JPH07131473A - Data communication device - Google Patents

Abstract

PURPOSE:To decrease the generation rate of an overhead and improve the transmission efficiency by putting all information data in write areas of a storage means in one frame and sending and receiving the frame when the write areas are successive. CONSTITUTION:The data communication device 2 has a 2-port memory 4 equipped with input/output ports of two systems. Then the device has a sent data control part 5 which puts head address data on the write areas in the frame and all the information data in the write areas in the frame, and sends and receives the frame when the write areas are successive, a sent data buffer 6, and a protocol transmission part 7. This device has a protocol reception part 16 which stores the information data in order by regarding the address data in the frame as the head address of the 2-port memory 4 when it is recognized that the received frame has the information data in the successive write area, a received data buffer 17, and a received data control part 18, and all the information data in the write areas are put in one frame, and sent and received.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication device for connecting a control device and an information processing device to each other via a communication line to form a local area network (LAN).

[0002]

2. Description of the Related Art In a modernized factory such as a plant, in order to construct an efficient production system, for example, a computer integrated production system (CIM) is used.
ted Manufacturing) is being actively introduced. This CIM divides the mode of production into a plurality of layers, and connects equipments and information processing devices in each layer and between layers via a communication line to form a LAN (Local).
Area network).

In order to optimize control and information processing, the above-mentioned control device and information processing device have different models to be adopted depending on the control target and information processing content, and communication protocols are often different. . Therefore, in recent years, a LAN is formed by a unified communication protocol of the data communication device by connecting the data communication device to the control device and the information processing device and connecting these data communication devices via a communication line. It is like this.

A conventional data communication device is a CPU (Central Processing) of a host device such as a control device or an information processing device.
Unit), a two-port memory provided so as to be directly accessible, and a transmission / reception data control unit that writes and reads information data to and from the two-port memory,
A transmission / reception data buffer unit that temporarily stores the information data when writing and reading the information data to / from the 2-port memory, and a protocol control unit that transmits / receives the information data stored in the transmission / reception data buffer unit by a predetermined communication protocol. (See FIG. 1).

The operation when the data communication apparatus having the above configuration is used in the token passing system of the ring LAN, for example, will be described. First, when a specific host device writes information data to the 2-port memory in the data communication device of its own station, the address data and information data corresponding to the written area are transmitted in a predetermined transmission unit. Therefore, it is stored in the transmission / reception data buffer unit. As shown in FIGS. 5 and 6, the address data and the information data stored in the transmission / reception data buffer unit are the address data of the frame 51 to be transmitted to another station when the protocol control unit acquires the transmission right by the token. They are incorporated into the area 52 and the update data area 53, respectively, and are transmitted by the communication protocol of the protocol control unit. After that, the data communication device of the other station that receives the frame 52 takes out the address data and the information data in the frame 52 and stores the information data in the area corresponding to the address data of the 2-port memory.

As a result, the 2-port memories of all stations transmit and receive frames between the data communication devices,
Since the host device has the same data content, the host device can obtain the information data of the host device of another station by accessing the 2-port memory of the data communication device of its own station. Therefore, in the conventional data communication device, even if the control device and the information processing device are different models, it is possible to form a LAN without being aware of the difference in communication protocol of each device.

[0007]

However, in the above-mentioned conventional data communication apparatus, since the information data is incorporated into the frame 51 for each predetermined transmission unit to be transmitted / received, for example, the information data in the 2-port memory is transmitted. When the writing reaches a large area, it is necessary to carry out the transmission and reception of the frame 51 in a large number of times so that the data amount corresponds to this area. In addition to the address data area 52 and the update data area 53 described above, the frame 51 is provided with various areas such as a frame header area 54. As a result, if the area in which the information data is written in the 2-port memory has a larger data amount than the communication unit, an overhead of redundantly transmitting and receiving the same data will inevitably occur, resulting in transmission efficiency. Will definitely decrease.

Therefore, it is an object of the present invention to provide a data communication device capable of reducing the occurrence rate of overhead.

[0009]

In order to solve the above-mentioned problems, the data communication device of the present invention has a storage means which is connected to each other through a communication line and is directly accessible by a host device. When the information data is written in a predetermined writing area of the storage means, the information data is incorporated in a frame together with the address data of the writing area so that the stored information data is the same in all stations. While receiving a frame from another station,
The information data in the frame is written in the storage means of the own station corresponding to the address data in the frame,
It has the following features.

That is, when the write area is continuous, the data communication apparatus incorporates the start address of the write area into the frame as address data and incorporates all the information data of the write area into the frame. When recognizing that the received data has the information data of the continuous writing area, the continuous data transmitting means for transmitting the information data is used as the head address of the storage means for the above information data. It is characterized in that it has a continuous data receiving means for storing in order.

[0011]

According to the above construction, when the writing area of the storage means is continuous, all the information data of the writing area can be incorporated into one frame and transmitted / received. Therefore,
It is possible to prevent the occurrence of overhead due to transmission and reception of a frame divided into a plurality of times, and as a result, it is possible to improve transmission efficiency.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The following will describe one embodiment of the present invention with reference to FIGS.

As shown in FIG. 3, the data communication apparatus according to the present embodiment is used as a part of the storage unit of the host device 1 by being connected to the host device 1 such as a control device or an information processing device. It is like this. Further, each data communication device 2 is connected in a ring shape, for example, via the communication line 3 to transmit / receive information data by a token passing ring LAN which acquires a transmission right by a token. The data communication device 2
Is a token-sharing LAN and time-sharing LAN
Can also be applied to.

As shown in FIG. 1, the data communication device 2 has a two-port memory 4 having two input / output ports.
(Storage means). This 2-port memory 4 is
When the data communication device 2 is connected to the higher-level device 1, a CP (not shown) of the higher-level device 1 via one input / output port
It is directly accessed by U, and the host device 1 writes and reads information data to and from an arbitrary address of the 2-port memory 4.

Further, one input / output port of the two-port memory 4 has a transmission data control section 5 (continuous data transmission means).
Is also connected to. The transmission data control unit 5 monitors whether or not the host device 1 has written information data into the 2-port memory 4, and when it recognizes the writing of the information data, it executes the write area determination operation. It has become.

That is, the transmission data control unit 5 determines whether or not the area in which the information data is written (hereinafter referred to as the write area) is a continuous address by executing the write area determination operation. Then, when it is determined that they are continuous, continuous instruction data indicating that they are continuous is formed,
While reading the first address data of the writing area and reading all the information data of the writing area,
When it is determined that they are not continuous, the address data and the information data in the write area are read within a predetermined transmission unit.

The transmission data control unit 5 is connected to the transmission data buffer 6 (continuous data transmission means),
The transmission data buffer 6 is set to 2 by the transmission data control unit 5.
The continuous instruction data, address data, and information data read from the port memory 4 are temporarily stored. The transmission data buffer 6 is connected to the protocol transmission unit 7 (continuous data transmission means),
The protocol transmission unit 7 reads the address data and the information data of the transmission data buffer 6 when the transmission right is acquired by the token, and uses these address data and the information data as the address data area 9 and the update data of the frame 8 of FIG. It is adapted to be incorporated in each of the regions 10.

The frame 8 is a frame start delimiter area 11 in which data indicating the beginning of the frame 8 is stored.
Frame header area 1 that stores protocol information data
2. Address data area 9 for storing address data,
Update data area 10 for storing information data, frame 8
It has a structure in which an FCS (Frame Check Sequence) area 13 storing data used to determine whether data in the frame is correct and a frame end delimiter area 14 storing data indicating the end of the frame 8 are arranged in this order.

The protocol transmitter 7 for transmitting the frame 8 is connected to the physical layer interface 15. The physical layer interface 15 has a transmission terminal to which the communication line 3 is connected. When the frame 8 is transmitted from the transmission terminal, the physical layer interface 15 converts the frame 8 into a signal form suitable for transmission. There is. Further, the physical layer interface 15 also has a receiving terminal, and when receiving the frame 8 from this receiving terminal, the physical layer interface 15 converts the frame 8 into a signal form suitable for signal processing of the data communication device 2. Has become.

In the physical layer interface 15 described above,
The protocol receiving unit 1 as an output destination of the received frame 8
6 (continuous data receiving means) is also connected. The protocol receiving unit 16 is connected to the reception data buffer 17 (continuous data receiving means) and stores the continuous instruction data, address data, and information data in the frame 8 in the reception data buffer 17. This reception data buffer 17 is connected to the above-mentioned two-port memory 4 via a reception data control unit 18 (continuous data receiving means). Then, the reception data control unit 18 uses the frame 8
Is determined by the continuation instruction data, and when it is determined that the information data is continuous, the address data in the address data area 9 is set as the head address of the 2-port memory 4 and the information data is sequentially set. It is designed to be stored.

The configuration of the data communication device 2 is changed to OSI (Op
The two-port memory 4, the transmission data control unit 5, the transmission data buffer 6, the reception data buffer 17, and the reception data control unit 18 correspond to an upper layer in correspondence with the reference model of “en System Interconnection”. The protocol transmission unit 7 and the protocol reception unit 16 correspond to the data link layer. Further, the physical layer interface 15 corresponds to the physical layer.

The operation of the data communication device 2 having the above configuration will be described.

First, when the host device 1 writes information data to a predetermined address of the 2-port memory 4, the transmission data control unit 5 which detects this writing operation uses an address in which the writing area of the 2-port memory 4 is continuous. It will be determined whether or not there is. When it is determined that the write area is continuous, continuous instruction data indicating that the write area is continuous is formed, and the address data at the beginning of the write area is read and all information data in the write area is read. It will be stored in the transmission data buffer 6. On the other hand, if it is determined that they are not continuous, the address data and information data in the write area are read out and stored in the transmission data buffer 6 within a predetermined transmission unit.

At this time, as shown in FIG. 4, the protocol transmission unit 7 confirms the content of the token when the token is acquired, and the token is the local station (ME) or empty (EMPT).
When it is recognized that Y) is indicated and there is no transmission data, all the data in the token is deleted. On the other hand, when it is recognized that the token indicates its own station (ME) or empty (EMPTY), and there is transmission data,
The transmission right is acquired, and the transmission data is transmitted by incorporating the transmission data into the frame 8 which is a token indicating the own station (ME).

Therefore, as described above, when the continuous instruction data, the address data, and the information data are stored in the transmission data buffer 6 as the transmission data, the protocol transmission unit 7 that recognizes the existence of these transmission data. When recognizing that the token indicates its own station (ME) or empty (EMPTY), the transmission data is incorporated into the frame 8 and transmitted to another station. As a result, when the writing area is continuous, all the information data existing in this writing area is incorporated in one frame 8 and transmitted.

After that, the protocol transmission unit 7 counts the feedback time until the frame 8 of its own station returns, and when the feedback time exceeds a predetermined time, it is timed out and the frame 8 is retransmitted. Will be done. on the other hand,
When the frame 8 is returned within the predetermined time, whether the data of the frame 8 is right or wrong is determined based on the data of the FCS area 13.

Next, when the frame 8 transmitted from another station is input to the protocol receiving unit 16, the protocol receiving unit 16 determines whether the contents of the token and the data of the frame 8 are correct. And the token is empty (EMPT
Y) or another station (NOT ME) is recognized, and after confirming that the data of frame 8 is normal, the information data of frame 8 is stored in the reception data buffer 17 and 8 will be transmitted to other stations.

When the information data and the like are stored in the reception data buffer 17, the reception data control unit 18 determines whether or not the continuation instruction data is stored in the reception data buffer 17 to determine the continuous writing area. Will be determined. Then, when it is determined that the information data is a continuous writing area, the address of the 2-port memory 4 corresponding to the address data stored in the reception data buffer 17 is the start address of the information data to be rewritten. Assuming that there is, the information data will be sequentially stored from this head address.
As a result, when the writing area is continuous, all the information data existing in this writing area is recorded in one frame 8.
It is transmitted / received in a state of being incorporated in the memory and stored in the 2-port memory 4.

As a method of discriminating the above information data and address data in the frame 8 having the information data of the continuous writing area, the first data following the frame header area 12 is the address data of the address data area 9. Then, there is a method in which the data following the address data to the data in the area immediately before the frame end delimiter area 14 are used as the information data.

As described above, the data communication device 2 of this embodiment
When the write area of the 2-port memory 4 is continuous, the start address of the write area is incorporated into the frame 8 as address data, and all the information data of the write area is incorporated into the frame 8 for transmission. When the continuous data transmitting means such as the data control unit 5 and the recognition that the received frame 8 has the information data of the continuous writing area, the address data in the frame 8 is stored in the 2-port memory 4.
And a continuous data receiving means such as a received data control unit 18 for sequentially storing information data as the first address of the.

As a result, the data communication device 2 of this embodiment is
When the write area of the 2-port memory 4 is continuous, all the information data in the write area can be incorporated into one frame 8 to be transmitted / received. Therefore, the frame 8 is transmitted / received in plural times. Therefore, it is possible to prevent the occurrence of overhead, and as a result, it is possible to improve the transmission efficiency.

[0032]

As described above, in the data communication apparatus of the present invention, when the write area is continuous, the start address of the write area is incorporated into the frame as address data and the write area Continuous data transmitting means for transmitting all information data by incorporating it in a frame, and, when recognizing that the received frame has information data in a continuous writing area, stores the address data in the frame in the storage means. A continuous data receiving means for sequentially storing the above information data as a head address is provided.

Thus, when the writing area of the storage means is continuous, all the information data in the writing area can be incorporated into one frame to be transmitted / received, so that the frame is transmitted / received in plural times. As a result, it is possible to prevent the occurrence of overhead, and as a result, it is possible to improve the transmission efficiency.

[0034]

[Brief description of drawings]

FIG. 1 is a block diagram showing a data communication device of the present invention in association with an OSI reference model.

FIG. 2 is an explanatory diagram showing the structure of a frame.

FIG. 3 is an explanatory diagram showing a state in which data communication devices are mutually connected.

FIG. 4 is a state transition diagram of a data communication device corresponding to a data link layer.

FIG. 5 illustrates a conventional example and is an explanatory diagram illustrating a frame configuration.

FIG. 6 shows a conventional example and is a state transition diagram of a data communication device corresponding to a data link layer.

[Explanation of symbols]

 1 Upper Device 2 Data Communication Device 3 Communication Line 4 2 Port Memory (Storage Means) 5 Transmission Data Control Unit (Continuous Data Transmission Means) 6 Transmission Data Buffer (Continuous Data Transmission Means) 7 Protocol Transmission Unit (Continuous Data Transmission Means) 8 Frame 9 Address data area 10 Update data area 11 Frame start delimiter area 12 Frame header area 13 FCS area 14 Frame end delimiter area 15 Physical layer interface 16 Protocol receiver (continuous data receiving means) 17 Receive data buffer (continuous data receiving means) 18 Received data control unit (continuous data receiving means)

Claims (1)

[Claims] 1. A predetermined storage unit for storing information data stored in a storage unit, which is connected to each other via a communication line and is directly accessible by a host device, to be the same in all stations. When the information data is written in the writing area, the information data together with the address data of the writing area is incorporated into the frame and transmitted to another station, while the frame from the other station is received when the frame is received from the other station. In a data communication device for writing the information data in the frame to the storage means of its own station corresponding to the address data, when the writing area is continuous, the leading address of the writing area is incorporated in the frame as address data. At the same time, the continuous data transmitting means for transmitting all the information data of the writing area by incorporating it in a frame, and the information of the writing area in which the received frames are continuous. When it is recognized that it has data, it has a continuous data receiving means for sequentially storing the information data by using the address data in the frame as a head address of the storage means, and data communication. apparatus.