CN108536126B - Point inspection instrument and point inspection method of DCS (distributed control system) - Google Patents
Point inspection instrument and point inspection method of DCS (distributed control system) Download PDFInfo
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- CN108536126B CN108536126B CN201810348107.3A CN201810348107A CN108536126B CN 108536126 B CN108536126 B CN 108536126B CN 201810348107 A CN201810348107 A CN 201810348107A CN 108536126 B CN108536126 B CN 108536126B
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Abstract
The invention discloses a point detector, when the output current of a constant current source in an RTD module flows through a first resistor, the two ends of the first resistor generate corresponding differential pressure, the output current can be calculated after being collected by a voltage collecting signal source, then the current which has linear relation with the output current is output to a second resistor by utilizing the current output signal source to provide a first target voltage signal for the RTD module, the RTD module considers that a corresponding resistance value signal is collected, so that the detection or calibration of the RTD module can be realized by adjusting the current output from the current output signal source to the second resistor, the resistance output signal source is not needed, the precision of the point detector is ensured, the defect that the resistor needs to be frequently replaced in the detection or calibration process in the prior art is overcome, and the use process of the point detector is simple. In addition, the invention also discloses a point inspection method of the DCS, which has the above effects.
Description
Technical Field
The invention relates to the field of detection, in particular to a point inspection instrument and a point inspection method of a DCS.
Background
The DCS widely applied to industrial production is a comprehensive control system, and in order to ensure that the DCS can run safely, stably and in a long period, comprehensive inspection and maintenance need to be carried out on the DCS regularly, particularly an IO module of a main controller used in the DCS.
The existing point inspection instrument for inspecting or calibrating the IO module comprises a plurality of signal sources, which are in one-to-one correspondence with each module in the IO module. For example, the signal source corresponding to the RTD module is a resistance output signal source, wherein the RTD module is a thermal resistance module. In practical applications, since there are few resistance output signal sources for inspection or calibration in the market and the accuracy is low, in the prior art, resistors with different resistance values are usually set for the point inspection instrument to replace the resistance output signal sources. However, this method not only improves the accuracy, but also makes the application process of the point detector more complicated due to the need of frequently replacing resistors with different resistances in the process of detection or calibration, which brings a problem of low automation degree.
Therefore, how to overcome the defect of frequent resistor replacement in the process of inspection or calibration on the basis of ensuring the accuracy of the point inspection instrument is a technical problem which needs to be solved by the technical personnel in the field at present.
Disclosure of Invention
The invention aims to provide a point inspection instrument and a point inspection method of a DCS (distributed control system), which can overcome the defect that a resistor is frequently replaced in the inspection or calibration process on the basis of ensuring the precision of the point inspection instrument.
In order to solve the above technical problem, the present invention provides a spot inspection instrument applied to a DCS system, including:
a first resistor and a second resistor;
the voltage acquisition signal source is connected with the first resistor in parallel and used for acquiring voltages at two ends of the first resistor;
the current output signal source is connected with the second resistor and used for providing a first target voltage signal for the RTD module through the second resistor;
wherein the RTD module is a thermal resistance module of a DCS controller.
Preferably, when the RTD module is checked or calibrated, the connection relationship between the second resistance and the RTD module is specifically:
a first end of the second resistor is connected with an input positive end of the RTD module through a first lead, and a second end of the second resistor is connected with an input negative end of the RTD module through a second lead; the connection end of the second lead and the current output signal source is connected with the common end of the RTD module through a third lead;
wherein the line resistances of the first wire, the second wire and the third wire are all equal.
Preferably, the method further comprises the following steps:
the first switch is connected with the first resistor in series and used for controlling whether the output current of the RTD module internal constant current source flows through the first resistor or not; the second switch and the third switch are respectively connected between the current output signal source and the second resistor in series, and the fourth switch is connected between the voltage acquisition signal source and the first resistor in series;
when the second switch is closed, the current output signal source provides a first positive voltage signal for the RTD module through the second resistor; when the third switch is closed, the current output signal source provides a 0V voltage signal for the RTD module through the second resistor;
wherein the first target voltage signal comprises the first positive voltage signal and the 0V voltage signal.
Preferably, the method further comprises the following steps:
a third resistor;
a fifth switch connected in parallel with the third resistor;
correspondingly, the current output signal source is further connected with the third resistor and is used for providing a second target voltage signal for the TC module through the third resistor;
wherein the TC module is a thermocouple module of the DCS controller.
Preferably, the method further comprises the following steps:
a sixth switch and a seventh switch respectively connected in series between the current output signal source and the third resistor;
when the sixth switch is closed, the current output signal source provides a second positive voltage signal to the TC module through the third resistor; when the seventh switch is closed, the current output signal source provides a negative voltage signal for the TC module through the third resistor;
wherein the second target voltage signal comprises the second positive voltage signal and the negative voltage signal.
Preferably, the digital quantity signal source in the point detector comprises a digital output signal source, a digital acquisition signal source and a frequency output signal source;
when a DI module and an SOE module are respectively checked, a high level detection end of the digital output signal source is respectively connected with the anode of the DI module and the anode of the SOE module, and a low level detection end of the digital output signal source is respectively connected with the cathode of the DI module and the cathode of the SOE module; when a DO module is detected, the high-level detection end of the digital acquisition signal source is connected with the anode of the DO module, and the low-level detection end of the digital acquisition signal source is connected with the cathode of the DO module; when the PI module is checked or calibrated, the high level detection end of the frequency output signal source is connected with the anode of the PI module, and the low level detection end of the frequency output signal source is connected with the cathode of the PI module;
wherein the DI module is a digital quantity input module of the DCS controller; the SOE module is a sequential event module of the DCS controller, the DO module is a digital output module of the DCS controller, and the PI module is a pulse input module of the DCS controller.
Preferably, the voltage acquisition signal source is connected with the voltage acquisition signal source in parallel.
Preferably, the current output signal source specifically includes a first current output signal source and a second current output signal source;
when the current type AI module is respectively checked or calibrated, the anode of the first current output signal source is connected with the anode of the second current output signal source, and the cathode of the first current output signal source is connected with the cathode of the second current output signal source;
wherein the current type AI module is an analog input module of the DCS controller.
In order to solve the above technical problem, the present invention provides a point inspection method for a DCS system, which is based on any one of the above point inspection instruments, and includes:
acquiring voltages at two ends of a first resistor by using a voltage acquisition signal source;
calculating the output current of an RTD module internal constant current source according to the voltage at two ends of the first resistor;
and outputting a target current having a linear relation with the output current to a second resistor through a current output signal source to provide a first target voltage signal for the RTD module.
Preferably, if the point detector further includes a third resistor and a fifth switch, when the TC module is checked or calibrated, the method specifically includes:
after the fifth switch is switched off, outputting forward current or reverse current to the third resistor by using the current output signal source to provide a second target voltage signal for the TC module;
providing the second target voltage signal to the TC module directly after the fifth switch is closed.
When the output current of the constant current source in the RTD module flows through the first resistor, the two ends of the first resistor generate corresponding differential pressure, the output current can be calculated after being collected by the voltage collecting signal source, then the current which has linear relation with the output current is output to the second resistor by the current output signal source so as to provide a first target voltage signal for the RTD module, and the RTD module considers that a corresponding resistance signal is collected after collecting the first target voltage signal, so that the RTD module can be detected or calibrated by adjusting the current output from the current output signal source to the second resistor, thus the point detector can ensure the precision of the point detector without using a resistance output signal source and overcome the defect that the resistor needs to be frequently replaced in the detecting or calibrating process in the prior art, the point inspection instrument is simple in use process. In addition, the invention also provides a point inspection method of the DCS, which has the above effects.
Drawings
In order to illustrate the embodiments of the present invention more clearly, the drawings that are needed in 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 that other drawings can be obtained by those skilled in the art without inventive effort.
Fig. 1 is a schematic structural diagram of a spot inspection instrument according to an embodiment of the present invention;
fig. 2 is a schematic wiring diagram of a digital signal source in a point inspection instrument according to an embodiment of the present invention;
fig. 3 is a flowchart of a point inspection method of the DCS system according to an embodiment of the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without any inventive step, are within the scope of the present invention.
The invention aims to provide a point inspection instrument and a point inspection method of a DCS (distributed control system), which can overcome the defect that a resistor is frequently replaced in the inspection or calibration process on the basis of ensuring the precision of the point inspection instrument.
In order to make the technical solutions of the present invention better understood, the present invention will be further described in detail with reference to the accompanying drawings and specific embodiments.
Fig. 1 is a schematic structural diagram of a point detection instrument according to an embodiment of the present invention. The point inspection instrument provided by the invention is applied to a DCS (distributed control system), as shown in figure 1, the point inspection instrument 1 comprises:
a first resistor 10 and a second resistor 11;
a voltage acquisition signal source 12 connected in parallel with the first resistor 10 and used for acquiring the voltage at two ends of the first resistor 10;
a current output signal source 13 connected to the second resistor 11 and configured to provide a first target voltage signal to the RTD module through the second resistor 11;
the RTD module is a thermal resistance module of the DCS controller, and the first target voltage is a voltage signal capable of simulating resistance required when the RTD module is checked or calibrated.
In practical applications, in order to meet the requirement of the precision of the point detector 1, the first resistor 10 and the second resistor 11 should be precision resistors, for example, the precision of the first resistor 10 and the precision of the second resistor 11 are higher than or equal to one ten thousandth.
The precision resistor is mainly different from a common resistor in resistance error, resistance and temperature coefficient. The classification is described as follows:
for a resistor with a resistance value of more than 1 omega, the resistor with a resistance value error within +/-0.5% compared with the identification resistance value can be called a precision resistor, the precision can be 0.01% in a higher precision mode, namely the precision of one ten thousandth stated by an electronic engineer, the resistor is generally a thin film resistor, and the resistor made of the material can meet the requirements of a production process generally. The precision of the common series of the resistors with the resistance value of more than 1 omega is more than +/-5 percent, and the most common resistor on an electronic product is the resistor with the precision of 5 percent, which does not belong to the precision resistor range.
The resistor with the resistance value below 1 omega can generally reach the precision within +/-1 percent, and the actual resistance value error is very small even if the precision resistor is manufactured, because the resistance value cardinal number is very small, the error is 1 percent. Higher precision can be achieved within +/-0.5 percent, but the process requirement and the technical requirement are higher.
The first resistor 10 is used for cooperating with the voltage collecting signal source 12, so as to calculate the current flowing through the first resistor 10 according to the voltage at two ends of the first resistor 10 collected by the voltage collecting signal source 12. Therefore, when the first resistor 10 is connected in series to the excitation end and the common end of the RTD module, and the output current of the internal constant current source of the RTD module flows through the first resistor 10, the voltage collected by the voltage collection signal source 12 corresponds to the output current of the internal constant current source of the RTD module, and the output current of the internal constant current source of the RTD module can be obtained by calculation.
The second resistor 11 is used for being matched with the current output signal source 13 to convert the current output by the current output signal source 13 to the corresponding voltage signal. In this way, after the magnitude of the output current of the RTD module internal constant current source is calculated, the current having a linear relationship with the output current of the RTD module internal constant current source can be output to the second resistor 11 by controlling the current output signal source 13, so as to provide the RTD module with the first target voltage by using the voltage across the second resistor 11.
Specifically, the output current of the internal constant current source of the RTD module flows through the first resistor 10 through the excitation end of the RTD module, corresponding voltages are generated at two ends of the first resistor 10, then the voltages at two ends of the first resistor 10 are collected by using the voltage collection signal source 12, and after the collection voltage of the voltage collection signal source 12 is obtained, the output current of the internal constant current source of the RTD module is calculated. Then, according to the requirement of checking or calibration, the current output signal source 13 is adjusted to output a current having a linear relation with the output current of the RTD module internal constant current source so as to generate first target voltages with different magnitudes at two ends of the second resistor 11, and the process of checking or calibrating the RTD module by using resistors with different resistance values is simulated. Of course, when a voltage signal equivalent to a resistance having a resistance value of 0 Ω is generated, a current having the same magnitude and the opposite direction to the output current of the RTD module internal constant current source is output by the current output signal source 13, and a voltage signal of 0V is generated across the second resistor 11.
In summary, with the adoption of the spot detector provided by the invention, when the output current of the constant current source in the RTD module flows through the first resistor, the two ends of the first resistor generate corresponding voltage difference, the output current can be calculated after being collected by the voltage collecting signal source, then the current having a linear relation with the output current is output to the second resistor by using the current output signal source, so that the first target voltage signal can be provided for the RTD module, and the RTD module considers that the corresponding resistance value signal is collected after collecting the first target voltage signal, so that the detection or calibration of the RTD module can be realized by adjusting the current output from the current output signal source to the second resistor, therefore, the application of the spot detector not only needs no resistance output signal source, ensures the precision of the spot detector, but also overcomes the defect that the resistor needs to be frequently replaced in the detection or calibration process in the prior art, the point inspection instrument has the advantages of simple use process,
in order to improve the precision of the point detector, based on the above embodiment, as a preferred implementation manner, when the RTD module is tested or calibrated, the connection relationship between the second resistor 11 and the RTD module is specifically as follows:
a first end of the second resistor 11 is connected with an input positive end of the RTD module through a first lead, and a second end of the second resistor 11 is connected with an input negative end of the RTD module through a second lead respectively; the connection end of the second lead and the current output signal source 13 is connected with the common end of the RTD module through a third lead;
the first lead is a lead connected between the first end of the second resistor 11 and the input positive end of the RTD module, the second lead is a lead connected between the second end of the second resistor 11 and the input negative end of the RTD module, and the third lead is a lead connected to the connection end of the second lead and the current output signal source 13 and the common end of the RTD module; and the line resistances of the first conducting wire, the second conducting wire and the third conducting wire are all equal.
In the preferred embodiment, the resistances of the first conducting wire, the second conducting wire and the third conducting wire are all equal, so that the interference of the resistances can be avoided, and the voltage signal collected by the RTD module is ensured to be equal to the voltage at the two ends of the second resistor 11, instead of ensuring the sum of the voltage at the two ends of the second resistor 11 and the voltage at the two ends of the resistances, thereby improving the precision of the point detector.
In order to improve the reusability of the signal source in the point inspection instrument, based on the foregoing embodiment, as a preferred implementation manner, the point inspection instrument 1 provided in the embodiment of the present invention further includes:
a first switch connected in series with the first resistor 10 for controlling whether the output current of the RTD module internal constant current source flows through the first resistor 10; a second switch and a third switch respectively connected in series between the current output signal source 13 and the second resistor 11, and a fourth switch connected in series between the voltage acquisition signal source 12 and the first resistor 10;
when the second switch is closed, the current output signal source 13 provides a first positive voltage signal to the RTD module through the second resistor 11; when the third switch is closed, the current output signal source 13 provides a 0V voltage signal for the RTD module through the second resistor 11;
wherein the first target voltage signal includes a first positive voltage signal and a 0V voltage signal.
The first switch can be connected in series between the first resistor 10 and the excitation end of the RTD module, so when the first switch is closed, the internal constant current source of the RTD module and the first resistor 10 form a loop, the output current of the internal constant current source of the RTD module can flow through the first resistor 10 through the excitation end, when the first switch is opened, the internal constant current source of the RTD module and the first resistor 10 cannot form a loop, and the output current of the internal constant current source of the RTD module cannot flow through the first resistor 10 through the excitation end. Of course, it is understood that the second switch may also be connected in series between the first resistor 10 and the common terminal of the RTD module, and the invention is not limited thereto.
The second switch and the third switch are arranged in order to reverse the direction of the current flowing through the second resistor 11 without rewiring. If two second switches and two third switches are provided, one second switch is provided between the anode of the current output signal source 13 and the first end of the second resistor 11, and the other second switch is provided between the cathode of the current output signal source 13 and the second end of the second resistor 11, so as to realize the input of the forward current to the second resistor 11; one third switch is arranged between the anode of the current output signal source 13 and the second end of the second resistor 11, and the other third switch is arranged between the cathode of the current output signal source 13 and the first end of the second resistor 11, and is used for inputting reverse current to the second resistor 11.
The on and off of the fourth switch controls whether the voltage collecting signal source 12 is used for collecting the voltage across the first resistor 10.
When the second switch and the third switch are both off, the current output signal source 13 may be used for inspection or calibration of other IO modules of the DCS controller, such as a current-mode AI module (current-mode analog input module), which may implement multiplexing of the current output signal source 13; when the fourth switch is turned off, the connection between the voltage acquisition signal source 12 and the first resistor 10 is disconnected, and the voltage acquisition signal source cannot be continuously used for acquiring the voltage at the two ends of the first resistor 10, so that the voltage acquisition signal source can be used for inspection or calibration of other IO modules of the DCS controller, and multiplexing of the voltage acquisition signal source 12 is realized.
The IO module in the DCS mainly comprises an AO module (analog output module), a current type AI module, a voltage type AI module (voltage type analog input module), a TC module (thermocouple module), a RTD module, a DI module (digital input module), an SOE module (sequential event module), a PI module (pulse input module) and a DO module (digital output module). Different signal sources often derive from different producers, if the signal source that contains in the appearance is examined to the point is more, then can cause the integration degree low, bulky problem for the appearance portability is examined to the point is relatively poor.
Therefore, based on the above embodiment, as a preferred implementation manner, the spot detection instrument 1 provided in the embodiment of the present invention further includes:
a third resistor;
a fifth switch connected in parallel with the third resistor;
correspondingly, the current output signal source 13 is further connected to a third resistor, and is configured to provide a second target voltage signal to the TC module through the third resistor;
wherein the TC module is a thermocouple module of the DCS controller.
It should be noted that, in practical applications, in order to ensure the precision of the point detection instrument, the precision resistor should also be used as the third resistor, for example, the precision of the third resistor is higher than or equal to one ten thousandth; the second target voltage signal refers to a voltage signal used to verify or calibrate the TC module.
The third resistor is used in conjunction with the current output signal source 13 to replace the mV voltage output signal source of the prior art for testing or calibrating the TC module. The TC module, although the number of the corresponding sensor types is large according to the difference of the collected signals, the collected voltage values are small (mV signal) and need negative voltage, so in this embodiment, the third resistor is used to cooperate with the current output signal source 13, so that the current output by the current output signal source 13 passes through the third resistor to generate voltage, which is used as the voltage for checking or calibrating the TC module. Specifically, the fifth switch is connected in parallel with the third resistor, when the fifth switch is closed, the third resistor is short-circuited, and the TC module can acquire a 0mV voltage signal; when the fifth switch is turned off, a forward current or a reverse current may be output to the third resistor through the current output signal source 13 to provide the TC module with a positive voltage signal or a negative voltage signal as the second target voltage signal.
Compared with the prior art, the mV voltage output signal source is needed to be used for checking or calibrating the TC module, the current output signal source 13 used for calibrating the RTD module is used for checking or calibrating the TC module, the variety of signal sources can be reduced, the volume of the point detection instrument is reduced, and the portability of the point detection instrument is optimized.
In order to further improve the reusability of the signal source in the point inspection instrument, based on the foregoing embodiment, as a preferred implementation manner, the point inspection instrument 1 provided in the embodiment of the present invention further includes:
the sixth switch and the seventh switch are respectively connected between the current output signal source and the third resistor in series;
when the sixth switch is closed, the current output signal source provides a second positive voltage signal for the TC module through the third resistor; when the seventh switch is closed, the current output signal source provides a negative voltage signal for the TC module through the third resistor;
wherein the second target voltage signal includes a second positive voltage signal and a negative voltage signal.
Fig. 2 is a schematic wiring diagram of a digital signal source in a point inspection instrument according to an embodiment of the present invention. As shown in fig. 2, in order to reduce the types of signal sources, reduce the volume of the point detector, and optimize the portability of the point detector, based on the above embodiment, as a preferred implementation, the digital signal source in the point detector includes a digital output signal source 20, a digital acquisition signal source 21, and a frequency output signal source 22;
when the DI module and the SOE module are respectively inspected, the high level detection end of the digital output signal source 20 is respectively connected with the anode of the DI module and the anode of the SOE module, and the low level detection end of the digital output signal source 20 is respectively connected with the cathode of the DI module and the cathode of the SOE module; when the DO module is detected, the high-level detection end of the digital acquisition signal source 21 is connected with the anode of the DO module, and the low-level detection end of the digital acquisition signal source 21 is connected with the cathode of the DO module; when the PI module is checked or calibrated, the high level detection end of the frequency output signal source 22 is connected with the anode of the PI module, and the low level detection end of the frequency output signal source 22 is connected with the cathode of the PI module;
the DI module is a digital quantity input module of the DCS controller; the SOE module is a sequential event module of the DCS controller, the DO module is a digital output module of the DCS controller, and the PI module is a pulse input module of the DCS controller.
It should be noted that the wiring diagram shown in fig. 2 is only a wiring diagram of one channel. In practical application, for the condition that a plurality of channels are needed to complete the inspection or calibration, the wiring method is similar, and only the channels with the corresponding number need to be added. For example, if the PI module has 12 channels, then 11 channels may be added according to the wiring method of fig. 2.
When the point detection instrument provided by the embodiment is used for detecting or calibrating different modules, the upper computer can control the corresponding switch to be closed, and the digital quantity signal source corresponding to the module to be detected 23 is switched on. For example, when the module 23 to be tested is specifically a DI module or an SOE module, the switches K1 and K2 may be controlled to be closed, so that the module 23 to be tested is connected to the digital output signal source 20, and it should be noted that, when the digital output signal source 20 is used to test the SOE module, the digital output signal source 20 outputs high and low level signals at an interval of 1ms, and of course, the SOE generator may be directly used to replace the digital output signal source 20, which is not limited in the present invention. When the module 23 to be detected is a DO module, the switch K3 and the switch K4 may be controlled to be closed, so that the module 23 to be detected is connected to the digital acquisition signal source 21. When the module 23 to be tested is specifically a PI module, the switch K5 and the switch K6 may be controlled to be closed, so that the module 23 to be tested is connected to the frequency output signal source 22. That is, in this embodiment, by configuring corresponding switches for different digital signal sources, digital signal sources can be uniformly configured for the DI module, the DO module, the PI module, and the SOE module, thereby avoiding configuring different signal sources for different modules to be tested 23, reducing the types of signal sources, further reducing the volume of the point inspection instrument, and improving the portability of the point inspection instrument.
In order to further reduce the types of signal sources in the point inspection instrument and improve the portability of the point inspection instrument, based on the above embodiment, as a preferred implementation manner, the point inspection instrument 1 provided in the embodiment of the present invention further includes a fourth resistor connected in parallel with the voltage acquisition signal source 12.
It should be noted that, in practice, in order to ensure the precision of the point detector 1, the precision resistor should also be used as the fourth resistor, for example, the precision of the fourth resistor is higher than or equal to one ten thousandth.
The fourth resistor is connected in parallel with the voltage acquisition signal source 12 and can be used for detecting or calibrating the AO module. The AO module outputs a current signal of 0-22.7mA, which is an unconventional current signal of 4-20mA, and meanwhile, the acquisition range of the current acquisition signal source in the industry is 0-20mA, which cannot meet the detection or calibration requirement. Therefore, the invention comprehensively considers privacy of technical indexes, cost and the like, and the fourth resistor is adopted to convert the current signal into the voltage signal, so that the AO module is indirectly detected or calibrated according to the acquired voltage signal. Specifically, when the AO module is inspected or calibrated, the fourth resistor is connected in series between two output ends of the AO module, and the voltage acquisition signal source 12 is used for acquiring voltages at two ends of the fourth resistor, thereby implementing indirect inspection or calibration of the AO module.
Compared with the prior art, the method needs to adopt the current acquisition signal source to inspect or calibrate the AO module, adopts the voltage acquisition signal source 12 for calibrating the RTD module to inspect or calibrate the AO module, can reduce the types of the signal source, is favorable for reducing the volume of the point inspection instrument and optimizing the portability of the point inspection instrument, and can also adopt the voltage acquisition signal source 12 to indirectly inspect or calibrate the current signal of 20mA-22.7mA output by the AO module.
The current collection range of the current-mode AI module is generally 0-20mA, but the range of the current-mode AI module is 0-22.7mA, so that, in order to perform full-range inspection or calibration on the current-mode AI module, based on the above embodiment, as a preferred implementation, the current output signal source 13 specifically includes a first current output signal source and a second current output signal source;
when the current type AI module is respectively checked or calibrated, the anode of the first current output signal source is connected with the anode of the second current output signal source, and the cathode of the first current output signal source is connected with the cathode of the second current output signal source;
the current type AI module is an analog input module of the DCS controller.
The above detailed description is made on the embodiment of the point detector provided by the present invention, and the present invention also provides a point detection method of the DCS system corresponding to the point detector provided by any of the above embodiments.
Fig. 3 is a flowchart of a point inspection method of the DCS system according to an embodiment of the present invention. The point inspection method provided by this embodiment is based on the point inspection instrument provided by any of the above embodiments, as shown in fig. 3, and includes:
s30: and acquiring the voltage at two ends of the first resistor by using a voltage acquisition signal source.
S31: and calculating the output current of the RTD module internal constant current source according to the voltage at two ends of the first resistor.
S32: and outputting a target current having a linear relation with the output current to the second resistor through the current output signal source to provide a first target voltage signal for the RTD module.
Based on the above embodiment, as a preferred implementation manner, if the point detector further includes a third resistor and a fifth switch, when the TC module is checked or calibrated, the method specifically includes:
after the fifth switch is switched off, outputting forward current or reverse current to a third resistor by using a current output signal source to provide a second target voltage signal for the TC module;
the second target voltage signal is provided to the TC module directly after the fifth switch is closed.
The point inspection instrument and the point inspection method of the DCS provided by the invention are described in detail above. The embodiments are described in a progressive mode in the specification, the emphasis of each embodiment is different from that of other embodiments, and the same and similar parts among the embodiments are referred to each other.
It should be noted that, for those skilled in the art, it is possible to make various improvements and modifications to the present invention without departing from the principle of the present invention, and those improvements and modifications also fall within the scope of the claims of the present invention.
It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.
Claims (9)
1. The utility model provides a point appearance of examining, is applied to the DCS system, its characterized in that includes:
a first resistor and a second resistor;
the voltage acquisition signal source is connected with the first resistor in parallel and used for acquiring the voltage at two ends of the first resistor when the output current of the constant current source in the RTD module flows through the first resistor;
the current output signal source is connected with the second resistor and used for outputting current which has a linear relation with the output current through the second resistor so as to provide a first target voltage signal for the RTD module;
wherein the RTD module is a thermal resistance module of a DCS controller;
when the RTD module is checked or calibrated, the connection relationship between the second resistance and the RTD module is specifically as follows:
a first end of the second resistor is connected with an input positive end of the RTD module through a first lead, and a second end of the second resistor is connected with an input negative end of the RTD module through a second lead; the connection end of the second lead and the current output signal source is connected with the common end of the RTD module through a third lead;
the wire resistances of the first wire, the second wire and the third wire are all equal;
the first resistor is connected with the RTD module internal constant current source, when the output current of the RTD module internal constant current source flows through the first resistor, the two ends of the first resistor generate corresponding pressure difference, the output current is calculated after the voltage acquisition signal source acquires the output current, then the current output signal source outputs the current with linear relation with the output current to the second resistor so as to provide a first target voltage signal for the RTD module, the RTD module acquires the first target voltage signal and then obtains a corresponding resistance signal, and therefore the RTD module is checked or calibrated by adjusting the current output signal source to the second resistor.
2. The spot check meter according to claim 1, further comprising:
the first switch is connected with the first resistor in series and used for controlling whether the output current of the RTD module internal constant current source flows through the first resistor or not; the second switch and the third switch are respectively connected between the current output signal source and the second resistor in series, and the fourth switch is connected between the voltage acquisition signal source and the first resistor in series;
when the second switch is closed, the current output signal source provides a first positive voltage signal for the RTD module through the second resistor; when the third switch is closed, the current output signal source provides a 0V voltage signal for the RTD module through the second resistor;
wherein the first target voltage signal comprises the first positive voltage signal and the 0V voltage signal;
the first switch is connected between the first resistor and the excitation end of the RTD module in series or the first switch is connected between the first resistor and the common end of the RTD module in series; the first switch is arranged between the anode of the current output signal source and the first end of the first resistor, and the second switch is arranged between the cathode of the current output signal source and the second end of the first resistor and used for inputting a forward current to the first resistor; one third switch is arranged between the anode of the current output signal source and the second end of the second resistor, and the other third switch is arranged between the cathode of the current output signal source and the first end of the second resistor and used for inputting reverse current to the second resistor;
and the fourth switch is switched on and off to control whether the voltage acquisition signal source is used for acquiring the voltage at the two ends of the first resistor.
3. The spot check instrument according to claim 1 or 2, further comprising:
a third resistor;
a fifth switch connected in parallel with the third resistor;
correspondingly, the current output signal source is further connected with the third resistor and is used for providing a second target voltage signal for the TC module through the third resistor;
wherein the TC module is a thermocouple module of the DCS controller.
4. The spot detector of claim 3, further comprising:
a sixth switch and a seventh switch respectively connected in series between the current output signal source and the third resistor;
when the sixth switch is closed, the current output signal source provides a second positive voltage signal to the TC module through the third resistor; when the seventh switch is closed, the current output signal source provides a negative voltage signal for the TC module through the third resistor;
wherein the second target voltage signal comprises the second positive voltage signal and the negative voltage signal.
5. The point detecting instrument according to claim 4, wherein the digital quantity signal source in the point detecting instrument comprises a digital output signal source, a digital acquisition signal source and a frequency output signal source;
when a DI module and an SOE module are respectively checked, a high level detection end of the digital output signal source is respectively connected with the anode of the DI module and the anode of the SOE module, and a low level detection end of the digital output signal source is respectively connected with the cathode of the DI module and the cathode of the SOE module; when a DO module is detected, the high-level detection end of the digital acquisition signal source is connected with the anode of the DO module, and the low-level detection end of the digital acquisition signal source is connected with the cathode of the DO module; when the PI module is checked or calibrated, the high level detection end of the frequency output signal source is connected with the anode of the PI module, and the low level detection end of the frequency output signal source is connected with the cathode of the PI module;
wherein the DI module is a digital quantity input module of the DCS controller; the SOE module is a sequential event module of the DCS controller, the DO module is a digital output module of the DCS controller, and the PI module is a pulse input module of the DCS controller.
6. The point detector of claim 3, further comprising a fourth resistor connected in parallel with said voltage acquisition signal source.
7. The point detection instrument according to claim 3, wherein the current output signal source comprises a first current output signal source and a second current output signal source;
when the current type AI module is respectively checked or calibrated, the anode of the first current output signal source is connected with the anode of the second current output signal source, and the cathode of the first current output signal source is connected with the cathode of the second current output signal source;
wherein the current type AI module is an analog input module of the DCS controller.
8. A point inspection method of DCS system based on the point inspection instrument of any one of claims 1-7, characterized by comprising:
when the output current of the constant current source in the RTD module flows through the first resistor, the voltage at two ends of the first resistor is obtained by using the voltage acquisition signal source;
calculating the output current of an RTD module internal constant current source according to the voltage at two ends of the first resistor;
and outputting a target current having a linear relation with the output current to a second resistor through a current output signal source to provide a first target voltage signal for the RTD module.
9. The point inspection method according to claim 8, wherein if the point inspection apparatus further includes a third resistor and a fifth switch, when inspecting or calibrating the TC module, the method specifically includes:
after the fifth switch is switched off, outputting forward current or reverse current to the third resistor by using the current output signal source to provide a second target voltage signal for the TC module;
providing the second target voltage signal to the TC module directly after the fifth switch is closed.
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| CN201965485U (en) * | 2011-03-30 | 2011-09-07 | 南京化工职业技术学院 | Automatic verifying device for adjustor parameters |
| CN103809588B (en) * | 2014-02-27 | 2016-08-24 | 陕西科技大学 | The spot check instrument system of a kind of DEH and detection method |
| JP6280862B2 (en) * | 2014-11-26 | 2018-02-14 | 株式会社日立製作所 | Event analysis system and method |
| CN204989443U (en) * | 2015-07-30 | 2016-01-20 | 中山市华标检测有限公司 | Device is examined to withstanding voltage tester point |
| CN205210973U (en) * | 2015-11-30 | 2016-05-04 | 华电重工股份有限公司 | System is examined to equipment point |
| CN205490286U (en) * | 2015-12-15 | 2016-08-17 | 北京和利时电机技术有限公司 | Servo driver |
| CN206531917U (en) * | 2016-11-29 | 2017-09-29 | 晶科能源有限公司 | A kind of Electric Security Tester point inspection device |
| CN207114051U (en) * | 2017-08-17 | 2018-03-16 | 厦门奥通力工业自动化有限公司 | Exact constant temperature case is used in a kind of portable thermal couple/thermal resistance detection |
| CN107687911B (en) * | 2017-09-26 | 2019-07-09 | 福州大学 | A kind of Thermal Meter intelligence calibration system and method |
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