JPS5944148A - Communication control system in bus network - Google Patents

Abstract

PURPOSE:To prevent the impact of signals on a bus, by assigning successively bus occupying right by using addresses in a bus transmission system. CONSTITUTION:In a frame transmitted from each terminal, normal data are transmitted from SA (sending address) to DA (destination address) by F (frame pattern), DA, SA, C (control signal), DATA (data), and CRC2 (check code) parts. TA is an address of a station to occupy a transmission line subsequently, and CRC1 is a check code for the TA. Each station monitors the TA always, and when a frame including the TA for the self-station is transmitted, transmits the transmission data of the self-station on a bus after completing said frame.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Technical Field of the Invention The present invention relates to a communication control system between a plurality of terminal devices connected to a bus-like transmission path.

(b) Prior art and problems Figure 1 shows a Has-ne-no-1-work.
is the terminal device, 2 is the lotus, 3 is the terminal device, and 4th is the terminal device.
Indicates terminus. When transmitting a transmission frame at each end station device, the communication control force in such a Nomas network is determined by checking whether the transmission line is being used or not, and transmitting the frame only when the transmission line is free. If multiple terminal devices send out transmission frames almost simultaneously, a collision will occur.For this reason, each terminal device transmits the transmission frame to its own station. If the transmission frame received by the receiving unit and the transmission frame that was sent and the received transmission frame match, there is a collision.
ImIJ and other terminal equipment assume that no transmission frame is being sent and start the next operation, but if there is a mismatch, a collision has occurred, that is, one of the terminals is sending a transmission frame. The transmission frame is sent out again, but
The time from when it is determined that a collision has occurred until it starts transmitting the transmission frame again is set to a different value for each terminal device (thereby eliminating the possibility of another collision). However, this not only has the disadvantage that the number of terminal equipment connected to the path increases and the control becomes complicated, but also because the signal is not flowing on the bus at any given time, there is no signal at the beginning of the transmission frame.・It also has the disadvantage of requiring an ampoule.

(C) Purpose of the Invention The purpose of the present invention is to eliminate the above-mentioned drawbacks and provide a good communication control system.

(d) Structure of the Invention According to the present invention, the above object is achieved by connecting a plurality of terminal devices to a bus-like transmission line and creating a HAS network for communicating between arbitrary terminal devices. .A circuit for storing a device-7 tres indicating the order of pass and ownership in the first station device;
It is equipped with a comparison circuit, and a circuit that creates a device address of a terminal device that takes over the exclusive right of Hass based on the output of the comparison circuit, and superimposes and transmits the device address at a predetermined position of a transmission frame. Compare the device address of the terminal device that maintains the exclusive right of the lotus in the frame with the device address of the local station, and if they match, generate and transmit the device address of the terminal device that will take over the exclusive right of the lotus. Superimpose and transmit at a predetermined position of the frame,
This is achieved by providing a communication control method in a HAS network that is characterized by controlling not to transmit a transmission frame in the case of a mismatch.

<e>Examples of the invention Embodiments of the present invention will be described below with reference to the drawings.

Fig. 2 is a block diagram of an embodiment of a transmission frame according to the present invention.
(required) TA is the address of the terminal that should not send the next transmission frame to the transmission path - Station equipment address (required) DA is the address of the terminal equipment that is the source sending the information (required only when sending information) ) C is control information that carries data identification, serial number, etc. (necessary only when sending information) D A T A is information sent and received between terminal devices + 1li (necessary only when sending information) CRC, check for B'rA・Code (required) CRC is check code 1 for DA-DATA
(Required only when sending information).

FIG. 3 is a block diagram of the terminal equipment according to the present invention. Using the transmission frame shown in FIG. 3 and generates a reception timing signal to the frame reception control circuit 4.The next sending station address determination circuit 3 takes part ]A of the received frame from the received frame information and the received timing, and stores the own station address. The circuit 5 compares the address with the own address stored in the memory, and if they match and there is no CRC error, the frame transmission circuit 6 and frame transmission control circuit 7 of the transmitting section are permitted to transmit the frame. The frame reception control circuit 4 takes in the DA part of the received frame based on the received frame reliability and the reception timing signal, and sends the own station address signal in the own station address storage circuit 5.
The received frame is compared with the S reply, and only when they match, the received frame is controlled to be taken into the receive buffer memory 8.

It also checks the CRC attached to the end of the frame, and if there is no error, sends a reception completion signal to the frame transmission circuit 6, frame transmission control circuit 7, and reception packet decoding circuit il&9. The received packet decoding circuit 9 decodes the received frame information in the receive buffer memory 8 based on the reception completion signal, and notifies the control circuit 10 of the result.

Based on the content of the notification, the control circuit IO sends a 1h report to the terminal device via the terminal interface circuit 11, and then instructs the transmission packet generation circuit 12 to generate a frame. Based on the generation instruction, the transmission packet generator 1 generation circuit 12 generates a transmission packet on the transmission frame memory 13, and notifies the frame transmission control circuit 7 that there is a transmission packet. The frame transmission system fa11 circuit 7 receives the transmission enable signal from the next sending station ARS determination circuit 3 and the received packet decoding circuit 9.
At the point when both of the reception completion signals from the frame synchronization pattern generating circuit 14 and the next sending station Ars originating circuit 15 are received, frames 1 to 1 are sent from the frame synchronization pattern generating circuit 14 and the next transmitting station Ars originating circuit 15 through the selecting circuit 1G.
The frame is controlled to be sent to the frame transmitting circuit 6. In addition, if a notification is received from the transmission packet generation circuit 12 that there is a transmission packet number 1 to
The frame is controlled to be transmitted to the frame transmitting circuit 6.

Frame transmission (The d circuit 6 sends information from the selection circuit I6 to
control so that it is sent to

(r) Effects of the Invention As explained in detail above, according to the present invention, each terminal device is provided with a circuit for storing device addresses indicating the order of hash exclusive rights, so that each terminal device can transmit frames. You can eliminate the collision in "Has" 2.

At the same time, in the wooden sword method, since the signal from one of the terminal equipments is always sent out at the same time, l=J, there is no need to send out the Brie ampoules at the beginning of the frame.

[Brief explanation of drawings]

Figure 1 is a diagram showing the Hass network, where ■ indicates terminal equipment,
2 is a lotus, 3 is a terminal device, and 4 is a lotus couminator. Figure 2 is a configuration diagram of an embodiment of a transmission frame according to the present invention. address of the terminal station device to be sent (required) 1) A is the address of the α1j5 station device that is the source sending the information + U (required only when sending 16 reports) C is the control information (information that carries data identification, serial number, etc.) (Required only when sending data) D A TA is information exchanged between terminal devices (Required only when sending information) Check code for CRCμ 1゛A (Required) CRc2 is a check for D A - D A = FA・Ko 1ξ (necessary only when sending Joju U).

Claims (1)

[Claims] In bus network, where multiple terminal devices are connected to a bus-like transmission line and communication is performed between arbitrary terminal devices,
A circuit that stores a device address indicating the order of bus exclusive rights in each terminal device, a comparison circuit, and a device address of the terminal device that will take over the bus exclusive right based on the output of the comparison circuit, and generates a transmission frame. It compares the device address of the terminal device that will take over the bus exclusive right in the received transmission frame with the device address of the own station, and if they match, the device receives the bus exclusive right. A communication control method in a bus network, characterized in that a device address of a terminal device that takes over is generated, superimposed on a predetermined position of a transmission frame, and transmitted, and control is performed so that the transmission frame is not transmitted if there is a mismatch.