JPH10198628A - Overload state detector for bus converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent operation/monitor from being affected by the occurrence of communication error by accelerating operation such as the erasure of unwanted picture by previously detecting and reporting the overload state of bus converter. SOLUTION: A repetition task part 34 reads a repeating frame out of a reception buffer 32 and stores it in a repetition managing buffer 35. A reception buffer storage capacity managing part 50 manages the number of repeating frames temporarily stored in the repetition managing buffer 35 and when that number exceeds a prescribed threshold value, an overload state detecting signal is outputted. When time exceeding the use ratio of storage capacity in a high- order bus side reception buffer 32 or the repetition managing buffer 35 continues as fixed, this threshold value outputs the overload state detecting signal. Then, a working rate managing part 60 manages the working rate of arithmetic processor at the bus converter and when that working rate exceeds a prescribed threshold value, an overload state detecting signal is outputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bus converter for connecting a high-order bus and a low-order bus to absorb a difference in transmission speed and a difference in communication protocol between the two buses. To notify an operator in advance before a communication error frequently occurs.

[0002]

2. Description of the Related Art The present applicant has disclosed, for example, Japanese Patent Application Laid-Open No. 7-6129.
Japanese Patent Laid-Open Publication No. H10-21064 proposes a bus converter that connects an upper bus and a lower bus and absorbs a difference in transmission speed and a difference in communication protocol between the two buses. In such a bus converter, communication packets can be buffered to some extent in order to absorb differences in transmission speed and communication protocols. In operation such as normal operation and monitoring, the operation is performed within the processing capacity of the bus converter and the control station on the bus side having a low transmission speed. However, in a system in which steady operation is performed near the upper limit of the processing capacity, a slight increase in the communication amount may cause an overload state, which may affect operation and monitoring.

Now, it is assumed that the communication processing amount increases and an overload state exceeding the processing limit occurs. Then, the time during which the communication packet stays in the buffer inside the bus converter increases, and the buffer always becomes full. In such a state, communication errors such as a response time-out and a reception buffer busy may occur frequently. There are two modes for generating such an overload state. FIG. 2 is an explanatory diagram of an overload state when the bus converter is rate-limiting. It is assumed that the transmission speed of the upper bus is fast and the transmission speed of the lower bus is slow. If there is a large amount of communication request from the upper bus side, the processing limit of the bus converter is exceeded and an overload state occurs. FIG.
FIG. 4 is an explanatory diagram of an overload state when the lower bus side transmission rate is rate-limiting. This occurs when the communication load on the lower bus is abnormally high or when communication is concentrated on a specific communication station connected to the lower bus. If it falls below that, it will be overloaded.

[0004]

However, conventionally, when determining the overload state, the operation rate of the bus converter CPU is determined by monitoring the supervisory station (operator's station) on the upper bus side.
Display, and the monitoring person made a judgment, so it was not possible to recognize the occurrence of an overload condition, such as noticing that the communication via the There was a problem that it took time. Further, in an overload state in which the transmission speed on the lower bus side is rate-determining, there is a possibility that a communication error frequently occurs even though there is a margin in the operation rate of the bus converter CPU, and the operation rate of the bus converter CPU is increased. There is a problem that it is difficult to predict the occurrence of an overload state only by monitoring the state of the vehicle. An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide an overload state detection device for a bus converter that allows an operator to quickly and reliably recognize the occurrence of an overload state in advance.

[0005]

SUMMARY OF THE INVENTION The present invention, which achieves the above object, is a bus provided between an upper bus 10 and a lower bus 20, which absorbs differences in transmission speed and communication protocol between the two buses. The converter 30 reads the relay frame stored in the upper bus receiving buffer and temporarily stores the relay frame transmitted from the upper bus to the lower bus. A relay task unit 34 for temporarily storing and converting to a lower-layer bus communication protocol; a transmission manager 36 for transmitting the transmission frame converted by the relay task unit to the lower bus; By managing the number of relay frames temporarily stored in the buffer,
And a receiving buffer storage amount management unit that outputs an overload state detection signal when a predetermined threshold value is exceeded.

According to the configuration of the present invention, when an overload occurs, a relay frame between the upper bus having a higher transmission speed and the lower bus having a lower transmission speed stays in the reception buffer or the relay management buffer on the upper bus side. Therefore, the reception buffer storage amount management unit 50 monitors the relay frame staying state in the upper bus side reception buffer or the relay management buffer, detects an overload state at an early stage, and communicates with the upper bus or the lower bus. Prevents frequent communication errors at stations.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a configuration block diagram showing one embodiment of the present invention. In the figure, a high-speed bus 10 has a high transmission speed, and a large amount of information such as images and sounds is exchanged between communication stations like a man-machine interface. The lower bus 20 has a low transmission speed, and is connected to a station that collects information on the detecting end and the operating end at a fixed period, such as a control station installed on the site. The bus converter 30 connects a station connected to the upper bus 10 and a station connected to the lower bus 20, and absorbs a difference in transmission speed required for transmitting and receiving information and removes a difference in a communication protocol. Performs an arithmetic operation for absorption.

[0008] The bus converter 30 has a two-layer structure of communication firmware and a communication driver. Explaining in accordance with the hierarchical structure of the open system interconnection OSI, the communication firmware includes a physical layer that performs electrical and physical control of a line, a data link layer that performs transmission control without frame error, and a network that performs relay control. It has part of the function of the layer. The communication driver has a part of a function of a network layer that performs relay control, a transport layer that performs data transfer control, and a function of a session layer that controls data transmission right management and data transmission / reception synchronization. I have.

The reception buffer 31 is provided in the communication firmware of the upper bus 10 and temporarily stores the relay frame sent from the upper bus 10. The reception buffer 32 is provided in the communication driver on the upper bus 10 side, and is a buffer to be passed to the relay task unit 34, and also sorts relay frames to facilitate handling in the relay task unit 34. The relay task unit 34 converts the communication protocol of the relay frame, and converts the communication protocol from the upper bus 10 to the lower bus 20 or conversely converts the communication protocol from the lower bus 20 to the upper bus 10. I do.

[0010] The transmission management buffer 36 is provided in the communication driver on the lower bus 20 side.
Or, it manages whether it has been sent to the lower bus 20 side,
In addition, it manages the correspondence between the response frame from the partner station and the relay frame. The transmission buffer 37 is a lower bus 2
The relay frame to be transmitted to the lower bus 20 is temporarily stored in the communication firmware on the 0 side, and waits until the transmission order comes. The reception buffer 38 is provided in the communication firmware of the lower bus 20 and temporarily stores a response frame transmitted from the lower bus 20 and transfers the response frame to the relay task unit 34 via the transmission management buffer 36.

The transmission management buffer 40 is provided in the communication driver on the upper bus 10 side.
Alternatively, it manages whether the data has been transmitted to the upper bus 10 side.
The transmission buffer 41 is provided in the communication firmware of the upper bus 10 and temporarily stores a relay frame to be transmitted to the upper bus 10 and waits until the transmission order comes.

The reception buffer storage amount management unit 50 manages the number of relay frames temporarily stored in the upper bus side reception buffer 32 or the relay management buffer 35, and when a predetermined threshold value is exceeded, an overload state occurs. Outputs a detection signal.
The threshold is set to a usage ratio, for example, 80% with respect to the total storage capacity of the upper bus side reception buffer 32 or the relay management buffer 35, and when the usage ratio is exceeded for a certain period of time, for example, 3 seconds, the threshold is exceeded. Outputs the load state detection signal. The operation rate management unit 60 manages the operation rate of the arithmetic processing unit of the bus converter 30 and outputs an overload state detection signal when a predetermined threshold value is exceeded. Since the operation rate monitoring device is provided, it is used for detecting an overload state of the bus converter.

The operation of the apparatus having the above-described configuration will be described. In FIG. 1, the flow of a communication frame is represented by an arrow in the figure, and the communication frame is copied between buffers or flows on a line in the order of the numbers in the arrow. The description will be made below in the order of the numbers in the arrows. First, the bus converter 30 receives a relay frame addressed to the communication station on the lower bus 20 side from the communication station on the upper bus 10 side. The received communication frame is stored in the reception buffer 31 provided in the communication firmware on the upper bus 10 side. Then, the communication driver receives the reception interrupt from the communication firmware, fetches the received communication frame into the reception buffer 32 in the communication driver, and notifies the relay task unit 34.

Then, the relay task unit 34 reads a relay frame from the reception buffer 32 and stores it in the relay management buffer 35. Then, the relay task unit 34 converts the relay frame into a communication protocol for the lower bus 20 and issues a transmission request to the lower communication driver. Then
After storing the transmission frame in the transmission management buffer 36, the communication driver issues a transmission request to the communication firmware on the lower bus 20 side. Then, the communication firmware transmits the transmission frame stored in the transmission buffer 37 to the lower bus 2
It transmits to the communication station on the 0 side.

Then, a response frame is returned from the communication station of the transmission destination and stored in the reception buffer 38. Then
The communication driver on the lower bus 20 side transmits the transmission management buffer 3
6 to search for a response frame corresponding to the transmission frame. Then, based on the communication station information stored in the transmission management buffer 36, the response frame is returned to the relay task unit 34, and the transmission management buffer 36 successfully receives the response frame with respect to the current relay frame. Check. In (10), the relay task unit 34 converts the response frame into a communication protocol for the upper bus 10 and sends a transmission request to the upper communication driver. (11)
Then, the response frame is moved from the transmission management buffer 40 to the transmission buffer 41. In (12), the communication firmware on the upper bus 10 transmits a response frame to the communication station on the upper bus 10.

Next, an operation for detecting an overload state will be described. When there is a communication request from the upper bus 10 that exceeds the processing capacity of the bus converter 30, the reception buffer 32 of the upper bus 10 of the bus converter 30 gradually overflows, and the transmission source of the upper bus 10 In such a communication station, a busy error occurs in the reception buffer. In order to detect such an overload state, the CPU load rate signal of the operation rate management unit 60 is used, for example, a moving average of the CPU load rate for one minute is used. Even if the CPU load ratio increases, there is still room for the reception buffer 32 to reach a complete overflow state.

When a large number of communication stations are connected to the lower bus 20 or when communication is concentrated on a specific communication station, the bus converter 30 is overloaded even if the processing amount is sufficient. sell. In such a state, the relay management buffer 35 is always full, so that a communication response time-out error occurs in the transmission source communication station on the upper bus 10 side. In order to detect such an overload state on the lower bus 20 side, the reception buffer storage amount management unit 5
0 is provided to manage the number of relay frames temporarily stored in the upper bus side reception buffer 32 or the relay management buffer 35, and when a predetermined threshold is exceeded, an overload state detection signal is output.

The overload state detection signal may be output to a communication station on the upper bus 10 side by providing a unified task inside the bus converter 30 such as a system management task. The management unit 50 and the operation rate management unit 60 may be provided separately. Preferably, in order to prevent the overload state detection signal from being generated unnecessarily frequently, the next overload state detection signal is prevented from being transmitted until a predetermined time elapses after the overload state detection signal is transmitted. Good to do. Even if a large amount of alarms are temporarily communicated, the operator may have trouble responding, and the operator may overlook the alarms. Useful.

[0019]

As described above, according to the present invention, an overload state of the bus converter 30 is detected and notified in advance, so that, for example, the operator can quickly perform unnecessary operations such as erasing an unnecessary screen. The operation and monitoring can be prevented from being affected by the occurrence of a communication error or the like. Further, the receiving buffer storage amount management unit 50 is provided so that an overload state on the lower bus 20 side can be detected, so that occurrence of an overload state that cannot be recognized only by monitoring the CPU operation rate can be grasped in advance. This has the effect.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing one embodiment of the present invention.

FIG. 2 is an explanatory diagram of an overload state when the bus converter is rate-limiting.

FIG. 3 is an explanatory diagram of an overload state when the lower bus side transmission rate is rate-limiting.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Upper bus 20 Lower bus 30 Bus converter 50 Buffer storage amount management part 60 Operating rate management part

Claims (5)

[Claims] A bus converter (30) provided between an upper bus (10) and a lower bus (20) for absorbing a difference in transmission speed and a difference in communication protocol between the two buses. An upper bus side receiving buffer (32) for temporarily storing the relay frame transmitted to the lower bus side, and a relay frame stored in the upper bus side receiving buffer and temporarily storing it in the relay management buffer (35);
A relay task part (3
4), a transmission management unit (36) for transmitting the transmission frame converted by the relay task unit to the lower bus, and managing the number of relay frames temporarily stored in the upper bus side reception buffer or the relay management buffer. An overload state detection device for a bus converter, comprising: a reception buffer storage amount management unit (50) for outputting an overload state detection signal when a predetermined threshold value is exceeded. 2. The overload of a bus converter according to claim 1, wherein said transmission management unit manages whether a frame has been transmitted to a partner station normally after being transmitted or transmitted to a bus. State detection device. 3. The threshold value of the reception buffer storage amount management unit is a usage ratio of the upper bus side reception buffer or the relay management buffer to a total storage capacity and a duration of the usage ratio. An apparatus for detecting an overload state of a bus converter according to claim 1. 4. A bus converter according to claim 1, wherein said bus converter manages an operation rate of an arithmetic processing unit of said bus converter and outputs an overload state detection signal when a predetermined threshold value is exceeded. A rate management unit (60) is provided.
An overload state detection device for a bus converter according to claim 1. 5. The lower-bus-side receiving buffer (38) for temporarily storing a response frame sent from the lower-side bus as a response to the transmission frame, the lower-bus-side receiving buffer. The relay task unit reads the response frame stored in the relay task buffer, temporarily stores the response frame in the relay management buffer, and converts it into the communication protocol of the upper bus, and transmits the upper transmission frame converted by the relay task unit to the upper bus side The overload state detection device for a bus converter according to claim 1, further comprising: an upper-side transmission management unit (40) that performs the operation.