CN102082463B - Method for realizing redundancy of 4-20-mA current output in distributed control system (DCS) and circuit - Google Patents
Method for realizing redundancy of 4-20-mA current output in distributed control system (DCS) and circuit Download PDFInfo
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- CN102082463B CN102082463B CN2011100272322A CN201110027232A CN102082463B CN 102082463 B CN102082463 B CN 102082463B CN 2011100272322 A CN2011100272322 A CN 2011100272322A CN 201110027232 A CN201110027232 A CN 201110027232A CN 102082463 B CN102082463 B CN 102082463B
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Abstract
The invention relates to a method for realizing redundancy of 4-20-mA current output in a distributed control system (DCS). In the method, two 4-20-mA current output modules are provided; and the data output (DO) of each module is connected to the data input (DI) of the other module respectively. In the method, 1) when one output module detects that the state of a DI channel changes, the output current of the 4-20-mA current module is the actually required output current; 2) when one current output module detects that the state of the DI channel does not change, the output DO channel current of the other current module with redundancy function is below 1/2 of the actually required output current; and 3) when one current output module detects that the circuit output state of a feedback circuit, namely a current effectiveness detection circuit, changes, the module cuts off the current output through a switch, sets the own DO and informs the other current output module by changing the DO state, and the other current output module which receives a DO signal doubles the output current of the corresponding channel, so that the current redundancy output function is realized.
Description
Technical field
The present invention relates to redundant implementation method and unique electric current validity testing circuit of 4-20mA electric current output in a kind of DCS system, belong to the industrial control technology field.
Background technology
Be transformed into 4-20mA electric current output loop and be widely used, be used as two aspects usually at industrial control field:
1) transducer and transmitter play a part very important in instrument and meter and industrial automation field.In industrial control process, often need measure some parameters, and general signal of sensor a little less than, uncomfortable cooperation long-distance transmissions.The 4-20mA current circuit is owing to have the better resisting interference performance than voltage modulation signal, and signal is fit to long-distance transmissions, therefore becomes the standard of industrial process control.So the 4-20mA current circuit of standard has number of applications in industrial process control.
2) in addition, at industrial control field, using equipment such as a large amount of valves, motor, these equipment all are the 4-20mA current drives.Under present universal pattern, the output of 4-20mA electric current all is single output, does not possess redundancy feature, and the validity of electric current output can not be fed back fast.Like this because the module hardware fault when causing the size of current of size of current and required output of actual output widely different, will cause the said equipment cisco unity malfunction, in the time of seriously even can cause the production fault.
In order to guarantee the reliability of output current, must export the configuring redundancy function to electric current.
Summary of the invention
Technical problem to be solved by this invention provides the redundant implementation method of 4-20mA electric current output in a kind of DCS system; Guarantee the reliability of output current and adopt unique electric current validity testing circuit, propose a kind of circuit that does not under normal circumstances cause too big redundant current output.Use method described in the invention, at first can detect the validity of electric current output easily; Secondly can realize reliable and stable 4-20mA current redundant output.
The redundant implementation method of 4-20mA electric current output in a kind of DCS system; It is characterized in that; Be provided with 4-20mA electric current two electric current output modules A and B simultaneously; Each electric current output module all has the 4-20mA current output channels DO of DI input channel and redundancy feature, and the DO output of two modules is linked into the DI input of another module respectively.
When 1) said a certain output module detected the DI channel status and changes, then the output current of this 4-20mA electric current module size was the electric current of actual requirement output; When 2) a certain electric current output module detected the DI channel status and do not change, another electric current module output DO channel current size that then possesses redundancy feature was actual below 1/2 of output current that requires; 3) a certain electric current output module is that electric current validity testing circuit output state is when changing detecting feedback circuit; And judge with following detection mode: two 4-20mA electric current output module A are equipped with B and feed back and testing circuit: the electric current output module is exported linear voltage U, the sampling resistor of the 5-30 ohm of connecting separately on the DO electric current output loop of two modules; Through a differential amplifier circuit voltage drop that produces on this sampling resistor is amplified to U approachingly, requires error less than 1%U (can adjust) according to actual conditions; Calculate U-U0 through subtraction circuit, and difference is imported a comparison circuit; With the threshold value of 1%U-2%U as comparison circuit; When the output valve of subtraction circuit during greater than 1%U-2%U; Then electric current validity testing circuit output state changes: this module of electric current output this moment is through the output of switch excision electric current, with the DO output set of self; And, notify another electric current output module through changing the DO state, another electric current output module that receives this DO signal doubles the electric current output of respective channel, accomplishes the current redundant output function.
The redundancy of 4-20mA electric current output realizes circuit in the DCS system, it is characterized in that electric current output module A and electric current output module B are configured to one group of redundant module of exporting with B; The DO electric current output of said two modules is linked into the other side's DI input respectively; The DO electric current output-parallel of two modules is to the two ends of load; The DO electric current output of two electric current output modules is connected or is excised through a switch; Two modules are separately through setting up feedback circuit to detect output current, the sampling resistor of the 5-30 ohm of connecting separately on the DO electric current output loop of two modules; The voltage of sampling resistor is through a differential amplifier circuit; The voltage drop that produces on this sampling resistor is amplified to U0; Be provided with subtraction circuit and connect differential amplifier circuit and electric current output module respectively and export linear voltage U and calculate U-U0, the difference of the output of differential amplifier circuit is imported a comparison circuit; With the threshold value of 1%U-2%U as comparison circuit, when the output valve of subtraction circuit during greater than 1%U-2%U, then the output state of comparison circuit changes.Then through the electric current output excision of switch with self, and with self DO output set.
Operation principle of the present invention is: the electric current output module is exported linear voltage U, and through the voltage/current conversion circuit, the electric current varies directly with the voltage in feasible output.The electric current of output flows through one 10 ohm resistance, and the process differential amplifier circuit is amplified to this ohmically pressure drop with the voltage of current output approaching, requires error less than 1%U (can adjust according to actual conditions); Two voltages calculate its difference through subtraction circuit and as the input of comparator, 1% (can adjust according to actual conditions) of the linear voltage of output are used as the threshold value of comparator.Like this, when the output state of comparator changed, the error between the electric current of then expression reality output and the electric current that needs to export had surpassed the degree that can bear; This moment, the electric current output module was through the output of switch excision electric current, and through changing the electric current output module that one road DO state notifying matches with it, and the electric current output module that receives this DO signal doubles the electric current output of respective channel, accomplishes the current redundant output function.
The invention has the beneficial effects as follows: guarantee the reliability of output current and adopt unique electric current validity testing circuit, propose a kind of circuit that does not under normal circumstances cause too big redundant current output.Use method described in the invention, at first can detect the validity of electric current output easily; Secondly can realize reliable and stable 4-20mA current redundant output.The failure condition that solution runs in the use for the electric current output module is at the scene realized stable linear current output through the voltage/current conversion circuit.
Embodiment
Below in conjunction with accompanying drawing the present invention is described further.
Fig. 1 is the structure chart of one group of current redundant output; Fig. 2 is unique output current validity testing circuit structure chart.
As shown in Figure 1, module A and module B are configured to the module of one group of redundant output.The DO output of two modules is linked into the other side's DI input respectively; The electric current output-parallel of two modules is to the two ends of load; The electric current output of two modules can be connected or excise through a switch; Connect separately on the electric current output loop of two modules one 10 ohm sampling resistor, this resistance can not be too big, has influence on load-carrying ability if cross conference; Two modules detect the validity of output current through inventing described feedback circuit separately.Two modules detect the DI state of self earlier when receiving the instruction of wanting the output current size, when the DI state did not change, the output current size was for requiring 1/2 of output current; When the DI state that two modules detect self changes, then as requested size of current output; When two modules change at the feedback loop state that detects self, then through the electric current output excision of switch with self, and with self DO output set.
As shown in Figure 2, the invention describes the validity that a kind of feasible feedback circuit detects self output current.For the electric current output module, the failure condition that runs in the use at the scene is generally two kinds: no-output electric current and electric current output are less than normal.Usually the electric current output module is through exporting a linear voltage U, and realizes linear current output through the voltage/current conversion circuit, and the size of output current and linear voltage U are directly proportional; One 10 ohm resistance of series connection in the electric current output loop is because this resistance can reduce the load-carrying ability of circuit, so resistance can not be too big; Through a differential amplifier circuit voltage drop that produces on this sampling resistor is amplified to U0, requires U-U0 < 1%U; Calculate U-U0 through subtraction circuit, and difference is imported a comparison circuit; With the threshold value of 1%U as comparison circuit, when the output valve of subtraction circuit during greater than 1%U, then the output state of comparison circuit changes.Module detects this state displacement when effective (be anti-state frequent variations here this moment, module can disappear through software and tremble delay function and avoid this problem), through the electric current output excision of switch with self, and with self DO output set.
Below only with most preferred embodiment the present invention is done further explanation, so it is not to qualification of the present invention, and protection scope of the present invention is as the criterion with the content that is illustrated in claim.
Claims (1)
1. the redundant implementation method of 4-20mA electric current output in the DCS system; It is characterized in that; Be provided with 4-20mA electric current two electric current output modules A and B simultaneously; Each electric current output module all has the 4-20mA current output channels DO of DI input channel and redundancy feature, and the DO output of two modules is linked into the DI input of another module respectively; When 1) said a certain output module detected the DI channel status and changes, then the output current of this 4-20mA electric current module size was the electric current of actual requirement output; When 2) a certain electric current output module detected the DI channel status and do not change, another electric current module DO output channel size of current that then possesses redundancy feature was actual 1/2 of the output current that requires; 3) a certain electric current output module is that electric current validity testing circuit output state is when changing detecting feedback circuit; And judge with following detection mode: two 4-20mA electric current output module A and B are equipped with feedback circuit: the electric current output module is exported linear voltage U, the sampling resistor of the 5-30 ohm of connecting separately on the 4-20mA current output channels DO output loop of two modules; Through a differential amplifier circuit voltage drop that produces on this sampling resistor is amplified to U approachingly, differential amplifier circuit output voltage U 0 requires error less than 1%U; Calculate U-U0 through subtraction circuit, and difference is imported a comparison circuit; With the threshold value of 1%U as comparison circuit, when the output valve of subtraction circuit during greater than 1%U, then electric current validity testing circuit output state changes: this module of electric current output this moment is through the output of switch excision electric current, with the DO output set of self; And, notify another electric current output module through changing the DO state, another electric current output module that receives this DO signal doubles the electric current output of respective channel, accomplishes the current redundant output function.
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| CN103309329B (en) * | 2013-06-08 | 2016-01-06 | 杭州和利时自动化有限公司 | redundant output device |
| EP3336624B1 (en) * | 2016-12-19 | 2019-02-06 | Siemens Aktiengesellschaft | Arrangement with two redundant boards which monitor each other |
| CN109164787A (en) * | 2018-08-31 | 2019-01-08 | 杭州和利时自动化有限公司 | A kind of analog signals acquisition device |
| CN109600885B (en) * | 2019-01-11 | 2020-10-23 | 威创集团股份有限公司 | Large-current redundancy driving device |
| CN112162479B (en) * | 2020-11-05 | 2023-03-24 | 国核自仪系统工程有限公司 | Self-adaptive analog quantity redundancy output circuit based on hardware |
| CN113702731B (en) * | 2021-08-06 | 2023-10-03 | 海阳三贤电装有限公司 | Shielded wire withstand voltage detecting system |
| CN114137822A (en) * | 2021-11-01 | 2022-03-04 | 北京四方继保自动化股份有限公司 | 4 ~ 20mA current redundancy output conversion circuit |
| CN114185291B (en) * | 2021-12-02 | 2023-07-11 | 杭州和利时自动化有限公司 | Output control system |
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|---|---|---|---|---|
| CN2574062Y (en) * | 2002-10-17 | 2003-09-17 | 北京安控科技发展有限公司 | Current signal conditioning circuit |
| DE10249846A1 (en) * | 2002-10-25 | 2004-05-13 | Siemens Ag | Redundant arrangement of field devices for automization plant with monitoring of delivery of measuring signal current |
| CN101655713A (en) * | 2009-08-25 | 2010-02-24 | 北京广利核系统工程有限公司 | DCS analog quantity output module for engineer station |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2574062Y (en) * | 2002-10-17 | 2003-09-17 | 北京安控科技发展有限公司 | Current signal conditioning circuit |
| DE10249846A1 (en) * | 2002-10-25 | 2004-05-13 | Siemens Ag | Redundant arrangement of field devices for automization plant with monitoring of delivery of measuring signal current |
| CN101655713A (en) * | 2009-08-25 | 2010-02-24 | 北京广利核系统工程有限公司 | DCS analog quantity output module for engineer station |
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