JPS585061A - Multidrop transmission system - Google Patents

Abstract

PURPOSE:To receive a data transmission forecasting signal which consists of precedent data and length data at a reception side without paying sttention to section data such as pattern data, by transmitting the data transmission forecasting signal previously. CONSTITUTION:For transmission of transmitted data (DATA) from a controller 2 to an input and output equipment 5A, the transmission forecasting signal consisting of destination data (FDTA) showing the transmission destination of data, i.e. the address of the input and output equipment 5A and data length data (DLD) for showing the length to be transmitted as the number of bytes is transmitted prior to actual data transmission. The input and output equipment 5A whose reception is specified, on the other hand, discriminates the data length data and sets the number of bytes to be sent to a counter 10. After this setting, a completion signal S2 is changed from ''0'' to ''1'' and a confirmation command ACK for accelerating the transmission of the data is sent out to said controller 2. Therefore, the input and output equipments 5A previously knows the length of the data to be sent, so it receives the data without paying attention to a data sectioning code.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is directed to a transmission method in a multi-drop data transmission system in which a plurality of input/output devices are connected to one transmission line.

It is a time chart showing the sea-th conventional transmission method.

Conventionally, the 0*0 transmission line Y6C transmission system was
As shown in the figure, destination data FDTA indicating the input/output device to which the data DATA should be transmitted is set before transmission data DATAO to be transmitted to a specific input/output device, and the data DATA%FDT is set as a trap. C0D
B, the delimiter code C0DBK was used to differentiate data transmission. That is, the can input/output device is the delimiter code C0DI! iKI! Destination data FD entered by
After determining the TA, the next transmitted data DAT
It judges whether or not a message is transmitted to itself, and if it is addressed to itself, it takes in the data, and if it is sent to another user, it prohibits the manual transmission of that data. In this method, each input/output device determines the transmission data DATAo#Itb and the end 9 based on the delimiter code C0DIC, so the delimiter code C0DB is the transmission data DATAo#Itb.
It is necessary to use data that has an extremely low probability of existing in ATA, but recently, as the cost of transmitting image data such as graphics and program data as transmission data DATA increases, it is necessary to use data that has an extremely low probability of existing in ATA. The probability that the same data as the code C0DE exists is small, and there is a risk of malfunction. Therefore, conventionally, the transmission data DAT, which matches the delimiter code C0DE and has a high risk of
When transmitting a person, make sure that the delimiter code C0DE and the transmission data DATA do not match.
C conversion processing was performed, but this had the disadvantage of complicating the processing of data DATA and reducing the overall transmission speed. Therefore, the present invention has been developed to convert data from the control device to When transmitting data to each person's output station, the data transmission system is configured so that the data consisting of destination data and data length data is outputted to each input/output shears prior to the transmission data, The object of the present invention is to eliminate the above-mentioned drawbacks and provide a nine-multidrop transmission system.

Hereinafter, the present invention will be specifically explained based on embodiments shown in the drawings.

FIG. 5 is a block diagram showing an example of a data transmission system to which the present invention is applied, and FIG. 2 is a time chart showing an example of a data transmission situation in a multi-drop transmission system using a wood WAK.

As shown in FIG. 5, the data transmission system 1 includes a control device 2, to which one end of a transmission line 3 is connected. The transmission line 3 includes a plurality of input/output devices 3A, 3
B, ID-...,... are connected well, it is a so-called multi-drop method, and each input/output device 3A, 3B, 3D
. . . are provided with an input data discrimination circuit 6 and an AND circuit 1 connected to the transmission line 3. A decoder $ and a counter 10 are connected to the discrimination circuit 6, an AND circuit 1 which is a gate circuit is connected to the decoder 8 and the counter 1g, and an input/output device main body 11 is further connected to the AND1gl path rKtl.

Since the data transmission system lll1 has the above configuration, the control device 2 transmits the transmission data D to the five input/output devices.
When transmitting ATA, a data transmission request C0TtalS is sent to the transmission line 3.

As shown in Figure 2, the gate delivery request COT indicates the addresses of the data O transmission destinations, that is, the five input/output devices, and the data length of the destination data FDTA and the transmission data DATA to be transmitted in bytes. This transmission request COT, consisting of the displayed data length data DLD, is input to the data discrimination circuit S of all the input/output devices SA, 5B, 5D, . . . via the transmission line y3. Each data discrimination circuit 6 is connected to the control device 2
The data transmitted from the data transmission request C0Tlk
If it is a data transmission request COT, the destination data F of the transmission request COT is determined.
The DT data is output to the decoder 9, and the data length data DLD1i and 10 are output. Decoder welfare destination data FDT
The control device 2 decodes the address in A, determines whether the input/output device of the other side with which the control device 2 wants to perform data transmission is the device itself or a device other than itself, and in the case of the device itself, outputs the force signal 81. 101 or 6 ”l■ (in this case, therefore,
Only the output signal 81 from the decoder port of the input/output device 5 is II.
Becomes I. ).

On the other hand, the counter 10 receives the input data length data DLD.
Then, the data length, ie, the number of bytes, of the transmission data DAT to be transmitted is set, and when the setting is completed, the completion signal 82 is changed from 10- to -1-. In this state, each input/output device SA%SB, sD...
The five devices for which the value became -11 output a sure W command ACK to control device 2 to request data transmission, and control device 1
2 receives it and starts transmission of the transmission data DATAO. 0 data DATA is sent to each input/output device 5, SB, ! iD-
81%S of other signals input to the data discrimination circuit 6 and AND circuit 7 or AND-path TK
The input of data DATA to the input/output device main body 11 is prohibited except for the five persons who have both K2 and K "1".

Therefore, only five devices have to import the data DATAt to the Hayabusa 11, but each device 5, SB, SD...
- counter 10 receives data DAT via a discrimination circuit.
By subtracting the input bit number of A from the 9 data length specified by the transmission Hosui COT, the quant value becomes 10-, and the input transmission data DATA reaches the specified data length. , when the transmission of data DATA is completed, the signal 82 t is changed from ``i'' to Igl. Then, if the data (DATAC) transmission is taking place, the 5 MMDIIIiTs will be able to transmit the main body of data 1.
1 to prevent unnecessary data from being input into the main body 11. Further, by the signal 82, each data discriminating circuit 6 knows that the overnight transmission has been completed, and prepares for the next transmission from the control device 2. Further, when the data transmission is completed, a confirmation command ACK is output from the storage system containing the data DATA1[j] to the control device 2, and the control device 2 immediately starts the next data transmission operation.

The above embodiment is based on the case where the transmission data DATA is transmitted to five input/output devices.
Of course, when transmitting to other AIIH devices SB, 5D, etc., it can be done automatically by simply changing the destination data FDTA in the transmission request COT.

As explained above, according to the present invention, the transmission data DA
Prior to TAK, a data transmission request COT consisting of destination data FDT indicating the transmission destination of the transmission data DATA and data length data DLD indicating the data length of the transmission data DATA to be transmitted is sent to each input/output device 5A, 5B%S. D-・
Since the control device 2 is configured to output from the control device 2, each device SA, SB, 5D------ is transmitted by the transmission f-/DAT.
The AOf data can be known in advance, and therefore there is a high risk of confusion with the transmission data DAT code C0DH
Even if data DATA is not used, it is possible to know the start and end of data reliably, and it is possible to improve the reliability of data transmission. Even in the case of gram data, delimiter 9 code C
Since there is no need for data conversion processing to distinguish it from 0DB, the processing is simplified accordingly, and the overall transmission device can be improved.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a data transmission system to which the present invention is applied, and FIG. 2 is a block diagram according to the present invention. - Data transmission status of multi-drop transmission method. A time chart showing an example. FIG. 3 is a time chart showing a conventional transmission method. 1...Data transmission system 2...-Control device 3...Transmission line SA,! IB, 5D--------- Input/output device T---Gate circuit (AND circuit) 9------
・Decoder 10 --- Counter COT --- Data transmission request DLD --- Data length data DAT Person --- Transmission data FDT --- Destination data Sl, S2 ...Signal applicant Fujitsu Limited

Claims (1)

[Claims] In a multi-device data transmission system in which multiple terminal devices are connected to a control device and a control device via one transmission twin, each device is sent destination data indicating the @destination of the data. Only when the data output a certain signal, the data length data indicating the data length of the transmitted data to be transmitted, count the data length of the input transmitted data, and the transmitted data reaches the data length. A counter that outputs a constant signal with a counter and a counter that outputs a constant signal and handles the transmitted data according to the signal of the counter and the counter.
The control device is provided with a means for controlling the data, and when transmitting data from the control device to each terminal device, data consisting of the destination data and data length data is output to each terminal device prior to the transmission data. A multi-drop transmission system configured with