JPH03186038A - Automatic communication system deciding and switching device for local area data communication network - Google Patents

Abstract

PURPOSE:To eliminate the need to confirm which of a bus type and a loop type communication system is employed and the need for preparations or replacement of software or hardware and to connect a communication station to a data line by providing a specific level detector and two multiplexers. CONSTITUTION:A MODEM 3 discriminates whether or not there is a carrier signal on the data line 1 to detect whether an outputted voltage level is plus or minus. When it is decided that the bus type communication system is employed and the presence of the carrier signal is detected, received data RXDN from the data line 1 are transferred to the memory of the communication station 4. When no carrier is detected, on the other hand, sent data TXDC outputted from the memory of the communication station 4 are sent to the data line 1. Consequently, which of the bus type and loop type communication systems is used need not be confirmed and no preparations are made for software and hardware; and the communication data can easily be connected to the data line.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention is applicable to a local area data communication network (LAN).
The present invention relates to a communication system automatic discrimination switching device that enables a communication station to be connected to either a bus connection type or a loop connection type, which use different communication systems, without making any changes to the software or hardware.

[Conventional technology]

For local area data communication equipment installed in the same building or factory, the data line connecting multiple communication stations is grounded, and if no carrier signal is detected on the data line, the communication stage that becomes the transmitting station is grounded. a bus connection method involving detection of a carrier in which transmission data is sent from a station, and when the presence of a carrier signal is detected, reception data sent from another communication station is received;
When a large number of communication stations are connected to a loop-shaped data line and receive data transmitted from other communication stations without detecting the presence or absence of a carrier, the transmission fS of the communication station that is the transmitting station is A loop connection method that adds data and sends it to the data line is often used.

[Problem to be solved by the invention]

When connecting illumination to a data line, first determine whether the communication method used for the data line is a bus type or a loop type, and then Since the control software and hardware must be prepared separately for each communication station, a lot of time is consumed in replacing the communication system L2 and software and hardware, so it is not easy to connect and replace the communication stage. The problem is that it cannot be done easily.

The present invention has been made in view of the above-mentioned problems, and its purpose is to
local area data that makes it possible to connect the jHε stage to a data line without checking whether the data line is a il in communication network
An object of the present invention is to provide an automatic communication system discrimination switching device.

[Means to solve the problem]

The feature of the present invention is that local area data 1ffl
a level detector that is connected to the input side of a communication stage signal connected to the communication network, detects the presence or absence of a carrier in the data line or a carrier oven, and outputs a signal that determines the data line communication method; Only when the level detector detects the presence of carrier oven, the received data from the buffer and il! a first multiplexer that outputs together the transmitted data from the station's memory;
When the level detector detects the presence of a carrier oven, it sends out the output from the first multiplexer, while when it detects that there is no carrier oven, it directly receives the transmission data output from the memory of the communication station and sends it out. The communication method automatic discrimination switching device is equipped with two multiplexers.

[Effect]

If the level detector detects that there is a carrier oven on the data line, it is determined that the communication method is a loop type L, and the first multiplexer takes in the received data output from the buffer and transmits the data output from the communication station memory The data is taken in and input together to the second multiplexer, which then sends it out.

When the level detector detects a signal indicating the presence or absence of a carrier, it determines that it is a bus-connected type and disables the first multiplexer, while a detection signal indicating the absence of a carrier oven is input to the second multiplexer. be done.

When the absence of a carrier is detected, the mode is set to transmit, and the transmission data from the memory of the communication station is input directly to the second multiplexer, which sends it out. When the presence of a carrier is detected,
It enters reception mode and transfers the received data input from the data line to the communication station's memory.

〔Example〕

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

FIG. 1A is a circuit block diagram in which the device of the present invention is connected to a bus-type data line, and FIG. 1B is a circuit block diagram in which the device is connected to a loop-type data line.

In Figure 1 (A), the data circuit ill with both ends grounded.
The node 5 connected to the
A modulation/demodulation device 3 for demodulating S data is connected, and this modulation/demodulation device 3 has a lead wire for transmitting transmission data, a lead wire for receiving reception data, and a lead wire for inputting a carrier signal on the data line 1. The communication system automatic discrimination switching device 2 is connected to the communication system automatic discrimination switching device 2, which includes input terminals T1, T2, and T3 to which these lead wires are connected. A communication station 4 including a CPU (Central Processing Unit) and a memory is connected to this communication method automatic discrimination switching device 2.

As will become clear from the description given later, this communication system automatic discrimination and switching device 2 detects the presence or absence of a carrier signal in the data line l, that is, the positive or negative of the voltage level output when the modulation/demodulation device 3 identifies this, and This determines that the 1ffi signal system is a bus type, and detects the presence of carrier (No. 3).
(Fig. 3 (B) (d)) is transferred to the ijl signal station 4 memory, and when the absence of a carrier signal is detected, the transmission data TXDC (Fig. 3 ( B)(g)) data times &1
It is configured to send fS to 1.

On the other hand, (B) in the same figure shows a communication system connected to the communication station 4, terminals TI and T2 connected to the loop data line 6, and terminal T3 left open without being connected to any other device. An automatic mode discrimination switching device 2 is shown. In this case, as will become clear from the explanation given later, when the iJ1 communication system automatic discrimination switching device 2 detects a zero level signal indicating the presence of a carrier oven on the data line 6, it determines that the communication system is a loop type, The received data RXDN inputted from the data line 6 (FIG. 3 (A) (D)) and the transmitted data RXDN outputted from the memory of the communication station 4.
f, transmission/reception data TXDN (
3 (A) (L)) to the data line 6.

Figure 2 shows the level detector 2G, multiplexer 21 (MP
XI), a multiplexer 22 (MPX2), etc., shows the main parts of the communication system automatic discrimination switching device 2, and the details will be explained below.

The level detector 26 equipped with the terminal T3 includes, for example, a full-wave rectifier 27, an inverter 29, and a flip-flop FF.
28 and a parallel circuit with the inverter 30, the inverter 30
The output side of the inverter 30 and the full-wave rectifier 27 are inputted to the output side of the ant-game) 31 and il! outputs a signal 0PNC to the lead wire 32 via the full-wave rectifier 27 and the inverter 29, indicating the presence or absence of the carrier oven.
Signal CR3C indicating presence/absence of carrier in lead &1133 via FF28, inverter 30, and AND gate 31
As shown in Fig. 1 (B), when a carrier oven is used, the terminal T3 outputs a zero level signal C.
R3N (Fig. 3 (A) (A))> Therefore, the full-wave rectifier 27 does not output a signal, and therefore the inverter 29 has a carrier oven, that is, the positive level No. 13 (indicating that it is a loop type communication system). If the terminal T3 is connected to the modulation/demodulation device 3 as shown in FIG. 1(A), a positive/negative signal CR3N (the 3 (B) (A)> is input, and the full-wave rectifier 27 outputs it as a positive level, so the inverter 29 generates a zero level signal 0PNC (Fig. 3 (B)) indicating that there is no carrier oven. During this period, positive and negative signals CR3N (Fig. 3(B)) are output.
) (a)) The FF 28 which receives the input outputs a pulse signal indicating the presence or absence of a carrier by inverting this, and when a positive level is input, the inverter 30 outputs a zero level, especially a positive level signal. The zero level and positive level signals are respectively input to the AND gate 31 together with the positive level signal from the full wave rectifier 27.

Therefore, the AND gate 31 outputs a zero level signal indicating the absence of a carrier when the inverter 30 outputs a zero level, and outputs a positive level signal indicating the presence of a carrier when the inverter 30 outputs a positive level (see FIG. 3). B) (c)).

When the level detector 26 detects the presence of a carrier oven, the multiplexer 21 sends a positive level signal 0PNC, which determines that the communication method is a loop type, to the CPU of the communication stage thin 4, and outputs the i! I-communication station 4 CPU
The control signal CLTC (Fig. 3 (A)
)(H)> is input, and the received data RX is thereby transferred to the memory of the communication station 4 via the receiver 24.
Reception data RXDC (Fig. 3 (A)
) (to) signal C), and transmit data TXDC (Fig. 3 (A)) from the memory of the communication station 4.
(g)) and outputs the signal A to the multiplexer 22.

When the level detection H26 detects the presence or absence of a carrier,
It determines that the 1ffi communication system is a bus type, and when a carrier is present, a positive level signal indicating reception is possible.
When there is no carrier, a zero-level detection signal CR3C (FIG. 3 (B) (C)) indicating that transmission is possible is sent to the CPU of the communication station 4, which causes the control signal CLTC (
3 (B) (H)) are not output from the CPU, and therefore this control HAY signal is not input, the multiplexer 2
1 is inactive, and the signal from the multiplexer 21 is not input to the multiplexer 22.

The multiplexer 22 outputs a signal from the level detector 26 to
When the detection signal 0PNC (FIG. 3 (A) (B)) indicating the presence of a positive level carrier open indicating that the system is a loop type is input, the output signal A of the multiplexer 21
When it detects that there is no carrier open, the zero level fiT signal 0PNC (FIG. 3(B) (b)) from the level detector r1126 is input, and this is followed by the signal from the 1ffi signal station 4. The multiplexer 22 is operated to directly take in the transmission data TXDC (signal A') outputted from the memory without passing through the multiplexer 21, and send the signal B to the transmitter 23.

The operation when the communication method automatic discrimination switching device 2 configured as described above is connected to a loop type data line and a bus type data line will be explained with reference to the waveform diagrams shown in FIGS. 3(A) and 3(B). .

First, referring to FIG. 3(A), we will explain the case where the communication system automatic discrimination switching device 2 is connected to a loop type data line.Since it is a loop type communication system, the terminal T3 becomes an oven and detects the carrier. Therefore, the signal input to the level detector 26 is at zero level, and when this carrier open signal CR3N (Fig. 3 (A) (A)) is input, the positive level signal 0PNC (Fig. 3 (A)) is input. A) (b)) is output, and this signal is input to the multiplexer 22 and the CPU of the communication station 4, thereby cp
The control signal CLTC (Fig. 3 (
A)(H)) is input to the multiplexer 21. The multiplexer 21 connects the receiver 24 to the communication station 4.
The received data from the buffer 25 (Figure 3 (A)
e) Take in the signal C) as shown by the solid line Ll, and take in the transmission data TXDC (Fig. 3 (A) ())) from the memory of the 1ffi signal stage 4 as shown by the solid line L2. Transmission/reception data (signal A in FIG. 3(A)) is input to the multiplexer 22. and,
The multiplexer 22 takes in the transmission/reception data A from the multiplexer 21, inputs the transmission/reception data B (FIG. 3 (A) (N)) to the transmitter 23, and outputs the transmission/reception data TXDN.
(FIG. 3(A)) is output to the data line.

Next, a case where the communication system automatic discrimination switching vtW4 is connected to a data line of a bus type communication system will be described with reference to the waveform diagram of FIG. 3(B).

Since it is a bus type communication system, the terminal T3 is connected to the modulation/demodulation device 3, and the level detector 26 receives the positive and negative signals CR3N (Fig. 3 (B) (A)).
When the presence of a carrier is detected, the level detector 2G transfers the positive level signal CR5C (FIG. 3(B)(C)) to the CPU of the communication station 4, sets it to the reception mode, and
The output of the control signal CLTC (FIG. 3 (B) (H)) from the PU is prohibited, and the output signal C (FIG. 3 (B) (H)) from the multiplexer 21 of the buffer 25 and the output signal of the communication station 4 are prohibited. Transmission data from memory TXDC (3rd
(B) (G)) are controlled so that they are not output. On the other hand, since terminal T3 is connected to modem W13,
Zero level detection signal 0P indicating no carrier open
NC (FIG. 3(B)(b)) is inputted to the multiplexer 22 from the level detection lG26. As a result, the multiplexer 22 is operated so as not to take in the output signal A from the multiplexer 21, and the received data RXDC (FIG. 3 (B) (E)) output from the receiver 24 is il! The data is sent to the memory of communication station 4.

When the level detector 26 detects a positive level signal indicating no carrier, a zero level signal CR3 indicating no carrier is detected.
C (Fig. 3 (B) (C)) is the CP of communication station 4.
tJ and enters the transmission mode, and controls so that the control signal CLTC (FIG. 3(B) (H)) is not input to the multiplexer 21 from the CPLI. As a result, the transmission data TXDC (No. 18 A' in FIG. 3(B)(G)) from the memory of the communication station 4 is sent directly to the multiplexer 2
It is controlled so that it is input to 2. On the other hand, a zero-level detection signal 0PNC (FIG. 3 (B) (B)) indicating that there is no carrier oven is input from the level detector 26 to the multiplexer 22, and the transmission data TXDC (FIG. 3 (B)) from the memory of the communication station 4 is Figure 3 (B) (S) Signal A
') is directly connected to the multiplexer 22 as shown by the solid line L3.
The output signal B (Fig. 3 (B) (N)) is input to the transmitter 23, and the transmission data TXDN (Fig. 3 (B)
) (le)).

〔Effect of the invention〕

As described above, according to the present invention, i! A level detector that is connected to the input side of the 1-communication station and outputs a signal to detect the presence or absence of a carrier in the data line or a carrier oven, and to determine the data line communication method; A first multiplexer that outputs both the received data of the buffer and the transmitted data from the memory of the communication station only when the presence of the carrier oven is detected, and the output of the first multiplexer that outputs the output of the first multiplexer when the level detector detects the presence of the carrier oven. On the other hand, we configured a communication system automatic discrimination switching device that includes a second multiplexer that directly inputs and sends out transmission data from the memory of the communication station when the absence of a carrier oven is detected, so that the communication station can be connected to the data line. When connecting,
There is no need to check whether it is a bus-type 1ffi communication method or a loop-type communication method, and there is no need to make any preparations for software or hardware, and simply connect the communication method automatic discrimination switching device, so it costs a lot of money. This has the excellent effect of making it possible to easily connect a communication station to a data line without consuming time. Since this automatic discrimination switching device can use a circuit device with the same configuration for the data line of any communication system, it is suitable for mass production and can reduce production costs.

[Brief explanation of drawings]

FIG. 1(A) is a circuit diagram of an embodiment in which the device of the present invention is connected between a data line of a bus type communication system and a communication station, and FIG. FIG. 2 is a circuit block diagram of the main part of the embodiment of the device of the present invention, and FIG. Signal waveform diagram in the circuit block diagram of Gin where the device of the invention is connected to a data line of a loop type communication method, same figure (B)
is a signal waveform diagram in a special circuit block diagram in which the same device is connected to a data line of the bus type iJ1 communication system. l...Data line of bus type communication system, 2...Communication system automatic discrimination switching device, 21.22...Multiplexer, 23
...Transmitter, 24...Receiver, 25...Buffer, 26
...Level detector, 3.Modulator/demodulator, 4.Communication station, 5.Node, 6.Loop type communication system data line application.Ryukichi Abe, Patent Attorney, Shimizu Corporation (6) Figure 1 Figure 3 (B)

Claims (1)

[Claims] A level detector connected to the input side of a communication station connected to a local area data communication network, which detects the presence or absence of a carrier in a data line or a carrier open, and outputs a signal that identifies the data line communication method. and a first multiplexer that outputs both the received data from the buffer and the transmitted data output from the memory of the communication station only when the level detector detects the presence of a carrier open, and the level detector detects the presence of a carrier open. and a second multiplexer which, when detected, sends out the output from the first multiplexer, and which, when detecting no carrier open, directly inputs and sends out the transmission data output from the memory of the communication station. A communication method automatic discrimination switching device in a local area data communication network, characterized by: