JPH03204254A - Data receiver - Google Patents

Abstract

PURPOSE:To discriminate the kind of a received frame and to eliminate the need for a microprocessor for only transferring a data based on the result of discrimination by rewriting the content of a relevant block of a common memory based on a data for scan transmission. CONSTITUTION:Since a received frame is a scan frame, when a frame type discrimination circuit 21 of a scan reception control circuit 13 discriminates the scan frame, the succeeding data is converted into a parallel data by a serial/ parallel conversion circuit 22 of the scan reception control circuit 13 and stored tentatively in a buffer memory 24. Then the frame check sequence incorporated in the end of the reception frame is checked by the frame check circuit 23 to discriminate the normal reception, then a data in the buffer memory 24 by a DMA circuit 26 is transferred to a common memory 15 according to a real address generated by an address generating circuit 25. Thus, no microprocessor is required.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention (Industrial Application Field) The present invention relates to a data receiving device for a local area network (hereinafter abbreviated as LAN) system that employs a scan transmission method.

(Prior Art) LAN systems generally employ a message transmission method in which data is exchanged between stations, and a scan transmission method in which each station shares necessary data. In the former case, the transmitting station specifies the receiving station and sends data.
A station that receives data addressed to itself writes the received data into a memory and processes the data, and the data transmission frame in this case is called a message frame.

On the other hand, the latter includes a plurality of stations 2 (2a) connected via a transmission line 1, as shown in FIG.

2b, 2c, 2d, . . . ) each have a common common memory 3, and this common memory 3 is divided into a plurality of blocks and allocated to each station 2. Then, each station 2 writes the required data into the block assigned to it in the common memory 3, and transmits the data in that block by broadcast communication when the station transmits data. The other stations 2 that receive the transmission data via broadcast communication via the transmission path 1 update the contents of the blocks allocated to the transmitting station in the common memory 3. Note that the data transmission frame in this case is called a scan frame.

For this reason, conventionally, each station 2 has been provided with a data receiving device as shown in FIG. 4 in order to smoothly transmit and receive data using these data transmission methods. This data receiving device receives a data transmission frame sent via a transmission path 1 with a modem 4, converts it into digital data, and sends it to a transmission control circuit 5. The transmission control circuit 5 captures only received frames addressed to its own station or by broadcast communication, and writes them into the reception buffer memory 6. When the reception of the frame is completed, a reception completion signal S is sent to the first CPU (central processing unit) 7 to notify it. The first CPU 7 that received the reception completion notification stores the reception buffer memory 6
It extracts the received frame from , and determines whether it is a message frame or a scan frame. If it is a message frame, the data of the frame is transferred to the memory 8 for message transmission, and if it is a scan frame, it is transferred to the common memory 8 for scan transmission. Transfer to the corresponding block in memory 3. The second CPU 9 retrieves necessary data from the memory 8 and common memory 3, interprets the contents, performs necessary data processing, and controls operations.

However, in the conventional device described above, an expensive and large-scale microprocessor is used only to determine the type of received frame and transfer data based on the determination result. Therefore, the cost of the entire device has to be high, and the circuit implementation has become complicated as the number of peripheral circuits increases. Furthermore, if an attempt is made to increase the data transmission speed, the load on the transmission control circuit 5 becomes extremely large, and the reception buffer memory 6 must be replaced with one capable of high-speed processing.

(Problems to be Solved by the Invention) As described above, in the conventional data receiving device of this type, the cost of the entire device must be high, and the circuit implementation is also complicated. Furthermore, it has been extremely difficult to increase the data transmission speed.

Therefore, the present invention can reduce the cost of the entire device and simplify the circuit implementation by omitting the microprocessor that only determines the type of received frame and transfers data based on the determination result. , it is an object of the present invention to provide a data receiving device that can easily realize an increase in data transmission speed.

[Structure of the Invention] (Means for Solving the Problems) In the present invention, each station has a common memory, this common memory is divided into a plurality of blocks and allocated to each station, and each station stores required data. A network system that adopts a scan transmission method in which the data is written to a block assigned to the transmitting station in the common memory and transmitted, and other stations that receive this transmitted data update the contents of the block assigned to the transmitting station in the common memory. In the data receiving device, a data determining means for determining whether or not received data is data for scan transmission; and a data importing means for importing received data determined by the determining means to be data for scan transmission; The data updating control means rewrites the contents of the corresponding block of the common memory based on the data taken in by the reading means.

(Function) By taking such measures, the data type of the scan transmission data is determined by the data determining means, and then the data is taken in by the data importing means. In response, the data transmission control means rewrites the contents of the corresponding block in the common memory. On the other hand, data addressed to the own station other than the scan transmission data is captured and written to the memory as before.

(Embodiment) An embodiment in which the present invention is applied to each station 2 of the LAN system shown in FIG. 3 will be described below with reference to FIGS. 1 and 2.

FIG. 1 is a block diagram showing the overall configuration of a data receiving apparatus in this embodiment. In the figure, the modem 11 is
It converts the data of the data transmission frame sent via the transmission path 1 into a digital signal, and the received frame after data conversion is output to the transmission control circuit 12 and the scan reception control circuit 13. The transmission control circuit 12 takes in only the message frame addressed to its own station from among the received frames, and writes the data of the frame into the memory 14 for message transmission.

On the other hand, the scan reception control circuit 13 takes in only the scan frame of the broadcast communication from among the received frames, and uses the data of the frame to the scan transmission common memory 13.
This is to rewrite the contents of the corresponding block in No. 5.

The CPU 16 uses the memory 14 and the common memory 15.
It extracts the necessary data from the computer, interprets the contents, performs the necessary data processing, and controls the operation.

FIG. 2 is a block diagram showing a specific configuration of the scan reception control circuit 13. As shown in the figure, this scan reception control circuit 13 detects a frame identification code included in a transmission frame and determines whether the frame is a message frame or a scan frame, and the serial/parallel conversion circuit 22, which will discuss the determination result later, and a frame type determination circuit 21 that notifies the frame check circuit 23, which converts the serial digital signal sent from the modem 11 into parallel data in response to being notified from the frame type determination circuit 21 that it is a scan frame. If it is notified that it is a scan frame from the serial/parallel conversion circuit 22 that converts and sends it to the buffer memory 24 and address generation circuit 25, which will be described later, and the frame type determination circuit 21, the scan frame is normally received. DMA (direct memory access) circuit 26 to check whether the
The frame check circuit 23 notifies the above serial/
A buffer memory 24 temporarily stores the parallel data sent from the parallel conversion circuit 22, and extracts data indicating the block number or address of the corresponding scan frame from the parallel data sent from the serial/parallel conversion circuit 22. When the address generation circuit 25, which generates the real address of the common memory 15 for scan transmission, is notified that a normal scan frame has been received from the frame check circuit 23, the contents of the buffer memory 24 are transferred to the address mentioned above. Generation circuit 25
It is composed of a DMA circuit 26 that transfers the address to the common memory 15 for scan transmission according to the address generated by the DMA circuit 26, and the like.

In this embodiment with such a configuration, when each station 2 constructing the LAN performs scan transmission, the station serving as a transmitting station stores the necessary data in the block assigned to its own station in the common memory 3 for scan transmission. write to. Then, when transmitting from its own station, the data in the block is transmitted as a scan frame to other stations by broadcast communication. Each of the other stations receives the frame data on the transmission line 1 via the modem 11, converts it into a digital signal, and inputs it into the transmission control circuit 12 and the scan reception control circuit 13. Here, since the received frame is a scan frame, when the frame type determination circuit 21 of the scan reception control circuit 13 determines that it is a scan frame, the following data is serialized in the scan reception control circuit 13. The data is converted into parallel data by the /parallel conversion circuit 22 and temporarily stored in the buffer memory 24. Furthermore, a block number and the like are extracted from the data of the received frame to generate a real address on the common memory 15. after that,
When the frame check sequence incorporated at the end of the received frame is checked in the frame check circuit 23 and normal reception is determined, the data in the buffer memory 24 is generated by the DMA circuit 26 in the address generation circuit 25. It is transferred to the common memory 15 according to the real address. Note that if the frame check circuit 23 determines that the frame has been received abnormally, the received data is discarded.

On the other hand, when message transmission is performed at each station 2 constructing a LAN, the station serving as a transmitting station writes necessary data into the message transmission memory 14, as in the conventional case. Then, the data stored in the memory 14 is transmitted as a message frame by specifying a destination station.

At the receiving station, the frame data on the transmission line 1 is received via the modem 11, converted into a digital signal, and input into the transmission control circuit 12 and the scan reception control circuit 13. Here, since the received frame is a message frame addressed to the own station, the transmission control circuit 12
The following data is stored in the message transmission memory 14.
will be written to.

In this way, the data written to the common memory 15 and the memory 14 by scan transmission or message transmission is processed by the CPU 16 and used for controlling various operations.

As described above, according to this embodiment, the microprocessor and its peripheral circuits, which were conventionally used only to determine whether a message frame or a scan frame is determined and to transfer data, are omitted, and instead are used for scan reception. Control circuit 13
Since this method is used, the following effects (1) to (3) are achieved.

(2) Since the buffer memory 24 incorporated in the scan reception control circuit 13 has a capacity that can store data for one frame, the scan reception control circuit 13 can be made of one gate array. As a result, it is possible to reduce the cost of the entire device and also to simplify circuit implementation. Furthermore, current consumption can also be reduced.

(2) Since the transmission control circuit 12 does not perform any processing related to scan frames, the load is significantly reduced. As a result, the processing of the transmission control circuit 12 is freed, and the data transmission speed can be increased within the operating range of the scan reception control circuit 13.

- The time required to receive a scan frame and update the contents of the common memory 15 can be shortened by simplifying the circuit that handles the scan frame.

■ If two or more CPUs are used as in the past, the software becomes complicated because data is exchanged between the CPUs, but in this embodiment, only one CPU 16 is required, so the software is simple and the throughput is also low. Rise.

■ The transmission control circuit 12 must be configured so that it does not receive the scan frame, but since the scan frame is broadcast using a group address, the transmission control circuit 12 must be configured not to receive the corresponding group address. By changing the settings so that the
A normal transmission control circuit configured by I is an LSI
It can be applied without changing the internals of .

Incidentally, even if the scan frame has a variable length, this can be handled by configuring the DMA circuit 26 to set the number of transfers by detecting something indicating the data length if there is a data length in the scan frame. Also, buffer memory 2
Needless to say, a shift register can be used in place of the modem 11, and a receiver can be used in place of the modem 11. It goes without saying that various other modifications can be made without departing from the spirit of the invention.

[Effects of the Invention] As described in detail above, according to the present invention, it is possible to omit a microprocessor that only determines the type of a received frame and transfers data based on the determination result, and the entire device It is possible to provide a data receiving device that can reduce costs and simplify circuit implementation, and can easily achieve high data transmission speed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the overall configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing the specific configuration of a scan reception control circuit in the same embodiment, and FIG. 3 is a block diagram showing a general LAN (local FIG. 4 is a block diagram showing a conventional device. DESCRIPTION OF SYMBOLS 1... Transmission path, 2... Station, 11... Modem, 12... Transmission control circuit, 13... Control circuit for scan reception, 14... Memory for message transmission, 15... Common memory for scan transmission, 16...C
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Claims (1)

[Claims] Each station has a common memory, this common memory is divided into a plurality of blocks and allocated to each station, each station writes required data to the block allocated to the own station of the common memory and transmits it, Other stations that receive this transmission data update the contents of the block assigned to the transmission station in the common memory.In a data reception device of a network system that employs a scan transmission method, the received data is data for scan transmission. data determining means for determining whether or not the data is scan transmission data; data importing means for importing received data determined by the determining means to be data for scan transmission; 1. A data receiving device comprising: data update control means for rewriting the contents of the data receiving device.