JPH0482441A - Home bus system - Google Patents

Abstract

PURPOSE:To reduce transmission delay and to surely prevent the collision of transmission signals from occurring by providing only one repeater when signal transmission distance is extended by using the repeater. CONSTITUTION:This system is formed by providing the repeater 3 which amplifies and relays the transmission signals among plural signal lines l1-l3 by using one repeater 3, and with a control circuit 5 which sends the same signal to another signal lines l1-ln via input/output parts 4 when the transmission signals on the signal lines l1-ln are detected by either plural input/output parts 4 of a terminal 1. Therefore, since no plural repeaters 3 are connected among the signal lines l1-ln, the relay of the transmission signal on the signal lines l1-ln can be performed only with slight transmission delay. Thereby, it is possible to surely prevent the collision of the transmission signals by a CSMA/CD system occurring.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a home bus system that prevents collisions of transmission signals using the C3MA/CD method.

[Prior Art] As shown in FIG. 5, a home bus system connects a plurality of terminal devices 1 to a two-wire signal line l, and these terminal devices 1
It is used to transmit signals between the two.

This type of home bus system uses a balanced signal transmission method (so-called AMI method) using a transformer, and the transmission signal transmitted via the signal line 1 is determined by the PACT priority as shown in Figure 9. priority code PR1 indicating the transmission address data SA indicating the self-address of the transmitting terminal 1
, destination address data DA indicating the address of the destination
, control code CC, which is a code related to control, and data D
Byte counter BC1 indicating the length of ATA; Data to be transmitted DATA; Error check code FCC for checking transmission errors; Dummy DM, which is free time set aside to allow time for processing data.
Y, and a reply code ACK, which is returned from the sending party and indicates whether or not the received signal is acceptable. Here, priority code PR
1 Sending address data SA, destination address data DA
, control code CC, byte counter BC, error check code FCC, and reply code ACK are the 8-bit data part of start pulse ST, b, ~b, parity P for checking errors in every 8 bits, and stop pulse. It has an 11-bit configuration consisting of SP. Further, the signal configuration of the data DATA is the same as that of the priority code PR, etc., but differs from the priority code PR etc. in that it has the number of bytes indicated by the byte counter BC. Furthermore, the dummy DMY is designed to have an empty time of 11 bits. In this home bus system, 9
．． Signal transmission is performed at a signal transmission rate of 6 kbps. In this AM1 type home bus system, as shown in FIG. 6, when the bit data is 0'', a square wave pulse is output, and when the bit data is 1'', the pulse is not output.
In addition, in order to make it a balanced type, the pulse indicating "0" is a bipolar signal with the polarity opposite to the previous one, and the amplitude of the pulse is
It is ゜5■, and the on-duty is 1. /(1,
+12) = -50%. Note that this signal is hereinafter referred to as an AMI signal.

In the terminal device 1, as shown in FIG. 7, signals are transmitted through a transformer T whose primary winding has an intermediate tap and whose secondary winding is connected between the signal lines 1. Here, a voltage is applied to the intermediate tap of the transformer T, and the transistors Q, Q2 connected between both ends of the primary winding of the transformer T and the ground are connected via inverters IN, IN2. When the control circuit 2 is turned on, the AMI signal is sent to the signal line l. Here, the terminal device 1 is connected to the signal 1i1. with the polarity shown in FIG. When connected to l, transistor Q2
When transistor Q1 is turned on, a pulse on the (+) side is output, and when transistor Q1 is turned on, a pulse on the (-) side is output. The signal transmitted via the signal line l is controlled by detecting the voltage induced in the windings on both sides of the intermediate tap of the primary winding of the transformer T by comparators CP, CP2, and from the outputs of these comparators CPCP2. The circuit 2 determines the bit data and receives it.

More specifically, the operation of the circuit shown in FIG. 7 will be explained. Now, when a pulse on the (+) side is transmitted through the signal line i, a back electromotive force is generated in the winding section shown on the lower side of the figure from the center tap of the primary winding of the transformer T, causing the comparator CP to
, the input voltage ■, decreases below the reference voltage V ref,
Therefore, the output of the comparator CP becomes "L", and the control circuit 2 determines that the bit data is "O°" from the rl- output of the comparator CP.Conversely, (-
) side pulse is transmitted through the signal line l, the input voltage V2 of the comparator CP is the reference voltage V ref
The control circuit 2 then outputs the “L” value of the comparator CP2.
It is determined that the bit data is "0" from the output of ". Then, if there is no pulse, it is determined that the bit data is "1". In this way, the AMI signal input via the signal line l is transmitted to the control circuit of the terminal device 1. 2 receives it.

In addition, when sending a signal to the signal line l, the control circuit 2
When output port 02 of is set to rL, transistor Q2
is turned on, the (+) side signal is sent to the signal line l via the transformer T, and when the output Q1 is set to "L", the (-)
side signal is sent out.

Incidentally, in this type of home bus system, the first start pulse ST is set to be a pulse on the (+) side, so that collisions of transmission signals can be detected by the C8MA/CD method. In other words, this C8
In the MA/CD system, when a certain terminal 1 is about to start transmission, if another terminal 1 is transmitting, it will synchronize with the start pulse ST of the previous terminal 1 and start transmission later. For example, if the terminal device 1 transmits a transmission signal, and for example, the transmission signal of the previous terminal device 1 transmits the data shown in FIG. 6, and there is no pulse at the third bit of the subsequent terminal device 1, then
In the later terminal device 1, the data sent by itself differs from the 3rd bit of the transmission signal superimposed on the signal line l, and the later terminal device 1 loses the competition at the 3rd bit, and is unable to transmit the data. By stopping the signal transmission,
This is to prevent collisions of transmitted signals.

However, in this type of home bus system, the level of the AMI signal is attenuated by the line resistance of the signal line 1, so there is a problem that the signal transmission distance cannot be extended beyond a certain distance.

One possible way to solve this problem is to extend the transmission distance by connecting repeaters that amplify and output the transmitted signal between multiple transmission lines. A comparator CP connects the input/output circuit section of the control circuit 2 of the terminal device 1 shown in FIG.
, -CP6 may be connected to inverters IN, -IN, respectively. In this repeater 3", the transmission signal from the first signal line ! is detected by the comparator cp6.cp through the transformer T2, and the output of each comparator CP6.CP is detected by the transistors Qs and Q.
s is turned on and transmitted to the second signal line 12 via the transformer T, the transmission signal of the first signal line l is relayed to the second signal line 12, and conversely, the transmission signal of the first signal line l is transmitted to the second signal line 12. 12 transmission signals are detected by comparators cp, , cp, and are detected by transistors Q3 .
By turning on Q, the transmission signal on the second signal line 12 is relayed to the first signal lines.

[Problems to be Solved by the Invention] However, when a plurality of such repeaters 3 are used for long-distance transmission, the transmission delays at the individual repeaters 3 are added up, making it difficult to solve the above-mentioned C8MA/CD method. There was a problem in that the collision prevention effect of the transmission signal used could not be properly obtained, resulting in malfunction.

The present invention has been made in view of the above points, and its purpose is to be able to extend the signal transmission distance,
Moreover, it is an object of the present invention to provide a home bus system that can reliably prevent collisions of transmission signals using the C3MA/CD method.

[Means for Solving the Problems] In order to achieve the above object, the present invention includes a repeater that amplifies and relays a transmission signal sent from a terminal device between a plurality of signal lines. A plurality of correspondingly provided input/output sections, and when a transmission signal is detected in one of these input/output sections, the same transmission signal as the above transmission signal is sent from the input/output section corresponding to the other signal line. The above-mentioned repeater is composed of a control circuit that controls the operation.

[Function] By providing a repeater as described above, the present invention makes it possible to extend the signal transmission distance with the repeater, and also allows the relay to be used when connecting a large number of signal lines to lengthen the signal transmission distance. C3MA/C
The D method is used to reliably prevent transmission signal collisions.

[Example] An embodiment of the present invention is shown in FIGS. 1 to 4.

As shown in FIG. 1, this embodiment uses one repeater 3 to amplify and relay transmission signals between a plurality of signal lines 1 to 17. As shown in FIG. 2, the input/output section of the control circuit 2 of the terminal device 1 shown in FIG. , . . . , 17 is detected, the same transmission signal as that transmission signal is transmitted to the other signal lines 1 . . However, in the input/output unit 4 of this embodiment, each ':I:/halator CP z , CP +z, CP
21, CP zzs=(7) Input the outputs to the control circuit 5 individually I z, I 1□, ■21+ ■22+・
It differs from the input/output section of the terminal shown in FIG. 7 in that...

In the repeater 3 of this embodiment, for example, on the signal line, as shown in FIG.
If the (+) side pulse shown in a) is transmitted, this pulse causes the output of the comparator cP,2 to become as shown in Fig. 3 (
As shown in b), it becomes rl, and thus the control circuit 5
It is determined that a pulse on the (10) side exists on the signal line eI, and at this time, the output ports 022, 0, 2 . ..., 0. , as rl-J as shown in FIG. 3(C), a (+) side pulse is sent to each signal it ez to 1o as shown in FIG. 3(d). In substantially the same way, the pulses on the signal line 1 and the upper side are also sent to each signal line 12 to 11, and the transmission signals of any of the other signal lines 12 to 1 are sent to the other signal lines in the same way. 11 to 17. According to this embodiment, a plurality of repeaters 3 are connected to signal lines 11 to 1. Since there is no connection between the signal lines 11 and 11, the transmission signal can be relayed to all signal lines 11 to 11 with only a transmission delay of a short time (indicated by t3 in Fig. 3) as shown in Fig. 3. . Note that the pulse width of the relayed pulse is set as tl so that it does not become longer than the pulse width of the regular pulse. Therefore, when transmission signals collide as shown in FIGS. 4(a) and 4(e), for example, collision detection using the CSMA/CD method can be performed reliably by not causing a large transmission delay. In the case of FIG. 4, there is a pulse at the 2nd bit of the terminal device 1 transmitting the signal at the end of the signal line 11, and there is a pulse at the 2nd bit of the terminal device 1 transmitting the signal after the signal line 12. This is the case where there is no pulse, and as mentioned above, signal line 1
This figure shows a case where the terminal device 1 of No. 2 loses the contention at the 2nd bit and stops sending out the transmission signal. Since it is equipped with a repeater that amplifies and relays the transmitted transmission signal, the signal transmission distance can be extended with the repeater, and multiple input/output sections are provided corresponding to each signal line. (3) a control circuit that causes the same transmission signal as the above transmission signal to be sent from the input/output section corresponding to the other signal line when a transmission signal is detected in any of these input/output sections;
Since it is configured as an e-repeater, it is possible to use only one repeater even when connecting multiple signal lines to extend the signal transmission distance.For this reason, when connecting multiple repeaters between signal lines The transmission delay is not large as in C8MA.
The /CD method has the advantage of reliably preventing collisions of transmission signals.

[Brief explanation of the drawing]

Figure 1 is a system configuration diagram of an embodiment of the present invention, Figure 2 is a specific circuit diagram of the same repeater, Figure 3 is an explanatory diagram of the same operation, and Figure 4 is the operation when transmission signals collide. Explanatory diagram, 5th
The figure is a system configuration diagram of a conventional example, Figure 6 is a waveform diagram of the transmission signal as above, Figure 7 is a circuit diagram of the terminal device as above, Figure 8 is a circuit diagram of a conventional repeater, and Figure 9 is a transmission signal diagram. This is the signal format of the signal. 1 is a terminal device, 3 is a repeater, 4 is an input/output section, 5 is a control circuit, 11 to 1. is a signal line. Agent Patent Attorney Ishi 1) Chief 7 Figure 3 1t3 ◆→To 1 ↑ Figure 7 Voluntary initiative to write an amendment to the procedure 1, Indication of the case 1990 Patent Application No. 197399 2, Name of the invention Home bus system 3, Amendment Relationship with the patent applicant's case Address of patent applicant 1048 Kadoma, Kadoma City, Osaka Prefecture Name (51
13) Matsushita Electric Works Co., Ltd. Representative Toshio Miyoshi 4, Agent postal code 530 5, Date of amendment order 6, Number of claims increased by amendment None [11 Specification of the present application, page 2, line 9, line 18 [Correct transmission address data J to "self address" in lines 19 to 19. [2] Correct "destination address data" in lines 10 and 19 of page 2 of the above to "recipient address". Agent Patent Attorney Ishi 1) Choshichi

Claims (1)

[Claims] (1) A home bus system that uses the CSMA/CD method to prevent transmission signal collisions is equipped with a repeater that amplifies and relays the transmission signal sent from the terminal device between multiple signal lines. A plurality of correspondingly provided input/output sections, and when a transmission signal is detected in one of these input/output sections, the same transmission signal as the above transmission signal is sent from the input/output section corresponding to the other signal line. A home bus system characterized in that the repeater is configured with a control circuit that controls the repeater.