JPS62161232A - Multiplex communication system for single communication line - Google Patents

Abstract

PURPOSE:To improve the efficiency and to simplify the constitution by allowing a node making transmission to monitor a signal level on a communication line sequentially at each bit and to compare the sent data, discriminating it as data collision when no coincidence is obtained as the result of comparison so as to stop the transmission. CONSTITUTION:Units (nodes) 1-6 are provided respectively with microcomputers 1b-6b. When a sent data is D1, a start signal STR1 is sent and when not D1, a start signal STR2 is sent. In sending 1-bit data, the transmission data is checked to discriminate whether or not collision takes place on the data line. In the discrimination, the coincidence/dissidence between the data on a data line 10 and the sent data is detected and when dissident, it is discriminated as occurrence of collision. When any collision is detected, the transmission is stopped to await an idle data line, and when an idle data line 10 is detected during the standby, the data D1 is retransmitted.

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" This invention relates to a multi-meter communication system for A2 communication lines suitable for use when transmitting and receiving signals between a plurality of devices mounted on a vehicle, for example. Regarding.

``Prior art'' The configuration of a transmission system or reception system mounted on a vehicle is 9 simple! It is desirable to have a light V. Therefore, in the past, two nodes were connected using one communication line (optical fiber, coaxial cable, etc.); Connecting between multiple nodes using a single communication line and one or more address lines (connections, etc. have been developed,
The configuration was simplified.

[Problems to be Solved by the Invention] However, the efficiency with which signal lines are used in conventional systems is still not sufficient, and the simplification of the structure has been slow.

This invention was made in view of the above-mentioned circumstances, and allows transmission and reception between multiple nodes using only one communication line, thereby improving the efficiency of communication line usage and significantly improving the configuration. The purpose of this invention is to provide a multiplex communication system for communication lines that can be simplified.

"Means for Solving the Problems" In order to solve the above problems, the present invention connects the input/output ends of a plurality of nodes each having a digital signal transmission/reception function with one communication line, and A node uses a unique node address that does not overlap, a sending node sends its own node address and the other party's node address as node data, and a receiving node uses the data on the communication line as its own node address. In a transmitting/receiving system configured to read this data only when the signal contains is sequentially monitored bit by bit and compared with the transmitted data, and if a match is not obtained in this comparison, it is determined that there is a data collision and the transmission operation is stopped.

``Effect J: When data collides on a communication line, the node that sent out P1~ on the non-priority side of the communication line among the conflicting nodes will detect a mismatch in its monitoring results and stop sending. Consequently, a node with no mismatch is selected as an alternative, and only this node continues the transmission operation.

"Example" Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a diagram showing the configuration of an embodiment in which the present invention is applied to a two-way transmission and reception system for a motorcycle.

The transmitting/receiving system shown in the figure includes an on-vehicle radio unit (node) 1, air suspension units l to (node) 2 that can adjust the vehicle height, and a radio switch that allows the driver to arbitrarily control both units 1-. A unit (node) 3, an air suspension switch unit (node) 4, a radio switch unit (node) 5 for a fellow passenger to control the radio unit 1, and a suspension unit for the radio units 1 to 1 and the suspension unit 7. Display unit (node) 6 that displays the operating status of both of 2.
It is composed of. The input/output E 1 a to 6a of the units 1 to 6 are each connected to one data line (harness >10 J3), and all the data between 1 to 6 are connected to the unit 1 via the data line 1o only. Signals are sent and received.The above system uses a LAN (Local A) for mutual data communication.
A form of rea Network) that can be used by any child.

The units 1 to 6 are each microcomputer 1b.
~6b. As shown in FIG. 2, the output terminal 1c of the microcomputer 1b is connected to the transistor T through a resistor.
'r, and the collector of the transistor Tr is connected to the data line 1o via the input/output terminal 1a of the unit 1 and connected to the positive power supply (voltage V
cc). Further, the input terminal 1d of the microcomputer 1b is connected to the collectors of transistors 1 to Tr, and the emitters of the transistors Tr are grounded. The units 2 to 6 have the same configuration as the unit 1.

Next, the characteristics of the data line 1o will be explained.

First, the output terminals 1C to 1C of the microcomputers 1b to 6b
One signal level from 6c is high level (H)
At this time, since the data line 10 is grounded through one of the transistors Tr, the signal 9 level on the data line 1o becomes a low level (L). Further, output *a: When any signal level from IC to 6c is low level (1-), the signal level on data line 1o becomes high level (]''). However, the low level (L) side of the data line 10 has priority, and the data line 10 is connected to J3.
When any one of the input/output terminals 1a to 6a of the input/output terminals 1 to 6 becomes low level, the data line 10 is forced to the low level regardless of the level of the other input/output terminals.

Next, the data signals sent from the units 1 to G onto the data line 10 will be explained. This signal is of an asynchronous type, as shown in FIG. 3. That is, 5.5 bits of the low level start signal (SrR(L))
(STIt 1), high level start bit (
Q of S(T1)), 5 bits, Q of the start bit gap (G(L)), 5 bits, Bb;t of data section, 0°5 bits of parity (P(H))
, 0°5b1 of the parity gap (G(L)) and 1b of the end signal (END(H)) (14 bits in total). Also, the data part is 1
For each bit, the first 0.5 bit is data D, and the remaining 0.5 bit is gap G. When data D is at a high level (hereinafter referred to as 1), it is a gap G, and when data D is low. The gear V-tube G is set to be H when the level (hereinafter referred to as "lower level") is reached. In this way, the data signal 1b; [a gap G is set for each] allows the detection of the usage state of the data line 10 and the detection of collision between data signals on the data line 10 to be performed immediately, as will be described later. This is to ensure that. Also, when a second, third or more data signal follows this data signal, the start signal (STR(L)) of these data signals is
is 1 bit (STR2), and the entire data signal is 1 bit (STR2).
It is set to 2 bits.

Therefore, when a signal is being sent out on the data line 10 (especially when the data line 10 is in use), the signal level H on the line 10 is always 1 bit or less. Therefore, the signal level F1 on the data line 10 is 1
．． By detecting whether the number is 5 bits or more, it is possible to detect whether the data line 10 is unused. Note that a receiving unit address and a transmitting unit address are stored in the data portion of the first data signal, respectively.

Furthermore, two types of transmission methods are used to transmit the data signal as described below. Of the units 1 to 6, the radio unit 1 and air suspension unit 2, which process a large amount of data, are connected to other units (slave units) 3
It is the master unit that manages the transmission of 6 to 6. Data signals are transmitted from the master unit 1.2 to the slave unit (display unit) 6 in the data format shown in FIG. 4(a).
Third. . . . each data signal D+, D2, D3.

... is performed unilaterally as shown in FIG. 1 (hereinafter, transmission using this transmission method will be referred to as "asynchronous transmission").

Furthermore, data signals are transmitted from the slave units (switch units I~) 3~5 to the mask unit 1.2 using the data formats 1~ shown in Figures 4(b) and (C). As shown, the first data signal shown in FIG. 4(b) is first sent from the master unit 1 or 2 to any one of the slave units 3, 4, and 5. The IQ of the receiver 1 to 3 or 4 or 5 is the first data 1. -8 transmission (, Shunira I address 2 specified transmission unit 1 to 1 or 21 \ Figure 4 (C) 1
．． Second. Each data signal D+, D2, 3rd degree...
D3, . . . are transmitted (hereinafter, transmission using this transmission method will be referred to as "synchronous transmission"). Thus, the transmission of signals of slave units 3-5 is managed by master unit 1 or 2. More specifically, the slave units 3.5 are managed by the master unit 1, and the slave units 4 are managed by the master unit 2. Therefore, the data signal is not unilaterally transmitted to the master units 1 to 1.2, and the processing of the mask unit 1.2 is not interrupted by 11, 11 input for receiving the data signal.

1゛Execution operation'' Figures 6 to 9 show each microcombiner 1b to 6b.
This is a flowchart tl-I'' showing the processing procedure for transmitting and receiving data signals executed within the process.As shown in FIG. (The functions of these flags will be described later).First, it is determined whether the f-tarine 10 is unused or a cup (step 602).

This determination is made when the signal level of the data line 10 is 1.5bi.
This is done by detecting whether it is at the L level for a time corresponding to t. Then, this determination result is positive (Yes)
When , it goes to the next step 603 and negates (N
o>, the same determination is made and the data line 10 is held until it becomes unused.

Next, in step 603, it is determined whether or not the collision flag is set, and if it is set, the process moves to step 606 after the timer time TINT3 of step 605 has elapsed, and if the collision flag has not been set, the process moves to step 606. After the timer time TINT4 of 604 has elapsed, the process moves to step 606.

In this case, the initial determination in step 603 is
Since the collision flag is reset in 01 (N
O). Also, the timer time TrNT4 is the timer time T
It is set longer than INT3 (the reason will be explained later).

Then, in step 606, it is determined again whether the data line is unused, and if this determination is (No>), the process returns to step GO2, and if (YES), the process proceeds to step 607.In step 607, The data to be sent is D
It is determined whether it is Dl, and if it is Dl, step 60
8, the start signal 5TRI is transmitted, and if it is not 1]1, the process moves to step 609 and the start signal 5TR2 is transmitted.
(See Figure 4). Next, the process moves to step 610 to transmit one bit of data, and then the process moves to step 611 to check the transmitted data to determine whether a collision has occurred on the data line. This judgment operation is performed to determine if the data on the data line 10 matches the transmitted data.
A discrepancy is detected, and when a discrepancy is detected, it is determined that a collision has occurred, and the principle of this detection is as follows. In other words, as mentioned above, the data line 10 is configured so that the low level side is prioritized, so if the level of the data line 10 is low when a high level signal (pippl~) is sent, the other This is a case where the unit is sending out a low-level signal, and a data collision is occurring.

For example, two transmitting units 1.2 as shown in FIG.
Suppose that the units transmit contentfully, the transmission signal of each unit and the data on the data line are the same until time to, but at time t.

At J3, the signal of unit 1, which is at a low level, is removed one time, and the level of data line 1o becomes low.

Therefore, in the sending unit 2, a mismatch in the sending data is detected, and a data surface conflict is detected here.

If a collision is determined in step 611 above, step 6
A collision flag is set in step 12, followed by step 602.
Then, when the data line 10 becomes empty, the state becomes ``Samurai''. That is, if a collision is detected, the transmission j5 is set to 11, and the data line is cleared by 1!1. and,
Standby status (when the empty data line 10 is detected in the fish, step 6゜3, GO5 is set to Wi-C suit 7'G)
Retransmit from T1- to D+ to O6, 607, 607, 608 1. - Do.

In this case, while passing step GO5, the timer time T
INT3, and the timer ","f TIN before collision detection
■It is shorter than 4. This means that the data transmission after the collision is detected is the retransmission of the data that was once stopped (data D1
This is because the data is sent out at a slightly faster timing.

On the other hand, if no collision is detected, the determination in step 611 is (No), and the process then proceeds to step 613.
The data sent is the data end (see Figure 4).
It is determined whether or not the data ends, and if it fails at the data end, the process returns to step 610 to continue transmitting data bit by bit. When the data end is detected in step 613, the process moves to step 614, where it is determined whether all the data to be transmitted has been sent, and whether the transmission is complete. If this determination is <No>, step 60
7, and from then on data D2, data D (...
data transmission. Also, in step 614 (YES)
), the process moves to step 615 and it is determined whether the ACK flag is set to 1- (YES).
If so, end the operation and return to the main pressure fixing routine.
If (No), the process moves to step 616 and the ACK signal (
It is determined whether there is an acceleration signal). In this case, in the initial reset at step 601, the AC
Since the K flag has been reset, the first determination in step 615 is (No>), and the process moves to step 616. Also, the ACK signal determined in step 616 is determined when the receiving unit correctly receives the transmitted data. If this ACK signal is output, the determination at step 616 is YES, and the series of transmission processing is completed and the process returns to the main routine.

On the other hand, if the receiving unit cannot correctly receive the transmitted data and does not output an ACK signal, the determination at step 616 is (NO) and step 617
Then, after setting the ACK flag, the process moves to step 607 and retransmission starts again from data D1. When this retransmission is completed, the process proceeds to step 615 via the determination in step 614. After retransmission, the flag is locked at 80, so the determination at step 615 is YES, and the transmission process ends without waiting for the determination of the presence or absence of the CK signal (step 616). Rau1
Return to Main Luzhin. That is, the retransmission is done only once, leaving the data line free for the pond unit. Furthermore, as is easily understood from the above explanation, the function of the GK flag is to complete retransmission only once.

The above is the operation of asynchronous transmission in this embodiment.

Next, the operation of the receiving unit when the above-mentioned asynchronous transmission occurs will be explained based on FIG. 7.

The procedure for asynchronous reception is shown in Figure 7.

First, it is determined whether a start signal has been received (step 701). This determination is made by detecting whether the signal level of the data line 10 continues for a period of time equivalent to i,5 bits or more. When the determination result in step 701 is negative (No), this subroutine is immediately ended and the process returns to the main routine.

When the determination result in step 701 is t1 constant (Yes), it is determined in the next step 702 whether or not a start bit has been detected. If this determination is negative (No), the same determination is made and the process waits until the start bit is detected.

In this way, reception of stars 1 to 15, start pitch 1
- Reading of data is started upon detection of violation.

Next, when the start bit is detected and the determination result in step 702 is affirmative (Yes), the start/stop synchronization timer is read again from cell l-L (step 703 and step 704); Readings are made at fixed time intervals using the Asho Domon.

In the next step 705, data (16.5 bits or 1
2 bits), that is, the end (,, received the number +ffi L), and the answer is negative (N
In case of o), the process from step 703 onward is repeated. Thus, the determination tl' in step 705 is made.

Until the result becomes affirmative (Yes), 16.5 bits or 12b1 minutes of data from STR to END is received. Then, the determination result in step 705 is affirmative (Yes).
In this case, a parity check is performed in step 706 to determine whether the read data is correct. If the result of this determination is negative (NO), this subroutine is immediately ended and the process returns to the main routine.

On the other hand, when the determination result in step 706 is a decision (Yes), it is determined whether the received signal is data or 7dress (
Step 707).

In this case, if the received data is data D1, the read data is divided into receiving unit addresses D, ΔDR and sending unit addresses S, A, as shown in FIG. 4(a).
Since it is DR, the determination in step 707 is rADR3I.
Also, the received data is data D2, D3...
. . , the read/V data becomes DATA as shown in the figure, so the determination at step 707 is rDA-rAj 1,j.

Is it uke (11 data is l) +? ');
II, if one is 4..., star 1
- Determination is made based on the difference in length of signals 5TR1 and 5TR2. In the case of moving from step 707 to step 708, it is determined whether the address data D and ADR match the address of the own station, and if they do not match, the reception process is immediately stopped and the main routine returns. return. On the other hand, if it matches the address data of your own station, step 7
09, it is determined whether or not the reception has been completed. If not, the process returns to step 702 and the above reception operation is repeated until all data is received. In addition, if it is determined in step 707 that [DATAj], the determination in step 708 is unnecessary, and the process immediately proceeds to step 709.
leading to.

and if it is determined (YES) in step 709,
The process moves to step 710, and ACK111 is output as a response signal that all the data to be received have been completely received.

This completes the series of reception operations and returns to the main routine.

j″lL is the transmitting and receiving operation at Jj in the non-1iill!/lE-mode.

Next, the transmission and reception operations in the peer mode will be explained.

As shown in FIG. 8, the procedure for requesting data at the same time is to first reset the collision flag and the CK flag (step 801), and then determine whether the data line 10 is unused (step 802). When the result of this determination is positive (Yes), the process proceeds to the next step 803, and when the result is negative (NO), the same determination is made and the data line 10 is held until it becomes unused. In step 803, it is determined whether or not the collision flag set in step 810 (e) is set. If this determination result is negative (No), the timer time T INT4 elapses 1
((Step 804), proceed to the next step 806. Also, when the determination result in step 803 is affirmative (Yes), the timer time T[NT1 is smaller than the timer time TINT3 (step 805), and the next step Proceed to step 806. In step 806, the step 802
Similarly, it is determined whether the data line 10 is unused.

If the result of this determination is affirmative (Yes), the process advances to the next step 807. Note that steps 801 to 806 above are steps 601 to 60 of the asynchronous transmission subroutine in FIG.
This is the same process as 6.

Next, in step 807, STR1 is used as the star 1 to signal.
(5,5bit) is transmitted. In the next step 808, 1 bit of the data request signal shown in FIG. 4(b) is transmitted. Then, immediately after that, check for collisions in the transmitted data,
(Step 809), and when the answer is 1'1 (Yes), set a collision flag.Step 810), return to Step 802 and re-execute the 10 occlusion 3. Conclusion of determination in Step 809 When is negative (NO), it is determined in the next step 811 whether it is the end of the signal (16, 5 old [) or not, and when the answer is negative (No), step 80
B Repeat the process for Jul. Above step 809~
811 is step 6 of the asynchronous transmission subroutine in FIG.
It is executed in the same manner as No. 11-613. .

The determination result in step 811 is: Lj, 1t (Start when Yes>). The signal is verified, and it is checked whether the unit is in reception mode and data is returned (step 812. The discrimination result is negative (
If the answer is NO, it is determined whether the flag is set to 80 (step 813), and the answer is negative (N
O), the flag is set to 80 (step 81).
4) The process from step 807 onward is re-executed and the data request signal is sent once again. If the determination result in step 813 is 15 (Yes), the program is immediately terminated.

On the other hand, if the determination result in step 812 is affirmative (Yes), then in the next step 815 it is determined whether or not Star 1 to Pi 1- have been detected. If the answer is negative <No, the same judgment is made and the Samurai's are repeated until Star 1 - Pi 1 - is detected.

Then, if the determination result in step 815 is 1 affirmative (Yes), the tine for the starting and stopping students is set to P21~step 816), and the data is read (step 81).
7) Perform readings at constant 11.1 interval.

In the next step 818, it is determined whether or not the data (12 bits) has ended, and if the answer is negative (No), the processing from step 816 onwards is repeated.

If the determination result in step 818 is affirmative (Yes), a parity check is performed in the next step 819, and if the result is negative (NO), the program is immediately terminated. Also, the determination result in step 819 is affirmative (
If Yes), the next step 820 is shown in FIG. 4(C).
D+, D2.

Determine whether reception of data D3... is completed,
If the answer is negative (No), the processing from step 815 onward is repeated. When the determination result in step 820 is 1), a shift signal (80K) is sent.
3 (step 821), this program ends.

Steps 815-821t, steps 702-706 and step 70 of the asynchronous reception subroutine in FIG.
9.710 (, Executed as a wolf.

In addition, the procedure for data return in synchronous transmission is shown in Fig. 9. First, it is determined whether the start signal has been received or if the start signal has been received (step 901), and if the answer is negative (No), this program is immediately executed. finish.

When the determination result in step 901 is affirmative (Yes), it is determined in the next step 902 whether or not a start bit has been detected. If the answer is negative (NO), the same judgment is made and the process waits until the start signal is detected.

When the determination result in step 902 is affirmative (Yes), the timer for start-stop synchronization is switched on and the data is read (steps 903 and 904), and the data is read at fixed time intervals at the start-stop synchronization. I do. In the next step 905, it is determined whether or not the data (16°5 bits) is the end. If the answer is negative (No), the process from step 903 onward is repeated 1°, and step 9
If the determination result of 05 is 11 (Yes), a parity check is performed in step 906, and if the result is negative (No), the program is immediately terminated. Further, when the determination result in step 906 is affirmative (Yes), the process advances to the next step 907. Step 901 above
Steps 701 to 906 are executed in the same manner as steps 701 to 706 of the asynchronous reception subroutine in FIG.

In step 907, the address of the data request signal is verified to determine whether the data request signal is for the unit in question. If the result of this determination is negative (NO), the program is immediately terminated. If the result of this determination is affirmative (Yes), the ACK flag is reset (step 908), and the process proceeds to the next step 909.

Next, the unit l- enters the transmission mode and first transmits 5TR2 as a start signal (step 909), and transmits 1 bit of data. Then, in step 911, it is determined whether or not the data (12 bits) has ended, and if the answer is negative (NO), the processes from 2-up 910 onwards are repeated. 12 bits of data from STR to END is transmitted until it becomes affirmative (Yes).

When the determination result in step 911 is affirmative (Yes), in the next step 912, D+, D2 in FIG.
, D3, . D+ by the time it becomes (YesS),
D2. D3. - send the data.

When the determination result in step 912 is 5 (Yes), the AC
It is determined whether the K flag is set (step 913). If the result of this determination is negative (NO), it is determined in step 914 whether or not there is an 80K (accrual signal).

This clearance signal is transmitted by the unit with the data requester when the unit with the data requester correctly receives the reply data.

If the result of the determination in step 914 is negative (NO), the ACK flag is set to 1 in the next step 915, and the processing from step 909 onwards is re-executed.

Further, if the determination result in step 914 is affirmative (Yes), this program is ended. Above step 911~
Step 915 is executed in the same manner as steps 613 to 617 of the asynchronous transmission 1-na route in FIG.

Note that this embodiment has the following effects.

■If an ACK signal is not sent from the receiving unit after transmission is complete, the same data will be sent once again, so even if there is a data transfer error, the same data will be sent immediately. is sent out, so the receiving unit can receive the correct data at 17. In addition, since retransmission is performed only once, the same unit 1- does not continue to use the data line 10 for retransmission, and the usability of the data line 10 is reduced.
r is good.

(Since the two-piece j-cline 10 has priority on the low level side, the sender with competing S will stop the transmission if the higher level bit appears first, and the first part of the data will be Since Jζ shown in FIG. 4 is the receiving unit I address, this receiving unit address is used in order of priority ]'?
; can be added.

(2) If the received data is 1, the receiving unit outputs an ACK signal as a response signal, so the transmitting unit can know whether data transfer is possible.

"Effects of the Invention" As explained above, according to the present invention, the input and output ends of a plurality of nodes that perform digital signal transmission and reception functions are each connected by one communication line, and each node is overlapped. A node that transmits data has a node address of 1, and a node that performs transmission sends its own node address and the node address of the other party as node data, and a node that performs reception transmits the data on the communication line as its own node address. In a transmitting/receiving system configured to read this data only when the level is lυ, the communication line is configured so that either high or low level is given priority, and the transmitting node The level is sequentially monitored bit by bit and compared with the transmitted data, and if a match is not obtained in this comparison, it is determined that the data has collided with 'f' and the transmission operation is stopped. ? ! 2
Transmission and reception of data can be performed between a number of nodes using only one communication line without interference. Therefore, it is possible to improve the utilization efficiency of communication lines and to greatly simplify the system configuration.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a vehicle transmission/reception system to which the present invention is applied, Fig. 2 is an electric circuit diagram of the system shown in Fig. 1, Fig. 3 is a block diagram of a data signal, and Fig. 4 is a block diagram of the system shown in Fig. 3. Data formats 1 to No. 5, Fig. 5 is an explanatory diagram showing the process of avoiding collision between two γ-ray signals, Fig. 6 is a reflow chart showing the procedure for transmitting data from C and L, and Fig. 7 The figure is non-same jjl J receiving f+
Flowchart 1-p-t-1 showing the procedure for data return, FIG. 8 shows a flowchart showing the procedure for data return. 1 to 6...Conit (node), la to 6a・
...Input/output terminal, 1b to 6b...Microcomputer, 10...Data line. Applicant Honda Motor Co., Ltd. Figure 2 Figure 8 Figure 7

Claims (2)

[Claims] (1) The input and output ends of multiple nodes that have digital signal transmission and reception functions are each connected by a single communication line, and each node has a unique node address that does not overlap.
A transmitting node sends its own node address and the other party's node address as node data, and a receiving node reads this data only when the data on the communication line includes its own node address. In the transmitting/receiving system configured as above, the communication line is configured so that either high or low level is given priority, and
The transmitting node sequentially monitors the signal level on the communication line bit by bit and compares it with the transmitted data, and if a match is not obtained in this comparison, it determines that there is a data collision and stops the transmitting operation. A single communication line multiplex communication system characterized by: (2) The single communication line multiplex communication system according to claim 1, wherein the communication line is a single wire harness for a vehicle.