in the description of each figure below, the same reference numerals indicate the same or corresponding parts.

[Prior art and its problems]

Conventional data transmission systems of this type constantly transmit data between a center device and multiple terminals, and the terminal data held by the center device is sent back to the host computer according to the request, or At the request of the host computer, the center device collects terminal data by communicating with the terminal, and sends the data back to the host computer. In such a data transmission system, the host computer must always collect terminal data at appropriate timing intervals and thereby understand the content of the terminal data or its changes, and exchange data in the center equipment with the host computer. Not only does the amount of communication increase, but the transmission of terminal data that really needs to be sent as soon as possible is delayed, and the processing content of the host computer increases, increasing the burden on the functions that the host computer is supposed to process. There is a big drawback: Also, if you consider that the terminal data includes data indicating abnormal conditions and failures of the entire terminal device,
These status signals are also important information for a host computer. However, if these status signals are not sent to the host computer without a transmission request from the host computer, the host computer determines that the terminal is operating correctly even if the terminal is in an abnormal state. There is also a fear that incorrect signal processing may be performed. Further, when an abnormality occurs in such a transmission system, in order to investigate the cause of the abnormality, it is necessary to investigate which data caused the abnormality to occur. However, when sending back terminal data that the center device currently owns in response to a command sent from a host computer, or terminal data that has been collected by communicating with the terminals, as in the past, the data is stored in the computer first. Since the transmitted data does not necessarily remain, it is difficult to investigate the cause of the abnormality. In addition, abnormalities are often caused by abnormalities in the elements that make up the system, such as abnormalities in the terminals or signal paths of the transmission system, but it is difficult to confirm this with the above configuration. . This is because even if communication data between the host computer and the center device is occasionally memorized, it cannot become a chronological record of the occurrence of the cause. Therefore, in order to solve this problem, a method was proposed in which the time-series changing state of terminal data is stored in the center device, and the changing terminal data is sequentially sent from the center device to the host computer. However, in this case as well, for some reason the host computer reads the latest terminal data from the center device,
In addition, if the unsent changed terminal data remains in the center device at this point, after reading from this host computer, the unsent changed terminal data that is already old and unnecessary at that point will be returned to the center device. A possible problem is that data is sent from the center device to the higher-level computer, and the higher-level computer mistakenly receives it as new changed terminal data.

[Purpose of the invention]

This invention eliminates the above-mentioned problems, and each time the center device communicates with a terminal, it is possible to check whether a change has occurred in comparison with the previous communication data, or if there is an abnormality or state change on the terminal side during terminal communication. If a new change occurs, the center device automatically sends changed terminal data to the host computer due to the change, which improves the processing of the host computer. In addition to reducing the number of functions, change information is preferentially transmitted to the host computer in the shortest possible time. Especially, after the host computer has read the latest terminal data from the center device, old change terminal data may be accidentally transferred to the center device. The purpose of the present invention is to provide a data transmission system that is free from the risk of data being transmitted from the computer to the host computer.

[Key points of the invention]

The main points of the present invention are: a center device that controls data transmission and has the function of receiving data from connected terminals; a plurality of terminals connected from the center device via a transmission path (signal path, etc.); A data transmission system consisting of a center device and a host computer connected via a data transmission path. means for transmitting the address data of the terminal to be detected (referred to as the terminal to be detected), data specifying the details of the change, etc. to the center device, and the center device receives the terminal data from the terminal to be detected for change at least at predetermined time intervals. A receiving means and a terminal data storage means (terminal data memory, etc.) for storing the received terminal data.
, a means (such as a CPU) for detecting that the terminal data has changed, and a changed terminal data storage means (changed terminal data) that sequentially stores only the terminal data for which this change has been detected (changed data, etc., hereinafter referred to as changed terminal data). In a data transmission system, the host computer reads the terminal data in the terminal data storage means, and a means (such as a CPU) for sequentially and preferentially transmitting the changed terminal data to the host computer. In such a case, an erroneous transmission prevention means is provided to prevent the center device from transmitting unsent changed terminal data regarding the terminal related to the reading, which has already been stored in the changed terminal data storage means, to the host computer. However, in a preferred embodiment, the erroneous transmission prevention means is a storage means (such as a RAM) provided in the center device for each of the changed terminal data (for storing a sent flag, etc.). ).

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a configuration diagram of a change terminal data memory in RAM owned by a center device as an embodiment of the present invention, FIG. 2 is an explanatory diagram of how to use the change terminal data memory, and FIG. FIG. 4 is a configuration diagram of the terminal data memory in the RAM owned by the device, FIG. 4 is a configuration diagram of the data transmission system, and FIG. 5 is an explanatory diagram of the data transmission format. In the system configuration diagram of the data transmission system shown in FIG.
It is connected to a large number of terminals 4 (4-1, ~, 4-n), and is connected between the center device 3 and the terminals 4 as shown by arrows a and b, or between the terminals as shown by arrows c and d. Data transmission takes place. Although the signal path between the center device and the terminals is configured in a loop shape in Figure 4, it may also be configured in a multi-drop type or in a branch type. be. The function of the terminal is to accept digital or analog input signals from outside the system6.
Both are transmitted via the signal path 5 as serial data. The terminal also has a function of outputting data received via the signal path 5 to the outside of the system as an output signal 7. Furthermore, each terminal 4
Each device is assigned a unique terminal address TAD, and has a built-in address switch (not shown) for setting it. In the case of transmission between terminals (hereinafter referred to as N:N transmission method), in this example, consecutive even-numbered addresses and odd-numbered addresses are determined to mutually transmit data.
This is because the transmission procedure has been determined in advance, and it can be considered as just one example.
When an address is designated, the input signal 6 of the terminal with the odd address is transmitted, the terminal with the even address receives this, and outputs it as an output signal 7 to the outside of the system. Data transmission between the terminals then takes place in such a way that the input signal 6 of the even-addressed terminal is transmitted and the odd-addressed terminal receives it. On the other hand, transmission between the center device and terminals (hereinafter 1:N
(referred to as a transmission method) is also performed as follows.
The center device is connected to the host computer 1 via a transmission line (RS232C cable or data bus) 2,
The host computer 1 sends terminal operation signals and the like to the center device 3, and the center device 3 that receives these sends output data (output signal 7) to the terminal using the 1:N transmission method. It also receives terminal input data (input signal 6) using the 1:N transmission method and transmits the received terminal data to the host computer 1. In addition, since the center device 3 receives all the signals on the signal path 5, it can also monitor data in the N:N transmission method. In this case, the data transmission itself is performed between terminals, but the content In response to a request from the host computer 1 by monitoring the
It is also possible to transmit designated terminal data to the host computer 1 from among the N:N transmission data stored by the center device 3 through this monitor.
It is also possible for the center device 3 to detect changes in data transmitted using these N:N transmission methods and transmit them to the host computer 1. These 1:N and N:N transmission methods will be explained below. FIG. 5 shows an example of the transmission format of the 1:N transmission method transmitted by the center device 3. First, the center device 3 transmits block address data BAD including the block address and data indicating that 1:N block communication should be started.
Note that the block address here refers to the address TAD of terminal 4 divided into groups (blocks) of a predetermined number (however, each terminal address within this group is
TAD is the address assigned to this group (pre-ordered). The block address data BAD is received by all the terminals, and the terminal with the address TAD belonging to this block address is set to a receiving state. next,
Terminal address value 0→1→2...→ from center device 3
Output data of the terminal is sequentially transmitted to addresses 7 and 8, and these output data are received by the terminal that matches the self-address value and outputted from the terminal 4 as an output signal 7. The output data for each terminal address includes parity for preventing transmission errors, data for thumb check, etc., and is configured so that when a data error occurs, the received data can be ignored. Conversely, when the center device 3 receives input data as the input signal 6 from the terminal 4, it first specifies the block address BAD with which to communicate, as shown in the transmission format example of FIG. 52. As a result, in the same manner as described above, the terminal 4 having the address TAD belonging to the block address in question sequentially transmits data in order of decreasing address value in the order of 0→1→2→...→7. If the terminal with the previous address value does not send,
After the terminal with the next address value waits for a certain period of time and confirms that no data is being transmitted, it transmits its own input data. This time is set to be shorter in ascending order of address, so that the terminal with the later address can always transmit when the terminal with the earlier address is not transmitting. With this configuration, even if the terminal being used skips over the middle of the address, failures due to missing numbers in the address will not occur. Also, data transmission between 4 terminals (N:N transmission)
In this case, the transmission format shown in FIG. 52 is used as is. In this case, the data transmitted by the terminal is simply received by a terminal that has a specific address relationship with the terminal, and
monitors these transmitted data and stores the data in the RAM of the center device. Although the transmission format in FIG. 5 shows the case of block communication, it is also possible to perform communication for each individual terminal address. FIG. 3 is a configuration diagram of the terminal data memory M1 in the RAM owned by the center device. In this example, if the maximum number of terminals is 64 terminals, the terminal address TAD is provided with address values 1, 2, ..., 64, and the input data of these terminals (input signal 6)
and status data are sent to a CPU (not shown) in the center device.
are sequentially stored in the RAM. In the example shown in Figure 3, the input data length of each terminal is 32 bits, so the individual input data Di (Di ₀ , Di ₁ , Di ₂ , Di ₃ ) that make up the input data each have 8 bits, and the total This means that it constitutes 32-bit input data. In addition, if the condition of the terminal is abnormal, for example, data transmission is impossible between the center device and the terminal, or the analog input amount of the terminal is outside the predetermined range (for example, a signal circuit is disconnected), Since failure data is sent from the terminal, the status data SD is sent by the CPU in the same way.
is stored as. Regardless of whether the center device uses the 1:N transmission method or the N:N transmission method, all transmission data is received by the center device, so input data from all terminals is held in the terminal data memory M1 in the RAM of the center device. ing. On the other hand, since new terminal data is received by the center device every time it communicates with a terminal, the center device transfers the new terminal data to each terminal that has previously received the data as shown in Figure 3. After comparing the data and checking whether there is a change, the corresponding terminal data in FIG. 3 is updated. If there is a change here, the terminal in question should monitor the input data change as described below (referred to as a changing terminal).
If it is registered, the change data of the configuration shown in FIG. 1 is stored in the change terminal data memory (also called change memory) M2 in the RAM of the center device.
are stored sequentially within the In this case, if the terminal data input by the center device is a digital signal, multiple verification (for example, data is established when the data matches three times in a row), or if it is an analog signal, there is a restriction on the width of change. By providing functions such as processing and averaging to prevent terminal data from being received in an incorrect form even if there is a simple nozzle signal, it is possible to compare the data received by the center device as is. It is. Each storage area for change data in FIG. 1 contains the address TAD of the terminal (one of the change terminals) that the center device has determined has actually caused a data change, and the individual input data Di (Di ₀ to Di ₃ ) In addition, the failure data sent from the terminal can be used as status data.
Store it in the SD location. Additionally, communication abnormalities for each terminal address determined by the center device are also stored as status data SD. FIG. 2a is an explanatory diagram of how to use this change memory M2. The change data is stored in the change memory M2 in the order of occurrence in the order in which the occurrence of any change is detected. However, the changed data of all the terminals is not stored, but only the changed terminals are stored. In this case, the change data is stored in the data area corresponding to the value next to the value of the change data storage counter CNT1 in FIG. 2b, and
Let the value of CNT1 be +1. In the area of the change memory M2 in FIG. 2a, change data 1 to n are sequentially stored, and this number indicates the value of the change data storage counter CNT1. If so, it is stored again as change data 1 and used repeatedly. This change data is sequentially transmitted from the center device to the host computer, but the value of the counter CNT1 of the transmitted change data is stored in the change data transmission counter CNT2 shown in FIG. The value of CNT2 is increased by +1. Next, the transmitted flag FD in the change terminal data memory M2 in FIG. 1, which is the main subject of the present invention, will be explained. A new problem arises when the registration of a changed terminal as described above is cancelled. This is because change data that has not been sent to the host computer exists in the center device, and change data of a terminal whose registration as a change terminal has been canceled may also exist among the change data that has not been sent. At this time, it means that after the registration of a terminal at a certain address as a changed terminal is canceled, change data for that terminal is sent from the center device. In this case, if there is only one cancellation, it would be easy for the host computer to ignore this change data. However, if under certain conditions, the registration of a certain terminal as a changed terminal is canceled, and then the next condition occurs again, the same terminal is registered as a changed terminal, and subsequent changed data of that terminal is requested. If the unsent change data for the terminal before the re-registration is sent after the re-registration, the computer will transfer the change data from the previous registration to the changes after the re-registration. Because it is mistakenly identified as data,
Misjudgment occurs in the host computer. It is also assumed that for some reason, at a certain point in time, the host computer reads from the center device the latest terminal data at that point regarding a certain changed terminal from the terminal data memory M1, and at this point the changed terminal data of the center device is read from the terminal data memory M1. Assuming that there remains unsent change data for the change terminal in memory M2, after this point the center device sends the unsent change data to the host computer because it is no longer old and unnecessary. There is a risk that the host computer will make a wrong judgment. In order to prevent such erroneous judgments by the host computer, the sent flag is included in the change data in Figure 1.
If an FD is set up and there is change data of a terminal whose registration has been canceled as a change terminal among the change data that has not been sent, or the center device receives change data from the host computer before the change data, the center device receives the change data from the change terminal before the change data. If there is past unsent change data for the changed terminal when terminal data is requested, the sent flag for this unsent changed data is set.
Set the FD so that the transmission of change data to the host computer is prohibited. The handling of these terminals as changing terminals can also be applied to terminals that perform N:N transmission between terminals. In other words, the terminal data that is being monitored by the center device can also be constantly monitored and that terminal data can be transmitted from the center device to the host computer, so the host computer can also freely monitor the N:N transmitted data. For example, it is also possible to take appropriate measures when an abnormal condition occurs. In addition, the changing terminal data memory M2 in Figure 1 stores changes in terminal data and occurrences of failures in chronological order, which is important when considering system behavior when an abnormal state occurs. It can be used as a document. Therefore, when the center device receives a change data dump command from the host computer, it sends the unsent change data to the host computer in the order in which it was sent in the past, allowing the host computer to investigate the cause of the abnormality. is possible. By configuring as above, terminal data is monitored in the center device every time there is communication,
Changed terminal data can be transmitted to the host computer with priority compared to other communication data. In such a transmission system, for example in an FA factory, when an emergency switch signal is activated, this signal can be transmitted with priority over other signals, and the signal level of the emergency switch can be raised to a higher level every time. Since the computer does not need to receive the information via the center device, the processing function of the host computer can be significantly reduced.

【Effect of the invention】

As is clear from the above description, according to the present invention, the center device has a means for registering the address of the terminal (changing terminal) whose terminal data is to be detected through the host computer or independently. At the same time, each time the center device communicates with a terminal, it compares it with the previously received terminal data, and if it has changed, it compares it with the registration status of the address mentioned above, and if the terminal is registered as a changed terminal, it By providing a means to automatically send this data as change data to the host computer, the host computer can not only easily configure the terminal data processing function, but also prioritize the input data of notable terminals (change terminals). It can be realized to receive the information. In addition, when the registration as a change terminal is cancelled, by having a function to cancel the data of the canceled terminal from the unsent change data, the center device can send erroneous change data to the host computer after the above registration cancellation. can be prevented from happening. In particular, even when the center device receives a request from the host computer to send the current data of the changed terminal, by providing a means to similarly prevent the unsent changed data of the terminal at that address from being sent to the host computer. A highly reliable system can be achieved. Furthermore, by including terminals of N:N transmission method in this change terminal, N:
N transmission data can also be monitored effectively. In addition, by having a function to dump change data, it can be used as reference material to investigate the cause in the event of an abnormality in the transmission system, and it is possible to strengthen the RAS function of the transmission system. Effects can be obtained.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a variable terminal data memory in a center device as an embodiment of the present invention, and FIG. 2 is an explanatory diagram of how to use the variable terminal data memory.
FIG. 3 is a block diagram of the terminal data memory in the center device, FIG. 4 is a block diagram of the data transmission system, and FIG. 5 is an explanatory diagram of the data transmission format. 1: Host computer, 2: Transmission path, 3: Center device, 4 (4-1, ~, 4-n): Terminal, 5: Signal path, 6: Input signal, 7: Output signal, M1: Terminal data memory , M2: change terminal data memory,
TAD: Terminal address, Di (Di ₀ to Di ₃ ): Individual input data, SD: Status data, FD: Sent flag.

Claims (1)

[Scope of Claims] 1. A center device that controls data transmission and has the function of receiving data from connected terminals, a plurality of terminals connected from the center device via a transmission path, and a center device and data A data transmission system consisting of host computers connected via a transmission path, in which the host computer has the address of a terminal that is to detect a predetermined change in terminal data (hereinafter referred to as change detection target terminal). data, data specifying the contents of the change, etc., to the center device, and the center device includes means for receiving the terminal data from the change detection target terminal at least at predetermined time intervals, Terminal data storage means for storing changed terminal data, means for detecting that the terminal data has changed, and changed terminal data storage means for sequentially storing only the terminal data for which this change has been detected (hereinafter referred to as changed terminal data). and means for sequentially and preferentially transmitting the changed terminal data to a higher-level computer, wherein when the higher-level computer reads the terminal data in the terminal data storage means, the changed terminal data storage means A data transmission system characterized by comprising an erroneous transmission prevention means for preventing a center device from transmitting unsent changed terminal data regarding the terminal related to the reading, which has already been stored in the means, to a host computer. 2. The data transmission system according to claim 1, wherein the erroneous transmission prevention means is a storage means provided in the center device for each of the changed terminal data.