JPH05130675A - Multiplex transmission system - Google Patents

Abstract

PURPOSE:To improve transmission reliability. CONSTITUTION:Plural terminal equipments 2 in which respective inherent addresses are set up are connected to a master equipment 1 through a signal line L. The master 1 specifies each terminal 2 by a transmission signal, individually accesses the specified terminal 2 and executes mutual signal transmission with each specified terminal 2. The master 1 is provided with signal characteristic detecting parts 13 to 15 for detecting the signal characteristics of returned signals from respective terminals 2. Each terminal 2 makes its return signal to the signal having optimum signal characteristics based upon a signal characteristic correcting command outputted from the master 1 in accordance with the detected result of the signal characteristics.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multiplex transmission system used for lighting control systems, security systems, etc. in the fields of home automation and building automation.

[0002]

2. Description of the Related Art As shown in FIG. 7, a multiplex transmission system is constructed by connecting a base unit 1 and a plurality of terminals 2 via a signal line L as a signal transmission medium, such as a lighting control system and a security system. Is used for. In this multiplex transmission system, a unique address is set in each of the terminals 2, and the parent device 1 transmits a transmission signal having the signal format shown in FIG.

The transmission signal is a mode signal MD that defines the data content of a synchronization signal SNC for the terminal 2 to detect the start of signal transmission of the master unit 1, a subsequent address signal AD and a control signal CD, and a transmission signal. An address signal AD indicating the unique address of the terminal 2, a control signal CD indicating the control contents such as on / off signals of a load connected to the terminal 2, an error detection signal for detecting a transmission error of a transmission signal. FC
C, a reply signal band RSP provided as a time zone for returning a reply signal from the terminal device 2 to the master device 1.

In this multiplex transmission system, the master unit 1 identifies each terminal unit 2 by the address signal AD of the transmission signal and sequentially and cyclically accesses the terminal unit 2, and the terminal unit 2 receives the address signal AD.
A load (not shown) according to the control signal CD of the transmission signal when the address set in
And the like, and the monitoring data of the operation of the load is returned to the master unit 1 in the reply signal band RSP.

[0005]

By the way, in the conventional multiplex transmission system of this type, the wiring form (topology) between the master unit 1 and each terminal unit 2, the surrounding environment at the installation location of the terminal unit 2, Alternatively, the reception state on the side of the base unit 1 may vary depending on the transmission distance to the base unit 1 and the reception state may be extremely poor depending on the terminal device 2. That is, the conventional multiplex transmission system of this type has a drawback of lacking transmission reliability.

The present invention has been made in view of the above points, and an object thereof is to provide a multiplex transmission system capable of improving the transmission reliability.

[0007]

According to the present invention, in order to achieve the above object, a signal characteristic detecting section for detecting a signal characteristic of a reply signal from a terminal is provided in a master unit, and a signal characteristic detection result is obtained. The terminal device is provided with signal characteristic adjusting means for adjusting the response signal from the terminal device to the optimum signal characteristic in response to the corresponding correction command of the signal characteristic from the master device.

[0008]

According to the present invention, with the above-described configuration, the reception state of the reply signal from the terminal is detected by the master unit based on the signal characteristic, and when the signal characteristic is not proper, the terminal unit returns the response. The signal characteristic of the signal is corrected so that the parent device can properly receive the reply signals from all the terminal devices.

[0009]

(Embodiment 1) FIGS. 1 to 3 show an embodiment of the present invention. As shown in FIG. 1A, the master device 1 of the multiplex transmission system according to the present embodiment amplifies a signal processing unit 10 including a microcomputer and a transmission signal (logic signal) created by the signal processing unit 10. The signal amplification unit 11 for transmitting to the signal line L and the return signal band RSP via the signal line L.
Reply signal detector 12 that detects the current mode reply signal returned from terminal 2, pulse width detector 13 that detects the pulse width of the reply signal from terminal 2, and detects the current value of the reply signal Current value detection unit 14 and start timing detection unit 1 that detects the start timing of the reply signal
5 and 5. Here, the reply signal detection unit 12 detects the reply signal at a certain detection level (threshold value), shapes the waveform, converts the waveform into a logic level, and outputs the logic level to the signal processing unit 10. From the converted signal, "1", "0" judgment and error judgment are performed.

As shown in FIG. 1B, the terminal device 2 transmits from the master device 1 via a signal processing unit 20 including a microcomputer, a storage device 21 for storing a unique address and the like, and a signal line L. The transmission signal detection unit 22 for detecting the transmission signal to be transmitted and the response signal transmission unit 23 for returning the current mode return signal to the master unit 1. Here, the signal processing unit 20 is for controlling the load in which the transmission signal from the master device 1 is connected to the terminal device 2, for example, and when the address signal of the transmission signal matches its own address, Etc., a control output is given, and a monitoring input indicating the operation of the load at that time is returned to the master unit 1 in the reply signal band RSP.

By the way, when the transmission state between the master unit 1 and the terminal unit 2 is in an ideal state, a reply signal ((b) in the figure) returned by the terminal unit 2 as shown in FIG. The signal characteristics of the return signal ((a) in the figure) received by the parent device 1 are the same. Here, the signal characteristics are the start timing, pulse width and current value of the return signal shown in FIG.

However, in general, as shown in FIG. 3 (a), a signal of a reply signal returned by the terminal device 2 and a reply signal received by the master device 1 according to the state of the transmission path. The characteristics will be different. The broken line in FIG. 3A shows the return signal having the signal characteristic in the ideal transmission state. Therefore, in the present embodiment, the signal transmission can be favorably performed between the master unit 1 and the terminal unit 2 as follows. First, base unit 1
When the terminal receives the reply signal from the terminal device 2, each of the detection units 13 to 15 detects the start timing, pulse width and current value of the reply signal. Then, the signal processing unit 10 determines how the characteristics of the reply signal returned by the terminal device 2 should be such that the reply signal received by the master device 1 approaches the optimum reply signal.
Then, the obtained signal characteristics are sent to the terminal 2.

The terminal device 2 stores in the storage device 21 data relating to signal characteristics for sending a reply to the master device 1, and when the correction command from the master device 1 is received, the storage device 21 stores the data. The signal characteristic data is rewritten with the data received from the parent device 1. Then, in the subsequent signal transmission, a reply signal is returned according to the updated signal characteristic data. By doing so, as shown in FIG. 3B, the reception signal received by the master unit 1 becomes the same as that on the ideal transmission path, and good signal transmission can be performed.

By the way, as shown in FIG.
When the signal processing unit 10 is connected to a higher-level network, the signal processing unit 10 sends the detected signal characteristic to the higher-level network, and the characteristic of the reply signal returned by the terminal 2 is sent to the higher-level network. How do i
You may make it ask | require whether the reply signal which the main | base station 1 receives approaches an optimal reply signal, and it may make it send to the terminal device 2 according to the signal characteristic calculated | required.

Further, the master unit 1 simply detects the signal characteristics, and sends back the data relating to the detected signal characteristics as it is to the terminal unit 2 so that the terminal unit 2 can perform the signal characteristic correction processing. May be. Furthermore, the above process is 1
Although it is possible to perform the operation once, the optimum signal characteristics may be obtained by repeating the operation several times.

(Embodiment 2) FIGS. 4 to 6 show another embodiment of the present invention. As described in the first embodiment, it is most preferable to bring all the signal characteristics close to the optimum state, but in the simplest case, only the pulse width may be optimized. Therefore, this embodiment shows a case where only the pulse width is optimized. Therefore, in this embodiment, as shown in FIG. 4, the master unit 1 is provided with only the pulse width detection unit 13.

The characteristic operation of this embodiment will be described below with reference to FIG. Now, assuming that the reply signal from the terminal device 2 is received by the master device 1, at this time, the master device 1 detects the pulse width of the reply signal by the pulse width detection unit 13. Then, the detection result is transmitted to the terminal device 2. In the terminal 2 that receives this transmission signal, the storage device 21
The data is compared with the data as the optimum pulse width of the reply signal stored in, and the data is corrected so that the reception state of the reply signal in the master unit 1 becomes optimum. Then, the reply signal is returned with a pulse width corresponding to the correction data.

By the way, in the above description, the correction of the pulse width is performed on the side of the terminal device 2, but the master device 1 sends the optimum pulse width data to the terminal device 2 and the terminal device 2 transmits the data. The pulse width may be corrected. Further, as shown in FIG. 6, by performing transmission / reception between the master device 1 and the terminal device 2 several times, the terminal device 2 side corrects the pulse width so that the pulse width becomes gradually appropriate. It may be performed.

In the method of FIG. 6, the pulse width of the reply signal received by the base unit 1 is narrower than the proper value, and in this case, the base unit 1 requests the terminal unit 2 to widen the pulse width. I do. In response to the request, the terminal 2 first widens the pulse width by 10 μsec in response to the request and sends back a reply signal. The base unit 1 that has received this reply signal has a pulse width that is too wide this time, and therefore requests to narrow the pulse width. When receiving the second request for changing the pulse width, the terminal device 2 sends back a reply signal narrower than the above-mentioned correction width, in this case, 5 μsec, which is narrower than the pulse width of the previous reply signal. Hereinafter, by repeating the correction request for gradually approaching the pulse width to the optimum pulse width, the optimum reception state is gradually obtained. In this case, there is an advantage that the processing in the master device 1 and the terminal device 2 is not complicated.

[0020]

As described above, according to the present invention, a signal characteristic detecting unit for detecting the signal characteristic of a reply signal from a terminal is provided in the parent device and the signal characteristic from the parent device according to the detection result of the signal characteristic is provided. Since the terminal device is provided with a signal characteristic adjusting means for making the return signal from the terminal device an optimum signal characteristic in accordance with the correction command of 1. When the signal characteristics are not proper, the terminal device has an advantage that the signal characteristics of the reply signal are corrected and the master device can receive the reply signals from all the terminals satisfactorily.

[Brief description of drawings]

FIG. 1A and FIG. 1B are block diagrams showing respective configurations of a master unit and a terminal unit according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a transmission / reception waveform of a reply signal in an ideal transmission state.

FIG. 3 is an explanatory diagram of a method of optimizing a reply signal of the above.

FIG. 4 is a block diagram showing a configuration of a base unit according to another embodiment.

FIG. 5 is an explanatory diagram of a method of optimizing the pulse width of the reply signal of the above.

FIG. 6 is an explanatory diagram of a method of optimizing the pulse width of another reply signal.

FIG. 7 is a system configuration diagram of a multiplex transmission system.

FIG. 8 is a signal format of a transmission signal of the master unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 base unit 2 terminal device 10 and 20 signal processing unit 13 pulse width detection unit 14 current value detection unit 15 start timing detection unit 21 storage device L signal line

Claims (1)

[Claims] 1. A master unit and a plurality of terminals each having a unique address set are connected via a signal transmission medium, and the master unit identifies each terminal by a transmission signal and individually accesses the master unit. In a multiplex transmission system in which signals are transmitted to and from each other, the master unit is equipped with a signal characteristic detection unit that detects the signal characteristics of the return signal from the terminal, and the master unit that responds to the detection results of the signal characteristics The multiplex transmission system, wherein the terminal device is provided with signal characteristic adjusting means for making the return signal from the terminal device an optimum signal characteristic in accordance with the signal characteristic correction command.