CN109884384B - Signal acquisition circuit compatible with current and voltage input - Google Patents
Signal acquisition circuit compatible with current and voltage input Download PDFInfo
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- CN109884384B CN109884384B CN201910264633.6A CN201910264633A CN109884384B CN 109884384 B CN109884384 B CN 109884384B CN 201910264633 A CN201910264633 A CN 201910264633A CN 109884384 B CN109884384 B CN 109884384B
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Abstract
The invention discloses a signal acquisition circuit compatible with current and voltage input, which comprises: signal input end, sampling resistor R S Filter capacitor C 1 Voltage follower circuit, in-phase proportional amplifying circuit and filter capacitor C 2 A signal output terminal; the signal input end is respectively connected with the sampling resistor R S Filter capacitor C 1 The input end of the voltage follower circuit is connected with the sampling resistor R S And filter capacitor C 1 The other end of the voltage follower circuit is grounded, the output end of the voltage follower circuit is connected with the input end of the in-phase proportional amplifying circuit, and the output end of the in-phase proportional amplifying circuit is respectively connected with the filter capacitor C 2 The signal output end is connected with the filter capacitor C 2 The other end of which is grounded. The signal acquisition circuit can complete the acquisition of + -10V voltage signals, can also complete the acquisition of 0-20mA current signals, and can convert the acquired signals into signals in the range of 0-2.5V and output the signals.
Description
Technical Field
The invention relates to the technical field of signal acquisition circuits, in particular to a signal acquisition circuit compatible with current and voltage input.
Background
Currently, the output signals of sensors and meters used in the industrial control field are generally in the form of standard 4-20mA current signals or 1-5V voltage signals, but in some cases, signals in other current or voltage ranges, such as 0-20mA, 0-10V, etc., exist. Typically, the industrial site will use a PLC (Programmable Logic Controller, programmable control device) or other acquisition module to acquire the signals output by these sensors. However, existing PLC or other acquisition modules typically have one acquisition channel that can only perform acquisition of one property signal (one of current or voltage) and the range of the input signal is limited. This requires that the type, characteristics, signal output form, etc. of the sensor must be known in advance when in use, greatly reducing the versatility of the acquisition module and increasing the complexity of wiring.
Disclosure of Invention
The embodiment of the invention provides a signal acquisition circuit compatible with current and voltage input, which is used for simultaneously being compatible with industrial standard current and voltage signals, so that an acquisition module does not need to consider the form of input signals when in use, and can be directly accessed as long as the signal range meets the requirement.
In order to solve the technical problems, the technical scheme adopted is as follows:
a current and voltage input compatible signal acquisition circuit comprising: signal input end, sampling resistor R S Filter capacitor C 1 Voltage follower circuit, in-phase proportional amplifying circuit and filter capacitor C 2 A signal output terminal; the signal input end is respectively connected with the sampling resistor R S Filter capacitor C 1 The input end of the voltage follower circuit is connected with the sampling resistor R S And filter capacitor C 1 The other end of the voltage follower circuit is grounded, the output end of the voltage follower circuit is connected with the input end of the in-phase proportional amplifying circuit, and the output end of the in-phase proportional amplifying circuit is respectively connected with the filter capacitor C 2 The signal output end is connected with the filter capacitor C 2 The other end of the first electrode is grounded; the in-phase proportional amplifying circuit is used for converting a signal input of 0-20mA or 0-10V into a signal output in a range of 1.25V-2.5V or converting a signal input of-10V-0 into a signal output in a range of 0-1.25V.
Optionally, the voltage follower circuit is composed of an operational amplifier F 1 F is formed of 1 The positive electrode input end of (a) is connected with the signal output end, F 1 The negative input terminal of which is connected to the output terminal thereof.
Optionally, the in-phase proportional amplifying circuit includes: operational amplifier F 2 Resistance R 1 、R 2 、R 3 And R is f -a 10V voltage source; operational amplifier F 2 Through resistor R 2 And F is equal to 1 Is connected with the output end of the power supply; operational amplifier F 2 Through resistor R 1 Is connected with a-10V voltage source; resistor R 3 And F at one end of (2) 2 The other end of the positive electrode is grounded; resistor R f And F at one end of (2) 2 Is connected with the negative electrode input end of F 2 Is connected with the output end of the power supply.
Optionally, a resistor R 1 ＝R 2 =12kohm, resistance R 3 ＝R f =1.5kohm, resistor R S =0.5K ohms; filter capacitor C 1 ＝C 2 ＝0.1uF。
Optionally, the signal acquisition circuit further includes a zener diode D 1 The negative electrode of the power supply is connected with the signal output end, and the positive electrode of the power supply is grounded.
Optionally, a zener diode D 1 Stable voltage uz=3.0v.
From the above technical solutions, the embodiment of the present invention has the following advantages:
the signal acquisition circuit comprises a sampling resistor, a voltage follower circuit formed by an operational amplifier at one stage and an in-phase proportional amplifying circuit formed by the operational amplifier at the other stage; the input end of the signal acquisition circuit is a sensor, and the output end is a sampling channel of an AD (Analog-to-Digital converter), so that the circuit can be used as a part of a signal acquisition module.
The signal acquisition circuit can complete the acquisition of voltage signals and current signals; which is capable of converting a 0-20mA current signal and a 0-10V voltage signal input into a signal output in the range of 1.25V-2.5V, and converting a-10V-0 voltage signal input into a signal output in the range of 0-1.25V; the range of 0-2.5V meets the voltage range requirements of most AD conversion modules. Therefore, the signal acquisition circuit can complete the acquisition of the 0-20mA current input signal and the + -10V voltage input signal, and compared with the existing acquisition module, the type of the acquired signal is expanded on the one hand, and the input range of the acquired signal is expanded on the other hand.
Further, the output signal passes through a capacitor C 2 Filtering and inputting into an AD acquisition channel, and a voltage stabilizing diode D 1 Can play a role in protection, and avoid the damage of accidental spike voltage to the acquisition channel.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
Fig. 1 is a circuit diagram of a signal acquisition circuit according to an embodiment of the present invention.
Detailed Description
In order that those skilled in the art will better understand the present invention, a technical solution in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in which it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
The terms "comprising" and "having" and any variations thereof in the description and claims of the invention and in the foregoing drawings are intended to cover non-exclusive inclusions. For example, a process, method, system, article, or apparatus that comprises a list of steps or elements is not limited to only those listed steps or elements but may include other steps or elements not listed or inherent to such process, method, article, or apparatus. The following will each explain in detail by means of specific examples.
Referring to fig. 1, the embodiment of the invention provides a signal acquisition circuit compatible with 0-20mA current and + -10V voltage input. The signal acquisition circuit includes: signal input end, sampling resistor R S Filter capacitor C 1 Voltage follower circuit, in-phase proportional amplifying circuit and filter capacitor C 2 A signal output terminal;
input signals from the sensor enter from the signal input end and pass through the capacitor C 1 After filtering, first enter the operational amplifier F 1 The voltage follower circuit can effectively improve input impedance and reduce output impedance, and has good isolation effect without changing signal amplitude.
The signal then passes through a pass-through operational amplifier F 2 In-phase proportional amplifying circuit composed of equal elements and capable of inputting 0-20mA and 0-10V signalsThe signal output is converted into a range of 1.25V-2.5V, and the signal input of-10V-0 is converted into a signal output in a range of 0-1.25V.
The signal output by the in-phase proportional amplifying circuit passes through a capacitor C 2 The filtered signals reach the signal output end and can be used as output signals to be input into an AD acquisition channel.
Wherein, the voltage stabilizing diode D 1 The protection function is achieved, and damage to the acquisition channel caused by accidental spike voltage can be avoided.
In fig. 1, since the net input current of the ideal integrated op-amp is zero, there is i f ＝i 1 Namely, the formula (1) holds:
wherein U is N And U P Respectively operational amplifiers F 2 Voltage at the negative and positive inputs, U o Is the voltage at the signal output.
The method can be obtained after simplifying the formula (1):
u is known according to the principle of virtual short of the in-phase and anti-phase input ends of the operational amplifier P ＝U N ＝U i ，U i Is an operational amplifier F 1 The positive electrode input terminal of (a), so that the formula (2) can be changed to the formula (3):
alternatively, the resistor r1=r2=12k ohms, r3=rf=1.5k ohms, and rs=0.5K ohms.
When the input signal is a current signal of 0-20mA, the sampling resistor R is used for s The 0-20mA current signal can be converted into a 0-10V voltage signal, so that the 0-20mA current signal and the 0-10V voltage signal can be summarized as the samethe-10V-0 voltage signal is another case. As can be seen from equation (3), when the signal is input, U i When=0, output signal U o =1.25v; when U is i When=10v, output signal U o =2.5v; when U is i When= -10V, output signal U o ＝0。
That is, the output signal ranges from 0V to 2.5V, which meets the voltage range requirements of most AD conversion modules. It can be seen that the signal acquisition circuit shown in fig. 1 can complete the acquisition of input signals of 0-20mA current and + 10V voltage.
The key points of the signal acquisition circuit are as follows:
1. the circuit comprises a sampling resistor, a voltage follower circuit formed by an operational amplifier at one stage and an in-phase proportional amplifying circuit formed by the operational amplifier at the other stage.
2. The input end of the circuit is a sensor, and the output end of the circuit is a sampling channel of AD, so that the circuit can be used as a part of a signal acquisition module.
Based on the characteristics, the signal acquisition circuit can be compatible with input signals of 0-20mA current and +/-10V voltage, and the input signal of the existing acquisition module at present can only be in a fixed form (current or voltage), and the input range is smaller. Therefore, the technical scheme of the invention better solves the problems in the prior art.
In the foregoing embodiments, the descriptions of the embodiments are each focused, and for those portions of one embodiment that are not described in detail, reference may be made to the related descriptions of other embodiments.
The above embodiments are only for illustrating the technical solution of the present invention, and are not limiting; those of ordinary skill in the art will appreciate that: the technical scheme described in the above embodiments can be modified or some technical features thereof can be replaced equivalently; such modifications and substitutions do not depart from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims (3)
1. A current and voltage input compatible signal acquisition circuit, comprising:
signal input end, sampling resistor R S Filter capacitor C 1 Voltage follower circuit, in-phase proportional amplifying circuit and filter capacitor C 2 A signal output terminal;
the signal input end is respectively connected with the sampling resistor R S Filter capacitor C 1 The input end of the voltage follower circuit is connected with the sampling resistor R S And filter capacitor C 1 The other end of the voltage follower circuit is grounded, the output end of the voltage follower circuit is connected with the input end of the in-phase proportional amplifying circuit, and the output end of the in-phase proportional amplifying circuit is respectively connected with the filter capacitor C 2 The signal output end is connected with the filter capacitor C 2 The other end of the first electrode is grounded;
the in-phase proportional amplifying circuit is used for converting 0-20mA or 0-10V signal input into signal output in the range of 1.25V-2.5V or converting-10V-0 signal input into signal output in the range of 0-1.25V;
the voltage follower circuit is composed of an operational amplifier F 1 F is formed of 1 The positive electrode input end of (a) is connected with the signal input end, F 1 The negative electrode input end of the capacitor is connected with the output end of the capacitor;
the in-phase proportional amplifying circuit includes: operational amplifier F 2 Resistance R 1 、R 2 、R 3 And R is f -a 10V voltage source;
operational amplifier F 2 Through resistor R 2 And F is equal to 1 Is connected with the output end of the power supply;
operational amplifier F 2 Through resistor R 1 Is connected with a-10V voltage source;
resistor R 3 And F at one end of (2) 2 The other end of the positive electrode is grounded;
resistor R f And F at one end of (2) 2 Is connected with the negative electrode input end of F 2 Is connected with the output end of the power supply;
also comprises a zener diode D 1 The negative electrode of the power supply is connected with the signal output end, and the positive electrode of the power supply is grounded.
2. The signal acquisition circuit of claim 1, wherein,
resistor R 1 ＝R 2 =12kohm, resistance R 3 ＝R f =1.5kohm, resistor R S =0.5K ohms;
filter capacitor C 1 ＝C 2 ＝0.1uF。
3. The signal acquisition circuit of claim 2, wherein,
voltage stabilizing diode D 1 Stable voltage uz=3.0v.
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| CN110134052B (en) * | 2019-06-19 | 2024-04-26 | 深圳市佳运通电子有限公司 | Digital signal acquisition circuit compatible with multiple output forms |
| CN110217661A (en) * | 2019-07-02 | 2019-09-10 | 比亦特网络科技（天津）有限公司 | A kind of novel Intelligent lift system with little Tong monitoring function |
| CN112630524A (en) * | 2021-03-05 | 2021-04-09 | 江苏瑞电智芯信息科技有限公司 | Low-current signal acquisition processing circuit and acquisition processing method |
| CN113485508A (en) * | 2021-07-09 | 2021-10-08 | 珠海格力电器股份有限公司 | Voltage reference regulating circuit, processing circuit and servo driver |
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| CN202059389U (en) * | 2011-04-29 | 2011-11-30 | 中国电子科技集团公司第三十六研究所 | Voltage sampling circuit |
| CN204272074U (en) * | 2014-12-11 | 2015-04-15 | 力合科技（湖南）股份有限公司 | Switching value input circuit and there is its water quality monitoring harvester |
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