JP2009003729A - Data processing system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect even a fault which cannot be detected by self-diagnosis of modules, to disconnect a faulty module from a bus without an influence upon a data processing system, in the data processing system employing bus connection in a daisy chain system. <P>SOLUTION: Data monitoring circuits 2A to 2N monitor whether modules are abnormal or not in accordance with transmission output signals of the modules. Each module receives an abnormality detection signal of the module from the data monitoring circuits, as a bus breakaway request signal and disables transmission data buffers DB0 to DBN of the module and enables back plane-side buffers 1A to 1N for module bypass. Abnormality storage registers R0 to RN select the transmission data buffers and the buffers for module bypass by power supply to the module and the breakaway request signal from the data monitoring circuits or an abnormality detection signal resulting from self-diagnosis. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a data processing system in which a plurality of functional modules and I / O modules are connected by a daisy chain method, and more particularly to a module separation method without stopping the system.

  This type of data processing system is applied to a monitoring control device in an electric power system or various factories, and has, for example, a programmable controller (hereinafter referred to as PLC) configuration that realizes an intended data processing function by a combination configuration of various modules. There are many things.

  The PLC is composed of a microcomputer (CPU: central processing unit) and a memory (storage element) as functional modules, and inputs signals from various input devices (sensors, switches, etc.) installed on the device or operation panel. Various output devices (solenoid valves, motors, indicator lights, etc.) can be controlled via the I / O module based on the processing result of the data processing function that is captured by the O module and programmed in advance in the functional module.

  In general, in a data processing system, there are a multi-drop bus connection method and a daisy chain bus connection method for data transmission / reception between data processing devices. FIG. 5 shows a multi-drop bus connection system, in which data processing devices (modules) MOD0 to MODn are mounted in slots # 0 to #n, respectively, and multi-drop communication drivers / receivers (transmission circuit / reception circuit). ) To enable data transmission / reception between any data processing devices through the backplane BP bus. FIG. 6 shows a daisy chain bus connection method. Each data processing device backplane (module) MOD0 to MODn transmits data only from the driver to the receiver of the adjacent data processing device through the serial bus of the backplane. The adjacent data processing device receives data only from the reverse adjacent receiver.

Here, in a data processing system using a PLC, when a module fails, it is required to replace it without stopping the system except for the failed module, and to minimize the influence of the failed module on the entire equipment. For this purpose, it is necessary to be able to insert and remove a faulty module in a live line state without turning off the power of the PLC, and a daisy chain system capable of transferring a large amount of data while making a rough coupling between modules is suitable (for example, Patent Document 1). reference).
JP 2000-200121 A

  In a conventional PLC with a multi-drop bus connection, it is necessary to use an expensive driver / receiver IC for communication so that the drive element is not damaged even when two different modules drive the bus at the same time. Further, when the number of connected modules is large, a complicated protocol is required, and a dedicated LSI is also required, which increases costs. Furthermore, if protocol software is required, a microcomputer is required and a low-cost I / O module cannot be realized.

  In order to reduce costs without using these communication-dedicated driver / receiver ICs and communication LSIs, a daisy chain system is suitable for each module as shown in FIG. In the case of this daisy chain method, since the driver / receiver IC is not multi-drop connection, a general-purpose inexpensive logic IC can be used. In addition, data reception is conscious only from the adjacent module, and transmission only needs to be conscious of the reverse adjacent module, so there is an advantage that a bus interface can be realized with an LSI of a gate array level without requiring a protocol like protocol. is there.

  However, in the daisy chain system, when a failure occurs in a module in the middle, the signal is interrupted, and data cannot be sent to a module sandwiching the failure module. For example, the influence on the entire system is high. For this reason, each module performs a self-diagnosis, and when it is abnormal, it is necessary to leave the daisy chain and bypass the backplane. The self-diagnosis of the transmission / reception circuit and the internal circuit is possible as it is, and even if the receiver IC from the bus fails, it can be detected because there is no reception data for a certain time.

  However, failures near the exit of the module, such as a failure in the transmission circuit, a failure in the transmission data buffer, and a failure in the connector, cannot be detected by the module itself, and these failures become failures of the entire system.

  An object of the present invention is to provide a data processing system capable of detecting a failure that cannot be detected by self-diagnosis of a module in a data processing system connected by a bus in a daisy chain system and disconnecting the failed module from the bus without affecting the system. There is to do.

  The present invention detects the occurrence of a failure in the data transmission path of the module (transmission circuit failure, transmission data buffer failure, connector failure, etc.) by monitoring transmission data on the bus, and on the bus by detecting this failure occurrence. The module can be separated from the bus by the control of the bypass buffer and the transmission data buffer of the module, and has the following configuration.

(1) In a data processing system that transmits and receives data between a plurality of modules through a daisy chain bus connection provided on a backplane.
A data monitoring circuit that is provided on the backplane in correspondence with each module, and monitors the presence or absence of abnormality of the module from the transmission output signal for each module;
Each module includes means for receiving a module abnormality detection signal from the corresponding data monitoring circuit as a bus disconnection request signal, disabling the data transmission circuit of the module, and enabling a module bypass buffer on the backplane side. ,
It is characterized in that the failed module can be disconnected from the bus.

  (2) The data monitoring circuit detects a failure of the module based on a mismatch of a redundant signal or data added to transmission output data of the corresponding module, or a synchronization of a reception clock.

  (3) The data monitoring circuit detects a failure of the module when the transmission output data of the corresponding module is absent for a longer time than the time required to circulate a daisy chain bus.

(4) Each of the modules is provided with an abnormality storage register.
Remembers the module power-up, enables the module's transmit data buffer and disables the module bypass buffer output,
Storing a disconnection request signal from the data monitoring circuit or an abnormality detection signal from a self-diagnostic unit in the module to disable the transmission data buffer of the module and enable the output of the module bypass buffer; To do.

  As described above, according to the present invention, occurrence of a failure in a data transmission path of a module (such as a failure in a transmission circuit, a failure in a transmission data buffer, a failure in the connector) is detected by monitoring transmission data on the bus. The module can be disconnected from the bus by controlling the bypass buffer on the bus and the transmission data buffer of the module. Can be disconnected from the bus without giving.

(Embodiment 1)
FIG. 1 is a main part configuration diagram of a data processing system showing an embodiment of the present invention. 6 is different from FIG. 6 in that the backplane BP and each module MOD0 to MODn are connected by bus in the daisy chain system, the data transmission path failure of the modules MOD0 to MODn (transmission circuit failure, transmission data). A data monitoring circuit that monitors whether there is an abnormality from the transmission output data on the bus (buffer failure, failure of the same connector, etc.) is provided for each module, and a bypass buffer on the bus by detecting the occurrence of failure for each module The control module and the transmission data buffer of the module enable the module to be disconnected from the bus.

  On the bus of the backplane BP, module bypass buffers 1A to 1N that bypass modules connected thereto are provided. The operation of the buffers 1A to 1N is enabled when the corresponding module is not mounted. In the present embodiment, the backplane BP is provided with data monitoring circuits 2A to 2N for monitoring the output signals of the modules, and when the data monitoring circuit detects a failure of the module, the module bypass buffers 1A to 1N The buffer 1X to which the failed module is connected is enabled, and the data transmission buffer of the module is disabled to avoid signal collision.

  The detection signals of the data monitoring circuits 2A to 2N are stored in the abnormality storage registers R0 to RN as the bus disconnection request signals as the same signals as the self-diagnosis abnormality detection signals of the modules MOD0 to MODn, and the abnormality storage registers R0 to RN are abnormal. In the detection state, the buffers 1A to 1N are enabled and held through the drivers B0 to BN, and the transmission data buffers DB0 to DBN are disabled.

  Output data monitoring by the data monitoring circuits 2A to 2N adds a redundancy signal and data (CRC, parity, checksum, etc.) to transmission data on the bus, and gives a bus disconnection request signal to the module due to this mismatch. The module that receives the signal disables the transmit data buffer, enables the backplane module bypass buffer, disconnects the failed module from the daisy chain bus system, and removes the remaining normal modules and buses. Avoid adverse effects.

  An example of a data monitoring circuit for one slot is shown in FIG. 2 and shows the monitoring principle. In this example, the bus signal is modulated by NRZI and made redundant by CRC. When the bus signal is input, the clock extraction circuit 11 extracts the reception clock from the bus signal. At this time, it can be considered that the clock is out of synchronization. The NRZI decoder 12 decodes the NRZI-modulated bus signal with the reception clock, and performs an abnormality detection by the bit unstuff circuit 13 from the decoded signal. If NRZI is used for modulation, the inserted 0 data is removed by bit unstuffing when 1 data of a certain length or more continues, but if 0 is not added at the place where it should be inserted, it can be determined as abnormal.

  Also, abnormality detection by the CRC calculation & check circuit 14 is obtained from the decoded signal. In CRC calculation & check, when CRC data is added to a frame, CRC calculation abnormality can be regarded as abnormal. These abnormalities are passed as a bus disconnection request signal to the module in the slot through the backplane.

  In this example, the clock extraction is out of synchronization, and in detecting bit / unstuff 0 abnormality, CRC abnormality, etc., the abnormality is not detected by detecting the abnormality only once. It is preferable to prompt the bus to leave as an abnormal output to the module.

(Embodiment 2)
In the present embodiment, as the module output data monitoring means, the absence of data that is longer than the time interval in which data circulates through the daisy chain bus is detected as a module abnormality.

  An example of a data monitoring circuit for one slot is shown in FIG. 3 and shows the monitoring principle. When a token passing or time slot method is used as a transmission method for the bus signal, each module sequentially sends data to the bus. That is, when the module in the slot has a data transmission opportunity, it sends data to the bus and passes the transmission opportunity to the next module. Here, if the module in the slot gets a transmission opportunity, the time to give it to the module in the next slot is determined in advance, and if the data flowing in the bus for a longer time is monitored, it will be abnormal. It can be considered. The one-shot timer can realize that the bus is blank for a certain period of time. The bus signal is used as a retrigger signal for the one-shot timer 15, and the time-up signal is abnormal.

  FIG. 4 shows an example of a data monitoring circuit in which the present embodiment is combined with the abnormality detection circuit of the first embodiment.

(Embodiment 3)
In FIG. 1, abnormality storage registers R <b> 0 to RN are provided in the module as registers for controlling the removal of the module that receives the bus withdrawal request signal of the data monitoring circuit. In the present embodiment, the abnormality storage registers R0 to RN are cleared when the power is turned on, and are set by the abnormality output of the backplane data monitoring circuits 2A to 2N or the abnormality detection of the self-diagnosis in the module. By setting the abnormality storage register, the module does not transmit data to the daisy chain bus, and bypasses the signal of the slot on the backplane.

  The abnormality storage registers R0 to RN are provided for the purpose of avoiding the repeated removal / return of the module in the slot and for quickly replacing a faulty module on a live line by arranging it on the module side. The module in the slot is detached from the daisy chain bus system due to an abnormality detected by the data monitoring circuit. At this time, when the data monitoring circuit outputs abnormality detection, the module in the slot is detached from the bus. When the module in the slot is detached from the bus, the bus data monitoring circuit returns to a state where no abnormality is detected. As a result, the module of the slot is restored from the separation again. That is, the module repeats separation and return.

  That is, the abnormality storage registers R0 to RN can be arranged in the abnormality output section of the slot of the backplane, but are arranged in the module of the slot and cleared when the power of the module of the slot is turned on. .

  If the abnormality storage registers R0 to RN are arranged on the backplane side, they can only be cleared by powering on the backplane, a manual switch, or the like. When the power supply of the backplane is killed, the entire system is stopped and a manual switch operation is also required.

  In this respect, if the abnormality storage registers R0 to RN are arranged on the module side, they can be cleared by turning on the power of the module. Therefore, this system works effectively in a system that is equipped with a hot-swap function to minimize system stoppage. In other words, when replacing a module in the failed slot, it can be cleared automatically by the act of installing a new module, and it is not necessary to stop the backplane or operate a manual switch so that it can participate in the daisy chain bus. be able to. Specifically, by installing an abnormal memory register, disconnecting the failed module from the backplane with a hot wire, and mounting a normal module with a hot wire, the abnormal memory register is initialized with the power-on signal of the replacement module itself, You can join the bus. Therefore, it can also correspond to a hot-swap sequence.

The principal part block diagram of the data processing system which shows embodiment of this invention. Data monitoring circuit example. Data monitoring circuit example. Data monitoring circuit example. Multi-drop bus connection diagram. Daisy chain bus connection diagram.

Explanation of symbols

MOD0 to MODn Module BP Backplane 1A to 1N Module bypass buffer 2A to 2N Data monitoring circuit B0 to BN Driver DB0 to DBN Transmission data buffer R0 to RN Abnormal storage register

Claims (4)

In a data processing system that transmits and receives data between multiple modules via a daisy chain bus connection on the backplane,
A data monitoring circuit that is provided on the backplane in correspondence with each module, and monitors the presence or absence of abnormality of the module from the transmission output signal for each module;
Each module includes means for receiving a module abnormality detection signal from the corresponding data monitoring circuit as a bus disconnection request signal, disabling the data transmission circuit of the module, and enabling a module bypass buffer on the backplane side. ,
A data processing system characterized in that a faulty module can be disconnected from a bus.   2. The data monitoring circuit according to claim 1, wherein a failure of the module is detected based on a mismatch of a redundant signal or data added to transmission output data of a corresponding module, or a synchronization of a reception clock. Data processing system.   3. The module according to claim 1, wherein the data monitoring circuit detects a failure of the module when the transmission output data of the corresponding module is absent for a longer time than the time required to circulate the daisy chain bus. The data processing system described. Each of the modules is provided with an abnormality storage register, and this abnormality storage register is
Remembers the module power-up, enables the module's transmit data buffer and disables the module bypass buffer output,
Storing a disconnection request signal from the data monitoring circuit or an abnormality detection signal from a self-diagnostic unit in the module to disable the transmission data buffer of the module and enable the output of the module bypass buffer; The data processing system according to any one of claims 1 to 3.

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