CN2672633Y - Multipath temperature signal pretreating circuit - Google Patents

Abstract

The utility model relates to a front-end electronic device controlled by a computer, used for temperature sensor signal collection and processing, and having multiple signal collection and processing channels. It is mainly used in large-scale multi-measurement point temperature automatic monitoring and control system. A multi-channel temperature signal preprocessing circuit, including an organic case, multiple temperature signal inputs, and a reference voltage generation circuit. In the multi-channel output modulation circuit, the multi-channel output modulation circuit outputs signals; the reference voltage generation circuit is connected to the input end of the input circuit; the output end of the input circuit is connected to the amplifier circuit and then connected to the multi-channel output modulation circuit or the output end of the input circuit The signal processing circuit of the reference terminal (cold terminal) is further connected to the multi-channel output modulation circuit, and the two connection modes are selected and set by jumpers/switches; the computer control terminal is connected to the multi-channel output modulation circuit. The utility model has strong applicability, and is a front-end device that can be used for collecting and processing thermocouple signals, and can also be used for collecting and processing thermal resistance signals; the integration degree is high, and the number of channels included in a single machine is large; multiple channels are simultaneously collected and processed, Fast processing.

Description

Multi-channel temperature signal preprocessing circuit (2)

Technical field:

The utility model relates to a front-end electronic device controlled by a computer, used for temperature sensor signal collection and processing, and having multiple signal collection and processing channels. It is mainly used in large-scale multi-measurement point temperature automatic monitoring and control system.

Background technique:

At present, the temperature signal measurement or monitoring equipment for a single measurement point has been commercialized no matter whether it uses a thermistor or a thermocouple as a temperature measurement element. However, as a standard, multi-channel, computer-controlled, it is not only suitable for thermocouples as temperature sensors, but also suitable for thermistors as temperature sensors, and can be used for large-scale temperature sensors with multiple measurement points. The temperature signal acquisition and processing equipment of the automatic monitoring and control system is still seen.

Invention content:

The purpose of the utility model is to avoid the disadvantages of the prior art and provide a multi-channel temperature signal preprocessing circuit. Used for the acquisition and preprocessing of temperature sensor signals, it is a computer-controlled multi-channel temperature signal acquisition and processing equipment, through which multi-point temperature monitoring can be realized. It is mainly used in large-scale multi-point temperature automatic monitoring and control systems.

The purpose of this utility model can be realized by adopting the following technical solutions: a multi-channel temperature signal preprocessing circuit, including a cabinet, a plurality of temperature signal inputs (CH _x ), a reference voltage generation circuit (C), its main features include Multiple input circuits (A _x ) are connected to corresponding multiple temperature signal inputs (CH _x ) and amplification circuits (B _x ); the amplification circuits (B _x ) are connected to the multi-output modulation circuit (F), and the multiple output The modulation circuit (F) outputs the signal; the reference voltage generating circuit (C) is connected to the input end of the input circuit (A _x ); the output end of the input circuit (A _end ) is connected to the amplifier circuit (B _end ) and then to the multi-channel output modulation circuit (F) Connection or the output terminal of the input circuit ( _end A) is connected to the reference terminal (cold terminal) signal processing circuit (D) and then connected to the multi-output modulation circuit (F). The two connection methods use jumpers/ Switch selection setting; the computer control terminal is connected to the multi-channel output modulation circuit (F).

The multi-channel temperature signal preprocessing circuit also includes the multiple temperature signal inputs (CH _x ), multiple input circuits (A _x ), and multiple amplifying circuits (B _x ), where X is 1-256 .

The utility model also includes a manual control circuit (E) connected with a multi-channel output modulation circuit (F).

The input circuit (A _x ) is a bridge composed of R ₁ , R ₂ , R ₃ and a thermistor R _t ; R _t is an external thermistor, and its AGND terminal is an analog signal ground terminal, and H' The terminal with L' is the output terminal, and adopts the three-wire system input connection mode.

The input circuit (A _x ) described above can also form a bridge circuit composed of R ₁ , R ₂ , R ₃ and thermocouples, except that R ₁ and R ₂ are defaulted, R ₃ is short-circuited, and the AGND terminal is an analog signal ground Terminals, H' and L' terminals are output terminals, using two-wire input mode.

The amplifying circuit (B _x ) of the utility model is that the output terminal H' of the input circuit (A _x ) is connected to the positive input terminal of the ultra-low bias voltage drift operational amplifier _A1 through a resistor RA, and the analog signal ground terminal AGND is connected through a capacitor CA Between the H' terminal and the positive input terminal of the ultra-low bias voltage drift operational amplifier A ₁ ; the analog signal ground terminal AGND is connected to the H' terminal and the positive input terminal of the ultra-low bias voltage drift operational amplifier A ₁ through a resistor RF or RG Between, RF or RG can be selected through jumpers/switches; the output of amplifier A ₁ is connected to the multi-output modulation circuit (F).

The amplifying circuit (B _x ) also includes an output terminal L' of the input circuit (A _x ) connected to the negative input terminal of the ultra-low bias voltage drift operational amplifier _A1 through a resistor RB, and the analog signal ground terminal AGND is connected through a capacitor CB Connected between the L' terminal and the negative input terminal of the ultra-low bias voltage drift operational amplifier A ₁ ; the resistors RH and RI are connected in parallel between the negative input terminal and the output terminal of the operational amplifier A ₁ , and RH and RI can be connected through the jumper/ switch to select.

The reference terminal (cold terminal) signal processing circuit (D) of the multi-channel temperature signal preprocessing circuit, the analog signal ground terminal AGND is connected to the positive input terminal of the ultra-low bias voltage drift operational amplifier U ₁ through the resistor R6; the analog signal ground terminal AGND is connected to the negative input terminal of the ultra-low bias voltage drift operational amplifier U ₁ through Q3, C4, R5, and P1; the analog signal ground terminal AGND is connected to P1 and the negative input terminal of the ultra-low bias voltage drift operational amplifier U ₁ through C3; P2 and R7 are connected between the negative input terminal and output terminal of U ₁ ; the "+" terminal of the sensor SENSOR is connected to the negative input terminal of the ultra-low bias voltage drift operational amplifier U ₁ , and the "-" terminal is connected to the negative voltage source -V, The sensor can be built-in (that is, connected inside the case) or external (that is, connected outside the case).

The multi-channel output modulating circuit F of the described multi-channel temperature signal preprocessing circuit has a multi-channel modulation output device, which adopts high-precision, high-speed analog switches to form; there is also a decoding circuit, which realizes the gating control function, and it is mainly composed of a decoding circuit. Encoder and some logic devices; there is a box number identification circuit, which is also the gate signal generation circuit of the decoding circuit. The box number identification circuit is composed of a numerical comparator, a switch and other components; at the same time, there is an output buffer/isolation circuit, and an output buffer/isolation circuit is set in the multi-channel output modulation circuit F, which is a follower composed of an integrated operational amplifier. circuit; the multi-channel output modulation circuit F has two output modes to choose from, one is a buffer output mode, that is, the output signal is output through the above-mentioned output buffer/isolation circuit; the other is a direct output mode, that is, it does not pass through the output buffer/isolation circuit, And directly output the signal; two ways can be selected and set through the output mode selection jumper/switch.

The rear panel of the chassis is provided with connectors, which are cascade input connectors and cascade output connectors; the front panel of the chassis is provided with channel input connectors; the front panel of the chassis is provided with 220VAC voltage indicators; There is also an AC voltage input on-off control switch and a fuse box.

The beneficial effect of the utility model is that it has strong applicability, and it is a front-end device that can be used to collect and process thermocouple signals and heat resistance signals; it has high integration, and the number of channels included in a single machine is large; Simultaneous collection and processing of channels, fast processing speed; high sensitivity, the minimum amplitude of the input signal is in the order of μV; multiple selection 1 modulation output mode is implemented; computer control, multi-chassis cascading can be implemented.

Description of drawings:

Fig. 1 is the circuit structure block diagram of the utility model embodiment;

Fig. 2 is the structural block diagram of the first kind of input circuit of the utility model;

Fig. 3 is the structural block diagram of the second input circuit of the utility model;

Fig. 4 is the structural block diagram of amplifying circuit of the present utility model;

Fig. 5 is a structural block diagram of the reference junction (cold junction) signal processing circuit of the present invention.

Detailed ways:

Below in conjunction with the preferred embodiment shown in accompanying drawing, be described in further detail:

As shown in Figure 1, the multi-channel temperature signal preprocessing circuit has a chassis, multiple temperature signal inputs CH _x , and a reference voltage generation circuit C. Its main features include multiple input circuits A _x and corresponding multiple temperature signal inputs CH _x , the amplifier circuit B _x is connected; the amplifier circuit B _x is connected to the multi-channel output modulation circuit F, and the multi-channel output modulation circuit F outputs signals; the reference voltage generation circuit C is connected to the input end of the input circuit A _x ; the output of the input circuit A _end The terminal is connected to _{the end of} the amplifier circuit B and then connected to the multi-channel output modulation circuit F or the output terminal _of the input circuit A is connected to the reference terminal (cold terminal) signal processing circuit D and then connected to the multi-channel output modulation circuit F, two connection methods Use jumpers/switches to select settings; the computer control terminal is connected to the multi-channel output modulation circuit F. There are 32 Xs of multiple temperature signal inputs CH _x , multiple input circuits A _x , and multiple amplifier circuits B _x . It can realize cascade connection of multiple chassis, direct control by a single computer, and can cascade up to eight chassis, reaching 256 input channels. The manual control circuit E is connected with the multi-channel output modulation circuit F.

Figure 2 is a structural block diagram of the first input circuit. The input circuit A _x is a bridge composed of R ₁ , R ₂ , R ₃ and thermistor R _t ; R _t is an external thermistor, its AGND terminal is the analog signal ground terminal, and the H' and L' terminals are The output terminal adopts the three-wire system input connection mode.

Figure 3 is a block diagram of the second input circuit structure. The input circuit A _x can also form a bridge circuit composed of R ₁ , R ₂ , R ₃ and thermocouples, but R ₁ and R ₂ are defaulted, R ₃ is short-circuited, and its AGND terminal is the analog signal ground terminal, H The 'and L' end is the output end, and the two-wire input connection is adopted.

Figure 4 is a block diagram of the amplifier circuit. The amplifying circuit B _x is the output terminal H' of the input circuit A _x , which is connected to the positive input terminal of the ultra-low bias voltage drift operational amplifier A ₁ through the resistor RA, and the analog signal ground terminal AGND is connected to the H' terminal and the ultra-low bias voltage through the capacitor CA. Placed between the positive input terminals of the voltage drift operational amplifier A ₁ ; the analog signal ground terminal AGND is connected between the H' terminal and the positive input terminal of the ultra-low bias voltage drift operational amplifier A ₁ through a resistor RF or RG, and RF or RG can pass through The jumper/switch is selected; the output terminal of the amplifier A ₁ is connected with the multi-channel output modulation circuit F.

The amplifying circuit B _x also includes the output terminal L' of the input circuit A _x connected to the negative input terminal of the ultra-low bias voltage drift operational amplifier A ₁ through a resistor RB, and the analog signal ground terminal AGND is connected to the L' terminal and the ultra-low bias voltage drift operational amplifier through a capacitor CB. Low bias voltage drift between the negative input terminals of operational amplifier _A1 ; resistors RH and RI are connected in parallel between the negative input terminal and output terminal of operational amplifier _A1 ; RH and RI can be selected by jumpers/switches.

Fig. 5 is a structural block diagram of the reference junction (cold junction) signal processing circuit. The reference terminal (cold terminal) signal processing circuit D of the multi-channel temperature signal preprocessing circuit, the analog signal ground terminal AGND is connected to the positive input terminal of the ultra-low bias voltage drift operational amplifier U ₁ through the resistor R6; the analog signal ground terminal AGND passes through Q3, C4, R5, and P1 are connected to the negative input terminal of the ultra-low bias voltage drift operational amplifier U ₁ ; the analog signal ground terminal AGND is connected to P1 and the negative input terminal of the ultra-low bias voltage drift operational amplifier U ₁ through C3; P2 , R7 is connected between the negative input terminal and output terminal of U ₁ ; the "+" terminal of the sensor SENSOR is connected to the negative input terminal of the ultra-low bias voltage drift operational amplifier U ₁ , and the "-" terminal is connected to the negative voltage source -V, the sensor It can be built-in (that is, connected inside the case) or external (that is, connected outside the case). The reference junction (cold junction) signal processing circuit is used to collect and process the temperature signal at the reference junction. It is an inverting summing amplifier circuit, which is composed of an operational amplifier with ultra-low bias voltage and ultra-low bias voltage drift, and its circuit form is an inverting summing amplifier circuit. The summation circuit has two input branches, one is from the static bias current generation circuit, which is mainly composed of low temperature drift coefficient reference diode Q3 and bias resistors R5 and P1; the other is from the temperature sensor, as mentioned above, the temperature sensor It can be built-in (that is, installed on the circuit board and placed inside the box), or external (that is, placed outside the box), and the lead wire enters the circuit inside the box through the input connector of the 32nd channel; each chassis The 32nd channel is a special channel, it can accept the signal input of thermocouple or thermal resistance, also can accept the signal input of external sensor, use jumper/switch to select and switch between different input modes.

The rear panel of the box of the multi-channel temperature signal preprocessing circuit is provided with connectors, which can be cascade input connectors and cascade output connectors; the front panel of the box is provided with channel input connectors; multi-channel temperature signal preprocessing The circuit is powered by 220VAC voltage. The 220VAC input connector is a single-phase 3-PIN universal socket. The 220VAC input connector is located on the rear panel of the box. There is also a 220VAC input on-off control switch and a fuse installed on the rear panel of the instrument. box, the front panel of the chassis is provided with a 220VAC voltage indicator light.

The manual control circuit E is a logic level setting circuit, which is composed of switches and TTL inverters. This circuit can also realize the multi-choice 1 modulation output function. When working in a single chassis, it can realize 32-choice 1 modulation output; when working in multiple chassis, it can realize up to 256-choose 1 modulation output.

Multi-output modulation circuit F has multi-channel modulation output devices, which are composed of high-precision, high-speed analog switches; there is also a decoding circuit to realize the gating control function, which is mainly composed of decoders and some logic devices; there is a box Number identification circuit, which is also the strobe signal generation circuit of the decoding circuit. The box number identification circuit is composed of a numerical comparator, a switch and other components; at the same time, there is an output buffer/isolation circuit, and an output buffer/isolation circuit is set in the multi-channel output modulation circuit F; it is a follower composed of an integrated operational amplifier circuit. The multi-channel output modulation circuit F has two output modes to choose from, one is the buffer output mode, that is, the output signal is output through the above-mentioned output buffer/isolation circuit; the other is the direct output mode, that is, it does not pass through the output buffer/isolation circuit, but directly output signal. Both methods can be selected by setting the output mode selection jumper/switch.

Claims (10)

1. A multi-channel temperature signal preprocessing circuit, comprising a casing, a plurality of temperature signal inputs (CH _x ), a reference voltage generating circuit (C), and its feature includes a plurality of input circuits (A _x ) corresponding to it A temperature signal input (CH _x ) is connected to the amplifying circuit (B _x ); the amplifying circuit (B _x ) is connected to the multi-channel output modulation circuit (F), and the multi-channel output modulation circuit (F) outputs signals; the reference voltage generation circuit ( C) Connect to the input end of the input circuit (A _x ); the output end of the input circuit (A _end ) is connected to the amplifier circuit (B _end ) and then connected to the multi-channel output modulation circuit (F) or the output of the input circuit (A _end ) The terminal is connected to the reference terminal (cold terminal) signal processing circuit (D) and further connected to the multiple output modulation circuit (F); the computer control terminal is connected to the multiple output modulation circuit (F). 2. multi-channel temperature signal preprocessing circuit as claimed in claim 1, it is characterized in that also comprising described a plurality of temperature signal inputs (CH _x ), a plurality of input circuits (A _x ), a plurality of amplifying circuits (B _x ) of X is 1-256. 3. The multi-channel temperature signal preprocessing circuit according to claim 1 or 2, further comprising a manual control circuit (E) connected to a multi-channel output modulation circuit (F). 4. multi-channel temperature signal preprocessing circuit as claimed in claim 3 is characterized in that input circuit (A _x ), the electric bridge that is made up of R ₁ , R ₂ , R ₃ and thermistor R ₁ ; R ₁ is External thermistor, its AGND terminal is the analog signal ground terminal, and the H' and L' terminals are the output terminals. 5. The multi-channel temperature signal preprocessing circuit as claimed in claim 4, characterized in that the input circuit (A _x ) is a bridge circuit made up of R ₁ , R ₂ , R ₃ and thermocouples; wherein R ₁ , R ₂ is defaulted, R ₃ is short-circuited, its AGND terminal is the analog signal ground terminal, and the H' and L' terminals are output terminals. 6. The multi-channel temperature signal preprocessing circuit according to claim 5, characterized in that the amplifying circuit (B _x ) is an output terminal H' of the input circuit (A _x ) connected to an ultra-low bias voltage drift operation through a resistor RA The positive input terminal of the amplifier A ₁ , the analog signal ground terminal AGND is connected between the H' terminal and the ultra-low bias voltage drift operational amplifier A ₁ positive input terminal through the capacitor CA; the analog signal ground terminal AGND is connected to the terminal through the resistor RF or RG Between the H' terminal and the positive input terminal of the ultra-low bias voltage drift operational amplifier A ₁ , RF or RG can be selected by a jumper/switch; the output terminal of the amplifier A ₁ is connected to the multi-output modulation circuit (F). 7. The multi-channel temperature signal preprocessing circuit according to claim 6, characterized in that the amplifying circuit (B _x ) also includes an output terminal L' of the input circuit (A _x ) connected to an ultra-low bias voltage through a resistor RB The negative input terminal of the drift operational amplifier A ₁ , the analog signal ground terminal AGND is connected between the L' terminal and the negative input terminal of the ultra-low bias voltage drift operational amplifier A ₁ through the capacitor CB; the resistors RH and RI are connected in parallel to the negative input terminal of the operational amplifier A ₁ Between the input terminal and the output terminal, RH and RI can be selected by jumpers/switches. 8. The multi-channel temperature signal preprocessing circuit as claimed in claim 7, is characterized in that it also includes a reference junction (cold junction) signal processing circuit (D), and the analog signal grounding terminal AGND is connected to the ultra-low bias through a resistor R6 Set the positive input terminal of the voltage drift operational amplifier U ₁ ; the analog signal ground terminal AGND is connected to the negative input terminal of the ultra-low bias voltage drift operational amplifier U ₁ through Q3, C4, R5, and P1; the analog signal ground terminal AGND is connected to P1 through C3 and ultra-low bias voltage drift operational amplifier U ₁ negative input; P2 and R7 are connected between the negative input and output of U ₁ ; the "+" end of the sensor SENSOR is connected to the ultra-low bias voltage drift operational amplifier U ₁ negative The input terminal, and the "-" terminal is connected to the negative voltage source -V, and the sensor can be built-in (that is, connected inside the chassis) or external (that is, connected outside the chassis). 9. multi-channel temperature signal preprocessing circuit as claimed in claim 8, it is characterized in that also comprising multi-channel output modulation circuit F multi-channel modulation output device, comprises decoding circuit, realizes gating control function, by decoding Composed of devices and logic devices; there is a box number identification circuit, which is also a strobe signal generation circuit for the decoding circuit; the box number identification circuit is composed of numerical comparators and switches; An output buffer/isolation circuit is set in the circuit F, and a follower circuit composed of an integrated operational amplifier is adopted; the output mode of the multi-channel output modulation circuit F is a buffer output mode, and the output signal or direct output mode is output through the above-mentioned output buffer/isolation circuit, That is, the signal is directly output without the output buffer/isolation circuit; the two methods can be selected and set through the output mode selection jumper/switch. 10. multi-channel temperature signal preprocessing circuit as claimed in claim 9, it is characterized in that also comprising that the rear panel of cabinet is provided with connector, is the cascade connection input connector and is the cascade connection output connector; The front panel of cabinet is provided with Channel input connector; the front panel of the chassis is provided with a 220VAC voltage indicator; the rear panel of the chassis is also equipped with an AC voltage input on-off control switch and a fuse box.

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