JPH0519844A - Output circuit of controller - Google Patents
Output circuit of controllerInfo
- Publication number
- JPH0519844A JPH0519844A JP3173594A JP17359491A JPH0519844A JP H0519844 A JPH0519844 A JP H0519844A JP 3173594 A JP3173594 A JP 3173594A JP 17359491 A JP17359491 A JP 17359491A JP H0519844 A JPH0519844 A JP H0519844A
- Authority
- JP
- Japan
- Prior art keywords
- output
- controller
- voltage
- operational amplifier
- input voltage
- 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
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- Testing And Monitoring For Control Systems (AREA)
- Feedback Control In General (AREA)
Abstract
Description
【産業上の利用分野】本発明は、プロセス制御に使用さ
れる調節計に関する。FIELD OF THE INVENTION The present invention relates to a controller used for process control.
【従来の技術】従来の調節計をプロセス制御に使用した
構成を図２に示す。図２において、１はＰＶ指示計、２
はＳＶ指示計、３と４は連動する運転モード切換スイッ
チ、５はＰＩＤ演算回路、６は手動設定用可変電源、７
は手動操作用可変電源、８は出力回路、９は演算増幅
器、１０はトランジスタ、１１は出力指示計、１２はプ
ラス出力端子、１３はマイナス出力端子、１４は調節
計、１５は電空変換器、１６は記録計、１７は警報計、
ＰＶは測定値信号、ＳＶは設定値信号、Ｖｉは出力回路
の入力電圧、Ｒ１〜Ｒ４は抵抗、Ｖｃｅ（ｓａｔ）はコ
レクターエミッタ間飽和電圧、Ｖｏは出力電流Ｉｏのた
めの電源、Ｉｏは出力電流、ｒ１５は電空変換器の入力
抵抗、ｒ１６は記録計の入力抵抗、ｒ１７は警報計の入
力抵抗、ｒ１〜ｒ４は配線抵抗である。測定値信号ＰＶ
と設定値信号ＳＶの偏差はＰＩＤ演算回路５によりＰＩ
Ｄ演算され、運転モードスイッチ４を介して出力回路８
へ入力される。出力回路８へ入力された入力電圧Ｖｉ
（０〜１００％／ＤＣ１〜５Ｖ）は、演算増幅器９と抵
抗Ｒ１〜Ｒ４とトランジスタ１０で構成する電圧電流変
換回路により出力電流Ｉｏ（０〜１００％／ＤＣ４〜２
０ｍＡ）となり、調節計１４の出力端子１２と１３より
外部へ出力される。この調節計１４の出力は、プロセス
を制御するために電空変換器１５へ接続される。特に重
要な制御ループの場合は、調節計１４の出力を記録計１
６で記録したり、警報計１７にて異常表示する場合もあ
る。しかし、調節計１４の出力へ無制限に計器を接続す
ることはできない。数１式により許容負荷抵抗ＲＬとし
て制限される。2. Description of the Related Art FIG. 2 shows a configuration using a conventional controller for process control. In FIG. 2, 1 is a PV indicator, 2
Is an SV indicator, 3 and 4 are interlocked operation mode changeover switches, 5 is a PID arithmetic circuit, 6 is a variable power source for manual setting, 7
Is a variable power source for manual operation, 8 is an output circuit, 9 is an operational amplifier, 10 is a transistor, 11 is an output indicator, 12 is a positive output terminal, 13 is a negative output terminal, 14 is a controller, and 15 is an electropneumatic converter. , 16 is a recorder, 17 is an alarm,
PV is a measured value signal, SV is a set value signal, Vi is an input voltage of the output circuit, R1 to R4 are resistors, Vce (sat) is a collector-emitter saturation voltage, Vo is a power supply for the output current Io, and Io is an output. Current, r15 is the input resistance of the electropneumatic converter, r16 is the input resistance of the recorder, r17 is the input resistance of the alarm meter, and r1 to r4 are the wiring resistances. Measured value signal PV
The deviation between the set value signal SV and
D calculation is performed, and the output circuit 8 is output via the operation mode switch 4.
Is input to. Input voltage Vi input to the output circuit 8
(0 to 100% / DC1 to 5V) is output current Io (0 to 100% / DC4 to 2) by the voltage-current conversion circuit configured by the operational amplifier 9, the resistors R1 to R4, and the transistor 10.
0 mA), which is output from the output terminals 12 and 13 of the controller 14 to the outside. The output of this controller 14 is connected to an electropneumatic converter 15 for controlling the process. In the case of a particularly important control loop, the output of the controller 14 is recorded by the recorder 1
In some cases, the data may be recorded in 6 or the alarm meter 17 may display an abnormality. However, it is not possible to connect an unlimited meter to the output of the controller 14. The allowable load resistance RL is limited by the equation (1).
【数１】 一般に、許容負荷抵抗ＲＬの値は１０００Ωである。こ
れは、電空変換器の入力抵抗が３００Ω、記録計および
警報計の入力抵抗が２５０Ωであることに配線抵抗や余
有度を考慮して決められている。[Equation 1] Generally, the value of the allowable load resistance RL is 1000Ω. This is determined considering that the input resistance of the electropneumatic converter is 300Ω and the input resistance of the recorder and the alarm meter is 250Ω in consideration of wiring resistance and margin.
【発明が解決しようとする課題】上記従来技術では、調
節計１４の出力へ許容値を超えた抵抗を誤って接続した
場合、入力電圧Ｖｉの値が小さい時は、正常な出力電流
Ｉ0 が流れて良好なプロセス制御が出来るが、入力電圧
Ｖｉが大きくなっていくと、ある値より出力電流Ｉ0 が
一定となり、プロセス制御が出来なくなる。具体的に、
Ｖｏ＝２９Ｖ，Ｒ４＝２５０Ω，Ｖｃｅ（ｓａｔ）＝３
Ｖ，ＲＬ＝１０００Ωで設計された調節計に負荷抵抗Ｒ
Ｌ＝１２００Ωを接続出来るか考えてみると下記とな
る。Ｉ0＝４ｍＡのとき、数１式よりＲＬは、In the above prior art, when a resistance exceeding the allowable value is erroneously connected to the output of the controller 14, when the input voltage Vi has a small value, a normal output current I 0 is obtained. Although the current flows, good process control can be performed, but as the input voltage Vi increases, the output current I 0 becomes constant from a certain value, and process control becomes impossible. Specifically,
Vo = 29V, R4 = 250Ω, Vce (sat) = 3
The load resistance R is applied to the controller designed with V, RL = 1000Ω.
Considering whether L = 1200Ω can be connected, the following is obtained. When I 0 = 4 mA, RL is calculated from Equation 1 as follows.
【数２】 となりＲＬ＝１２００Ωは接続出来る。Ｉ0＝１２ｍＡ
のとき、数１式よりＲＬは、[Equation 2] Next, RL = 1200Ω can be connected. I 0 = 12 mA
Then, from equation 1, RL is
【数３】 となりＲＬ＝１２００Ωは接続出来る。しかし、Ｉ0＝
１７.９４ｍＡとなると、数１式よりＲＬは、[Equation 3] Next, RL = 1200Ω can be connected. However, I 0 =
At 17.94 mA, RL is
【数４】 となりＲＬ＝１２００Ωは接続出来ません。同様に、Ｉ
0＝２０.８ｍＡのときも、数１式よりＲＬは、[Equation 4] Next, RL = 1200Ω cannot be connected. Similarly, I
Even when 0 = 20.8 mA, RL is
【数５】 となりＲＬ＝１２００Ωは接続出来ません。上記より、
入力電圧ＶｉのＤＣ１〜５Ｖ変化に対して出力電流Ｉ0
はＤＣ４〜１７.９４ｍＡしか変化出来ないことがわか
る。本発明の目的は、上記問題点を防止するために調節
計１４に簡単な回路により負荷抵抗の値をチェックする
機能を設けた出力回路を提供することにある。[Equation 5] Next, RL = 1200Ω cannot be connected. From the above,
Output current I 0 with respect to DC1 to 5V change of input voltage Vi
It can be seen that can change only DC4 to 17.94 mA. An object of the present invention is to provide an output circuit in which the controller 14 is provided with a function of checking the value of the load resistance by a simple circuit in order to prevent the above problems.
【課題を解決するための手段】上記目的は、調節計の出
力端子間電圧を演算増幅器により求め、出力回路の入力
電圧Ｖｉと比較する回路を設けることにより達成され
る。The above object is achieved by providing a circuit for obtaining the voltage across the output terminals of the controller by an operational amplifier and comparing it with the input voltage Vi of the output circuit.
【作用】演算増幅器により求めた調節計の出力端子間電
圧が、出力回路の入力電圧Ｖｉより大きいときは比較器
の出力によりアラームランプ点燈やリレー駆動を行い、
調節計の運転員に負荷抵抗が許容値を超えていることを
知らせる。これにより、運転員は調節計の負荷抵抗が許
容値を超えていることを容易に判断出来、調節計の運転
を停止し、計装ループをチェックし、負荷抵抗が許容値
を超えないように計装ループの見直しを行う。When the voltage between the output terminals of the controller, which is obtained by the operational amplifier, is higher than the input voltage Vi of the output circuit, the alarm lamp is lit and the relay is driven by the output of the comparator.
Inform the operator of the controller that the load resistance exceeds the allowable value. This allows the operator to easily determine that the load resistance of the controller exceeds the allowable value, stop the operation of the controller, check the instrumentation loop, and make sure that the load resistance does not exceed the allowable value. Review the instrumentation loop.
【実施例】以下、本発明の一実施例を図１により説明す
る。図１において、１８は演算増幅器、１９は比較器、
２０は発光ダイオード、２１はリレー、２２はリレーの
逆起電力防止ダイオード、２３と２４は警報出力端子、
Ｒ５とＲ６は抵抗、Ｒ７は負荷抵抗、ＶＡは発光ダイオ
ード及びリレー用の電源、Ｖｃは演算増幅器の出力電圧
である。その他の符号は、図２の場合と同様である。出
力回路８の入力電圧Ｖｉにより出力電流Ｉ0が流れ、こ
の出力電流Ｉ0と負荷抵抗Ｒ７によりプラス出力端子１
２とマイナス出力端子１３間に発生した電圧を、演算増
幅器１８と抵抗Ｒ５とＲ６で構成される演算増幅回路に
より求める。ここで、抵抗Ｒ５をＲ５＝Ｋ・Ｒ６とする
と、演算増幅器１８の出力電圧Ｖｃは数６式となる。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, 18 is an operational amplifier, 19 is a comparator,
20 is a light emitting diode, 21 is a relay, 22 is a counter electromotive force prevention diode of the relay, 23 and 24 are alarm output terminals,
R5 and R6 are resistors, R7 is a load resistor, VA is a power source for the light emitting diode and the relay, and Vc is an output voltage of the operational amplifier. Other reference numerals are the same as those in FIG. An output current I 0 flows due to the input voltage Vi of the output circuit 8, and the positive output terminal 1 is caused by the output current I 0 and the load resistance R7.
The voltage generated between 2 and the negative output terminal 13 is obtained by the operational amplifier circuit composed of the operational amplifier 18 and the resistors R5 and R6. Here, assuming that the resistance R5 is R5 = K · R6, the output voltage Vc of the operational amplifier 18 is given by the equation (6).
【数６】 この出力電圧Ｖｃと入力電圧Ｖｉを比較器１９で比較す
る。比較器１９の出力は、Ｖｃ≦ＶｉのときＯＦＦし、
Ｖｃ＞ＶｉのときＯＮとなる。ここで、具体的に、Ｖｏ
＝２９Ｖ，Ｒ４＝２５０Ω，Ｖｃｅ（ｓａｔ）＝３Ｖ，
ＲＬ＝１０００Ω，Ｋ＝３、で設計された調節計に負荷
抵抗Ｒ７＝１２００Ωと１０００Ωを接続した場合につ
いて考えてみると下記となる。Ｒ７＝１２００Ωのとき
は、入力電圧Ｖｉ＝５Ｖで出力電流Ｉ0は１７.９４ｍＡ
で飽和しているので、出力電圧Ｖｃは数６式より、[Equation 6] The comparator 19 compares the output voltage Vc with the input voltage Vi. The output of the comparator 19 is turned off when Vc ≦ Vi,
It turns on when Vc> Vi. Here, specifically, Vo
= 29V, R4 = 250Ω, Vce (sat) = 3V,
Considering the case where the load resistors R7 = 1200Ω and 1000Ω are connected to the controller designed with RL = 1000Ω and K = 3, the following is obtained. When R7 = 1200Ω, the input voltage Vi = 5V and the output current I 0 is 17.94 mA.
Since it is saturated at, the output voltage Vc is
【数７】 となりＶｃ＞Ｖｉとなる。また、出力電流Ｉ0が飽和し
ないとき、（例えば入力電圧Ｖｉ＝１Ｖ，出力電流Ｉ0
＝４ｍＡ）でも、出力電圧Ｖｃを数６式より求めると、[Equation 7] Then Vc> Vi. When the output current I 0 is not saturated (for example, the input voltage Vi = 1 V, the output current I 0
= 4 mA), if the output voltage Vc is calculated from the equation 6,
【数８】 となりＶｃ＞Ｖｉとなる。上記の場合、いずれも比較器
１９の出力がＯＮとなり、負荷抵抗が許容値を超えてい
ることを、発光ダイオード２０を点燈することにより表
示すると共にリレー２１を駆動してその接点出力を警報
出力端子２３と２４へ出力する。次に、Ｒ７＝１０００
Ωのとき、入力電圧Ｖｉ＝５Ｖと１Ｖについて、出力電
圧Ｖｃを数６式より求めると、入力電圧Ｖｉ＝５Ｖ，出
力電流Ｉ0＝２０ｍＡの場合は、[Equation 8] Then Vc> Vi. In any of the above cases, the fact that the output of the comparator 19 is ON and the load resistance exceeds the allowable value is indicated by turning on the light emitting diode 20 and the relay 21 is driven to alarm its contact output. Output to the output terminals 23 and 24. Next, R7 = 1000
When the input voltage Vi = 5V and the input voltage Vi = 5V and 1V, the output voltage Vc is calculated from the equation (6). When the input voltage Vi = 5V and the output current I 0 = 20 mA,
【数９】 となりＶｃ＝Ｖｉとなる。入力電圧Ｖｉ＝１Ｖ，出力電
流Ｉ0＝４ｍＡの場合は、[Equation 9] Then, Vc = Vi. When the input voltage Vi = 1 V and the output current I 0 = 4 mA,
【数１０】 となりＶｃ＝Ｖｉとなる。上記の場合、いずれも比較器
１９の出力はＯＦＦとなり、発光ダイオード２０を消燈
させると共に、リレー２１も駆動しません。これによ
り、入力電圧Ｖｉと出力電圧Ｖｃを比較することによ
り、調節計１４の出力に接続された負荷抵抗が許容値を
超えているかいないかを検出することが出来る。[Equation 10] Then, Vc = Vi. In any of the above cases, the output of the comparator 19 is turned off, the light emitting diode 20 is turned off, and the relay 21 is not driven. Accordingly, by comparing the input voltage Vi with the output voltage Vc, it is possible to detect whether or not the load resistance connected to the output of the controller 14 exceeds the allowable value.
【発明の効果】本発明によれば、調節計の出力に接続さ
れた負荷抵抗の値が、許容値を超えているかいないか
を、容易に判断出来るので、本運転に入る以前に負荷抵
抗が許容値を超えないように対策出来る効果がある。ま
た、調節計の出力回路の負荷抵抗Ｒ７が断線などして出
力回路が開放となった場合は、調節計の出力端子間電圧
がＶｏ−Ｖｃｅ（ｓａｔ）となり、これによりＶｃ＞Ｖ
ｉとなるため出力回路の断線検出も可能となる。According to the present invention, it is possible to easily judge whether or not the value of the load resistance connected to the output of the controller exceeds the allowable value. There is an effect that measures can be taken so that the allowable value is not exceeded. When the load resistance R7 of the output circuit of the controller is opened and the output circuit is opened, the voltage between the output terminals of the controller becomes Vo-Vce (sat), which results in Vc> V.
Since it becomes i, it becomes possible to detect the disconnection of the output circuit.
【図１】本発明の一実施例の調節計の出力回路図であ
る。FIG. 1 is an output circuit diagram of a controller according to an embodiment of the present invention.
【図２】従来の調節計の出力回路図である。FIG. 2 is an output circuit diagram of a conventional controller.
８…出力回路、９…演算増幅器、１０…トランジスタ、
１４…調節計、１８…演算増幅器、１９…比較器、２０
…発光ダイオード、２１…リレー、２２…リレーの逆起
電力防止ダイオード、Ｖｉ…出力回路の入力電圧、Ｉ0
…出力電流、Ｖｃ…演算増幅器の出力電圧。8 ... Output circuit, 9 ... Operational amplifier, 10 ... Transistor,
14 ... Controller, 18 ... Operational amplifier, 19 ... Comparator, 20
... light-emitting diodes, 21 ... relay 22 ... relay of the counter electromotive force prevention diode, Vi ... input voltage of the output circuit, I 0
... Output current, Vc ... Output voltage of operational amplifier.
Claims (1)
れる調節計の出力回路において、調節計の出力端子間電
圧と前記演算増幅器の入力電圧を比較する比較器を設
け、調節計の出力端子間電圧が前記演算増幅器の入力電
圧を超えたことを前記比較器が検出したときは、前記比
較器出力により、リレー動作および発光ダイオード点燈
を行い、調節計の出力に接続される負荷抵抗が許容値を
超えていることを表示する機能を有することを特徴とす
る調節計の出力回路。Claim: What is claimed is: 1. An output circuit of a controller comprising an operational amplifier, a resistor and a transistor, wherein a comparator for comparing a voltage between output terminals of the controller and an input voltage of the operational amplifier is provided. When the comparator detects that the voltage between the output terminals of the controller exceeds the input voltage of the operational amplifier, relay output and lighting of a light emitting diode are performed by the output of the comparator and connected to the output of the controller. The output circuit of the controller, which has a function of indicating that the applied load resistance exceeds an allowable value.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3173594A JPH0519844A (en) | 1991-07-15 | 1991-07-15 | Output circuit of controller |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP3173594A JPH0519844A (en) | 1991-07-15 | 1991-07-15 | Output circuit of controller |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0519844A true JPH0519844A (en) | 1993-01-29 |
Family
ID=15963495
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP3173594A Pending JPH0519844A (en) | 1991-07-15 | 1991-07-15 | Output circuit of controller |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0519844A (en) |
-
1991
- 1991-07-15 JP JP3173594A patent/JPH0519844A/en active Pending
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