CN105182895A - Terminal resistance automatic coupling method and system of programmable logic controller (PLC) expansion bus - Google Patents
Terminal resistance automatic coupling method and system of programmable logic controller (PLC) expansion bus Download PDFInfo
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- CN105182895A CN105182895A CN201510619902.8A CN201510619902A CN105182895A CN 105182895 A CN105182895 A CN 105182895A CN 201510619902 A CN201510619902 A CN 201510619902A CN 105182895 A CN105182895 A CN 105182895A
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B19/00—Programme-control systems
- G05B19/02—Programme-control systems electric
- G05B19/04—Programme control other than numerical control, i.e. in sequence controllers or logic controllers
- G05B19/05—Programmable logic controllers, e.g. simulating logic interconnections of signals according to ladder diagrams or function charts
- G05B19/054—Input/output
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05B—CONTROL OR REGULATING SYSTEMS IN GENERAL; FUNCTIONAL ELEMENTS OF SUCH SYSTEMS; MONITORING OR TESTING ARRANGEMENTS FOR SUCH SYSTEMS OR ELEMENTS
- G05B2219/00—Program-control systems
- G05B2219/10—Plc systems
- G05B2219/11—Plc I-O input output
- G05B2219/1109—Expansion, extension of I-O
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Abstract
The present invention discloses a terminal resistance automatic coupling method of a PLC expansion bus. The method is applied to a PLC control system which is formed by concatenating a PLC and a plurality of expansion modules via the expansion bus and possesses a bus topology structure, and comprises the steps of setting the in-place signal lines in a forward bus interface and a backward bus interface of each expansion module respectively, wherein the in-place signal lines possess the in-place signals of default levels; when the power-up initialization is carried out on the PLC, using each expansion module to generate an in-place signal of a specific level, and transmitting the signal to the in-place signal line of the backward bus interface of the prior level expansion module via the forward bus interface of the current-level expansion module; using the expansion module to determine whether the current-level expansion module is the last expansion module in the bus topology structure according to the level type of the in-place signal of the backward bus interface; if yes, matching the terminal resistance of the current-level expansion module to the expansion bus. The present invention also discloses a corresponding system. By implementing the technical scheme of the present invention, the terminal resistance can be matched automatically and rapidly.
Description
Technical field
The present invention relates to programmable logic controller (PLC) (ProgrammableLogicController, PLC) field, particularly relate to a kind of terminal resistance automatic matching method and system of PLC expansion bus.
Background technology
In the prior art, PLC is expansion I/O (Input/Output, input or output) point or function, generally need various I/O module or functional module to be coupled together formation PLC control system by expansion bus, PLC is communicated with I/O module or functional module by this expansion bus.
Such as Serial Peripheral Interface (the serialperipheralinterface adopted between existing PLC and expansion module, or Controller Area Network BUS (ControllerAreaNetwork SPI), etc. CAN) expansion bus carries out connecting and communicating, in a particular application, before PLC communicates with expansion module, need the matching process of terminal resistance.Wherein, terminal resistance is the resistance on a pair order wire of the far-end (in two communication port of lie farthest away) being connected in parallel on bus topolopy, and its effect is to eliminate the signal reflex in telecommunication cable, effectively strengthening signal intensity.But in prior art, carry out in the system of cascade at PLC and expansion module, need which rank of expansion module of artificial judgment to be the expansion module of afterbody, and be manually connected in the terminal resistance at this expansion module place.
Summary of the invention
In view of the deficiencies in the prior art, the terminal resistance automatic matching method of a kind of PLC expansion bus of the embodiment of the present invention and system, automatically can identify afterbody expansion module in PLC control system, and automatically realize the coupling of terminal resistance.
In order to reach foregoing invention object, embodiments provide a kind of terminal resistance automatic matching method of PLC expansion bus, being applied to PLC and multiple expansion module has in the PLC control system of bus topolopy by expansion bus cascade, and the method comprises the steps:
Each expansion module described forward direction bus interface and after a signal wire in place is set in bus interface, and make described signal wire in place has the signal in place of acquiescence level;
When carrying out power-up initializing in PLC and described multiple expansion module, each expansion module produces the signal in place of a particular level, and be delivered to by its forward direction bus interface on the signal wire in place of the backward bus interface of its previous stage expansion module, make the signal in place on the signal wire in place of the backward bus interface of described previous stage expansion module remain in described particular level;
According to the multilevel type of the signal in place on the signal wire in place of its backward bus interface, each expansion module described judges whether expansion module at the corresponding levels is last expansion module in bus topolopy;
An expansion module determines expansion module at the corresponding levels wherein when being last expansion module in bus topolopy, is matched on described expansion bus by the terminal resistance in expansion module at the corresponding levels.
Preferably, described acquiescence level is the one in high level and low level, and described particular level is the another kind in high level and low level.
Preferably, it is characterized in that, according to the multilevel type of the signal in place of its backward bus interface, each expansion module described judges that whether expansion module at the corresponding levels is that the step of last expansion module in bus topolopy comprises further:
If described expansion module detects that the signal in place of its backward bus interface is particular level, then judge that expansion module at the corresponding levels is not last expansion module in bus topolopy;
If described expansion module detects that the signal in place of its backward bus interface is for acquiescence level, then judge that expansion module at the corresponding levels is last expansion module in bus topolopy.
Preferably, described wherein an expansion module determines expansion module at the corresponding levels when being last expansion module in bus topolopy, and the terminal resistance in expansion module at the corresponding levels is matched to the step on described expansion bus:
By controlling the closed of electronic switch, the terminal resistance in last expansion module described is connected on described expansion bus.
Correspondingly, the another aspect of the embodiment of the present invention additionally provides a kind of terminal resistance automatic patching system of PLC expansion bus, it comprises, PLC and multiple expansion module, described PLC and described multiple expansion module form bus topolopy by expansion bus cascade, each expansion module all has a forward direction bus interface and a backward bus interface, in described forward direction bus interface and describedly arrange a signal wire in place in bus interface afterwards, described signal wire in place has the signal in place of acquiescence level;
Wherein, each expansion module includes:
Specific signal generation unit in place, for when described expansion module powers on, produce the signal in place of a particular level, described particular level is different from described acquiescence level;
Transmitting element, for being delivered to the signal wire in place of the backward bus interface of its previous stage expansion module by its forward direction bus interface, the signal in place on the signal wire in place of the backward bus interface of described previous stage expansion module is made to remain in described particular level;
Judging unit, for judging according to the multilevel type of the signal in place on the signal wire in place of its backward bus interface whether expansion module at the corresponding levels is last expansion module in bus topolopy;
Judging processing unit, when being last expansion module in bus topolopy for determining expansion module at the corresponding levels at described judging unit, the terminal resistance in expansion module at the corresponding levels being matched on described expansion bus.
Preferably, described acquiescence level is the one in high level and low level, and described particular level is the another kind in high level and low level.
Preferably, described judging unit comprises:
Detecting unit, for detecting the multilevel type of the signal in place of its backward bus interface;
Determining unit, for when the signal in place detected by described detecting unit is particular level, then judges that expansion module at the corresponding levels is not last expansion module in bus topolopy; Or for when the signal in place detected by described detecting unit is for acquiescence level, then judge that expansion module at the corresponding levels is last expansion module in bus topolopy.
Preferably, the terminal resistance in last expansion module described, especially by controlling the closed of electronic switch, is connected on described expansion bus by described judgement processing unit.
Preferably, described expansion bus is MLVDS(MultipointlowVoltageDifferentialSignaling, multiple spot low-voltage differential signal) bus.
Implement the embodiment of the present invention, there is following beneficial effect:
The technical scheme that the embodiment of the present invention provides, by arranging a signal wire in place in bus interface before in each expansion module of the PLC system by expansion bus cascade and rear bus interface, each signal wire in place has the signal in place of acquiescence level; When this PLC system powers on, produce the signal in place of a particular level in expansion module and flow in the signal wire in place of the rear bus interface of previous stage expansion module, the level of its signal in place is changed; Thus namely can judge that whether current extensions module is last expansion module in bus topolopy exactly by the height of level on the signal wire in place of the rear bus interface that judges each expansion module, and by the terminal resistance Auto-matching on last expansion module on expansion bus.In the program, last lower expansion module can be determined rapidly and accurately and by terminal resistance Auto-matching on expansion bus.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only some embodiments of the present invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to these accompanying drawings.
Fig. 1 is the structural representation of a terminal resistance automatic patching system embodiment of a kind of PLC expansion bus provided by the invention;
Fig. 2 is the structural representation of an embodiment of expansion module in Fig. 1;
Fig. 3 is the structural representation of an embodiment of judging unit in Fig. 2;
Fig. 4 is the schematic diagram of the terminal resistance control circuit embodiment in expansion module;
Fig. 5 is the structural representation of the terminal resistance control circuit embodiment in expansion module;
Fig. 6 is the main flow schematic diagram of an embodiment of the terminal resistance automatic matching method of a kind of PLC expansion bus provided by the invention.
Embodiment
Below in conjunction with accompanying drawing, explanation is referred to embodiments of the invention.
As shown in Figure 1, the structural representation of a terminal resistance automatic patching system embodiment of a kind of PLC expansion bus provided by the invention is shown.In this embodiment, the terminal resistance automatic patching system of this PLC expansion bus comprises PLC1 and adopts expansion bus to carry out cascade between multiple expansion module 2, PLC1 and multiple expansion module 2; Wherein, in one embodiment, this expansion bus adopts MLVDS bus, it belongs to bus type topological structure half-duplex operation, the expansion bus mentioned below is all described with MLVDS expansion bus, when being understandable that, in other examples, the bus of other types can also be adopted.Expansion module 2 adopts cascade system, and each expansion module is all independently individual, and also do not have priority, but each expansion module 2 possesses independently address, in one example in which, PLC can cascade 8 expansion modules.In this bus type topological structure, PLC serves as host role, and expansion module serves as from machine role, and bus interface comprises expansion bus clock, expansion bus data and address wire etc.Wherein expansion bus clock sends by PLC is leading, and expansion module carries out exchanges data by the beat of this expansion bus clock.In some instances, can to reach 55MHz even higher for this clock frequency.Particularly, each expansion module 2 has a forward direction bus interface and a backward bus interface, and wherein, front bus interface connects forward expansion module 2 above or PLC, and rear bus interface connects expansion module 2 below backward.In forward direction bus interface and arrange a signal wire in place in bus interface afterwards, signal wire in place has the signal in place of acquiescence level, this acquiescence level is the one in high level and low level, and such as, in one example in which, this acquiescence level is high level.
As shown in Figure 2, the structural representation of an embodiment of the expansion module 2 in Fig. 1 of the present invention is shown.In this embodiment, each expansion module 2 includes:
Specific signal generation unit 20 in place, for when expansion module powers on, produces the signal in place of a particular level, particular level is different from acquiescence level, be understandable that, this acquiescence level is the one in high level and low level, then particular level is the another kind in high level and low level; That is, when this acquiescence level is high level, this particular level is then low level, otherwise or;
Transmitting element 22, for being delivered to the signal wire in place of the backward bus interface of its previous stage expansion module by its forward direction bus interface, makes the signal in place on the signal wire in place of the backward bus interface of previous stage expansion module remain in particular level;
Judging unit 24, for judging according to the multilevel type of the signal in place on the signal wire in place of its backward bus interface whether expansion module at the corresponding levels is last expansion module in bus topolopy;
Judge processing unit 26, when being last expansion module in bus topolopy for determining expansion module at the corresponding levels at judging unit, the terminal resistance in expansion module at the corresponding levels is matched on expansion bus.Particularly, in certain embodiments, by controlling the closed of electronic switch, the terminal resistance in last expansion module can be connected on expansion bus.
In the lump with reference to shown in Fig. 3, it is the structural representation of judging unit 24 in Fig. 2.Wherein, this judging unit 24 comprises:
Detecting unit 240, for detecting the multilevel type of the signal in place of its backward bus interface;
Determining unit 242, for when the signal in place detected by detecting unit 240 is particular level, then judges that expansion module at the corresponding levels is not last expansion module in bus topolopy; Or for when the signal in place detected by detecting unit is for acquiescence level, then judge that expansion module at the corresponding levels is last expansion module in bus topolopy.
Please refer to shown in Fig. 4 and Fig. 5 simultaneously, show schematic diagram and the structural representation of the terminal resistance control circuit embodiment in the present invention in expansion module; In each expansion module 2, be provided with the circuit that the schematic diagram that has as shown in Figure 4 is corresponding, wherein, according to the signal of receiver (receiver), control the closed of electronic switch K, thus terminal resistance R is connected on expansion bus.As shown in Figure 5, then one that shows that expansion module in the embodiment of the present invention adopts concrete terminal resistance control circuit structure, in the circuit, wherein, chip D19 is as MLVDS bus transceiver; According to TER-SW signal, control chip D20 determines whether expansion module at the corresponding levels is last expansion module, if judged result is last expansion module, then starts the closed of inner electronic switch, terminal resistance R36 is connected on expansion bus.
Correspondingly, as shown in Figure 6, the main flow schematic diagram of an embodiment of the terminal resistance automatic matching method of a kind of PLC expansion bus provided by the invention is shown.In this embodiment, the terminal resistance automatic matching method of this PLC expansion bus, be applied to PLC and multiple expansion module and have in the PLC control system of bus topolopy by expansion bus cascade, the method comprises the steps:
Step S10, each expansion module forward direction bus interface and after a signal wire in place is set in bus interface, and make signal wire in place has the signal in place of acquiescence level, such as in one example in which, this acquiescence level is high level;
Step S12, when carrying out power-up initializing in PLC and multiple expansion module, each expansion module produces the signal in place of a particular level, and be delivered on the signal wire in place of the backward bus interface of its previous stage expansion module by its forward direction bus interface, the signal in place on the signal wire in place of the backward bus interface of previous stage expansion module is made to remain in particular level, wherein, this particular level is different from the acquiescence level of back, when in previous step S10, acquiescence level is high level, then in step S12, this particular level is low level, be understandable that, vice versa, namely in another example, this acquiescence level is set to low level, and this particular level is set to high level,
Step S14, according to the multilevel type of the signal in place on the signal wire in place of its backward bus interface, each expansion module judges whether expansion module at the corresponding levels is last expansion module in bus topolopy;
Particularly, in this step, if expansion module detects that the signal in place of its backward bus interface is particular level, then judge that expansion module at the corresponding levels is not last expansion module in bus topolopy;
If expansion module detects that the signal in place of its backward bus interface is for acquiescence level, then judge that expansion module at the corresponding levels is last expansion module in bus topolopy.
Step S16, one of them expansion module determines expansion module at the corresponding levels when being last expansion module in bus topolopy, is matched on expansion bus by the terminal resistance in expansion module at the corresponding levels.
Particularly, by controlling the closed of electronic switch, the terminal resistance in last expansion module can be connected on expansion bus.
More details, in the lump referring to figs. 1 to the explanation of Fig. 5, can not repeat at this.
Implement the embodiment of the present invention, there is following beneficial effect:
The technical scheme that the embodiment of the present invention provides, by arranging a signal wire in place in bus interface before in each expansion module of the PLC system by expansion bus cascade and rear bus interface, each signal wire in place has the signal in place of acquiescence level; When this PLC system powers on, produce the signal in place of a particular level in expansion module and flow in the signal wire in place of the rear bus interface of previous stage expansion module, the level of its signal in place is changed; Thus namely can judge that whether current extensions module is last expansion module in bus topolopy exactly by the height of level on the signal wire in place of the rear bus interface that judges each expansion module, and by the terminal resistance Auto-matching on last expansion module on expansion bus.In the program, last lower expansion module can be determined rapidly and accurately and by terminal resistance Auto-matching on expansion bus.
Above disclosedly be only present pre-ferred embodiments, certainly can not limit the interest field of the present invention with this, therefore according to the equivalent variations that the claims in the present invention are done, still belong to the scope that the present invention is contained.
Claims (9)
1. a terminal resistance automatic matching method for PLC expansion bus, be applied to PLC and multiple expansion module and have in the PLC control system of bus topolopy by expansion bus cascade, it is characterized in that, the method comprises the steps:
Each expansion module described forward direction bus interface and after a signal wire in place is set in bus interface, and make described signal wire in place has the signal in place of acquiescence level;
When powering in PLC and described multiple expansion module, each expansion module produces the signal in place of a particular level, and be delivered to by its forward direction bus interface on the signal wire in place of the backward bus interface of its previous stage expansion module, make the signal in place on the signal wire in place of the backward bus interface of described previous stage expansion module remain in described particular level;
According to the multilevel type of the signal in place on the signal wire in place of its backward bus interface, each expansion module described judges whether expansion module at the corresponding levels is last expansion module in bus topolopy;
An expansion module determines expansion module at the corresponding levels wherein when being last expansion module in bus topolopy, is matched on described expansion bus by the terminal resistance in expansion module at the corresponding levels.
2. the terminal resistance automatic matching method of a kind of PLC expansion bus as claimed in claim 1, is characterized in that, described acquiescence level is the one in high level and low level, and described particular level is the another kind in high level and low level.
3. the terminal resistance automatic matching method of a kind of PLC expansion bus as claimed in claim 2, it is characterized in that, according to the multilevel type of the signal in place of its backward bus interface, each expansion module described judges that whether expansion module at the corresponding levels is that the step of last expansion module in bus topolopy comprises further:
If described expansion module detects that the signal in place of its backward bus interface is particular level, then judge that expansion module at the corresponding levels is not last expansion module in bus topolopy;
If described expansion module detects that the signal in place of its backward bus interface is for acquiescence level, then judge that expansion module at the corresponding levels is last expansion module in bus topolopy.
4. the terminal resistance automatic matching method of a kind of PLC expansion bus as claimed in claim 3, it is characterized in that, described wherein an expansion module determines expansion module at the corresponding levels when being last expansion module in bus topolopy, and the terminal resistance in expansion module at the corresponding levels is matched to the step on described expansion bus:
By controlling the closed of electronic switch, the terminal resistance in last expansion module described is connected on described expansion bus.
5. the terminal resistance automatic patching system of a PLC expansion bus, it comprises, PLC and multiple expansion module, described PLC and described multiple expansion module form bus topolopy by expansion bus cascade, it is characterized in that: each expansion module all has a forward direction bus interface and a backward bus interface, in described forward direction bus interface and describedly arrange a signal wire in place in bus interface afterwards, described signal wire in place has the signal in place of acquiescence level;
Wherein, each expansion module includes:
Specific signal generation unit in place, for when described expansion module powers on, produce the signal in place of a particular level, described particular level is different from described acquiescence level;
Transmitting element, for being delivered to the signal wire in place of the backward bus interface of its previous stage expansion module by its forward direction bus interface, the signal in place on the signal wire in place of the backward bus interface of described previous stage expansion module is made to remain in described particular level;
Judging unit, for judging according to the multilevel type of the signal in place on the signal wire in place of its backward bus interface whether expansion module at the corresponding levels is last expansion module in bus topolopy;
Judging processing unit, when being last expansion module in bus topolopy for determining expansion module at the corresponding levels at described judging unit, the terminal resistance in expansion module at the corresponding levels being matched on described expansion bus.
6. the terminal resistance automatic patching system of a kind of PLC expansion bus as claimed in claim 5, is characterized in that, described acquiescence level is the one in high level and low level, and described particular level is the another kind in high level and low level.
7. the terminal resistance automatic patching system of a kind of PLC expansion bus as claimed in claim 6, it is characterized in that, described judging unit specifically comprises:
Detecting unit, for detecting the multilevel type of the signal in place of its backward bus interface;
Determining unit, for when the signal in place detected by described detecting unit is particular level, then judges that expansion module at the corresponding levels is not last expansion module in bus topolopy; Or for when the signal in place detected by described detecting unit is for acquiescence level, then judge that expansion module at the corresponding levels is last expansion module in bus topolopy.
8. the terminal resistance automatic patching system of a kind of PLC expansion bus as claimed in claim 7, it is characterized in that, terminal resistance in last expansion module described, especially by controlling the closed of electronic switch, is connected on described expansion bus by described judgement processing unit.
9. the terminal resistance automatic patching system of a kind of PLC expansion bus as described in any one of claim 5 to 8, is characterized in that, described expansion bus is MLVDS bus.
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| CN201510619902.8A CN105182895B (en) | 2015-09-25 | 2015-09-25 | The terminal resistance automatic matching method and system of a kind of PLC expansion bus |
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| CN201510619902.8A CN105182895B (en) | 2015-09-25 | 2015-09-25 | The terminal resistance automatic matching method and system of a kind of PLC expansion bus |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN112346403A (en) * | 2020-11-12 | 2021-02-09 | 深圳市海浦蒙特科技有限公司 | Extend module connecting circuit |
| CN114361884A (en) * | 2021-12-27 | 2022-04-15 | 西安现代控制技术研究所 | CAN bus terminal resistor automatic matching design method for boxed missile |
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| CN105182895B (en) | 2018-04-03 |
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