JP2677895B2 - Multiplex transmission method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a multiplex transmission system for transmitting data between multiple nodes connected to a plurality of networks.

(Prior Art) Conventionally, in this type of multiplex transmission system, a microprocessor (CPU) that performs electronic processing control includes a multiplex transmission control IC that performs transmission control of a multiplex communication network, a transmission / reception buffer, and an interface. A common signal transmission line (data bus) that consists of twisted pair electric wires, etc.
Are connected to each other to form a bus-type multiplex communication network, and a multiplex communication network having various responsiveness (for example, different transmission speeds) with the above configuration is used as a transmission control unit (gateway node) having a gateway function by a CPU. ) Was used to connect and perform multiplex transmission. Then, when a transmission error occurs when transmitting the transmission data from one network to the other network,
The same transmission data is retransmitted from the transmission source multiplex node, and the gateway node transmits the retransmitted transmission data to the receiving side network via the data bus.

(Problems to be Solved by the Invention) However, in the above transmission method, when a data transmission error such as a local error occurs in the transmission side network, that is, the gateway node correctly receives the transmission data. Regardless, even if the other multiplex node in the transmission side network is defective and does not send the ACK signal, the source node judges that it is a transmission error and retransmits the same transmission data, so the gateway node uses the gateway function. The transmission control of the same transmission data retransmitted by must be performed again, unnecessarily increasing the transmission amount of data to be transmitted to the reception side network, so that the data transmission in the reception side network becomes crowded, The problem that it interferes with the transmission of other transmission data (for example, data transmission within the receiving side network) was there.

The present invention has been made in view of the above problems,
An object of the present invention is to provide a multiplex transmission method capable of efficiently performing data transmission without adversely affecting data transmission of other networks when data is retransmitted due to a transmission error.

(Means for Solving the Problem) In order to achieve the above object, in the present invention, at least two multi-nodes connected to each other via a common signal transmission path, and at least each multi-node connected to each other. Two
Signal transmission paths of one system and transmission control means connected to the signal transmission paths and performing signal transmission between the signal transmission paths, and each of the multiplex nodes responds to a transmission request from any of the multiplex nodes. In the multiplex transmission method for transmitting predetermined transmission data by means of the above, the transmission control means includes a storage means for storing data input via any of the signal transmission paths, and a time detection means for detecting an input time of the data. And the data stored last in the storage means,
When the comparison result is the same and the input time detected by the time detecting means is within a predetermined time set in advance, the newly input data is transmitted. A multiplex transmission method that does not perform is provided.

(Operation) When new transmission data is input, the transmission control means compares the above-mentioned data with the last stored data, detects the input time, and these data match, and the data input If the time is within a predetermined time, it is determined that the data is the same as the already transmitted data, and transmission control is performed so that the data is not transmitted to the signal transmission path on the receiving side.

Therefore, the reception side network does not take in the same transmission data again, so that even if the data is retransmitted, the data transmission in the reception side network is not adversely affected.

(Embodiment) An embodiment of the present invention will be described in detail below with reference to the drawings of FIGS. 1 to 3.

FIG. 1 is a configuration block diagram showing a configuration of a multiplex transmission system according to the present invention. In the figure, each multiple node 11-1
Although 3 and 21 to 23 have different responsiveness (for example, transmission rate), they have the same configuration block, and therefore the configuration of the multi-node 11 will be described as a representative for convenience of description.

In the multiplex node 11, the CPU 11a that performs electronic processing control has a multiplex transmission control I that controls transmission of the multiplex communication network.
A communication control circuit 11b including C, a transmission / reception buffer and an interface is added.

The CPUs of the multiplex nodes 11 to 13 have the same responsiveness (for example, responsiveness with a high data transmission rate), and are connected by a common multiplex transmission path (data bus) 10a via each communication control circuit. It composes network 10, and each communication control circuit uses CP in the above buffer when transmitting.
After writing the data from U, when the writing is completed, the data in the buffer is transferred to the data bus 10 via the interface.
In addition, the data input from the data bus 10a via the interface is written to the buffer at the time of reception, and when the writing is completed, the data in the buffer is sent to the CPU.

The CPUs of the multi-nodes 21 to 23 have the same responsiveness (for example, responsiveness lower than the data transmission rate of the CPUs of the multi-nodes 11 to 15), and the common data bus 20a via the respective communication control circuits. Network connected by 20
And each communication control circuit has multiple nodes 11 to 13
Similar to the communication control circuit, the CPU sends and receives data signals to and from the CPU and the data bus 20a.

Data buses 10a and 20a are 100Kbps or more and several 10K
It is a data bus consisting of twisted pair electric wires etc. of bps transmission speed, and the multiple nodes 11 to 13 and 21 to 23 are the above data bus 10
Signals such as data frames and ACK signals are transmitted via a and 20a.

The transmission control unit (gateway node) 30 includes a CPU 30a for controlling multiplex transmission, communication control circuits 30b and 30c, and an internal memory.
30d, a timer counter circuit 30d, etc. are added.
The communication control circuits 30b and 30c are each composed of a control IC, a buffer for each network for transmitting and receiving data signals to and from the network, an interface, etc., and when transmitting, write data from the CPU 30a to the buffer, The data in the buffer is sent to the networks 10 and 20 via the interface, and at the time of reception, the data input from the networks 10 and 20 is written to the above buffer via the interface. The data signal is sent to the CPU 30a to send / receive data signals to / from the networks 10 and 20.

The CPU 30a is connected to the networks 10 and 20 via the communication control circuits 30b and 30c, respectively, and reads out new data stored in the network buffer that is fetched from the data buses 10a and 20a for each multiplex node. The last written data in the internal memory 30d is compared with the new data to determine whether the two data match. Further, when the new data is input, the CPU 30a controls the timer counter circuit 30d to perform counting until the input is completed, and the count value is within a preset predetermined time T (for example, T = 5msec). The set predetermined time T is set to 5 msec because the data frame of the data signal is usually a little over 4 msec, and the time taken for the data signal and the AC of the data frame to be described later.
This is because it is considered that the retransmission is completed within 5 msec from the reception of at least the first data together with the time for recognizing the K signal area.

Then, the CPU 30a determines that the newly input data signal is the data signal retransmitted due to a transmission error when the both data match and the count value is within the predetermined time, and the other network To stop the transmission of the above data signal, and in other cases, that is, when both data do not match or the count value is other than the predetermined time T, the input data signal is judged as new data,
After writing the corresponding data in the internal memory 30d, reading it from the internal memory 30d, converting it to a data signal corresponding to the response of the other network, and then realizing the gateway function that returns to the multiple node that requested transmission. ing. Therefore, data signals can be transmitted between the buses of the networks 10 and 20.

FIG. 2 is a schematic diagram showing an embodiment of the format configuration of a data frame used in the multiplex transmission system of the present invention. The data frame F has a data structure including a start bit, ID data, data, and an ACK signal area.

The start bit is a specific bit indicating the start of frame F. The ID data is composed of an address indicating the destination, an address indicating the own station, information indicating the data length of the data, and the like. The ACK signal area is composed of a plurality of bit areas, and a bit area corresponding to the address of the multi-node is allocated to each multi-node, and each reception multi-node normally operates between the allocated bit areas. An ACK signal to be returned when a frame is received is arranged, and the transmission multiplex node confirms normal reception by the ACK signal to be returned.

Next, the reception processing operation of the gateway node in the data transmission between the networks will be described based on the flowchart of FIG. In this embodiment, a case where predetermined data is transmitted from the multiplex node 11 to the multiplex node 21 will be described.

When the CPU 30a receives a data signal from the network 10, the CPU 30a fetches the data signal from the communication control circuit 30b, compares the data signal with the data last written in the internal memory 30d, and the two data match. It is determined whether or not (step 101).

If the two data match, then it is determined whether the count value of the timer counter circuit 30e is greater than or equal to the predetermined time T (step 102). If the two data do not match, it is determined that the captured data signal is not a signal by re-transmission but a data signal newly transmitted from the network 10, and the captured data signal is written in the internal memory 30d. Then, the data signal is stored in the network transmission buffer of the communication control circuit 30c (step 103), and the timer counter circuit 30e
The count value of is cleared, the count is restarted from "0" again (step 104), and the receiving processing operation of the data signal to be input next is performed. In step 102, the count value of the timer counter circuit 30e is equal to or longer than the predetermined time T. Also in the case of, in the same manner as above, it is judged that the data signal taken in is the data signal newly transmitted from the network 10, and after storing the data signal in the internal memory 30d, the transmission for the network of the communication control circuit 30c is performed. The data is written in the buffer (step 103), the count value of the timer counter circuit 30e is cleared, and the count is restarted (step 104). If the count value is less than the predetermined time T, the fetched data signal is judged to be a signal by retransmission, and the timer counter circuit 30 is not written to the memory in step 103.
The count value of e is cleared, the count is restarted (step 104), and the reception processing operation of the data signal to be input next is performed.

Accordingly, when the data signal input from the network 10 is the same as the data last written in the internal memory 30d and the input time of the data signal is within the predetermined time T, the CPU 30a receives the input data signal. Has multiple nodes 11
It is judged that the data signal has been retransmitted from the network 20.
It is possible to skip the transmission process to. Further, when the two data do not match, or when the input time of the data signal is equal to or longer than the predetermined time T, the input data signal is a data signal newly transmitted from the network 10. It is possible to judge and perform the transmission processing to the network 20.

Therefore, in this embodiment, the gateway node can detect the retransmitted data signal when a transmission error occurs even though the gateway node is receiving the data signal correctly. Since the same data signal is not transmitted by the gateway function, the amount of data transmitted to the receiving network can be reduced.

In the present embodiment, the transmission control of the data signal from the network 10 to the network 20 has been described, but the present invention is not limited to this, and the transmission control of the data signal from both networks can be similarly implemented. Needless to say, in this case, data transmission can be performed more efficiently.

(Effects of the Invention) As described above, according to the present invention, at least two multi-nodes connected to each other via a common signal transmission path and signal transmissions of at least two systems to which the respective multi-nodes are connected. And a transmission control unit that is connected to each of the signal transmission lines and performs signal transmission between the signal transmission lines, and each of the multiplex nodes has predetermined transmission data according to a transmission request of any of the multiplex nodes. In the multiplex transmission system for transmitting the data, the transmission control means is provided with a storage means for storing data input via one of the signal transmission paths and a time detection means for detecting an input time of the data, and the storage means The data stored last in the means and the newly input data are compared, the comparison result is the same, and the input time detected by the time detecting means is predetermined. Since the newly input data is not transmitted within the fixed time, the same transmission data will not be transmitted to another network again even if the data is retransmitted. Data transmission can be performed efficiently without adversely affecting the data transmission in the above.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram showing the configuration of the multiplex transmission system according to the present invention, FIG. 2 is a schematic diagram showing an embodiment of the format configuration of a data frame used in the multiplex transmission system of the present invention, and FIG. 6 is a flowchart for explaining a reception processing operation of the transmission control unit shown in FIG. 1. 10,20 ... Network, 10a, 20a ... Multiple transmission line (data bus), 11-13,21-23 ... Multiple node, 30 ... Transmission control unit (gateway node), 11a ... CPU, 30b, 30c
...... Communication control circuit, 30d ...... Internal memory, 30e ...... Timer counter circuit.

Claims (1)

(57) [Claims] 1. At least two multi-nodes connected to each other via a common signal transmission path, at least two systems of signal transmission paths to which the respective multi-nodes are connected, and respectively connected to the signal transmission paths. Transmission control means for performing signal transmission between the respective signal transmission paths, wherein each of the multiplex nodes transmits predetermined transmission data in response to a transmission request from any of the multiplex nodes, The control means is provided with a storage means for storing data input via any one of the signal transmission paths and a time detection means for detecting an input time of the data, and stores the data stored last in the storage means. , If the comparison result is the same and the input time detected by the time detecting means is within a predetermined time, the new input is made. Multiplex transmission method, characterized in that it does not transmit the data.