JPH0364144A - Signal reinforcement device in data bus system - Google Patents

Abstract

PURPOSE:To easily extend a transmission line length with a simple means by providing a signal reinforcement means onto a bus between a transmitter and a receiver. CONSTITUTION:A signal reinforcement means 3 is provided on a nearly midposition between a transmitter 1 and a receiver 2. Suppose that a transmission signal having a level and a period represented in a signal (a) is sent from the transmitter 1 to a data bus 10 via an interface unit(IFU) 4, the signal (a) is attenuated while it passes through the bus 10 and its signal level is decreased as a signal a', which reaches the signal reinforcement means 3. The signal reinforcement means 3 detects the received signal a', generates internally a signal (b) having the same signal level and period and sends it to the bus 10, then the signals a', b are superimposed on the bus, resulting that a signal (c) whose signal level is the sum of both the levels of the signals a', b and the resulting signal (c) is sent to the receiver 2. Thus, the signal transmission line is extended up to twice as maximum easily with simple constitution.

Description

[Detailed Description of the Invention] [4 Remarks] The present invention relates to a signal reinforcement device in a data bus system, and has the purpose of extending the transmission distance between transmitting and receiving devices. Between,
The apparatus is configured to provide a signal reinforcing means for detecting a received signal, internally generating a signal matching or approximating the received signal, synchronizing this signal with the received signal, and superimposing it on the received signal.

[Industrial application field]

The present invention relates to a device for extending the data transmission distance between transmitting and receiving devices in a system that transmits and receives data between a plurality of transmitting and receiving devices via a data bus.

[Conventional technology]

Conventionally, so-called data communication systems that exchange data between multiple transmitting and receiving devices via data buses have been well known in the industrial world. Home bus systems have been proposed that connect to one data bus and exchange data to obtain necessary information and control necessary devices.

However, when data is exchanged between a plurality of transmitting and receiving devices using such a data bus system, the data transmission distance between the transmitting and receiving devices becomes a problem.

In other words, in such a system, when transmitting data through a bus, the transmitting device 1 From bus 1
0 is attenuated during transmission, so if the signal transmission line becomes too long, the level of the received signal B becomes unstable and the threshold value T H+
(See Figure 4)

Therefore, at the current stage, the length of the signal transmission line is naturally subject to restrictions, and in reality, the maximum length of the signal transmission line is said to be 200 m.

For example, the home bus standard ET-2101 stipulates that the maximum bus line length is 200 m (within the range where the signal level specified in 3.2.5 and 3.2.13 of the same standard is guaranteed). However, this figure does not guarantee that it is possible to transmit up to a line length of 200 m, and the signal level will attenuate due to the various factors mentioned above, so it is difficult to actually develop a system that can extend the line length to 200 m. It was difficult to scale.

Therefore, when installing such a new system, there are problems such as the need to limit the number of information outlets to which transmitting and receiving equipment can be connected in a large system, and when expanding an existing system, There is a problem that communication becomes impossible and the system stops working.

Especially if the system has been used at the limit of the line length, if the user attempts to purchase new equipment and expand the equipment, or if the user replaces the equipment currently in use with equipment from another manufacturer. There was also a risk that the system would stop working.

Conventionally, methods have been adopted to solve this problem, such as strengthening individual driver circuits, using wires with thicker diameters, and using sub-wirings when increasing the number of driver circuits. At present, there is no satisfactory solution to this problem as it may result in increased costs.

[Problem to be solved by the invention]

An object of the present invention is to provide a signal reinforcement device that can solve the problem of line length limitations in communication systems using data buses as described above, and can easily extend the transmission line length using simple means. .

[Means to solve the problem]

In order to achieve the above object, the present invention employs the following technical configuration. That is, in a data bus system, a received signal is detected on a bus between a transmitting means and a receiving means, and a signal that matches or approximates the received signal is internally generated and synchronized with the received signal. This is a signal reinforcing device in a data bus system that is provided with a signal reinforcing means for superimposing the signal on the data bus system.

[For production]

In the present invention, by providing a signal reinforcing means on the bus between the transmitting device and the receiving device, a signal substantially identical to the transmitting signal is superimposed on the transmitting signal transmitted from the transmitting device onto the bus. Since the transmission signal is transmitted to the receiving device side while increasing the level of the transmitted signal, the length of the signal transmission line can be extended.

〔Example〕

A specific example of the signal reinforcement device according to the present invention will be described below.

The operating principle of the signal reinforcement device of the present invention will be explained based on FIGS. 1 and 2.

That is, the present invention utilizes the characteristic that, as shown in FIG. 2, when signals are simultaneously supplied from a plurality of transmitting devices on one data bus, the signal levels on the buses are added. In other words, the terminal transmitting device A is connected to the bus 10 in FIG. 2 as an interface unit (IFU).
A signal having the level and period indicated by the transmission signal a is sent out on the bus 10, and the other terminal transmitting device B is connected to the data bus 10 through the same IFU, and a signal having the level and period indicated by the transmission signal a is sent out on the bus 10. When transmitting signals having the same characteristics are transmitted on the bus, the two multiplied signals a and b are superimposed on the bus 10, and a signal C is obtained by adding the signal levels. In this case, the signal level of signal C is not simply the sum of the levels of signals a and b, but is usually slightly lower.

Therefore, as shown in the principle diagram of FIG.
In a system that performs data communication by connecting via 0, a signal reinforcing means 3 having the above-mentioned functions is provided on the bus 10 between at least one set of transmitting equipment 1 and receiving equipment 2.
It is intended to provide The signal reinforcing means 3 can be provided anywhere between the transmitting device 1 and the receiving device 2, but preferably at an intermediate location between them. Further, a plurality of such signal reinforcing means may be provided between the transmitting device 1 and the receiving device 2, or may be provided between the receiving devices.

In FIG. 1, a transmitting equipment terminal (2) is connected to a data bus 10 via an IFU 4, and a receiving equipment terminal (2) is similarly connected to the data bus 10 at a certain interval. A signal reinforcing means 3 is provided at an approximately intermediate position between the device 1 and the receiving device 2,
Now, suppose that a transmission signal with the level and period indicated by signal (a) is sent from the transmitting device ↑ to the data bus 10 via the IFU. This signal attenuates while passing through the bus, and becomes the signal (a' ), the signal reaches the signal reinforcing means 3 as a signal with a reduced signal level. Here, the signal reinforcing means 3 detects the received signal (a'), internally generates a signal (b) having the same signal level and period, and sends it to the bus 10. signal(
A') and (b) are superimposed and the signal levels are added to generate a signal C, which is sent to a receiving device.

The signal (d) reaching the receiving device is attenuated while passing through the bus, but compared to the prior art, a data signal with a smaller degree of attenuation is obtained. Threshold TH.

By designing the transmission signal output, signal reinforcement means, wire diameter, number of terminals, etc. so as to obtain a signal level exceeding TH, it is possible to extend the data transmission distance.

The signal reinforcement means used in the present invention comprises at least I
It has a structure that can be connected to a data bus via an FU, and
It has a means for receiving a transmitted signal and a signal generating means, and furthermore, it constantly monitors the data bus, and when it receives a signal passing through the bus, it generates a signal at the same or similar level as the received signal. It is preferable to have a function of transmitting a signal bit by bit in synchronization with a received signal.

In the present invention, the signal (C) newly generated by superimposing the transmission signal a' and the signal (b) output from the signal reinforcing means is slightly delayed with respect to the transmission signal a'. , there is no problem in practical use.

In the present invention, based on the above-mentioned principle, there is a risk that when noise gets on the data bus, a reinforcing signal is superimposed on it and a signal as shown in FIG. 5 is generated.

Therefore, in the present invention, in order to prevent such a situation, the data bus is constantly monitored, the timing of the data bus is detected, for example, a start bit or a stop bit, and the presence or absence of the bit is detected, and the signal is detected in advance. For example, during the pause period between frames (22 bits + 10m5), noise can be prevented by not transmitting the signal reinforcement means simultaneously or by removing or ignoring the signals that come during that period. Avoided. Furthermore, even if noise were to be converted into a signal, there is a high possibility that all IFUs would receive the noise and judge it as an error.

A flowchart for implementing the signal reinforcement device of the present invention is shown in FIG.

After initial settings (step a), signal reinforcement processing begins. First, the data bus is monitored and when data is transmitted, the position of the data is checked for each frame and synchronized (step b). Next, it is detected whether or not the data being transmitted has been completed. If it has been completed, the process returns to step b, and if it has not been completed, the process proceeds to step d. Step d is used in special cases to cause a short message interrupt. If it is detected that there is no short message interrupt, the bits of data including that level are detected.Step e) A signal equal to this is synchronized with the transmission signal and transmitted simultaneously.Step f) Both signals are superimposed on the data bus. let Next, the process returns to step C to detect the next bit (step g).

As described above, the signal reinforcing device of the present invention constantly monitors the transmission signal manually input to the data bus, transmits a bit equivalent to each bit of data, and superimposes it on the bit of the transmitted signal. You can easily synchronize from

〔effect〕

In the present invention, by using the above-mentioned signal reinforcement device, it is possible to easily extend the signal transmission line length by up to twice with a simple configuration. In contrast, the present invention can achieve the above effects at low cost.

[Brief explanation of drawings]

FIG. 1 is a diagram illustrating the present invention in detail. FIG. 2 is a diagram showing the process of superimposing data signals on the data bus. FIG. 3 is a flowchart showing one specific means for carrying out the present invention. FIG. 4 is a diagram showing problems in the conventional technology. FIG. 5 is a diagram showing an example where noise is superimposed. 1... Sending device terminal, 2... Receiving device terminal, 3
...Signal reinforcement device, 4...Interface unit (IF[I).

Claims (1)

[Claims] In a data bus system, a signal is provided between a transmitting means and a receiving means to detect a received signal, internally generate a signal that matches or approximates the received signal, synchronize it with the received signal, and superimpose it on the received signal. A signal reinforcement device in a data bus system, characterized in that a reinforcement means is provided.