JPS61237553A - Multiplex transmission equipment - Google Patents

Abstract

PURPOSE:To simplify the circuit by connecting power source terminals to the transmission line loop-connecting plural secondary stations and a primary station and supplying direct current to the secondary stations, and by transmitting/ receiving data to/from the secondary stations after a poling signal being sent from the primary station. CONSTITUTION:Plural number of secondary stations 2-4 are connected in loop to a primary station 1 by a two-core transmission line 5. Power source terminal is connected to the transmission line 5 and direct current is supplied thereto. The primary station 1 outputs the poling signal from its output terminal 1-0 and following that a data signal is outputted at prescribed interval. The secondary stations 2-4 actuate each part by the direct current and send the DC and data signal to the lower stations. When the poling signal received is poled to its own station, it receives the following data and sends the poling signal to the lower station. Thus, setting of the address becomes unnecessary, and multiplex transmission can be cone by simple circuits.

Description

[Detailed Description of the Invention] [Field of the Invention] The present invention is constructed by connecting a primary station (master station) and a plurality of secondary stations (slave stations) in a digital chain manner using a dedicated two-core wire. This invention relates to a multiplex transmission device.

[Summary of the invention]

The multiplex transmission device according to the present invention superimposes two
The primary station sends polling signals and data signals to the next station at predetermined intervals, and the primary station is connected to the primary station in a continuous loop in a digital chain, and the DC power supplied from the primary station is used as the power source for each secondary station. In addition to receiving a polling signal from a priority station, it receives data and sends out a polling signal. Such a configuration eliminates the need for power supply and address setting for each secondary station, making it possible to easily install the secondary stations.

[Prior art and its problems]

In general, in multiplex transmission equipment that configures a data transmission system by connecting a primary station and multiple secondary stations with a two-core dedicated line, the secondary stations are connected to any point on the common bus. A multi-drop system is often used, and in this case it is necessary to set a unique address for each secondary station. Such address settings are normally made using a DIP switch or the like provided at each secondary station.

However, when it is necessary to make the secondary station extremely compact, there is a problem in that the DIP switch limits the miniaturization. Furthermore, when setting up a large number of secondary stations at once, setting addresses is relatively easy, but when increasing or decreasing the number of secondary stations after configuring the multiplex transmission equipment system, the addresses may not be consecutive. Furthermore, there is a possibility that a plurality of secondary stations may be set to the same address by mistake, resulting in a transmission error. In addition, a shift register method is known in which addresses are not specified for each secondary station in order to facilitate work at the site where secondary stations are installed, but this method requires a signal line for clock signals in addition to data signals. Therefore, a transmission system cannot be constructed using inexpensive two-core wires, and there is a problem in that the price of the transmission cable increases. In addition, each secondary station requires its own DC power supply, and it is necessary to provide a direct current power supply to each secondary station or to supply power from the primary station through a separate power transmission line, resulting in a complicated configuration. was there.

[Purpose of the invention]

The present invention has been made in view of the problems of the conventional multiplex transmission device, and uses DIP switches to
It is an object of the present invention to provide a multiplex transmission device that does not require setting an address for the next station and can easily configure a system by supplying DC power to each secondary station using a two-baseline transmission cable.

[Structure and effects of the invention]

The present invention is a multiplex transmission device in which a primary station and a plurality of secondary stations are loop-connected in a digital chain manner via a transmission line, and the primary station transmits a polling signal, which is the right to transmit and receive, to the secondary station having the highest priority. A polling signal sending means that sends out a polling signal to the station, a DC power source whose power supply end is connected to a transmission line and supplies power to each secondary station, and a polling signal sending means that sends a polling signal to the secondary station at predetermined intervals. Each secondary station has a data transmission means for transmitting data, and each secondary station is connected to a transmission line and a filter means that is connected between input and output and passes the DC component and data signal obtained from the input terminal and blocks the polling signal. power supply means for supplying power to each part using DC power supplied from the primary station; a data transmission means for transmitting data to and from the primary station after receiving a polling signal; The present invention is characterized by comprising a boring signal sending means for sending a polling signal to the next station.

According to the present invention having such characteristics, a two-core transmission line is used to supply DC power to each secondary station, and also to transmit a polling signal and a data signal, and each secondary station receives the polling signal. Data transmission is performed by receiving the received data. After each secondary station completes its operation, it transmits a polling signal that gives it the right to transmit and receive to the next secondary station. Such a configuration makes it possible to transmit data to each secondary station using only two-core transmission lines.

Also, since addresses are not set for each secondary station, DIP
There is no need to provide a switch (and there is no need to supply DC power to each secondary station via a separate transmission line. Therefore, the secondary station can be made smaller and work efficiency when installing the secondary station is improved. It becomes possible to do so.

[Explanation of Examples]

FIG. 1 is a schematic block diagram showing an embodiment of a multiplex transmission apparatus according to the present invention. In this figure, primary station 1 and multiple 2
The next stations 2, 3, and 4 are loop-connected in a digital chain by a two-core transmission line 5.

In other words, the output terminal 1-o of the primary station is the terminal 2 connected to the highest order.
The output terminal 2-o of the secondary station 2 is connected to the input terminal 3-i of the next secondary station 3 via a transmission line 5. Similarly, the output terminal 3-o of the secondary station 3 is connected to the input terminal 4-i of the secondary station 40, and its output terminal 4-o is transmitted! Input terminal 1-i of primary station l via a5
It is connected to the. Primary station 1 is connected in a loop to 2
Polling signal that conveys data signals to the next station and secondary station 2
, 3.4 are transmitted intermittently at predetermined time intervals and are sequentially transmitted by superimposing a DC power supply.

(Configuration of the primary station) As shown in FIG. 2, the primary station 1 includes a polling signal transmitting circuit 11 that operates based on an external start signal, and a DC power supply that supplies power to each secondary station. It has 12. The DC power supply 12 supplies a DC power of E(Vl) to the output terminal 1-o of the primary station 1 via the block filter 13. The block filter 13 sends out a polling signal modulated at IMHz.The block filter 13 consists of a coil, etc., and transmits the polling signal from the polling signal transmission circuit 11 and the data signal obtained from the output terminal 1-o to the DC power supply 12 side. This is a filter to prevent this from happening.

In addition, the data signal receiving circuit 1 is connected to the input terminal 1-i of the primary station 1.
4 and a polling signal receiving circuit 15 are connected. The data signal receiving circuit 14 decodes the data signal sent from each secondary station and outputs it as a data signal, and its output is given to the data reproducing circuit 16. The data reproducing circuit 16 reproduces the received data signal and outputs it to the outside. Also, the polling signal receiving circuit 15 receives the polling signal from the secondary station connected to the last rank, and determines the reception timing from the polling signal transmitting circuit 1.
1 and sends out the polling signal again.

(Configuration of Secondary Station) FIG. 3 is a block diagram showing the configuration of the secondary station 2, and the other secondary stations 3.4 have similar configurations. Now, a low-pass filter 21 is connected to the input terminal 2-i of the secondary station 2.
and block filter 22 and polling signal detection circuit 2
3 is connected.

The low-pass filter 21 is a passive filter consisting of an LC, which blocks the signal at the frequency LM)Iz used as a polling signal regardless of the power supply state, and cuts off the signal at the frequency LM)Iz used as a polling signal regardless of the power supply state, and cuts off the signal at the frequency LM)Iz, which is used as a polling signal, from the direct current sent out from the transmission line A5 and at a frequency below IMIjz, for example, 60KHz. The modulated data signal is directly transmitted to the output terminal 2-o. The block filter 22 is constituted by a coil or the like and supplies only the DC voltage superimposed on the transmission line 5 to the power supply circuit 24. The power supply circuit 24 smoothes the applied power and supplies the power to each block of the secondary station 2, and also supplies it to the external power supply 25 as a power source for sensors and the like connected to the secondary station 2.

Further, the polling signal detection circuit 23 receives the polling signal applied via the transmission line 5 and provides the detection timing to the data signal transmission circuit 27.

The data signal transmitting circuit 27 transmits a data signal via the transmission line 5 based on the detection timing of the polling signal, and is supplied with a transmitting clock from the oscillator 26. The data signal transmission circuit 27 has a frequency of 60 KHz, for example.
This is a transmitting circuit that transmits NRZ code data modulated using
8 will be communicated. The polling signal transmitting circuit 28 is a transmitting circuit that transmits a polling signal to the subsequent secondary station 3 connected to the output terminal of the secondary station 2. and a low pass filter 21. The outputs of the data signal transmitting circuit 27 and the polling signal transmitting circuit 28 are connected to the subsequent secondary station 3 via the output terminal 2-o.

(Operation of this embodiment) Next, the operation of this embodiment will be explained with reference to waveform diagrams. FIGS. 4(a) to 4(d) are waveform diagrams showing signal waveforms at points a to d shown in FIG. 1. In this figure, DC power is supplied from a DC power supply 12 of a primary station 1 via a block filter 13 to each secondary station 2, 3.4 from an output terminal 1-o. In each secondary station, the DC power thus obtained is supplied to each block of the secondary station from a power supply circuit 24 via a block filter 22. Now, when the start signal is given to the primary station l, the polling signal transmission circuit 11 sends out the polling signal P1 as shown in FIG.
The polling signal P1 is detected by the polling signal detection circuit 23 of the secondary station 2, the detection timing is transmitted to the data signal transmission circuit 27, and the fourth
As shown in FIG. 2B, the data signal D2 is output from the secondary station 2 via the transmission line 5. The polling signal P1 is blocked by the low-pass filter 21, so the secondary station 3.4
Although the data signal D2 is not transmitted to FIG. 4(C),
As shown in (d), since it is below the cutoff frequency of the low-pass filter, it is transmitted to the primary station 1 via the transmission line 5 via the secondary stations 3 and 4. Therefore, the primary station 1 receives data through the data signal receiving circuit 14 and outputs the data of the secondary station through the data reproducing circuit 16.

Furthermore, the secondary station 2 sends out a re-polling signal from the polling signal transmitting circuit 28 and transmits it to the secondary station 3.

Then, the secondary station 3 repeats the same operation as the secondary station 2 described above, and receives the data signal D3 as shown in FIG. 4(C).
and a polling signal P3 is sent onto the transmission NIA 7.

The polling signal P3 is transmitted to the secondary station 4, and the same process is repeated by the secondary station 4.

Similarly, the secondary station 4 sends out a data signal D4 and a polling signal P4. The primary station 1 receives this D2. D3. D4 is sequentially reproduced, and when the re-polling signal P4 is received from the polling signal receiving circuit 15, the reception timing is changed to the polling signal transmitting circuit 1.
Give to 1. Therefore, the polling signal transmission circuit 11 sends out the re-polling signal P1 again, and the same operation is repeated thereafter.

In this way, the primary station 1 can receive data from each secondary station after sending out the polling signal P1.

At this time, since a DC power source is superimposed on the transmission line 5, there is no need to provide a power source for each secondary station.

In this embodiment, a multiplex transmission apparatus using three secondary stations has been described, but it goes without saying that a similar system can be constructed using an even larger number of secondary stations. In addition, in this embodiment, a low-pass filter is provided in each secondary station to pass the data signal as is and block only the polling signal, but the band cutoff filter that blocks only the frequency of the polling signal is replaced with a filter such as a bypass filter. It is also possible to do so.

Furthermore, in this embodiment, a multiplex transmission device in which the primary station receives the data signal sent from each secondary station has been described, but each secondary station is a receiving type secondary station, and the re-polling signal is transmitted from the primary station. It is also possible to sequentially and intermittently transmit data signals to each secondary station via the transmission line 5 following P1.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram showing an embodiment of a multiplex transmission device according to the present invention, and FIG. 2 is a schematic block diagram showing an embodiment of a multiplex transmission device according to the present invention.
FIG. 3 is a block diagram showing the configuration of the secondary station 1, FIG. 4 is a waveform diagram showing the waveforms of each part a % d of the transmission line of the multiplex transmission device. 1・−・−・−・Primary station 2.3.4・−m−−−・
Secondary station 5--...Transmission line 11--------
Polling signal transmitting circuit 12--DC power supply 13, 22--Block filter 14--Data signal receiving circuit 15
...Polling signal receiving circuit 21----m-
・・Low pass filter 23・−・−・−Polling signal detection circuit 24−・・−・−・Power supply circuit 27−−
---1・Data signal transmission circuit 28-・−・・−・
Polling signal transmitting circuit patent applicant Tateishi Electric Co., Ltd. Agent Patent attorney Yoshiki Okamoto (and one other person) Figure 1 Figure 2 Date 99 Figure 3 21 Figure 4 Procedures Amendment (voluntary) Showa June 17, 1960 1, Indication of the case 1985 Patent Application No. 078943 2, Name of the invention Name of multiplex transmission device (294) Tateishi Electric Co., Ltd. Representative Takao Miki 4 Agent address 8550 Osaka, Osaka Prefecture 5, 3rd floor, Shinkosan Building, 1-13-38 Nishihonmachi, Nishi-ku, Ichinishi-ku, Detailed explanation of the invention column 6 of the specification subject to the amendment Contents of the amendment (1) Page 10, line 10 and page 11 of the specification r in the 5th line
The description of 60KHzJ is changed to r60Kflz and 30 Kl
lz, correct it as J. (2) rNRZ code on page 11, lines 5 and 6 of the specification.”
The description will be corrected to "piphase code". that's all

Claims (4)

[Claims] (1) A multiplex transmission device in which a primary station and a plurality of secondary stations are loop-connected in a digital chain manner via a transmission line, and the primary station transmits a polling signal, which is the right to transmit and receive, to the two stations with the highest priority. a polling signal sending means for sending the re-polling signal to the next station; a DC power supply having a power supply end connected to a transmission line and supplying power to each of the secondary stations; and a predetermined interval from the secondary station after the polling signal sending means sends the re-polling signal. Each secondary station has: a filter means connected between the input and output to pass the DC component and data signal obtained from the input terminal and block the polling signal; a power supply means for supplying power to various parts with a DC power supply connected to the line and supplied from the primary station; a data transmission means for transmitting data with the primary station after receiving the polling signal; and a data transmission means for transmitting data to and from the primary station after receiving the polling signal. A multiplex transmission device comprising: polling signal sending means for sending a polling signal to a subsequent secondary station after transmission. (2) The polling signal sent by the polling signal sending means of the primary station and each of the secondary stations is a signal having a higher frequency than the data signal, and the filter means of each of the secondary stations blocks the polling signal. 2. The multiplex transmission device according to claim 1, wherein the multiplex transmission device is a low-pass filter that passes a data signal. (3) The data transmission means of the primary station is a data reception means that receives data signals from the secondary station transmitted at predetermined intervals, and the data transmission means of the secondary station receives the data signal from the primary station after receiving the polling signal. The multiplex transmission device according to claim 1, characterized in that the multiplex transmission device is data sending means for sending data to a station. (4) The data transmission means of the primary station is a data transmission means that transmits data to each secondary station at a predetermined timing after transmitting the polling signal, and the data transmission means of the secondary station transmits the data after receiving the polling signal. The multiplex transmission device according to claim 1, wherein the multiplex transmission device is data receiving means for receiving data.