JPH04286239A - Communication equipment - Google Patents

Abstract

PURPOSE:To provide communication equipment which is able to change and select a master station optionally and very easily without necessitating the change of the connection of a signal line, and has the large degree of freedom for system configuration. CONSTITUTION:Equipment constituting a slave station in a system is provided with a switching means 25,35,45 necessary for giving a function a the master station. Then, since any slave station becomes capable of being used as the master station by only operating the switching means 25,35,45, the change of the system configuration or the case of a fault can be easily dealt with, and down time can be drastically reduced.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to a multi-drop type communication device that enables one-to-multiple station communication between a host station and a plurality of slave stations via a master station, and more particularly, The present invention relates to a communication device suitable for a centralized control system in which a centralized control monitoring device such as a computer is used as a host station, and control devices for a plurality of inverters are used as slave stations.

0002

[Prior Art] As a conventional technology of a communication device that enables one-to-multiple station communication between a host station and N slave stations (N = an integer), one station among a plurality of slave stations A multi-drop (drop-in) system using the RS-422 standard or the RS-482 standard is known.

[0003] This conventional technology will be explained with reference to FIG. 5. As shown in FIG. Devices 2 to 5 such as devices
When performing one-to-multiple station communication with these devices as slave stations, a specific slave station, that is, devices 2 to 5
The device 2 to which the host station is connected serves as a master station for communication.

Since the device 2 connected to the host station 1 (personal computer) functions as a master station, the output of its transmitting section is connected to the receiving sections of the remaining slave stations 3 to 5. On the other hand, the receiving section is connected to the transmitting sections of the devices 3 to 5, so that the master station device 2 outputs the data received from the host station 1 from the transmitting section,
The data is received by the receiving section of each slave station device 3 to 5, and on the other hand, the data output from the transmitting section of each slave station device 3 to 5 is received by the receiving section of master station device 2, and then sent to the host station. The data will be transmitted to the first computer.

Therefore, in this prior art, a plurality of slave stations are divided into slave stations that are connected to a host station such as a personal computer and function as master stations, and literal slave stations that are connected to the master station. As a result, the master station and slave stations have different hardware configurations, or even if they have the same configuration, they have different connection forms, and the transmission between the master station and slave stations is different. It was necessary to cross the signal lines between the receiver and the receiver. In addition, among slave stations,
The connections are transmission section-to-transmission section and reception section-to-reception section, respectively.

[0006]

SUMMARY OF THE INVENTION In the above-mentioned prior art, no particular consideration was given to changing the master station, and there was a problem in terms of the degree of freedom in system configuration.

For example, in the system shown in FIG. 5(a), if the master station consisting of device 2 is to be changed to device 4, the signal will be changed as shown in FIG. 5(b). You need to change the line connections.

However, in such a system,
Normally, different connector mechanisms are generally used to connect signal lines depending on the type of signal line, in order to reduce the size of equipment, improve reliability, or facilitate work. Changing the connection of the signal line requires changing the signal line itself with the connector, and in the end, such changes cannot be easily made and the degree of freedom in system configuration is reduced. be.

[0009] An object of the present invention is to provide a communication device that allows a master station to be changed and selected arbitrarily and extremely easily without requiring any change in connection of signal lines, and which has a large degree of freedom in system configuration. There is a particular thing.

0010

[Means for Solving the Problems] In order to achieve the above object, the present invention provides at least two of the devices constituting the slave stations in the system with switching means necessary for giving the function as a master station. It is something that

[0011]

[Operation] A device equipped with a switching means can function as a master station by switching the switching means as needed. The selection of a master station can be arbitrarily changed by simply connecting a host station to a slave station that has a host station, and the system can be easily changed without changing the connection of signal lines or the like.

0012

DESCRIPTION OF THE PREFERRED EMBODIMENTS A communication device according to the present invention will be explained in detail below with reference to illustrated embodiments. FIG. 1 shows an embodiment of the present invention. In this figure, 20, 30, and 40 are three slave stations out of N slave stations, which are composed of, for example, an inverter control device, and are connected to a personal computer. This figure shows a system in which central monitoring and control is performed by a master station 1 consisting of the following.

In FIG. 1, 21, 31, 41
are data reception input connection terminals, 22, 32, 42 are data transmission output connection terminals, 23, 33, 43 are first transmission line terminals, 24, 34, 44 are second transmission line terminals, 25, 35
, 45 is a first switching means, 26, 36 and 46 are second switching means, and 27, 37 and 47 are communication processing circuits.

Data reception input connection terminals 21, 31, 41
is a terminal to which a signal line for data RD which the slave station which has become the master station should receive from the host station 1 is connected.

Data transmission output connection terminals 22, 32, 42
is a terminal to which a signal line for data SD to be transmitted from the slave station serving as the master station to the host station 1 is connected.

The first transmission line terminals 23, 33, and 43 are terminals to which a transmission line for data TxD to be transmitted from a slave station serving as a master station to other slave stations is connected.

The second transmission line terminals 24, 34, and 44 are terminals to which a transmission line for data RxD to be transmitted from the slave station to the slave station that has become the master station is connected.

The first switching means 25, 35, and 45 are switches, such as snap switches, which are switched and held in the on state and off state by manual operation, and the slave station to which they belong is selected as the master station. When the slave station is selected to operate only as a slave station, it is switched to the off state and kept in the off state.

The second switching means 26, 36, 46 are composed of electronic switch circuits that are controlled on/off by electrical control signals, and are normally in the off state, but the communication processing circuits 27, 37, The control signal S generated when 47 performs data transmission processing to the host station switches it to the on state.

Next, the operation of this embodiment will be explained. Here, slave station 20 out of N slave stations will be described.
is selected as the master station. Therefore, the switching means 25 of this slave station 20 is turned on, and the data RD signal line of the host station 1 is connected to the data of this slave station 20. Reception input connection terminal 21
, and the data SD signal line is connected to the data transmission output connection terminal 22.

On the other hand, all the first transmission line terminals 23, 33, 43 of each slave station 20, 30, 40 (and N) are commonly connected by a data TxD transmission line, and similarly, the first transmission line terminals 23, 33, 43 of each slave station 20, 30, 40 (and The terminals 24, 34, and 44 are commonly connected by a data RxD transmission line.

Therefore, in this state, the system configuration is as shown in FIG. 2(a), and the system operates as a 1-to-N communication system with the slave station 20 as the master station.

That is, first, data R is sent from the host station 1.
When data D is sent out, since the switching means 25 is in the on state, this data RD is first input to the communication processing circuit 27 of the slave station 20, and is also input to the first transmission line terminal 2.
3 to the data TxD transmission line, and is supplied to all other slave stations 30, 40, . . . , N.

Furthermore, if data is transmitted from any of the communication processing circuits 27, 37, 47, . . . of the slave stations 20, 30, . . . Since S is output, any one of the corresponding second switching means 26, 36, 46 is controlled to be on, and data is output from the corresponding second transmission line terminal 34, 44... It is sent out to the RxD signal line, is once taken into the slave station 20, and then sent out to the data SD signal line via the data transmission output connection terminal 22, and is input to the host station 1. The system operates as a one-to-N communication system with station 20 as the master station.

On the other hand, data transmission from the slave station 20 serving as the master station is transmitted to the host station 1 via the data transmission output connection terminal 22 from the switching means 26 which is then turned on. Become.

Note that in FIG. 2 (the same applies to the prior art shown in FIG. 5), data TxD connecting between each slave station is
The RS-485 and RxD transmission lines are each represented by a pair of lines, as these transmission lines are usually RS-485.
This is because a standard transmission format is generally adopted, so a configuration corresponding to this is shown.

Next, if it becomes necessary to change the master station from the slave station 20 to the slave station 30, first, the data RD and data SD signal lines of the host station 1 shown in solid lines in FIG. , the data reception input connection terminal 21 and data transmission output connection terminal 2 of the slave station 20.
2 and connected to the data reception input connection terminal 31 and data transmission output connection terminal 32 of the slave station 30, as indicated by the broken line host station. Next, slave station 20
The switching means 25 of the slave station 30 is operated to return it to the OFF state, and the switching means 35 of the slave station 30 is also operated to the ON state.

Therefore, at this time, the system configuration is as shown in FIG. 2(b), and the system operates as a 1-to-N communication system with the slave station 30 as the master station.

As is clear from FIGS. 2(a) and 2(b), according to this embodiment, when changing the master station, the data TxD and R
There is no need to change the connection form of the xD transmission line, including the slave station that has become the master station, simply by changing the connection of the data RD and data SD signal lines from the host station 1, and as the master station. The system configuration can be changed extremely easily by simply operating the switch of the selected slave station.

Furthermore, even if the connection of the data RD and data SD signal lines from the host station 1 is changed at this time, since there is no change in the signal type, it can be handled with the same connector. There is no need to change the wires; all you have to do is remove the connectors and change the connections, and the system configuration can be changed without requiring any preparation work.

Furthermore, in this embodiment, all slave stations can have the same configuration, and considerations such as preparing slave stations with different configurations in advance in anticipation of a change in the master station can be taken. It can be made unnecessary.

Next, a more specific embodiment of the present invention will be described with reference to FIG. In the embodiment of FIG. 3, the switching means 25 and 35 in the embodiment of FIG.
5A and switches 25B and 35B, and the switching means 26 and 36 are also composed of driver/receiver ICs 26A and 36A with control terminals for RS-485,
Accordingly, the transmission lines for data TxD and RxD connecting each slave station are also configured to use pairs of data TxDP and TxDN, and two pairs of data RxDP and RxDN.

Further, 28 and 38 are ICs consisting of a receiver and a driver for RS-232C, which are provided in consideration of the fact that the host station 1 is composed of a personal computer. It acts as an interface with...

The driver/receiver ICs 25A and 35A with control terminals have their receiver functions activated only when the switches 25B and 35B are turned on.
When switches 25B and 35B are off,
It functions so that the receiver function is stopped, thereby functioning as a switching means.

Similarly, a driver with a control terminal
The receiver ICs 26A and 36A are communication processing circuits 27 and 3.
The function of the receiver is activated only when the control signal S is supplied from 7, thereby functioning as a switching means.

It should be noted that these communication processing circuits 27 and 37 are usually constructed from microcomputers.

Therefore, in this embodiment, the master station is selected by selecting which slave station's switch 25B, 35B...
This is done by turning on.

Assuming that the switch 25B of the slave station 20 is turned on, the driver/receiver IC 25A with a control terminal is activated and connected to the host station 1.

Data RD from the host station 1 is input to the IC 25A via the IC 28, and thereby passes through the subsequent stage of the IC 25A, 35A, . . . of each slave station 20, 30, . ...to data R
Input as xD.

On the other hand, data TxD sent from the communication processing circuits 27, 37, . . . of each slave station passes through the front stages of the ICs 26A, 36A, . 1 with slave station 20 as the master station.
It will operate as a station-to-N station communication system.

Therefore, according to this embodiment as well, it is possible to easily select and change the master station simply by operating the switches 25A, 35A, . . . Since this is carried out in accordance with the RS-485 standard, the system configuration is simplified and data communication with less risk of error can be easily obtained.

By the way, in the above embodiment, the case where there is one host station has been explained, but the present invention uses n host stations 1a, 1b, 1c, 1d, . . . as shown in FIG. Communication may be performed by turning on only the switching means 25, 35, . . . of the slave station to which the host station actually used for control is connected.

[0043]

According to the present invention, the selection and change of the master station becomes extremely easy, so that the following effects can be obtained.

[0044] When a master station fails, in the conventional technology, it is necessary to repair the failed master station or to select another slave station as the master station by changing the connection of the signal line. , downtime becomes longer, and during this time all communication systems go down.

However, according to the present invention, since the master station can be easily changed, it is possible to easily deal with the change, and the downtime in the event of a failure of the master station can be greatly reduced.

[0046] Also, at this time, if the failure of the master station occurs in a part other than the first switching means, only the communication function of the master station itself is lost, and other stations The communication function will not go down. Therefore, the probability of functional failure of the entire communication system can be reduced,
High reliability can be obtained.

[0047]Furthermore, in the conventional technology, it is not possible to configure a system including a plurality of host stations, but according to the present invention, a plurality of host stations are used, and control can be performed from a host station arbitrarily selected from among them. can be done,
Flexible control is possible.

[Brief explanation of the drawing]

FIG. 1 is a block configuration diagram showing an embodiment of a communication device according to the present invention.

FIG. 2 is a block diagram for explaining the operation of an embodiment of the present invention.

FIG. 3 is a block diagram showing a more specific embodiment of the present invention.

FIG. 4 is a block diagram showing another embodiment of the present invention.

FIG. 5 is a block diagram showing a conventional example of a communication device.

[Explanation of symbols]

1 Host station 20, 30, 40 slave station 25, 35, 45 First switching means 26, 36, 46 Second switching means 27, 37, 47 Communication processing circuit

Claims (2)

[Claims] Claim 1: Data transmission between a host station and a plurality of slave stations using a multi-drop method, with a slave station connected to the host station among the plurality of slave stations being the master station, In this communication device of a type in which processing is performed via a master station, at least two of the plurality of slave stations have a data reception input connection terminal from the host station, a data transmission output connection terminal to the host station, and a data reception input connection terminal to the host station. a first switching means connected between the input connection terminal and the data reception input of the communication processing circuit in the slave station;
a second switching means connected between the data transmission output connection terminal and the data transmission output of the communication processing circuit; and a connection path between the first switching means and the data reception input of the communication processing circuit. The connected first transmission line terminal and the second
a second transmission line terminal connected to a connection path between the switching means and the data transmission output connection terminal, and a control means for closing the second switching means in response to a data transmission operation by the communication processing circuit. The first transmission line terminal and the second transmission line terminal of the plurality of slave stations are commonly connected to each other by the first transmission line and the second transmission line, respectively, and A communication device characterized in that data transmission is performed by operating only the first switching means of a slave station designated as a master station among the slave stations in a closed state. 2. In the invention according to claim 1, an RS-2 is provided between the data reception input connection terminal and the first switching means.
A receiver for RS-232C is inserted between the data transmission output connection terminal and the second switching means, and a driver for RS-232C is inserted between the data transmission output connection terminal and the second switching means. 1. A communication device comprising a driver/receiver with a control terminal for 485.