CN103576597A - Digital quantity input interface device, programmable logic controller comprising digital quantity input interface device and method of digital quantity input interface device - Google Patents
Digital quantity input interface device, programmable logic controller comprising digital quantity input interface device and method of digital quantity input interface device Download PDFInfo
- Publication number
- CN103576597A CN103576597A CN201210258040.7A CN201210258040A CN103576597A CN 103576597 A CN103576597 A CN 103576597A CN 201210258040 A CN201210258040 A CN 201210258040A CN 103576597 A CN103576597 A CN 103576597A
- Authority
- CN
- China
- Prior art keywords
- input
- interface device
- current
- optoelectronic switch
- digital
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Abstract
The invention provides a digital quantity input interface device and method used for a PLC, and the PLC comprising the digital quantity input interface device. The digital quantity input interface device comprises an input current limiting resistor, a sampling resistor, an optocoupler, a pulling-up resistor and an optoelectronic switch, wherein the input current limiting resistor is connected to the output end of an external sensor and receives an input signal; the sampling resistor is connected with the input current limiting resistor in series; the first input end and the second input end of the optocoupler are connected with the two ends of the sampling resistor in parallel respectively; one end of the pulling-up resistor is connected to the first output end of the optocoupler, the other end of the pulling-up resistor is connected to a power source, and the other output end of the optocoupler is connected to a digital ground; one output end of the optoelectronic switch and one end of the sampling resistor are jointly connected to the second output end of the optocoupler, the other output end of the optoelectronic switch is connected to the input public end of the PLC, the input end of the optoelectronic switch receives an input enable signal, and the optoelectronic switch is correspondingly switched on or off under control of the input enable signal.
Description
Technical field
The present invention relates to a kind of for the digital-quantity input interface apparatus and method of Programmable Logic Controller (PLC) and the Programmable Logic Controller that comprises digital-quantity input interface device.Particularly, relate to a kind of can save power for the digital-quantity input interface apparatus and method of PLC and the Programmable Logic Controller that comprises digital-quantity input interface device.
Background technology
Fig. 1 is for the circuit diagram of the digital-quantity input interface device of PLC in prior art.Wherein Fig. 1 shows the digital-quantity input interface of the direct current input type of PLC.In Fig. 1, only illustrate two input channels as example, in actual use, can have a plurality of input channels.The input channel shown in the top of Fig. 1 of take is example, and this digital-quantity input interface device 100 comprises: input current-limiting resistor R68, be connected to the output terminal of external sensor (not shown), and receive input signal; The sampling resistor R72 being connected in series with input current-limiting resistor R68; Optocoupler U17, two input end U17-5, U17-6 of the connection internal illumination diode of optocoupler U17 are in parallel with the two ends of sampling resistor R72 respectively; Pullup resistor R140, one end of pullup resistor R140 is connected to the output terminal U17-12 of optocoupler U17, and the other end of pullup resistor R140 is connected to power vd D, and another output terminal U17-11 of optocoupler U17 connects digitally GND.Wherein a corresponding output terminal of the optocoupler U17 in each input channel is connected to input common port Input_com together.
In addition digital-quantity input interface device 100 can also comprise the capacitor C117 that is parallel to the capacitor C56 at sampling resistor R72 two ends and is parallel to two output terminals of optocoupler U17, for filtering interfering.
By the digital-quantity input interface device 100 in Fig. 1, the output signal of external sensor is after-applied on two input end U17-5, the U17-6 of optocoupler U17 via the dividing potential drop of input current-limiting resistor R68 and sampling resistor R72, making the size of output signal of internal illumination diode external sensor of optocoupler U17 luminous or not luminous, is high level signal or low level signal thereby further make the output terminal U17-12 of optocoupler U17.Digital-quantity input interface device 100 just changes the output signal of external sensor into digital signal like this, and be input to PLC inside and process, and for controlling.
The input performance of considering PLC, the maximum input voltage of digital-quantity input interface device 100 is generally 30V.If the resistance value of input current-limiting resistor R68 is 3.3K,, the in the situation that of maximum input voltage 30V, input current-limiting resistor R68 will expend the power of about 0.237W.If there is the such input channel in 24 roads in a PLC, the power consumption causing due to input current-limiting resistor is approximately 24 * 0.237=5.688W.And large like this power consumption can cause following problem:
1, PLC inside is heated, heats up, and the temperature raising will reduce the serviceable life of inner other components and parts of PLC, and reduces reliability;
2, input current-limiting resistor becomes very boiling hot, and the temperature that has record to show to input on current-limiting resistor can reach 100 ℃, and the reliability of input current-limiting resistor is because high temperature reduces;
3, the power consumption of input current-limiting resistor, has wasted a large amount of power.
Therefore, need a kind of can save that power is raised the efficiency, for the digital-quantity input interface apparatus and method of Programmable Logic Controller.
Summary of the invention
The object of this invention is to provide for the digital-quantity input interface apparatus and method of Programmable Logic Controller and the Programmable Logic Controller that comprises this digital-quantity input interface device, it can be saved power, raises the efficiency and increase the service life.
According to an aspect of the present invention, provide a kind of digital-quantity input interface device for Programmable Logic Controller PLC, comprising: input current-limiting resistor, be connected to the output terminal of external sensor, receive input signal; With the sampling resistor that is connected in series of input current-limiting resistor; Optocoupler, the first and second input ends of optocoupler are in parallel with the two ends of sampling resistor respectively; Pullup resistor, one end of pullup resistor is connected to the first output terminal of optocoupler, and the other end of pullup resistor is connected to power supply, and wherein, another output terminal of optocoupler connects digitally; And optoelectronic switch, output terminal of optoelectronic switch is connected to the second output terminal of optocoupler together with one end of sampling resistor, another output terminal of optoelectronic switch is connected to the input common port of PLC, the input end of optoelectronic switch receives an input enable signal, under the control of input enable signal, optoelectronic switch is conducting and cut-off correspondingly.
Wherein said digital-quantity input interface device also comprises the capacitor of two output terminals that are parallel to the capacitor at sampling resistor two ends and are parallel to optocoupler, for filtering interfering.
Wherein said digital-quantity input interface device receives direct current input or exchanges the input signal of input.
According to an aspect of the present invention, a kind of method of the input of the digital quantity for digital-quantity input interface device as above is provided, in the scan period of an input quantity of PLC, described method comprises four-stage: in the stage 1, apply the input enable signal of the first state, make optoelectronic switch conducting, form the closed-loop path of input channel, and then make to input the electric current on current-limiting resistor, that is input channel loop current, rise to steady-state value; In the stage 2, the input enable signal that maintenance applies, optoelectronic switch keeps conducting, and the electric current on input current-limiting resistor, that is input channel loop current, remain steady-state value, and PLC carries out the scan operation of input quantity; In the stage 3, apply the input enable signal of the second state, make optoelectronic switch cut-off, the loop of input channel disconnects, and then makes to input the electric current on current-limiting resistor, that is input channel loop current, from steady-state value, starts to drop to 0; And in the stage 4, keep the input enable signal of the second state, and optoelectronic switch maintains cut-off, and the loop of input channel disconnects completely and keeps, and the electric current on input current-limiting resistor, that is input channel loop current, remain 0.
Wherein the first state is high level state, and the second state is low level state.
According to an aspect of the present invention, also provide a kind of Programmable Logic Controller PLC that comprises digital-quantity input interface device as above.
Accompanying drawing explanation
By the detailed description to example embodiment below in conjunction with accompanying drawing, will understand better the present invention.It should be clearly understood that described example embodiment is only as explanation and example, and the invention is not restricted to this.The spirit and scope of the present invention are limited by the particular content of appended claims.Brief description of drawings is described below, wherein:
Fig. 1 is for the circuit diagram of the digital-quantity input interface device of PLC in prior art;
Fig. 2 is according to the circuit diagram of the digital-quantity input interface device for PLC of the embodiment of the present invention;
Fig. 3 is according to the control sequential chart of the digital-quantity input interface device for PLC of the embodiment of the present invention.
Embodiment
Referring now to accompanying drawing, introduce according to the present invention in detail.
Fig. 2 is according to the circuit diagram of the digital-quantity input interface device for PLC of the embodiment of the present invention.
In current PLC design, for the input type shown in Fig. 1, the speed of input is not very fast conventionally, the CPU of PLC to the scan value of each input quantity once required time the longest be only 1-3ms.But, for specifically the time of carrying out scan operation of each input quantity is shorter than 300 μ s.If so in 1-3ms except 300 μ s At All Other Times during, can make each element in the input channel of PLC not work, can greatly reduce the power consumption in the input channel of PLC.But the input channel at the PLC as shown in Figure 1 of currently available technology, in the whole working time of PLC, each element in the input channel of PLC is always in running order, thereby the input current of input channel always exists, so the power dissipation ratio of the input channel of the PLC of prior art is larger.
Therefore, Fig. 2 according to the circuit diagram of the digital-quantity input interface device for PLC of the embodiment of the present invention, except increasing optoelectronic switch U200, other parts are identical with the digital-quantity input interface device for PLC of Fig. 1.In Fig. 2, input current-limiting resistor R68, sampling resistor R72 and optoelectronic switch U200 connect successively, output terminal of optoelectronic switch U200 is connected to the output terminal U17-6 of optocoupler U17 together with one end of sampling resistor R72, and another output terminal of optoelectronic switch U200 is connected to the input common port Input_com of PLC.The output terminal of the anode that is connected to internal photo of optical coupled switch U200 is connected with input enable signal Enable with a resistor via the driver Driver of series connection.Input enable signal Enable makes each scan period at CPU, only in the time durations that carries out scan operation for concrete each input quantity makes the input channel of input quantity, has input current to flow; When aforesaid operations finishes, the input current in input channel is cut off.During input current is cut off, in input channel, there is not electric current like this, on input current-limiting resistor R68, just do not have power consumption, and whole input channel does not exist power consumption yet yet.
Particularly, when input enable signal Enable is high level, the diode current flow of the input side of optoelectronic switch U200, thereby the MOSFET conducting of the outgoing side of optoelectronic switch U200, input channel forms closed-loop path, thereby has input current to flow in input channel; When input enable signal Enable is low level, the diode cut-off of the input side of optoelectronic switch U200, thereby the MOSFET of the outgoing side of optoelectronic switch U200 cut-off, input channel can not form closed-loop path, thereby does not have input current to flow in input channel.
Fig. 2 according to the digital-quantity input interface device for PLC of the embodiment of the present invention, it is suitable that the speed of enabling of optoelectronic switch U200 will be selected, if the photodiode of optoelectronic switch U200 inside turn on and off time T on and Toff is too slow, after optoelectronic switch U200 having stable behavior, do not have enough for input quantity is carried out the time of scan operation.Therefore optoelectronic switch U200 will select high speed optoelectronic switch.
In addition, for the digital-quantity input interface device sensor type that is connected to PLC, choose also very important, the sensor that is not suitable for connecting 24V two-wire system for the digital-quantity input interface device of PLC of the present invention.The suitable single line output transducer as shown in Figure 2 of digital-quantity input interface device for PLC of the present invention, wherein the output transducer mechanical contact switch device such as relay-contactor, push type button, switch etc. preferably, could convert basic switching signal and high low voltage signal to single-bit binary digital signal according to the digital-quantity input interface device for PLC of the embodiment of the present invention like this.
Note that the actuation time again of the sensor of all these kinds is very fast in the operation of input enable switch, could not affect like this value scanning of input channel.Also just based on this, the digital-quantity input interface device for PLC of the present invention is not suitable for connecting 24V two-wire system sensor.
Fig. 3 is according to the control sequential chart of the digital-quantity input interface device for PLC of the embodiment of the present invention.
In Fig. 3, first waveform is the waveform of the input end U17-6 of optocoupler U17, second rectangular wave pulse is the waveform of input enable signal Enable, and nethermost is that the maximum input voltage of supposing digital-quantity input interface device 100 is 24V at the current waveform of inputting on current-limiting resistor R68.
When if the drive current of driver driver is approximately 15mA, conventionally the optoelectronic switch of MOSFET type turn on and off time T on and Toff can all be less than 0.2ms.Like this, in the scan period of the 1ms of the fastest possible situation of the input channel of the CPU of PLC, the sequential of scanning process as shown in Figure 3.The scan period of whole 1ms is divided into four-stage, stage 1(0.2ms), stage 2(0.2ms), stage 2(0.2ms), stage 4(0.4ms).
In the stage 1, apply the input enable signal Enable of high level, make the voltage of input end U17-6 change 0V into from high voltage, optoelectronic switch U200 becomes conducting, now, input channel forms closed-loop path, and the electric current (that is input channel loop current) on input current-limiting resistor R68 rises to steady-state value, is approximately 6-8mA.
In the stage 2, keep the input enable signal Enable of high level, the voltage of input end U17-6 remains 0V, optoelectronic switch U200 keeps stable conducting state, and the electric current (that is input channel loop current) on input current-limiting resistor R68 remains steady-state value, is approximately 6-8mA.In this stage 2, the CPU of PLC can carry out the scan operation operation to input quantity.
In the stage 3, apply low level input enable signal Enable, make the voltage of input end U17-6 rise to high voltage from 0V, optoelectronic switch U200 becomes cut-off state, now, the loop of input channel disconnects, and the electric current (that is input channel loop current) on input current-limiting resistor R68 starts to drop to 0mA from steady-state value.
In the stage 4, keep low level input enable signal Enable, make the voltage of input end U17-6 remain high voltage, optoelectronic switch U200 maintains stable cut-off state, now, the loop of input channel disconnects completely and keeps, and the electric current (that is input channel loop current) on input current-limiting resistor R68 is 0mA.
As can be seen from Figure 3, even in the situation that the scan period of the fastest PLC input channel is 1ms, it is zero that electric current on input current-limiting resistor R68 approximately only has 0.5ms, therefore for above-mentioned situation, approximately can save 50% power consumption in the input channel of PLC.If the scan period of PLC input channel is longer, the power consumption that can save in the input channel of PLC can be more.
Synthesizing map 2,3 can be found out, use is according to the digital-quantity input interface device for PLC of the embodiment of the present invention, can avoid the input current-limiting resistor that the power problems due to input current-limiting resistor causes and the excessive shortcoming of temperature rise that comprises the PLC that inputs current-limiting resistor.
In Fig. 1 owing to there is no the failure of current time of optoelectronic switch control inputs passage, so in the whole work period of PLC, the power consumption in input current-limiting resistor and input channel loop exists all the time, even if the CPU of PLC is very long to the sweep time of input channel, still like this.So in prior art, the power consumption of input current-limiting resistor can cause the significant temperature rise of PLC self and internal air stream thereof.
Compare with the prior art of Fig. 1, the digital-quantity input interface devices and methods therefor for PLC of the present invention has reduced power consumption and the temperature rise of PLC inside, and has improved the efficiency of PLC, and then due to lower temperature rise, has also improved reliability and the serviceable life of PLC.
Obviously, the present invention also provides a kind of PLC that comprises above-mentioned digital-quantity input interface device, and power consumption and the temperature rise of this PLC inside reduce greatly, and efficiency obviously improves, and reliability and serviceable life are also improved.Will obtain client's satisfied approval.
Although Fig. 2,3 all describes the present invention to have the PLC of direct current input type, the invention is not restricted to this.Owing to thering is the PLC of interchange input type, current limliting, isolation and three links of rectification in ac input circuit, have been increased, so the present invention is applicable equally for the PLC with interchange input type.
Although illustrated and described the example embodiment of the present invention of considering, but it will be appreciated by those skilled in the art that, along with the progress of technology, can make various changes and revise and can replace its element and not deviate from true scope of the present invention with equivalent.
Claims (8)
1. a digital-quantity input interface device, for Programmable Logic Controller, this device comprises:
Input current-limiting resistor (R68), be connected to the output terminal of external sensor, receive input signal;
With the sampling resistor (R72) that is connected in series of input current-limiting resistor (R68);
Optocoupler (U17), the first and second input ends (U17-5, U17-6) of optocoupler (U17) are in parallel with the two ends of sampling resistor (R72) respectively;
Pullup resistor (R140), one end of pullup resistor (R140) is connected to first output terminal (U17-12) of optocoupler (U17), the other end of pullup resistor (R140) is connected to power supply (VDD), wherein, another output terminal (U17-11) of optocoupler (U17) connects digitally (GND); And
Optoelectronic switch (U200), output terminal of optoelectronic switch (U200) is connected to second output terminal (U17-6) of optocoupler (U17) together with one end of sampling resistor (R72), another output terminal of optoelectronic switch (U200) is connected to the input common port (Input_com) of Programmable Logic Controller, the input end of optoelectronic switch (U200) receives an input enable signal, under the control of input enable signal, optoelectronic switch is conducting and cut-off correspondingly.
2. digital-quantity input interface device as claimed in claim 1, wherein
Described digital-quantity input interface device (100) also comprises the capacitor (C117) that is parallel to the capacitor (C56) at sampling resistor (R72) two ends and is parallel to two output terminals of optocoupler (U17), for filtering interfering.
3. digital-quantity input interface device as claimed in claim 1, wherein
Described digital-quantity input interface device receives direct current input or exchanges the input signal of input.
4. for the method for the digital quantity input of digital-quantity input interface device as claimed in claim 1, in the scan period of an input quantity of Programmable Logic Controller, described method comprises four-stage,
In the stage 1, apply the input enable signal (Enable) of the first state, make optoelectronic switch (U200) conducting, form the closed-loop path of input channel, and then make to input the electric current on current-limiting resistor (R68), that is input channel loop current, rise to steady-state value;
In the stage 2, the input enable signal (Enable) that maintenance applies, optoelectronic switch (U200) keeps conducting, electric current on input current-limiting resistor (R68), that is input channel loop current, remaining steady-state value, Programmable Logic Controller is carried out the scan operation of input quantity;
In the stage 3, apply the input enable signal (Enable) of the second state, make optoelectronic switch (U200) cut-off, the loop of input channel disconnects, and then make to input the electric current on current-limiting resistor (R68), that is input channel loop current, from steady-state value, start to drop to 0;
In the stage 4, keep the input enable signal (Enable) of the second state, optoelectronic switch (U200) maintains cut-off, and the loop of input channel disconnects completely and keeps, and the electric current on input current-limiting resistor (R68), that is input channel loop current, remain 0.
5. method as claimed in claim 4, wherein
The first state is high level state, and the second state is low level state.
6. a Programmable Logic Controller that comprises digital-quantity input interface device as claimed in claim 1.
7. Programmable Logic Controller as claimed in claim 6, wherein
Described digital-quantity input interface device (100) also comprises the capacitor (C117) that is parallel to the capacitor (C56) at sampling resistor (R72) two ends and is parallel to two output terminals of optocoupler (U17), for filtering interfering.
8. Programmable Logic Controller as claimed in claim 6, wherein
Described digital-quantity input interface device receives direct current input or exchanges the input signal of input.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210258040.7A CN103576597A (en) | 2012-07-24 | 2012-07-24 | Digital quantity input interface device, programmable logic controller comprising digital quantity input interface device and method of digital quantity input interface device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201210258040.7A CN103576597A (en) | 2012-07-24 | 2012-07-24 | Digital quantity input interface device, programmable logic controller comprising digital quantity input interface device and method of digital quantity input interface device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN103576597A true CN103576597A (en) | 2014-02-12 |
Family
ID=50048612
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201210258040.7A Pending CN103576597A (en) | 2012-07-24 | 2012-07-24 | Digital quantity input interface device, programmable logic controller comprising digital quantity input interface device and method of digital quantity input interface device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN103576597A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103885381A (en) * | 2014-03-18 | 2014-06-25 | 深圳市汇川控制技术有限公司 | Wide-voltage PLC input circuit |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08223022A (en) * | 1995-02-08 | 1996-08-30 | Toshiba Corp | Digital input device |
| CN201607639U (en) * | 2009-10-12 | 2010-10-13 | 昆山乾坤机器制造有限公司 | Anti-interference input and output circuit for control system of numerical control cutting machine |
| CN101964653A (en) * | 2009-07-24 | 2011-02-02 | 南京南瑞继保电气有限公司 | Switching value input circuit |
-
2012
- 2012-07-24 CN CN201210258040.7A patent/CN103576597A/en active Pending
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH08223022A (en) * | 1995-02-08 | 1996-08-30 | Toshiba Corp | Digital input device |
| CN101964653A (en) * | 2009-07-24 | 2011-02-02 | 南京南瑞继保电气有限公司 | Switching value input circuit |
| CN201607639U (en) * | 2009-10-12 | 2010-10-13 | 昆山乾坤机器制造有限公司 | Anti-interference input and output circuit for control system of numerical control cutting machine |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103885381A (en) * | 2014-03-18 | 2014-06-25 | 深圳市汇川控制技术有限公司 | Wide-voltage PLC input circuit |
| CN103885381B (en) * | 2014-03-18 | 2016-09-07 | 深圳市汇川控制技术有限公司 | A kind of wide pressure PLC input circuit |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN205232541U (en) | LED driver embeds dial switch isolation control circuit | |
| CN102387628A (en) | LED (Light-Emitting Diode) dimming control circuit | |
| CN103379687A (en) | Semiconductor circuit and semiconductor apparatus | |
| CN103929854A (en) | LED drive device and LED dimming controller thereof | |
| CN103220865A (en) | Button-cell-powered LED (Light Emitting Diode) drive circuit and Bluetooth device | |
| CN106332406A (en) | LED driver circuit with multi-channel independent control | |
| CN201699683U (en) | Photoelectrical coupling circuit for improving data transfer rate | |
| CN104660233A (en) | Multiplex digital electronic branch switch | |
| CN103576597A (en) | Digital quantity input interface device, programmable logic controller comprising digital quantity input interface device and method of digital quantity input interface device | |
| CN203775494U (en) | An LED driving device and an LED dimming driving controller thereof | |
| CN103052201A (en) | LED control circuit, LED illuminating device and short circuit protection method | |
| CN102063082B (en) | Digital input circuit | |
| CN102223743B (en) | Light emitting diode (LED) driving control circuit and method thereof | |
| CN104049165A (en) | Electrical performance testing device of electromagnet | |
| CN104754800A (en) | Device for controlling input surge current of LED module | |
| CN204009435U (en) | A kind of based on monolithic processor controlled multi-channel DC relay drive circuit | |
| CN104362504A (en) | Light overshoot control circuit and light overshoot control method | |
| CN205566753U (en) | LED drive power supply attachs control circuit | |
| CN108594082A (en) | A kind of alternating current power-off signal transmission circuit and method | |
| CN104349528A (en) | Indicating lamp status display system | |
| CN203691701U (en) | Device for controlling input surge current of LED module | |
| CN206149552U (en) | A dimmer circuit for non - isolation LED drive power supply | |
| CN205726502U (en) | A kind of LED adjusting control circuit | |
| CN205946265U (en) | Linear constant -current drive circuit of full voltage LED | |
| CN105792443B (en) | It is driving IC power supply circuits in a kind of LED power |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| C06 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| AD01 | Patent right deemed abandoned |
Effective date of abandoning: 20170510 |
|
| AD01 | Patent right deemed abandoned |