JPH02223248A - Data bus terminal equipment of command response system - Google Patents

Abstract

PURPOSE:To detect a fault in a short time by detecting a bus silent state where no command or data, etc., exists on a data bus line, and generating interruption when the bus silent state continues exceeding prescribed time due to the fault of a bus controller. CONSTITUTION:A bus silent detection circuit 12 detects the bus silent state of the data bus line 5 i.e., a state where no command, etc., exists on the data bus line 5. And a time-out detection circuit 13 generates a time-out signal by measuring the continuous time of a detected bus silent state when the time continues exceeding the prescribed time, and an interruption generation circuit 14 generates the interruption when the time-out signal is outputted. In such a way, the fault of the bus controller can be quickly detected without complicating the program of data bus terminal equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data bus terminal device, and particularly to a data bus terminal device in which a plurality of data bus terminal devices and at least one bus control device are interconnected via a data bus line. , relates to a data bus terminal device using a command-response method in which all data transfers between these data bus terminal devices and between a data bus terminal device and a bus control device are started by a command sent from a bus control device.

[Conventional technology]

It is well known that conventional command-response type data bus terminal devices have been standardized as MIL-5TD-1553B and are used in systems that require high reliability, such as aircraft data buses. In a command-response type data bus, all data transfer is initiated by a command sent from the bus control device, and the data bus terminal device responds to the command, that is, sends and receives data and sends status. A failure in a bus control device causes a system failure, so when a failure occurs in a bus control device, it is important to promptly detect it and back it up. For this reason, conventionally, the microprocessor program that controls the main control of the data bus terminal device monitors the sending interval of commands sent from the bus control device to the local station, and even if the interval exceeds the specified time, the commands sent to the local station are When no commands were sent, it was detected that a failure had occurred in the bus control device.

The data bus terminal device that detected the failure functions as a new bus control device in place of the failed bus control device, thereby preventing system down.

[Problem to be solved by the invention]

As described above, the conventional data bus terminal device is also capable of detecting a failure of the bus control device and backing up the failure, but it has the following problems.

(1) In order to detect a failure in the bus control device, the microprocessor program of the data bus terminal device checks the command sent by the bus control device each time it is received, and measures the time until the next command. Therefore, the program to be executed by the microprocessor becomes complicated and the load on the microprocessor increases.

<2) When detecting failures by monitoring i-commands, it is important to note that the interval at which commands are sent to the own station may change due to changes in the data transfer schedule, etc., and that when many data bus terminal devices are connected, In consideration of the longer command sending interval, it is necessary to increase the timeout setting time, which increases the time delay between when the bus controller fails and when it is detected by the data bus terminal equipment. Prompt backup becomes difficult.

The present invention was made in view of these circumstances, and
The purpose is to provide a data bus terminal device that can quickly detect a failure in a bus control device without complicating the program of the data bus terminal device.

[Means to solve the problem]

In order to achieve the above object, the command-response type data bus terminal device of the present invention includes a bus silent detection circuit that detects a bus silent state of a data bus line, and a bus silent state detected by this bus silent detection circuit. A timeout detection circuit that measures the duration of the bus and generates a timeout signal when the bus remains silent for a predetermined period of time, and an interrupt generation circuit that generates an interrupt when the timeout signal is output from the timeout detection circuit. It has

[Effect]

In the command-response type data bus terminal device of the present invention, the bus silent detection circuit detects the bus silent state of the data bus line, that is, the state where no command etc. is present on the data bus line, and the timeout detection circuit detects the bus silent state of the data bus line, and the timeout detection circuit detects the bus silent state of the data bus line. A timeout signal is generated when the duration of the bus silent state continues for a predetermined time or more, and an interrupt generation circuit generates an interrupt when the timeout signal is output.

〔Example〕

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, in which a bidirectional data bus line 5 is connected to a plurality of data bus terminal devices 1, 2.3 and one bus control device 4. In this system, when the bus control device 4 is normal, commands are sent from the bus control device 4 to each data bus terminal device 1 to 3 via the data bus line 5 according to a predetermined data transfer schedule. The data bus terminal devices 1 to 3 send and receive data and send status in response to the command. Therefore, as long as the bus control device 4 is normal, a bus silent state in which commands, data, status, etc. frequently appear on the data bus line 5 and no commands, data, status, etc. appear for a continuous period of time does not occur. The present invention detects a failure in the bus control device 4 by paying attention to such a bus silent state.

Next, the configuration and operation of the data bus terminal device 1 that detects a failure in the bus control device 4 and performs backup when a failure is detected will be described.

The data bus terminal device l includes a line receiver receiver circuit 10 that directly drives the data bus line 5 or detects a signal on the data bus line 5, a data transmitting/receiving circuit 11 that transmits and receives data according to the data bus protocol, and a bus silent Detection circuit 12 and timeout detection circuit 1
3, an interrupt generation circuit 14, and a microprocessor (not shown). In addition to the programs necessary for the data bus terminal device 1 to function as a data bus terminal device, this microprocessor uses the data shown in FIG. The bus system i1J program 15 is executed.

The bus silent detection circuit 12 detects a bus silent state in which no command, data, status, etc. appear on the data bus line 5, and sets the bus silent signal S1 to, for example, logic "1" during the bus silent state. It is a circuit.

The timeout detection circuit 13 receives the bus silent signal S1.
Timing is started from the time when the bus silent signal Sl changes from logic "0" to logic "1", and the duration of the bus silent signal Sl being logic "1" is measured, and when logic "1" continues for a predetermined time or more, This circuit sets the timeout signal S2 to logic "1", for example.

Here, the above-mentioned predetermined time is set to a time commensurate with the minimum duration of the bus silent state that does not appear on the data bus line 5 when the bus control device 4 is normal. Therefore, if the bus control device 4 fails, the timeout signal S2 from the timeout detection circuit 13 becomes logic "1".

The interrupt generation circuit 14 receives the timeout signal S2 as an input, and latches the state when it becomes logic "1".
This is a circuit that generates an interrupt signal S3. This interrupt signal S3 generates an interrupt in a microprocessor (not shown), and the data bus control program 15 is activated. Note that the interrupt generation circuit 14 is then reset by an interrupt reset signal S9.

When started, the data bus control program 15 causes the data bus terminal device 1 to function as a bus control device.

The command word and data word transmitted by the bus control device are transmitted to the data transmitting/receiving circuit 1 as transmission data S6.
1, and the data transmitting/receiving circuit 11 outputs the transmission signal S5 accordingly.
is sent out onto the data bus line 5 via the data bus line 5. In addition, the status word and data word transmitted on the data bus line 5 by the other data bus terminal devices 2 and 3 are inputted as a reception signal S4 via the line receiver receiver circuit IO, and are sent to the data transmission/reception circuit 11 according to the protocol. Received according to. This received data S7 is read out by the data bus control program 15, and is sent to the data bus control program 15 for the purpose of controlling the data bus system.
checks the received data, and the data bus control program 15 controls the operation of the data transmitting/receiving circuit 11 using a control signal S8.

As described above, when a failure occurs in the bus control device 4, it is detected by the data bus terminal device 1, and the data bus terminal device 1 functions as a bus control device instead of the bus control device 4, and the system operates. will continue.

In this embodiment, the data bus line 5 is used as an input to the bus silent detection circuit 12, but instead of the data bus line 5, the received signal S4 output from the line receiver receiver circuit 10 is input to the bus silent detection circuit 12. However, it is also possible to detect the bus silent state. Since the same signal as that on the data bus line 5 appears in the received signal S4, it is possible to quickly detect a failure in the bus control device 4 as in the above embodiment. Similar modifications can be made to the embodiments described below.

FIG. 2 is a block diagram of another embodiment of the present invention;
The same numbers as in the figure indicate the same parts, 100°200.30
0,400 is a data bus terminal device, 130 is a timeout detection circuit, and 131 is a unique time setting circuit.0 This embodiment includes a plurality of data bus terminal devices 100, 200, 30.
Each of the 0 and 400 data bus terminals has a function as a bus term device, and while the system is in operation, only one of the data bus terminal devices functions as a bus control device. A failure of a data bus terminal device functioning as a control device is detected, and one data bus terminal device that detects the failure earliest functions as a new bus control device.

Now, when the data bus terminal device 400 is functioning normally as a bus control device, the data bus terminal device 400 is transferred to other data bus terminal devices 100, 200, 300 via the data bus line 5 according to a predetermined data transfer schedule. A command is sent to each data bus terminal device 1.
00, 200, and 300 send and receive data and send status as a response to the command. Therefore, as long as the data bus terminal device 400 is normal, a bus silent state in which commands, data, status, etc. frequently appear on the data path line 5 and none of them appear for a continuous period of time will not occur. 0 This embodiment focuses on such a bus silent state and detects a failure in the data bus terminal bag 2400 that is currently functioning as a bus control device.
This is done at 1F 100, 200, and 300.

The internal configuration of each data bus terminal device is the same as illustrated in data bus terminal device 100. The difference from the embodiment shown in FIG. 1 is that each data bus terminal device is provided with a unique time setting circuit 131 that sets a specific time unique to the data bus terminal device, and a timeout detection circuit 130 is provided with a bus silent signal. When the duration of time that S1 is at logic "1", that is, the duration of the bus silent state of data bus line 5, reaches the specific time set in the specific time setting circuit 131 or more, the timeout signal S2 is set to logic "1". The feature is that the interrupt generating circuit 14 generates an interrupt to the data bus control program 15. The unique times set in the unique time setting circuits (131) of each data bus terminal device are different. Now, data bus terminal equipment 100,200
TI each characteristic time set to ゜300.400
, T2. T3. Assuming T4 and the relationship TI<72<73<T4, if the data bus terminal device 1F400 functioning as a bus control device fails, the data bus terminal bag zioo with the shortest characteristic time will first respond to the failure. It will function as a new bus control device. Furthermore, if the data bus terminal device 100 that functions as a bus control device fails, the data bus terminal device 200 with the next shortest characteristic time will be the first to detect the failure and function as a new bus control device. Become.

Note that the minimum time among the unique times set in the data bus terminal device is the minimum time of the bus silent state duration that does not appear on the data bus line 5 when the data bus terminal device functioning as a bus control device is normal. Needless to say, the time should be set to be appropriate.

Generally, in this type of system, multiple data bus terminal devices are not allowed to operate as bus control devices at the same time.As a method to ensure this, the right to function as a bus control device is assigned to a data bus terminal device that actually functions as a bus control device. There is a method in which a terminal device transfers data to the only other data bus terminal device using a special command. However, this method requires that the data bus terminal device that transfers rights is operating normally until the transfer of rights is completed.
In the event of a failure, it becomes difficult to transfer rights by sending a special command, so even if another data bus terminal device detects a failure, it will not be able to transfer the right to function as a bus control device.

In contrast, in this embodiment, by stopping the data bus terminal device that is currently functioning as a bus control device, the data bus terminal device becomes the only data bus terminal device without the need for a special command to transfer rights. It becomes possible to transfer the function as a bus control device. Note that the transfer of the function as a bus control device to such a data bus terminal device is performed not only when the data bus terminal device functioning as the bus control device fails, but also when the power supply is independently turned on and off.

In a system that connects a group of terminal devices in which the function is ON10FF, there is also the effect that one bus control device can always be started up quickly.

〔Effect of the invention〕

As explained above, the command-response type data bus terminal device of the present invention detects a bus silent state in which there is no command or data on the data bus line, and detects a bus silent state when a failure of the bus control device occurs. Since an interrupt is generated when the process continues for more than a certain amount of time, the following effects can be obtained.

(1) The microprocessor that controls the data bus terminal device can learn that a failure has occurred in the bus control device through an interrupt. The load will not increase.

(2) When the bus control device is normal, commands from the bus control device to each data bus terminal device and responses from each data bus terminal device frequently appear on the data bus line, so one data bus terminal device The present invention, which detects bus control device failures based on the silent state of the data bus line, can detect failures in a shorter time than conventional devices that detect bus control device failures based on the interval between commands sent to the data bus line. becomes. Therefore, prompt backup is possible, and reliability of the entire data bus system can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of one embodiment of the invention, and FIG. 2 is a block diagram of another embodiment of the invention. In the figure, 1.2, 3, 100, 200, 300° 400...data bus terminal device 4...bus control device 5...data bus line 10...line tri-receiver circuit 11... Data transmission/reception circuit 12...bus silent detection circuit 13.130...timeout detection circuit 14...interrupt generation circuit 15...data bus control program 131...specific time setting circuit

Claims (1)

[Claims] A command-response type data bus terminal device includes a bus silent detection circuit that detects a bus silent state of a data bus line, and a bus silent detection circuit that measures the duration of the bus silent state detected by the bus silent detection circuit. , comprising a timeout detection circuit that generates a timeout signal when the bus silent state continues for a predetermined period of time or more, and an interrupt generation circuit that generates an interrupt when the timeout signal is output from the timeout detection circuit. Characteristic command-response type data bus terminal device.