JPH06261041A - Communications terminal equipment in daisy chain system network - Google Patents

Abstract

PURPOSE:To prevent the system-down of the entire network without interruption of a transmission line in a communications terminal equipment even when an electric power interruption takes place in the communications terminal equipment on the way of the transmission line. CONSTITUTION:Upper-order contacts 22a1, 23a1 and lower-order contacts 22a2, 23a2 of a changeover relay 21 located between a transmission line 10 and a driver/receiver circuit 31 are closed toward controller side contacts 22b1, 23b1, 22b2, 23b2 when a current is supplied from a power supply section 61. On the other hand, when no current is supplied from the power supply section 61, the upper contacts 22a1, 23a1 and lower contacts 22a2, 23a2 are thrown toward path contacts 22c1, 23c1, 22c2, 23c2. Thus, when the power supply section 61 is inactive, the transmission lines 10a, 10b are connected not through an internal circuit such as the driver/receiver circuit 31 of the communications terminal equipment 11 and the host and subordinate commutations terminal equipments make data communication not through the communications terminal equipment 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication terminal in a digital chain network in which communication terminals are connected in series via a transmission line.

[0002]

2. Description of the Related Art Conventionally, as a connection method of communication terminals in a bus type local area network (hereinafter referred to as a bus type LAN), a digital chain method in which communication terminals are arranged in series with a transmission line is known. .

FIG. 3 shows a bus type LA of a digital chain system.
1 shows a schematic configuration of N and a communication terminal (node) in the bus LAN.

Each communication terminal 71 in this network
a to 71c are power supply units 72a to 72c, communication controllers 73a to 73c, and repeater ICs 74a to 7c, respectively.
4c, which are connected in series via the transmission path 70 to perform data communication with another communication terminal.

In such a bus type LAN, when the communication controller 73b of the communication terminal 71b on the transmission line 70 runs away, the repeater IC 74b is
The transmission of data from the communication controller 73b to the transmission path 70 is stopped, and the data received from the transmission path 70 is operated so as not to be passed to the communication controller 73b. 71c
In order to guarantee communication such as, the data received from the line of the transmission path 70 is repeated to the opposite line as long as the power supply by the power supply unit 72b is continued.

[0006]

However, in the conventional digital chain bus type LAN, when a failure occurs in the communication controller of a communication terminal in the middle of the transmission path as described above, the repeater IC is provided with a power supply unit. As long as is operating, disconnect the connection between the transmission line and the communication controller,
Moreover, in order to ensure communication of other communication terminals, the received signal is repeated on the opposite line, but when the power supply unit goes down and power supply is stopped, the repeater IC does not operate at all and this communication terminal However, there is a problem that the transmission line is disconnected at that point and the entire network goes down.

Even if such a failure does not occur in the communication controller of the communication terminal, if the power supply unit goes down and the communication terminal is cut off, the repeater IC
Does not operate, the transmission line is disconnected at this communication terminal, and the whole network goes down.

By the way, as a connection method for a bus-type LAN communication terminal that is not affected by power interruption in the middle of such a transmission line,
There is a multi-drop method in which communication terminals are arranged in parallel with a transmission line.

The advantages and disadvantages of the DigiChain method and the multi-drop method are shown in Table 1 below.

[0010]

[Table 1] Therefore, although the DigiChain method is disadvantageous as compared with the multi-drop method as described above in terms of "effect of power interruption of node", the DigiChain method has an advantage of being "long" in terms of "transmission distance". Therefore, bus type LA
In order to extend the transmission distance in N, the multi-drop method requires the development of a new driver / receiver circuit, whereas the digital chain method does not pose any particular problem and is a relatively inexpensive driver. It is very advantageous because a bus type LAN having a long transmission distance can be constructed by a receiver circuit or the like.

Therefore, the present invention has been made in view of such a problem, and even if a power failure occurs in a communication terminal in the middle of a transmission line, the digital transmission chain system prevents the transmission line from being disconnected in the communication terminal. It is to provide a communication terminal in a network.

[0012]

In order to achieve the above object, according to the present invention, the communication terminal is connected in series with another communication terminal through a transmission line, and the power source section and a driving current from the power source section cause the above-mentioned problems. In a communication terminal in a DigiChain network having a communication controller for performing data communication with another communication terminal by a DigiChain method, an upper-side contact and a lower-side contact connected to the upper side and the lower side of the transmission path. And a controller-side contact that is connected to the communication controller, and when there is a current supply from the power supply unit, while holding the connection destinations of the upper-side contact and the lower-side contact at the controller-side contact, When there is no current supply from the power supply unit, disconnect the connection destination of the upper-side contact and the lower-side contact from the controller-side contact, Switching means for connecting the point and the lower contact point, characterized by including the.

[0013]

In the present invention, the switching means has the upper side contact and the lower side contact connected to the upper side and the lower side of the transmission line, and the controller side contact connected to the communication controller. During operation of the unit, the connection destinations of the upper-side contact and the lower-side contact are held at the controller-side contacts, respectively, and the transmission path and the communication controller are connected. On the other hand, when the power supply is not operating, the upper contact and the lower contact are disconnected from the controller contact to disconnect the transmission line from the communication controller, and the upper contact and the lower contact are disconnected. Connecting. As a result, the transmission line is connected with the communication terminal in which the power failure has occurred being disconnected.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a communication terminal in a digital chain network according to the present invention will be described below with reference to the drawings.

1 and 2 show the configuration of the communication terminal 11 according to this embodiment. FIG. 1 shows a state in which the power supply unit 61 normally supplies current, and FIG. 2 shows a power supply unit 61. Shows the states when the current supply is stopped.

First, the configuration of the communication terminal 11 according to this embodiment will be described with reference to FIG.

The communication terminal 11 has a switching relay 21 as switching means, a driver / receiver circuit 31, a transmission / reception selector circuit 41, a communication controller 51, and a power supply section 61 for supplying a current to each of these circuits.
Between a transmission line (hereinafter, referred to as an upper transmission line) 10a connecting to another communication terminal (not shown) higher than the self terminal and another communication terminal (not shown) lower than the self terminal It is connected to other upper and lower communication terminals via a transmission line (hereinafter, referred to as a lower side transmission line) 10b connecting the two.

Upper transmission line 10a and lower transmission line 1
0b is composed of a pair of plus (+) and minus (-).

The switching relay 21 includes a single-stable type negative side relay 22 for switching the connection between the negative side upper side transmission line 10a and the lower side transmission line 10b and the internal circuit such as the communication controller 51, and the plus side. And a lower side transmission line 10a and a lower side transmission line 10b, and a positive side relay 23 of the same type that switches connection between internal circuits such as the communication controller 51 and the like.

The relays 22 and 23 are respectively connected to the negative or positive upper side transmission line 10a, and the upper side contacts 22a1 and 23a1 are connected to the negative or positive lower side transmission line 10b. 23a2,
Controller side contacts 22b1, 22b2, 23b1, 23b2 connected to the communication controller 51 and the like, and a negative or positive upper side transmission line 10a and a lower side transmission line 10
b contacts 22c1, 22c2, 23c1, 2 for connecting to b
It has 3c2. As shown in the figure, only the upper contacts 22a1, 23a1 and the lower contacts 22a2, 23a2 are so-called movable contacts, and the other contacts are so-called fixed contacts.

The upper contact 22a which is a movable contact
1, 23a1 and lower contacts 22a2, 23a2, since both relays 22 and 23 are single-staving type relays,
When current is supplied from the power supply unit 61, it is closed to the controller side contacts 22b1, 23b1, 22b2, 23b2 side as shown in FIG. If there is not, the connection with the controller side contacts 22b1, 23b1, 22b2, 23b2 side is disconnected as shown in FIG. 2 by the biasing force of the spring, respectively, and the pass contacts 22c1, 23c1, 22c2, 23
It is configured to close on the c2 side.

Further, the driver / receiver circuit 31 includes an upper driver 32 and a receiver 33 for transmitting / receiving data to / from the upper transmission line 10a via the switching relay 21 when a current is supplied from the power supply section 61, and a lower side. Transmission line 1
0b and the lower side driver 34 which transmits / receives data, and the receiver 35 are comprised.

The transmission / reception data selector circuit 41 has a configuration similar to that of the conventional device, and has a waveform shaping circuit 42, a decoder 43, OR gates 44 and 45, and an AND gate 4.
It has 6, 47 etc.

The communication controller 51 has a data transmitting end (TXD), an upper data receiving end (RXD0), and a lower data receiving end (RXD1), through which data is transmitted / received and dedicated to control signals. It is configured to transmit various control signals from the signal end of.

Next, the operation of the communication terminal 11 according to the present embodiment configured as described above and the flow of data and the like in the communication terminal 11 will be described.

(1). When power is supplied from the power supply unit 61
1 (see FIG. 1) In this case, the negative side relay 22 and the positive side relay 23 of the switching relay 21 are supplied with current from the power source section 6 and, as shown in FIG.
3a1 and the lower-side contacts 22a2, 23a2 are kept closed on the controller-side contacts 22b1, 23b1, 22b2, 23b2, respectively, while the pass contacts 22c1, 22c2, 23
Hold the c1 and 23c2 sides open.

Therefore, the flow of data and the like in the communication terminal 11 is as follows.

First, the inverting input (-) that passes through the negative side of the upper transmission line 10a is input to the upper receiver 33 via the upper contact 22a1 of the negative relay 22 and the controller contact 22b1. The non-inverting input (+) is connected to the upper-side receiver 3 through the upper-side contact 23a1 of the plus-side relay 23 and the controller-side contact 23b1.
3 is input and received.

Here, the received data is input to the higher-order receiving end RXD0 of the communication controller 51 via the transmission / reception data select circuit 41, while the waveform is shaped by the waveform shaping circuit 42 and via the OR gate 45. Input to the lower driver 34 above. The inverted output (-) of the lower driver 34 is the negative relay 22.
Is output to the minus side of the lower transmission line 10b via the controller-side contact 22b2 and the lower-side contact 22a2, and its non-inverted output (+) is the controller-side contact 23b2 and the lower-side contact 23a2 of the plus-side relay 23. Is output to the plus side of the lower transmission line 10b via.

Further, similarly to this, the lower transmission line 1
The reverse input (-) from 0b is passed through the lower-side contact 22a2 and the controller-side contact 22b2 of the minus-side relay 22, while the non-inverting input (+) is set between the lower-side contact 23a2 and the controller-side contact 23b2 of the plus-side relay 23. The received data is input to and received by the lower-side receiver 35 via the transmission / reception data selector circuit 41, and is input to the lower-side receiving end RXD1 of the communication controller 51 while being waveform-shaped by the waveform shaping circuit 42, and , O
It is input to the upper driver 32 via the R gate 44.

The inverted output (-) from the upper side driver 32 is output to the negative side of the upper side transmission line 10a via the controller side contact 22b1 and the upper side contact 22a1 of the minus side relay 22 while the The non-inverting input (+) is connected to the upper-side transmission line 1 through the controller-side contact 23b1 and the upper-side contact 23a1 of the plus-side relay 23.
It is output to the plus side of 0a.

The transmission data from the data transmission terminal TXD of the communication controller 51 is AND gates 46 and 47.
And, via the NOT gates 44 and 45, input to the upper side driver 32 and the lower side driver 34, and in the same manner as above, the upper side transmission line 10a and the lower side transmission line 10
Meanwhile, the control signal from the communication controller 51 is output to the decoder 43 of the transmission / reception data select circuit 41.
After that, it is output to the upper transmission line 10a and the lower transmission line 10b in the same route as the transmission data.

Therefore, in this communication terminal 11, the power supply unit 6
As long as the current is supplied from 1, data communication can be performed with the other upper and lower communication terminals via the upper transmission line 10a and the lower transmission line 10b, respectively.

(2). The power supply 61 stopped the current supply
Case (see FIG. 2) In this case, the negative side and the positive side relays 22 and 23 of the switching relay 21 are also cut off from the current supply from the power supply unit 61 and are in an electric disconnection state.
The 3a1 and lower side contacts 22a2, 23a2 break the connection state with the controller side contacts 22b1, 23b1, 22b2, 23b2 and switch to the connection with the path contacts 22c1, 23c1, 22c2, 23c2.

In this case, from the power supply unit 61 to the communication controller 51, the transmission / reception data selection circuit 41,
Since the current supply to the driver / receiver circuit 31 is also stopped, all the circuits become inoperable.

At this time, the flow of data and the like in the communication terminal 11 is as follows.

First, the inverting input (-) from the upper transmission line 10a is transferred from the upper contact 22a1 of the minus relay 22 to the pass contacts 22c1, 22c2 and the lower contact 22.
Output to the minus side of the lower transmission line 10b via a2, while non-inverting input (+) from the upper transmission line 10a
Is output from the upper side contact 23a1 of the plus side relay 23 to the plus side of the lower side transmission line 10b via the path contacts 23c1, 23c2 and the lower side contact 23a2.

Further, similarly to this, the lower transmission line 1
The inverting input (-) and non-inverting input (+) from 0b are
Each is output to the minus side and the plus side of the upper transmission line 10a.

Therefore, according to this embodiment, the communication terminal 11
When the power supply unit 61 of the
And the lower-side transmission path 10b are drivers / drivers of the communication terminal 11.
Since the communication terminal 11 is connected via only the switching relay 21 without passing through an internal circuit such as the receiver circuit 31 and the communication terminal 11 is substantially disconnected from the network, the upper and lower transmission lines 10a and 10b are connected. Other communication terminals
Data communication can be performed by passing through the communication terminal 11.

As a result, even if the communication terminal in the middle of the transmission path is cut off, the communication path is not cut off by the communication terminal and the other communication terminal can continue the data communication.
It is possible to provide a digital chain system network which can prevent the entire communication network from being downed, and has a long transmission distance due to the existing driver / receiver, and which is not affected by the power interruption of an intermediate node.

[0041]

As described above, according to the present invention, the communication terminal is provided with the switching means, and when the current is supplied from the power source, the switching means connects the upper side contact and the lower side contact to each other. While holding the contacts on the controller side,
When the power supply is not operating, the upper and lower contacts are disconnected from the controller contacts to connect the upper and lower contacts. While the communication terminal is connected to the communication controller so that the communication terminal can perform data communication with another communication terminal, when the power supply unit is not operating, the upper-side contact and the lower-side contact are connected to each other, so that the communication terminal is connected. Can prevent the transmission line from being disconnected.

Therefore, even if the communication terminal on the transmission line is cut off, the upper and lower communication terminals are
Data communication can be performed by passing through the communication terminal,
This makes it possible to prevent the entire network from going down, and to provide a digital chain system network in which the existing driver / receiver has a long transmission distance and is free from the influence of power interruptions on intermediate nodes.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a communication terminal according to an exemplary embodiment of the present invention, showing a state in which a current is supplied from a power supply unit.

FIG. 2 is a block diagram showing a configuration of a communication terminal according to an embodiment of the present invention, showing a state in which no current is supplied from a power supply unit.

FIG. 3 is a block diagram showing a schematic configuration of a conventional digital chain bus type LAN.

[Explanation of symbols]

 10a Upper side transmission line 10b Lower side transmission line 11 Communication terminal 21 Switching relay (switching means) 22 Negative side relay 23 Positive side relay 22a1, 23a1 Upper side contact 22a2, 23a2 Lower side contact 22b1, 23b1, 22b2, 23b2 Controller side contact 22c1, 23c1, 22c2, 23c2 Path contacts 31 Driver / Receiver circuit 41 Transmission / reception data selector circuit 51 Communication controller 61 Power supply section

Claims (1)

[Claims] 1. A power supply unit and data communication between the other communication terminal and the other communication terminal by a digital chain method while being connected in series with another communication terminal via a transmission line. A communication terminal in a DigiChain network equipped with a communication controller that has an upper-side contact and a lower-side contact connected to the upper and lower sides of the transmission path and a controller-side contact connected to the communication controller. However, when there is a current supply from the power supply unit, while holding the connection destination of the upper side contact and the lower side contact to the controller side contact respectively,
When there is no current supply from the power supply unit, the upper side contact and the lower side contact are disconnected from the controller side contact, and a switching means for connecting the upper side contact and the lower side contact is provided. A communication terminal in a DigiChain network.