JPH077969B2 - Communication control method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a communication method using communication packets.

2. Description of the Related Art FIG. 3 is a block diagram showing an embodiment of a conventional information transmission system. Reference numeral 1 is an information transmission path for transmitting communication packets, and 2.1 to 2.n are communication control devices for communicating with each other via the information transmission path 1.

Conventionally, when one communication control device tries to continuously transmit a plurality of communication packets to another communication control device,
The transmission side communication control device sets an appropriate time for the interval from the transmission of the second communication packet to the transmission of the second communication packet, or the transmission is performed without any interval.

When the communication control device 1 continuously transmits a plurality of communication packets to the communication control device 2 according to the conventional method, first, the communication control device 1 first sends the communication control device 2 to the communication control device 2. The th communication packet is transmitted. The communication control device 2 cannot receive the next communication packet because the reception buffer cannot be used until the processing of the received communication packet is completed.
On the other hand, the communication control device 1 does not know when the reception data processing of the communication control device 2 will end, and therefore transmits the second communication packet immediately or after a lapse of a predetermined time. However, since the communication control device 2 is processing the received data, a response of "reception not possible" is returned. The communication control device 1 retransmits the second packet after a certain time period when it receives the "reception not possible" response. This sequence is applied to the communication control device 2
Repeat until can be received. Therefore, when the received data processing takes a long time, the retransmission packet is frequently transmitted on the information transmission line, so that the traffic on the information transmission line becomes large and other communication is hindered.

Means for Solving the Problem In order to solve the above-mentioned problems, the present invention receives a response indicating “currently unreceivable” when a communication control device on a transmitting side continuously sends out a plurality of communication packets or from a receiving side. In order to obtain the "waiting time information" until the next communication packet is sent from the receiving communication control device, the "processing time" required to process the receiving packet in the attribute table in the communication control device, The "processing waiting time" until the currently executed processing is completed is stored so that the transmission side communication control device can read it as appropriate.

Operation According to the present invention, the communication control device on the transmitting side can obtain the "waiting time information" required until the next communication packet is transmitted in advance by the above-mentioned method, so that unnecessary communication packets due to "reception not possible" are transmitted on the information transmission path. The transmission on the information transmission path is reduced, and the communication efficiency and the processing efficiency for retransmission are improved.

Embodiments Embodiments of the present invention will be described in detail below with reference to the drawings. An example of a system to which the communication control method of the present invention is applied is the same as the conventional system.

FIG. 4a shows the structure of the communication packet of the present invention. Start bit, master address indicating source address, parity bit for master address, slave address indicating destination address, parity bit and ACK bit for slave address, control field, parity bit and ACK bit for control field, and data field It is configured. FIG. 4b shows the contents of the data field. The data field is composed of data for each byte, a continue bit, a parity bit, and an ACK bit. The parity bit is a bit for performing a parity check. The ACK bit is a response bit for notifying the transmitting side that the receiving side has normally received the respective data, and returns an affirmative response "0" when receiving normally and a negative response "1" when receiving error. When the positive response is returned to the slave address, the control field is transmitted from the transmission side. When a negative response is returned, the communication ends at that point. The control field is composed of 4 bits as shown in FIG. 5 and indicates the data method, the packet control contents, and the unit lock control. Data can be transmitted from the slave to the master (read) or from the master to the slave (write). The data control contents include reading of slave status, data, lock address, and writing of memory address, command, and data. For example, when a data write is received, the slave side receives the data in the data field and stores it in the receive buffer. The unit is locked by the master locking the slave, and once locked, it does not accept communication packets from other masters that change the slave's state.

A communication control method in the system having the above components will be described. FIG. 1 is a diagram showing a communication sequence when the invention described in claim 1 is applied,
FIG. 2 is a diagram showing a communication sequence when the invention described in claim 2 is applied, and FIG. 6 is a configuration diagram of an information communication system used in an embodiment of the present invention. 3 is an information transmission line, 4.1 and 4.2 are communication control devices, 5.1 and 5.2 are packet transmission / reception units for communication packets, 7.1 and 7.2 are memory units, and 8.1,
8.2 is the data processing unit on the terminal side. FIG. 8 is a configuration diagram of the attribute table.

In the method according to claim 1 of the present invention, when the communication data is transmitted from the communication control device 2.1 to the communication control device 2.2, the "processing" is performed on the virtual address N on the attribute table 9 in the communication control device 2.2. "Time" 10.N is stored and communication is performed in the sequence described in FIG. When the transmission-side communication control device 2.1 continuously transmits a plurality of communication packets to the communication control device 2.2, the communication control device 2.1 precedes the transmission of the first communication packet, and "reads data" defined in the control field. After the "processing time" stored in the attribute table in the communication control device 2.2 is read out using the function of, the first communication packet is transmitted. Since the communication control device 2.2 receives the communication data from the communication control device 2.1 and then starts receiving data processing, it is in a state where it cannot receive the next communication packet. The communication control device 2.1 transmits the second communication packet with an interval of the "processing time" previously read. At this point of time, the processing of the communication packet received previously has been completed in the communication control device 2.2, and the second communication packet transmitted by the communication control device 2.1 is accepted. The third communication packet is further transmitted with an interval of "processing time". If this sequence is repeated and a plurality of communication packets are continuously transmitted, the communication control device 2.2 transmits the data as "unreceivable" without being eliminated, and the retransmission does not deteriorate the transmission efficiency or increase the traffic.

In the method according to the second aspect of the present invention, the communication control device 2.1 tried to transmit the communication data to the communication control device 2.2, but the communication control device 2.2 is processing the previously received communication packet. For this reason, when receiving the response of "not receivable", the function of "data read" defined in the control field is used before the communication control device 2.1 retransmits the communication packet to the communication control device 2.2. Then, the "processing wait time" 10.M stored in the virtual address M on the attribute table 9 in the communication control device 2.2 is read,
By supporting the waiting time until the communication control device 2.1 retransmits to the communication control device 2.2, the retransmission packet transmitted by the communication control device 2.1 to the communication control device 2.2 is prevented from being rejected again by "unable to receive". , Improve transmission efficiency.

EFFECTS OF THE INVENTION By adopting the present invention, the reception side communication control device is in the process of receiving data and becomes “unreceivable”, and the transmission side communication control device repeats retransmission and increases traffic on the information transmission path. It becomes possible to solve the point.

[Brief description of drawings]

1 is a communication sequence diagram of the first embodiment of the present invention, FIG. 2 is a communication sequence diagram of the second embodiment of the present invention, and FIG.
FIG. 4 is a configuration diagram of an embodiment of an information transmission system to which the present invention is applied, FIG. 4a is a configuration diagram of a communication packet to which the present invention is applied, FIG. 4b is a content diagram of a data field in the communication packet, and FIG. 6 is a definition diagram of a control field, FIG. 6 is a configuration diagram of a communication control device, FIG. 7 is a conventional communication sequence diagram, and FIG. 8 is a configuration diagram of an attribute table. 1 ... Information transmission path, 2.1 to 2.n ... Communication control device.

Continuation of the front page (56) Reference JP-A-61-186046 (JP, A) JP-A-55-80946 (JP, A) JP-A-62-146045 (JP, A) JP-A-60-28349 (JP , A)

Claims (2)

[Claims] 1. A plurality of communication control devices are connected to an information transmission line of one system, and each communication control device is provided with an attribute table that can register its own attributes and read from other communication control devices. However, in the case where one of the plurality of communication control devices becomes the transmission side of the communication packet and the other one becomes the reception side for one-to-one information communication, the transmission side is set in the attribute table. A processing time required for processing a communication packet received from the communication control device via the information transmission path and enabling reception of the next communication packet is stored in advance, and the transmission side communication control device continuously stores a plurality of times. When the communication packet is transmitted to the receiving side communication control device, the processing time on the attribute table in the receiving side communication control device is read prior to the transmission of the first communication packet, and the continuous transmission is performed. A communication control method characterized by adjusting the transmission interval of the communication packet. 2. Until the next communication packet becomes receivable after the processing currently performed on the communication packet received by the receiving side communication control device is completed in the attribute table according to claim 1. A communication control method comprising storing a processing waiting time, reading the processing waiting time before the transmission side communication control device transmits the communication packet, and adjusting the waiting time until the communication packet is transmitted.