JPH06164587A - 1:n communication system - Google Patents

Abstract

PURPOSE:To obtain a 1:N communication system in which a slave machine can output a request to transmit arbitrarily to a master machine, and the master machine can communicate with the arbitrary number of the slave machines. CONSTITUTION:All the slave machines C1, C2,... C. are provided with two different standard interface ports 2,3 on their upstream and downstream sides, and the ports 2,3 are mutually connected electrically by corresponding the same terminals excepting a ready-to-send terminal 11 with each other. Besides, a transmission data terminal 7 among signal terminals in the ports 2,3 is constituted so as to be capable of floating electrically, and simultaneously, a transmission request terminal 9 and a terminal ready terminal 12 are an open collector output. Further, a ready-to-send signal in the upstream side port 2 is inputted to an interface circuit 4. On the other hand, the ready-to-send signal is outputted to a downstream side port 3 independently apart from this, and simultaneously, an interval between the adjacent slave machines is connected by a communication cable 6 mutually connecting the same terminals in the ports 2,3 with each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a 1: N communication system in which a plurality of slave units are connected to one master unit so that the master unit and the slave units can communicate with each other. .

[0002]

2. Description of the Related Art As an interface port (connector) for connecting a computer and its terminal device to exchange data, there is an RS-232 port defined by the EIA (Electronic Industries Association). By using this RS-232 port, it is possible to connect a plurality of slave units to one master unit and to communicate between the master unit and the slave units.

FIG. 5 shows a conventional 1: N communication system in which a plurality of slave units are connected to one master unit so that the master unit and the slave units can communicate with each other. In this figure, reference numeral 81 is a master unit and 82 is N slave units. Then, the base unit 81 is provided with N RS-232 ports 83,
The slave unit 82 is provided with one RS-232 port 84, and the RS-232 port 83 on the master unit 81 side and the slave unit 8 are provided.
Between the RS-232 port 84 on the second side, RS-232
They are connected by a communication cable 85 at a ratio of 1: 1.

[0004]

However, in the above-mentioned conventional 1: N communication system, the main unit 81 and the slave unit 8 are connected.
It is necessary to provide RS-232 ports 83 equal to the number N of two, and there is a drawback that the configuration of the base device 81 becomes complicated accordingly. When the parent device 81 is installed at a position away from the child devices 82, N long RS-
The 232 communication cable 85 must be used, which is disadvantageous in that it is uneconomical. In addition, when communication is performed using a public line or the like using a modem (modulation / demodulation device), it is necessary to install one modem for each of the parent device 81 and all the child devices 82, and there are 2N modems for the entire system. In addition, there is a drawback that the cost for system configuration increases.

As a means for solving such a drawback, there is a communication system disclosed in Japanese Patent Laid-Open No. 62-171250. This communication system, as shown in FIG.
Each of the two RS-232 ports 92 and 93 is provided in each of the RS-232 ports 93, the connection is crossed in the slave unit 91, and a signal input / output from one RS-232 port 92 is transmitted to another RS232 port 93. It is designed to input and output from pins. In addition, 94 is a master unit, 95 is an RS-232 port provided in the master unit 94, and 96 is each slave unit 9
1 is an interface circuit, and 97 is a communication cable.

However, in the communication system according to the above publication, the input / output of one (for example, upstream) RS-232 port 92 is simply passed to the other (downstream) RS-232 port 93 side. However, since the transmission enable signal output from the parent device 94 is configured to pass through the child device 91, there is an inconvenience that only the child device 91 that has been permitted by the information from the parent device 94 can be sent. It was

The present invention has been made in consideration of the above matters, and an object of the present invention is to allow a slave unit to arbitrarily output a transmission request to a master unit and to transmit any transmission request to the master unit. It is to provide a 1: N communication system capable of communicating with a number of slave units.

[0008]

To achieve the above object, in a 1: N communication system according to the present invention, all of the slave units are provided with two different standard interface ports on the upstream side and the downstream side thereof. The interface ports are electrically connected to each other with the same terminals except the transmission enable terminals corresponding to each other, and the transmission data terminal among the signal terminals in the interface port can be electrically floated. At the same time, the transmission request terminal and terminal ready terminal are made open collector outputs, and the transmission enable signal from the upstream interface port is input to the interface circuit, and separately from this, the transmission enable signal is sent to the downstream interface port. Is output and the interface port is They are connected by connecting the communication cable of the same terminal to each other in.

[0009]

In the 1: N communication system configured as described above, the slave unit can arbitrarily output a transmission request to the master unit without paying attention to the communication state of other slave units. A transmission enable signal is sent to the slave unit according to the request from this slave unit. Thereby, the information from the child device can be arbitrarily sent to the parent device.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram schematically showing a 1: N communication system according to the present invention, in which P is a master unit,
C ₁ and C ₂ are slaves. In FIG. 1, for convenience, only _two slave units C ₁ and C ₂ are shown, but it is assumed that there are N slave units having the same configuration, and in the following description, the most upstream slave unit will be described. C ₁ and the downstream handset C _N (not shown)
And

Reference numeral 1 denotes a DTE (Da
ta terminal equipment) standard interface ports 2 and 3 are standard interface ports provided in the slave units C ₁ , C ₂ , ..., C _N , for example, the upstream side (master unit side) interface port 2 is a DTE. Interface port 3 on the downstream side (slave unit side) is a DCE (Data central Equipment)
Type interface port. The details of these interface ports 1 to 3 will be described later.

Reference numeral 4 denotes an interface circuit provided in the slave units C ₁ , C ₂ , ... C _N , which is, for example, an RS-232 interface circuit. 5 is the interface port 1 of the parent device P and the interface port 2 of the most upstream child device C _1.
A communication cable for connecting with, for example, DTE-D
It is a cross cable for TE connection. Reference numeral 6 is a communication cable for connecting the interface ports 2 and 3 between the adjacent child devices from the most upstream child device C _{1 to} the most downstream child device C _N , for example, a DTE-DCE straight cable. Details of these cables 5 and 6 will be described later. Corresponding terminals are electrically connected between the upstream-side interface port 2 and the downstream-side interface port 3 in each of the slaves C ₁ , C ₂ , ... C _N (this configuration will also be described later). To).

The interface port 1 of the parent device P and the interface ports 2 and 3 of the child device C ₁ are each composed of, for example, 25 pins (terminals). Then, the interface port 1 of the master device P is SD (transmission data) from above.
Terminal 7, RD (reception data) Terminal 8, RS (transmission request)
Terminal 9, CD (carry detection) terminal 10, CS (transmission possible) terminal 11, ER (terminal ready) terminal 12, DR (data set ready) terminal 13, ST2 (transmission clock) terminal 14, RT (reception clock) ) Terminal 15, ST1
A (transmission clock) terminal 16 is provided.

The interface port 2 provided on the upstream side of the child device C ₁ has the D port, as already described.
It is a TE type and is provided with a (RT) (reception clock) terminal 17 in addition to the configuration of the interface port 1 of the parent device P. Further, the interface port 3 provided on the downstream side of the child device C ₁ is of the DCE type and has the same terminal arrangement as the interface port 2 as described above.

The interface port 1 of the master P
, The RS terminal 9 and the DR terminal 13 are connected
In the interface port 2 of the cordless handset C ₁ , the RS terminal 9 and the DR terminal 13 are connected to each other through the crossover line 1.
Connected at 9. And in the illustrated example,
The terminal of the interface port 1 and the terminal of the interface port 2 of the child device C ₁ are cross-connected.

That is, the SD terminal 7 on the side of the parent device P and the child device C
The RD terminal 8 on the _1st side is connected by a line 20 of the cable 5, and the SD terminal 7 on the slave C ₁ side and the RD terminal 8 on the master P side are connected by a line 21. And R on the master side P
The S terminal 9 and the CD terminal 10 on the slave C ₁ side are connected by a line 22, and the RS terminal 9 on the slave C ₁ side and the CD terminal 10 on the master P side are connected by a line 23. Also, the parent device P
Side CS terminal 11 and cordless handset C ₁ side ER terminal 12 are connected by a line 24, and CS terminal 11 on cordless handset C ₁ side and base unit P
The side ER terminal 12 is connected by a line 25. Furthermore, the master unit P side of ST2 terminal 14 and the slave device C ₁ side (R
T) terminal 17 is connected by line 26, and ST1 terminal 16 on the side of handset C ₁ and RT terminal 15 on the side of base unit P are on line 2
Connected at 7.

Then, the terminals between the interface ports ₂ and 3 of the adjacent child devices, for example, the most upstream child device C ₁ and the next child device C ₂ are connected by the same terminals (pins) to communicate with each other. They are connected by a cable 6, and for example, connect the SD terminal 7 of the child device C _{1 and} the SD terminal 7 of the child device C ₂ . The same applies to the other terminals. In this example, the communication cable 6 is composed of 11 signal lines.

Further, the connection between the terminals of the upstream interface port 2 and the downstream interface port 3 in each of the slave units C ₁ , C ₂ , ... C _N is the same except for the CS terminal 11. The terminals are made to correspond to each other and are connected by a connection line. The connection of the CS terminal 11 will be described later.

Next, the internal structure of the child device C ₁ will be described. Reference numeral 28 denotes a transmitter whose input side is connected to a line 29 connected to the interface circuit 4 and whose output side is connected to a line 30 connecting between the SD terminals 7 of the interface ports 2 and 3. For example, as shown in FIG. It has an (output enable) terminal 31, and when this OE terminal 31 is inactivated, the transmitter output goes high.
It is configured to have impedance.

Reference numeral 32 denotes a transmitter whose input side is connected to a line 33 connected to the interface circuit 4 and whose output side is connected to a line 34 connecting between the RS terminals 9 of the interface ports 2 and 3, as shown in FIG. The output is open collector output (+1 when the input is high).
2V), and the output is off (high impedance) when the input is low. And
The line 34 is connected to −12V via a resistor 35.

An input side 36 is connected to a line 37 connected to the interface circuit 4, and an output side is a line 38 connecting the ER terminals 12 of the interface ports 2 and 3.
4 is a transmitter connected to, for example, an open collector output, the output is off (high impedance) when the input is high, and the output is off (-12 V) when the input is low. Is configured. The line 38 is connected to + 12V through the resistor 39.

40 is a line 41 connecting the RD terminals 8 of the interface ports 2 and 3 on the input side, and the CD terminal 10
A receiver that is connected to a line 42 that connects the lines and a line 43 that connects the DR terminals 13 and that is connected to lines 44, 45, and 46 that have output sides connected to the interface circuit 4, respectively, and includes a voltage converter, for example. -232 Converts a signal level voltage to a logic level voltage.

Reference numeral 47 denotes a receiver whose input side is connected to the CS terminal 11 of the upstream interface port 2 and whose output side is connected to the interface circuit 4. 48 is an input side connected to the interface circuit 4 and output side is the downstream side. In the transmitter connected to the CS terminal 11 of the interface port 3 of, the receiver 47 and the transmitter 48 are
For example, the voltage converters are configured to convert the RS-232 signal level voltage into a logic level voltage and the logic level voltage into an RS-232 signal level voltage, respectively.

The line 49 connecting the ST2 terminals 14 of the interface ports 2 and 3 and the line 50 connecting the ST1 terminals 16 are connected to the interface circuit 4 via the changeover switch 51. The line 52 connecting the (RT) terminals 17 of the interface ports 2 and 3 and the line 53 connecting the RT terminals 15 are connected to the interface circuit 4 via the changeover switch 54. Reference numeral 55 denotes an oscillator circuit, the output of which is turned on and off via switches 56 and 57, respectively (R
T) terminal 17 and ST1 terminal 16 are provided.

Although not described in detail, in the 1: N communication system, the parent device P can start the transmission by itself. Further, each of the slave units C ₁ , C ₂ , ... C _N has a unique ID code. And
Master unit P slave unit C _1, C _2, ... C data to be transmitted to the _N, the ID code are always given the slave unit C _1, C _2, ... base unit P from C _N A code is always attached to the data transmitted to.

The operation of the 1: N communication system configured as described above will be described with reference to FIG.

First, when the parent device P starts transmission, the process is as follows. The parent device P turns on the RS terminal 9 in the interface port 1. This RS signal is input to the CD terminals 10 of the slave units C ₁ , C ₂ , ... C _N via the communication cables 5 and 6. As a result, the slave units C ₁ , C ₂ , ... C
_N turns on the ER terminal 12. Cordless handsets C ₁ , C ₂ , ...
Since the transmitter 36 provided in C _N has an open collector output and the line 38 is connected to +12 V through the resistor 39, all the slave units C ₁ , C ₂ , ... C _N are in the ER terminal 12. When is turned on, the ER signal for the master P is turned on.

The ER signal enters the CS terminal 11 of the parent device P via the communication cable 5. As a result, the parent device P becomes S
Data is output from the D terminal 7. The data transmitted by the master P is the communication cables 5, 6 and the slaves C ₁ , C ₂ , ...
It is transmitted to the slave units C ₁ , C ₂ , ... C _N via C _N-1 . Base unit P
All the slave units C ₁ , C ₂ , ... C _N receive the data transmitted by the device, and a code collating circuit (not shown) checks whether or not the data is addressed to itself. The slave units C ₁ , C ₂ , ..., C _{N take} in the data only when the data is addressed to itself, and respond to the base unit P in some cases.

Next, the transmission of the slave units C ₁ , C ₂ , ..., C _{N to} the master unit P is performed as follows. First, the cordless handset C _X to be transmitted (not shown, the number of the cordless handset C _X is not limited to one) turns off the CS terminal 11 of the downstream interface port 3. Then, wait a sufficient time so that the child device downstream from itself does not transmit, and then R
Turn on the S terminal 9. The transmitter 32 provided in each of the slave units C ₁ , C ₂ , ..., C _N has an open collector output, and
Since the line 34 is connected to −12V via the resistor 35, when at least one of the slaves C _X to be transmitted turns on the RS terminal 9, R to the master P is set to R.
The S signal turns on. This RS signal is used in the communication cable 5
Through the CD terminal 10 of the parent device P, and the child device C ₁ ,
C _2, ... enter the DR terminal 13 of C _N, all handsets C _1, C ₂ via the communication cable 6, transmitted to ... C _N.

Upon receiving the RS signal, the parent device P turns on the EP terminal 12. This output enters the CS terminal 11 of the child device C ₁ via the communication cable 5. Then, each child device C ₁ ,
If C ₂ , ... C _N do not turn on the RS terminal 9,
When the CS terminal 11 of the interface port 2 on the upstream side is turned on, the CS terminal 11 is turned on for the interface port 3 on the downstream side. As a result, the CS terminal 11 of the upstream interface port 2 in the most upstream child device C _X that has the RS signal turned on is turned on.
As a result, the child device C _X has the OE terminal 31 of the transmitter 28.
(See FIG. 2) is enabled and data is transmitted from the SD terminal 7. The data transmitted by the child device C _X enters the RD terminal 8 of the parent device P via the communication cables 5 and 6 and is received by the parent device P. Since an ID code is attached to the data,
The parent device P can determine from which child device C ₁ , C ₂ , ... C _N the data is.

The slave unit C _X turns off the RS terminal 9 when there is no data to be transmitted. And yet, C of the interface port 2 on the upstream side of the child device C _X
When the S terminal 11 is on, the CS terminal 11 of the downstream interface port 3 is turned on.

By the way, the DTE type master unit P and the slave unit C ₁ ,
When synchronous communication is performed when C ₂ , ..., C _N are directly connected, the synchronous clock is output from the most downstream child device C _N. For that purpose, the switches 56 and 57 are turned on only in the most downstream child device C _N. The synchronization clock is the slave C ₁ ,
C _2, ... C _N in the (RT) line 52, ST1 line 5
0, so that each of the slave units C ₁ , C ₂ , ... C _N has switches 51 and 54 for obtaining a synchronous clock, respectively.
Switch as shown in. In this case, the switches 51, 5
Switching of 4,56,57 may be performed manually, each child device C _1, C _2, is ... C _N from the voltage level of each signal line,
It is judged whether or not the own device is at the end and which line the reception clock and the transmission clock are on, and the slaves C ₁ , C ₂ ,.
C _N itself may switch.

As can be understood from the above description of the embodiments.
In the present invention, the slave C₁, C ₂, ... C_NWhen
However, the RS signal can be output. Like this, cordless handset C₁，
C₂, ... C_NIt is said that the RS signal can be output arbitrarily from the side
That is extremely useful.

This is because, for example, when an alarm occurs in a child machine, according to the conventional method, the child machine will be alarmed until the parent machine P inquires of the child machine whether or not there is an alarm. I was not able to tell the parent machine P that it is doing.

On the other hand, in the above-mentioned 1: N communication system, the slave unit has only to output the RS signal at the time when the alarm is generated, which causes the CS signal to be returned from the master unit P. At that time, the child device can transmit alarm information to the parent device P.

Therefore, according to the present invention, the parent device P can quickly respond to the alarm state in the child device. Such an example is only an example, and in general, when a plurality of devices are connected to a communication network, a device can only passively transmit information.
Anyway, there are many inconveniences, and conversely, if active transmission is possible, the degree of freedom in information exchange is improved and the availability of communication networks (systems) is greatly increased.

The present invention is not limited to the above-mentioned embodiments, but can be modified in various ways. For example, a modem may be provided at any position between the master P and the slaves C ₁ , C ₂ , ... C _N. In this case, the slave unit and the modem may be connected to the same terminal (pin). Also, the parent device P
When a modem is provided between the master unit P and the slave unit C ₁ , the connection between the master unit P and the modem is the same terminal (pin) connection.
Even when a modem is used, the slave units C ₁ , C
The operation of ₂ , ..., C _N is the same as that of the parent device P. However, when performing synchronous communication, when the transmission clock and the reception clock are output from RT and ST2 of the modem,
The switch 5 is used in all the handsets downstream from the modem.
6 and 57 are turned off, and the switches 51 and 54 are switched to the contacts on the opposite side to that shown in FIG.

Further, in the above embodiment, when the master device P is the DTE type, the RS terminal 9 of the master device P and the CD of the slave device C ₁ are used.
A cross cable for connecting the terminal 10, the CS terminal 11 of the parent device P and the ER terminal 12 of the child device C ₁ is used, but the RS terminal 9 of the parent device P and the CS terminal 11 of the child device C ₁ machine P of the ER terminal 12 and the slave device C ₁ to DR terminal 13 and a may each be used cross cable for connecting.

In case of asynchronous communication, (RT) terminal 17, ST2 terminal 14, RT terminal 15, ST1 terminal 16
No wiring or circuit is required.

Further, the transmitter 28 shown in FIGS.
In the circuit configurations of 32 and 36, the photocoupler 58 is used for isolation, but if it is not necessary, a transistor may be used instead of the photocoupler 58.

Furthermore, in the above embodiment, the interface ports 1 to 3 conforming to RS-232 were used. As a matter of course, the one compliant with other standards such as 35 may be used.

[0043]

The present invention constructed as described above has the following effects. Only one interface port needs to be provided on the base unit. Even if the parent device and the child device group are separated, the child devices can be connected to each other with a short cable, and the same pin connection for normal DTE-DCE may be used. Even if the master unit and the slave units are separated, communication can be performed by providing a modem in the middle and using a public line or the like. In that case, one pair (two) of modems is sufficient. The slave unit can arbitrarily output a transmission request to the master unit without checking the communication status of the other slave units, and the master unit and the arbitrary number of slave units can communicate with each other. Therefore, it is possible to obtain an inexpensive 1: N communication system in which the configuration of the master unit and the slave unit is simple and there is no restriction in connection.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of a configuration of a master unit and a slave unit.

FIG. 2 is a diagram showing a circuit configuration of a transmitter used in the slave unit.

FIG. 3 is a diagram showing a circuit configuration of another transmitter used in the slave unit.

FIG. 4 is a diagram showing a circuit configuration of still another transmitter used in the slave unit.

FIG. 5 is a diagram for explaining a conventional example.

FIG. 6 is a diagram for explaining another conventional example.

[Explanation of symbols]

P ... Parent machine, C ₁ , C ₂ ... Child machine, 2, 3 ... Interface port, 6 ... Communication cable, 7 ... Transmission data terminal, 9
... Send request terminal, 11 ... Send enable terminal, 12 ... Terminal ready terminal.

Claims (1)

[Claims] 1. A 1: N communication system configured to connect a plurality of slave units to one master unit so that the master unit and the slave units can communicate with each other, all of the slave units. Two different standard interface ports are provided on the upstream side and the downstream side, and these interface ports are electrically connected by making the same terminals except the transmission enable terminals correspond to each other, and Of these, the transmission data terminal is configured to be electrically floatable, the transmission request terminal and terminal ready terminal are open collector outputs, and the transmission enable signal at the interface port on the upstream side is input to the interface circuit. On the other hand, separately from this, the transmit enable signal is output to the downstream interface port independently. A 1: N communication system in which adjacent cordless handsets are connected by a communication cable in which the same terminals in the interface port are connected.