CN2522938Y

CN2522938Y - Internal module connecting bus for on-site control machine

Info

Publication number: CN2522938Y
Application number: CN 01270230
Authority: CN
Inventors: 何国霖; 董世运; 卓明; 戈彦霞; 武芳瑛
Original assignee: Qinghua Tongfang Co Ltd
Priority date: 2001-11-05
Filing date: 2001-11-05
Publication date: 2002-11-27
Anticipated expiration: 2011-11-05

Abstract

The utility model discloses an internal module connecting bus of a spot controller, which belongs to a spot bus technology in an automatic system. The internal module connecting bus of the spot controller consists of a full duplex bus and a hub, one end of the full duplex bus is connected with the hub as an input/output port of the hub; the hub comprises a logic arithmetic circuit, of which a plurality of input ends are respectively connected with the input port of the hub, and the output end of the logic arithmetic circuit are connected with each the output port of the hub by a bus. The utility model solves the defects of poor reliability, double spending on hardware caused by redundant design and complicated software of a bus type connection, etc. required in the prior art. The utility model is essentially applied to the connection and communication of spot controlling modules in an automatic system.

Description

Internal module connecting bus for site controlling computer

Technical field

The utility model relates to the fieldbus in a kind of automated system, particularly internal module connecting bus for site controlling computer.

Background technology

Fieldbus is used in the bidirectional linked list multinode digital communication between the production scene realization computerized measurement equipment, and it is widely used in the automated system of industries such as manufacturing industry, process industry and traffic.At present, fieldbus adopts the universal serial bus topological structure to realize physical connection usually, and promptly all control modules, measuring unit all are connected on this universal serial bus with bus type.Though this connected mode has simple advantage, break down and will cause system to be paralysed comprehensively in the bus somewhere, so its functional reliability is poor.Particularly in requiring the automated system of high reliability, will there be great risk in this kind connected mode.In order to improve the reliability of total fieldbus, generally consider the Redundancy Design method, promptly adopt dual-bus structure.But this standby universal serial bus scheme can be brought the dual expense of communication hardware interface and communication line, and more outstanding is that the communication program expense is excessive, makes bitcom become complicated.

Summary of the invention

At the shortcoming that prior art exists, the utility model provides a kind of simple in structure, cost is low and reliability is high internal module connecting bus for site controlling computer.

Internal module connecting bus for site controlling computer of the present utility model comprises full duplex bus, and its design feature is, also comprises hub, and described full duplex bus one end is connected the I/O port as hub with described hub; Described hub comprises logical operation circuit, and a plurality of input ends of described logical operation circuit are connected with the input of hub respectively, and the output terminal of described logical operation circuit is connected with each output of hub by a bus.

According to technique scheme, be connected with the bus protection circuit between described logical operation circuit and the hub input end; Described bus protection circuit prevents that module from taking a described bus for a long time because of breaking down.

According to technique scheme, described bus protection circuit is made of monostalbe trigger.

According to technique scheme, described logical operation circuit is one to have the AND gate circuit of many input ends.

According to technique scheme, described logical operation circuit comprises NOT-AND gate integrated circuit and "NOT" circuit of input end more than; The data that the input end receiver module of described NOT-AND gate integrated circuit sends, the input of its output terminal and "NOT" circuit is connected, and the output of described "NOT" circuit connects a described bus.

The utility model connects the typical bus formula of fieldbus to change by hub becomes Y-connection, the bitcom that is applicable to the unibus system network topology is not being carried out under the situation of any change, its functional reliability is increased substantially, also avoided simultaneously the communication hardware interface that Redundancy Design caused and the dual expense of communication line, and shortcoming such as bitcom complexity.Advantages such as internal module connecting bus for site controlling computer of the present utility model also has simple in structure, and manufacturing cost and use cost is low and easy to use.

Description of drawings

Fig. 1 is circuit theory diagrams of the present utility model;

Fig. 2 is another structural circuit schematic diagram of the present utility model.

Embodiment

As shown in Figure 1, present embodiment realizes being connected to example with 4 control modules.Modules A～D is the control module in the site controlling computer, and the software and hardware of the corresponding task finished is arranged in each control module.Internal module connecting bus for site controlling computer is made up of hub 1 and full duplex bus 4, and full duplex bus 4 is the RS422 full duplex bus.

Hub 1 is by being connected with modules A～D.Logical operation circuit 2 is connected in series by NAND circuit IC25 and "NOT" circuit IC26, and wherein four input ends of NAND circuit IC25 are connected with IC15 with four RS422 receiver IC3, IC7, IC11T of hub 1 respectively.The output of "NOT" circuit IC26 is connected to RS422 transmitter IC4, IC8, IC12 and the IC16 of hub 1 by a bus 3.Hub 1 is all finished by the RS422 receiver and the RS422 transmitter of each self-configuring with the exchanges data of modules A～D.

At the utility model in use, communications protocol between the module and bitcom are all same as the prior art.When a certain module need take bus, first frame was listened bus, received data by the RS422 receiver from the RS422 bus.If the data that receive are " 0 ", promptly low level signal represents that then bus is shared by other module, and this module this moment communications protocol according to the rules waits for that bus is released; If what receive be " 1 " to data, i.e. high level signal, then communications protocol is according to the rules carried out bus test with the affirmation bus free time.The bitcom that is applicable to the unibus system network topology in the prior art is not appointed change for making application of the present invention, hub 1 only carries out exchanges data with half-duplex mode with each link block, and promptly module of a certain moment can only send data and maybe can only receive data.

For example: when modules A need take bus and carries out communication, receive data and data are judged from bus by RS422 receiver IC2 earlier, if digital " 0 " waits for that then bus is released; If numeral is " 1 " then send test patterns.When confirming that bus is after the free time, RS422 transmitter IC1 by modules A sends low level signal to full duplex bus 4, the RS422 receiver IC3 of hub 1 receives this low level signal, then signal is delivered to NAND circuit IC25 and inverter IC26.Signal exports a bus 3 to through inverter IC26, is delivered to RS422 transmitter IC4, IC8, IC12, the IC16 of hub 1 again, sends to RS422 receiver IC2, IC6, IC10, the IC14 of modules A～D at last by full duplex bus 4.In like manner, the low level information that module B, module C and module D send, each module also can both receive.

As seen from Figure 1, when the utility model uses, module 1～4 is carried out the half-duplex mode communication by full duplex bus 4 and hub 1, NAND circuit IC25 in the logical operation circuit 4 the input data of module 1～4 are carried out " with " NOT operation and the result is coupled on the bus 3 through "NOT" circuit IC26, a bus 3 is passed to it full duplex bus 4 again.According to this method for interchanging data, RS422 full duplex bus and hub become a kind of new structure bus of link block.

Figure 2 shows that the circuit diagram of the another kind of structure of the utility model internal module connecting bus for site controlling computer.This structure is to have increased bus protection circuit 5 on the basis of structure shown in Figure 1, with the reliability of further raising bus.From accompanying drawing 1 as can be seen, when a certain module, when breaking down as modules A, may send low level signal to bus for a long time, other all modules can both be received this low level signal from bus interface, and modules A will be monopolized bus for a long time like this, thereby make other module can't operate as normal.Bus protection circuit 5 can be avoided occurring because of the situation that module failure is monopolized bus.

Bus protection circuit 5 is the single-shot trigger circuit that monostable trigger IC17 and OR-circuit IC21 form, and monostable trigger IC17 model is 74HC133.2,3 pin of monostable trigger IC17 connect high level, and

input pin

14,15 connects resistance R 1 and capacitor C 1.Resistance R 1 and capacitor C 1 makeup time constant τ=R1C1, the width of this time constant decision monostable circuit output pulse.When 1 pin of monostable trigger IC17 has a negative edge trigger pulse, will be the low level pulse of τ=R1C1 at 4 pin output width.Under the situation of normal communication, the communication information that 1 pin of monostable trigger IC17 is received is the pulse train of being made up of high level and low level that module is sent.When signal when high level becomes low level, the negative edge of pulse makes 4 pin of monostable trigger IC17 produce the low level pulse that width is τ=R1C1, communication information is delivered on the bus by logical-arithmetic unit 2 behind OR-circuit IC21 again.A kind of possible situation is, when a certain module, break down as modules A, when sending low level signal for a long time, because of it the negative edge pulse can not occur again, therefore, after elapsed time τ=R1C1, to export high level signal on 4 pin of monostable trigger IC17, and force OR circuit IC21 to be output as high level simultaneously.Therefore, the low level signal of modules A can not be sent to bus again, so just plays the protection to bus.

The attachable control module of present embodiment can be for a plurality of; Full duplex bus 4 can be the full duplex bus of other conformance with standard standard, as RS232 etc.; NAND circuit IC25 in the logical-arithmetic unit 2 and "NOT" circuit IC26 can replace with an AND gate circuit that has many input ends, and its principle of work and the means of communication are same as described above.

Claims

1, a kind of internal module connecting bus for site controlling computer comprises full duplex bus, it is characterized in that also comprising hub, and described full duplex bus one end is connected the I/O port as hub with described hub; Described hub comprises logical operation circuit, and a plurality of input ends of described logical operation circuit are connected with the input of hub respectively, and the output terminal of described logical operation circuit is connected with each output of hub by a bus.

2, internal module connecting bus for site controlling computer according to claim 1 is characterized in that being connected with the bus protection circuit between described logical operation circuit and the hub input end; Described bus protection circuit prevents that module from taking a described bus for a long time because of breaking down.

3, internal module connecting bus for site controlling computer according to claim 2 is characterized in that described bus protection circuit is made of monostalbe trigger.

4, internal module connecting bus for site controlling computer according to claim 1 and 2 is characterized in that described logical operation circuit comprises NAND circuit and "NOT" circuit of input end more than; The data that the input end receiver module of described NAND circuit sends, its output terminal is connected with the input of "NOT" circuit, and the output of described "NOT" circuit connects a described bus.

5, internal module connecting bus for site controlling computer according to claim 1 and 2 is characterized in that described logical operation circuit is the AND gate circuit with many input ends.