Patent Application
20110101967
The claimed subject matter relates generally to industrial control systems and more particularly to inductive proximity sensors that employ materials with a high electrical resistivity and/or low temperature coefficient of resistivity to improve sensor performance.
Inductive proximity sensors are employed in a variety of applications, and more particularly, in automated assembly lines, in machinery, packaging, and automotive markets, for example. Generally, inductive sensors utilize an electromagnetic field to detect the presence/absence of an object, the distance to an object, or the nature of an object (ferrous or non-ferrous metal). These measurements are based on the detection of changes in the electromagnetic field which is generated by an oscillator.
In general, an inductive proximity sensor consists of a coil assembly, an oscillator, a trigger-signal level detector and an output circuit. When a ferrous or nonferrous metallic object moves into the electromagnetic field situated in front of the proximity sensor face, eddy currents are induced in the metallic object which produces a load on the oscillator. This additional load results in a loss of energy and a change in amplitude of oscillation and hence leads to object detection, which is often conveyed by a transistor or relay output switch indication.
One parameter of interest when considering such devices is the detection range, otherwise known as the nominal sensing distance. The nominal sensing distance is defined by a theoretical value corresponding to the detection of a standard one millimeter thick mild steel square target with axial approach. The target could be an object that is manufactured (object sensing) or a part of a machine (machine sensing). The latter is predominantly the case for inductive sensors.
Due to the harsh environments these sensors are utilized in, there is a market need for rugged packaging. One of the techniques used to provide such capability is the use of a metal housing and sensor face. Metal face inductive proximity sensors provide superior impact, abrasion, and chemical resistance compared to their plastic face counterparts. Austenitic stainless steel, in different grades, has been the preferred metal for the fabrication of the housing and sensor face because it is inexpensive and generally exhibits excellent corrosion resistance over time.
When an electromagnetic field interacts with the face of the sensor, eddy currents are formed on both the sensor face and target. If the face material has low electrical resistivity, such as copper or aluminum, for example, the intensity of these currents on the face are too great, and thus do not allow the electromagnetic field to adequately penetrate the material. A material with a high electrical resistivity is thus preferred in order to reduce the intensity of these eddy currents on the sensing face and allow for adequate penetration of the electromagnetic field through the sensing face. Austenitic stainless steel, in different grades, has the added benefit of allowing the electromagnetic field to adequately penetrate it.
Although a mechanically and economically suitable choice for the sensor face material, stainless steel does have some drawbacks. One problem is that stainless steel has undesirable temperature performance due to its physical properties. The electrical resistivity of a material varies as a function of temperature. The electrical resistivity of a material generally increases with increasing temperature and decreases with decreasing temperature. As a result, the magnitude of the induced eddy currents in the sensor face also varies with temperature changes.
Ideally, when the environmental temperature changes, the functionalities of the sensor, such as sensing distance, should not be affected. Therefore, temperature compensation circuits are often employed in inductive proximity sensors. However, in some situations, the temperature changes so quickly that the sensor housing/face combination endures these changes first. The temperature compensation circuits, most often buried in the middle of the sensor body, can not react promptly enough to the temperature change, thereby causing inaccurate sensing or false detection.
Existing stainless steel inductive proximity products are typically fabricated either by machining the housing and face as a singular stainless steel part or by fabricating the housing and sensor face as two distinct stainless steel parts and then laser welding them together. These conventional sensor construction techniques have led designers to look away from other sensor face materials. For instance, since stainless steel is an economically suitable choice for the actual housing of the sensor, it also makes sense to employ stainless steel as the face material, particularly due to the known complexities of joining dissimilar materials. Thus, for these reasons and others, designers have had little reason to look for solutions other than stainless steel for the sensor face material.
The following summary presents a simplified overview to provide a basic understanding of certain aspects described herein. This summary is not an extensive overview nor is it intended to identify critical elements or delineate the scope of the aspects described herein. The sole purpose of this summary is to present some features in a simplified form as a prelude to a more detailed description presented later.
An enhanced inductive proximity sensor having improved sensing distances or less sensitivity to temperature changes is provided. In one aspect, a material having a higher electrical resistivity and/or lower temperature coefficient of resistivity than stainless steel is selected for use as the sensor face in order to facilitate such properties.
When an electromagnetic field interacts with the face of the sensor, eddy currents are formed on the sensor face and target. A material with a high electrical resistivity, such as a titanium alloy, for example, can be employed to reduce the intensity of the eddy currents on the sensing face and allow for improved penetration of the electromagnetic field through the sensing face. In general, the electrical resistivity of these metallic materials also changes with temperature. Titanium alloys have a low temperature coefficient of resistivity. The high electrical resistivity and low temperature coefficient of resistivity associated with titanium alloys, for example, provides a significant advance for inductive proximity sensor applications. Thus, a sensor face constructed from such a material can increase the achievable sensing distance and also reduce the sensor's sensitivity to sudden temperature changes in the environment.
Advanced joining techniques can be employed to couple the face material to a housing material that may be dissimilar from that of the sensor face. In one particular aspect, titanium (or alloys thereof) can be employed as the face material and possibly the housing material. The shape and thickness of the sensor face and associated housing can vary depending upon application needs.
The use of titanium as the material for the entire housing, while being suitable from a functional perspective, may be less than suitable from a cost perspective. However, with advanced joining techniques for dissimilar metals, the use of titanium alloys as the sensor face coupled with stainless steel, nickel plated brass, anodized aluminum, a different titanium material, or other materials for the housing provides a cost-effective yet robust solution well suited for a wider range of operating conditions.
To the accomplishment of the foregoing and related ends, the following description and annexed drawings set forth in detail certain illustrative aspects. These aspects are indicative of but a few of the various ways in which the principles described herein may be employed. Other advantages and novel features may become apparent from the following detailed description when considered in conjunction with the drawings.
An enhanced inductive proximity sensor having improved sensing distances and less sensitivity to temperature changes is provided. In one aspect, an industrial control sensor is provided. The sensor includes a sensor circuit to detect changes in an electromagnetic field induced from an object or material passing in proximity of the electromagnetic field. This includes a housing that employs the sensor circuit as part of an inductive proximity sensor. A sensor face is attached to the housing, where the sensor face receives the changes in the magnetic field and transmits the changes to the sensor circuit, and where the sensor face has a higher electrical resistivity and/or a lower temperature coefficient of resistivity than stainless steel.
It is noted that the use of materials with a high electrical resistivity is desirable to reduce the magnitude of eddy currents generated in the sensing face and to reduce the influence on the oscillation. As a result, the sensor is less vulnerable to temperature changes. A material with a low temperature coefficient of resistivity will also provide a similar benefit. Yet another benefit of using a material with high electrical resistivity and/or low temperature coefficient of resistivity for the sensor face is that the sensing distance could be increased. Longer sensing distances are always pursued for inductive proximity sensors used in industrial applications. As a result, sensor circuitry is designed to detect even smaller changes to the electromagnetic field than ever before. More often, these changes in the eddy currents, as a result of temperature changes, are large enough to disturb the normal sensing operation of the inductive proximity sensor. In another aspect, using materials with a high electrical resistivity as the sensor face will result in a lower magnitude of eddy currents being generated in the sensor face and lower energy loss in the sensor circuitry. Therefore, a greater sensitivity or longer sensing distance can be achieved.
Referring initially to
By employing high electrical resistivity/low temperature coefficient of resistivity materials for the sensor face 120, increased sensing distances can be achieved as shown at 190. Such properties 130 also facilitate better performance as temperature changes such as less false-detection when temperatures change. It is noted that the sensor face 120 and the housing 134 are typically constructed from dissimilar materials. Thus, specialized joining techniques (described in more detail below) are provided to generate joints 194 between the sensor face 120 face and housing 134.
In general, an enhanced inductive proximity sensor 110 having improved sensing distances 190 and less sensitivity to temperature changes is provided. In one aspect, a material with a high electrical resistivity and/or low temperature coefficient of resistivity qualities than stainless steal is selected as the sensor face material at 120 to facilitate such properties. Advanced joining techniques at 194 are then employed to couple the face material 120 to a housing material 134 that may be dissimilar from that of the sensor face. In one particular aspect, titanium (or alloys thereof) can be employed as the face material and possibly the housing material. The shape and thickness of the sensor face 120 and associated housing 134 can vary depending on application needs. When an electromagnetic field 150 interacts with the face of the sensor 110, eddy currents are formed on the sensor face 120 and associated target. If the face material has a low electrical resistivity, such as copper or aluminum, for example, the intensity of these currents on the face is too great, and thus do not allow the electromagnetic field 150 to adequately penetrate the material. A high electrical resistivity material is thus preferred. The electrical resistivity also changes with temperature. Another reason for employing titanium is its low temperature coefficient of resistivity. The high electrical resistivity and low temperature coefficient of resistivity provide a significant advance for inductive proximity sensor applications. Thus, such sensor face material 120 can increase the achievable sensing distance 190 and also cause the sensor 110 to be less sensitive to sudden changes in temperature in the environment. The use of titanium as the material for the entire housing 134 may be less than suitable from a cost prospective. However with advanced joining techniques at 194 for dissimilar metals, the use of titanium as the sensor face 120 coupled with stainless steel, nickel plated brass or other materials for the housing 134 provide a cost-effective yet robust solution suited for a wider range of operating conditions.
In one aspect, an industrial control sensor 110 is provided. This includes the sensor circuit 140 to detect changes in the electromagnetic field 150 that is induced from an object or material 160 passing in proximity of the electromagnetic field. The sensor 110 includes the housing 134 that employs the sensor circuit as part of an inductive proximity sensor, for example. The sensor face 120 is attached to the housing 134, where the sensor face receives the changes in the electromagnetic field 150 and transmits the changes to the sensor circuit 140, where the sensor face has a higher electrical resistivity and/or a lower temperature coefficient of resistivity than stainless steel. The sensor face 120 can be titanium, for example. This includes a titanium alloy such as an alpha alloy, a beta alloy, or an alpha-beta alloy described below.
In one example, the housing 134 is stainless steel, where the housing is bonded via at least one joint weld 194 to the sensor face 120 having a dissimilar material from the housing. In another example, the dissimilar material is a titanium alloy and the housing 134 is stainless steel. Note that the joint weld 194 can be a friction weld or a laser beam weld, for example. In yet another example, the housing 134 and the sensor face 120 are constructed from titanium or from a titanium alloy. In yet another example, the housing 134 is brass, where the sensor circuit 140 activates at least one output 170 that is communicated to an industrial control system 180 for processing.
In another aspect, an industrial control method is provided. This includes detecting disturbances in an oscillator generated electromagnetic field induced from an object or material passing in proximity of the oscillator generated electromagnetic field; employing a housing for a sensor circuit as part of a proximity sensor, the sensor circuit produces the oscillator generated electromagnetic field; and coupling a sensor face to the housing, the sensor face detects the disturbances in the oscillator generated electromagnetic field and couples the disturbances to the sensor circuit, where the sensor face has a higher electrical resistivity and/or a lower temperature coefficient of resistivity than stainless steel.
In yet another aspect, an industrial control sensor 110 is provided. This includes means for detecting changes (sensor circuit 140, sensor face 120) in an electromagnetic field 150 induced from an object or material 160 passing in proximity of the electromagnetic field. This also includes means for housing (housing 134) the sensor circuit 140 as part of a proximity sensor 110. This also includes means for joining (e.g., joints 194) the sensor face 120 to the housing 134, the sensor face receives the changes in the electromagnetic field 150 and communicates the changes to the sensor circuit 140, where the sensor face has a higher electrical resistivity and/or a lower temperature coefficient of resistivity than stainless steel as illustrated at 130. In another aspect, the housing 134 is stainless steel and the sensor face 120 is titanium or a titanium alloy that includes alpha alloys, beta alloys, or alpha-beta alloys.
It is noted that components associated with the process 100 and industrial control system 180 can include various computer or network components such as servers, clients, controllers, industrial controllers, programmable logic controllers (PLCs), energy monitors, batch controllers or servers, distributed control systems (DCS), communications modules, mobile computers, wireless components, control components and so forth that are capable of interacting across a network. Similarly, the term controller or PLC as used herein can include functionality that can be shared across multiple components, systems, or networks. For example, one or more controllers can communicate and cooperate with various network devices across the network. This can include substantially any type of control, communications module, computer, I/O device, sensors, Human Machine Interface (HMI) that communicate via the network that includes control, automation, or public networks. The controller can also communicate to and control various other devices such as Input/Output modules including Analog, Digital, Programmed/Intelligent I/O modules, other programmable controllers, communications modules, sensors, output devices, and the like.
The network can include public networks such as the Internet, Intranets, and automation networks such as Control and Information Protocol (CIP) networks including DeviceNet and ControlNet. Other networks include Ethernet, DH/DH+, Remote I/O, Fieldbus, Modbus, Profibus, wireless networks, serial protocols, and so forth. In addition, the network devices can include various possibilities (hardware or software components). These include components such as switches with virtual local area network (VLAN) capability, LANs, WANs, proxies, gateways, routers, firewalls, virtual private network (VPN) devices, servers, clients, computers, configuration tools, monitoring tools, or other devices.
Turning now to
The following describes some example applications for inductive sensors 200. In one aspect, lead frame position detection can be supported. Inductive proximity sensors are used to detect to the position of integrated circuit lead frames. The proximity sensor in this case detects the position of the alignment hole. In electronic packaging, space is an important issue. This makes the separate amplifier proximity sensor a useful solution. In another example, Injection mold closure detection can be provided. Plastic injection machines can generate a lot of heat due to energy dissipations from molten materials. Therefore, in this application, the inductive proximity sensor should be resistant to high temperatures. Again, a separate sensing head can be used. The sensor is used to detect when the injection mold tool is closed, for example.
In another application example, lathe control can be provided. When the cutting tool is at a first position and the start button is depressed, the tool post motor operates and the cutting tool moves quickly. When the cutting tool reaches a second position, the speed of the motor reduces, causing the cutting tool to move slowly. In another aspect, float detection for flow control is provided. The needed flow value can be maintained through inductive proximity sensing external detection methods using a tapered pipe and a float covered in aluminum foil, for example. As noted previously, other applications can include material tracking controls such as employed by delivery vehicles that operate over a wide range of temperatures.
Referring to
In one particular aspect, the sensor face 450 and housing 440 are constructed from the same materials, such as titanium alloy. In this case, the sensor face 450 and housing 440 may be fabricated as a single component or they may be fabricated as separate components which are then joined together through the use of various joining techniques. Another aspect consists of the sensor face 450 and the housing 440 being constructed from dissimilar materials, such as a sensor face 450 made of titanium alloy joined to the housing 440 made of stainless steel, nickel plated brass, anodized aluminum, or a different titanium material, for example. Thus, specialized joining techniques (described in more detail below) are provided to attach the sensor face 450 and housing 440.
Referring to
An enhanced inductive proximity sensor 450 is shown adjacent to the conventional inductive proximity sensor 400 to illustrate performance differences. The enhanced inductive proximity sensor 450 consists of a housing 454 made of titanium, stainless steel, nickel plated brass, anodized aluminum, or other materials. A sensor face 460 made of titanium alloy, and having a higher electrical resistivity and/or lower temperature coefficient of resistivity than stainless steel, is located at one end of the housing 454. An electromagnetic field 470 penetrates the sensor face 460 and extends outward towards a metallic target object 480. As a result of the sensing face 460 being made of a titanium alloy having a higher electrical resistivity and/or lower temperature coefficient of resistivity than stainless steel, increased sensing distances 490 can be achieved.
Electrical resistivity is a measure of a material's opposition to the flow of electrical current through it. The amount of opposition varies with the type of material. According to electromagnetic theory, when conductors, such as a metal sensor face, are exposed to an electromagnetic field, such as that generated by a proximity sensor, a circulating flow of electrons, or eddy currents, are induced in the proximity sensor face. These eddy currents induce a magnetic field that opposes the electromagnetic field generated by the proximity sensor and prevents it from penetrating the sensor face. Materials with low electrical resistivity are good conductors and readily allow the movement of an electric current. Therefore, using a material with a low electrical resistivity, such as copper (1.7-3.8 microhm-cm) or aluminum (2.8-5.9 microhm-cm), for example, will produce strong eddy currents in the sensor face that prevent the electromagnetic field generated by the proximity sensor from adequately penetrating the material. The result is a proximity sensor with a greatly reduced or no sensing distance. A material with a high electrical resistivity is thus preferred in order to reduce the intensity of these eddy currents on the sensing face and allow sufficient penetration of the electromagnetic field through the sensor face.
Titanium and, more particularly, titanium alloys are well suited for use in inductive proximity sensors due to their higher electrical resistivity than stainless steels. However, not all forms of titanium are suitable for the intended proximity sensor application. Some titanium materials, such as the unalloyed ASTM Grades 1 through 4 (45-60 microhm-cm) and the light alloy ASTM Grades 7, 11 & 12 (52-55 microhm-cm), for example, have electrical resistivity values that are lower than that of stainless steel and thus are not suitable candidates for use as a proximity sensor face. Likewise, not all titanium alloys are suitable for use as a proximity sensor face as well. In general, titanium alloys with an electrical resistivity of approximately 170 microhm-cm or greater, such as, but not limited to, ASTM Grade 5 titanium alloy (Ti-6Al-4V) (177 microhm-cm) are particularly well suited for use as a proximity sensor face. By comparison, sensor faces made of stainless steel are typically made of UNS S30300/UNS S30400 stainless steel (72 microhm-cm) or UNS S316000/UNS 31603 stainless steel (74 microhm-cm). Therefore, it can be seen that titanium and, more particularly, titanium alloys have an electrical resistivity that is advantageously more than twice that of typical stainless steels used for sensing faces. The high electrical resistivity of titanium alloys provides a significant advance for inductive proximity sensor applications. Thus, a sensor face made from such a material can increase the achievable sensing distance. For example, under the same test conditions, sensors made with an ASTM Grade 5 titanium alloy sensor face were observed to exhibit a 20% (24 mm vs. 20 mm) increase in sensing distance over sensors made with a stainless steel sensor face.
Titanium alloys with a lower temperature coefficient of resistivity than stainless steel also offer advantages when exposed to temperature changes. The electrical resistivity of a material varies as a function of temperature. The electrical resistivity of a material generally increases with increasing temperature and decreases with decreasing temperature. For example, a typical UNS S30400 stainless steel sensor face has a temperature coefficient of resistivity of approximately 0.001/° C. while that of ASTM Grade 5 titanium alloy (Ti-6Al-4V) is approximately 0.00046/° C. Thus, when exposed to the same temperature range, the electrical resistivity of a sensor face made of ASTM Grade 5 titanium alloy (Ti-6Al-4V) will vary less over temperature than that of a sensor face made of UNS S30400 stainless steel.
For example, it was observed that under the same test conditions and with the same electrical circuits, a sensor with a face made of titanium alloy had a temperature sensitivity (voltage change over temperature) of 0.011 Volt/° C., while a sensor with a face made of stainless steel had a temperature sensitivity of 0.043 Volt/° C. For the same threshold, if not considering temperature compensation circuitry, environmental temperature changes could drive the sensor with a stainless steel sensor face over the threshold more easily and cause false detection. Additionally, because the titanium alloy sensor face has a high electrical resistivity and the sensor is more sensitive to the target, if the same sensing distance is assumed, then the titanium alloy sensor face could have a higher threshold (0.160 Volt, for example) than that of stainless steel (0.100 Volt, for example. Therefore, the use of titanium alloys with a lower temperature coefficient of resistivity than stainless steel can also reduce the sensor's sensitivity to temperature changes in the environment.
Another benefit associated with the use of a titanium alloys with a higher electrical resistivity and/or lower temperature coefficient of resistivity than stainless steel as a sensor face is that for the same sensing distance, a sensor face made of titanium alloy can have a greater thickness than a sensor face made of stainless steel. For example, it was observed that for the same sensing performance and with the same electrical circuits, the thickness of a sensor face made from titanium alloy (0.036″) was twice that of a sensor face made from stainless steel (0.018″). A thicker sensing face offers improved durability, impact resistance, and robustness to a proximity sensor product. In addition to the above mentioned benefits, titanium, in general, also has a unique set of properties that make it a desirable material for use in proximity sensor faces. These include suitable impact properties at low temperature and excellent corrosion resistance that often exceeds that of stainless steels in most environments. These properties address a market need for proximity sensors designed with rugged packaging to meet the demands of the harsh environments these sensors are utilized in.
While different techniques for joining the sensor face to the housing have been discussed here, it should be understood and appreciated that the above mentioned techniques are not intended to be restrictive or all inclusive. Other techniques for joining both similar and dissimilar metal combinations will be apparent to those skilled in the art, such as adhesive bonding, welding (in a variety of techniques), and brazing, for example.
Titanium is the ninth most abundant element in the earth; occurring only as rutile ore (TiO2) or as ilmenite ore (FeTiO3). Titanium has a unique set of properties that make it a desirable material. Titanium is a lightweight, non-magnetic, material whose density is approximately 60% of that of steel and approximately 50% of that of nickel and copper alloys. Titanium has an excellent strength-to-weight ratio and has a modulus of elasticity that is approximately 55% of that of steel. Titanium has good impact properties at low temperatures. Titanium also has excellent corrosion resistance in highly oxidizing to mildly reducing environments, including chlorides that exceed that of most stainless steels. Although titanium has a higher cost than stainless steel or brass, in the long run, titanium is often more economical because it has a service life of 20-40 years and is virtually maintenance free.
Titanium is an allotropic element that exists in two crystallographic forms. The first occurs in unalloyed (commercially pure) titanium at room temperature. This form is known as the alpha (α) phase. The alpha phase has a hexagonal close-packed (hcp) crystal structure. The second form occurs at approximately 1621° F. (883° C.) when the hexagonal close-packed crystal structure transforms into a body-centered cubic (bcc) crystal structure known as the beta (β) phase. The transformation temperature (beta transus) is strongly affected by the addition of other elements. The addition of the alpha stabilizers oxygen, nitrogen, and carbon can raise the transformation temperature. The addition of the beta stabilizer hydrogen can lower the transformation temperature. The addition of alloying elements or the presence of metallic impurities can raise or lower the beta transus. Titanium can be classified into three categories based upon their crystal structure: alpha alloys, alpha-beta alloys, and beta alloys.
At 1410 of
At 1420, alpha alloys are considered. Alpha alloys are predominantly single-phase alloys that contain elements of aluminum, tin, and/or zirconium. These alpha stabilizing elements, along with small amounts of oxygen, nitrogen, and carbon, have the effect of either stabilizing or increasing the transformation temperature. Alpha alloys contain large amounts of aluminum (up to 8% Al) to improve oxidation resistance at elevated temperatures. Alpha alloys, in general, have superior creep resistance than alpha-beta or beta alloys, a characteristic that makes them well suited to high temperature applications. Likewise, alpha alloys lack a ductile-to-brittle transition, a characteristic of beta alloys, which also makes them well suited to extremely low temperature applications. Alpha alloys exhibit excellent corrosion resistance and weldability.
At 1430, alpha-beta alloys are considered. Alpha-beta alloys have a two-phase microstructure that contains elements of aluminum, vanadium, chromium, and molybdenum. Large amounts of aluminum (up to 7% Al) serve to stabilize the alpha phase while varying amounts of vanadium, chromium, and molybdenum serve to stabilize the beta phase. Alpha-beta alloys contain from 10%-50% beta phase depending upon the quantity of beta stabilizers present and the heat treatment of the metal. Alpha-beta alloys have an excellent combination of strength and ductility. Alpha-beta alloys that are predominantly of the alpha phase are easily weldable while those that have a large amount of the beta phase, such as those that contain chromium, are not as easily welded.
At 1440, beta alloys are considered. Beta alloys contain a larger quantity of beta stabilizing elements and a smaller quantity of alpha stabilizing elements than alpha-beta alloys. Beta alloys are metastable in nature because cold work at ambient temperature or heating to a slightly elevated temperature can cause a partial transformation to the alpha phase. Beta alloys contain beta stabilizing elements such as vanadium, niobium, and molybdenum to reduce the transformation temperature. Beta alloys have excellent strength and hardenability. The strength of beta alloys comes from the intrinsic strength of the body-centered cubic microstructure and the precipitation of the alpha phase from the alloy through heat treatment. Beta alloys have a higher density, lower creep resistance, and less ductility than alpha-beta alloys. Beta alloys are generally not as easily welded.
Proceeding to 1510, detect disturbances in an oscillator generated field induced from an object or material passing in proximity of the oscillator generated field. At 1520, employ a housing for a sensor circuit as part of a proximity sensor, where the sensor circuit produces the oscillator generated field. At 1530, couple a sensor face to the housing, the sensor face detects the disturbances in the oscillator generated field and couples the disturbances to the sensor circuit, where the sensor face has a higher electrical resistivity or a lower temperature coefficient of resistivity than stainless steel. At 1540, employ the proximity sensor in an industrial control application.
It is noted that as used in this application, terms such as “component,” “module,” “system,” and the like are intended to refer to a computer-related, electro-mechanical entity or both, either hardware, a combination of hardware and software, software, or software in execution as applied to an automation system for industrial control. For example, a component may be, but is not limited to being, a process running on a processor, a processor, an object, an executable, a thread of execution, a program and a computer. By way of illustration, both an application running on a server and the server can be components. One or more components may reside within a process or thread of execution and a component may be localized on one computer or distributed between two or more computers, industrial controllers, or modules communicating therewith.
The subject matter as described above includes various exemplary aspects. However, it should be appreciated that it is not possible to describe every conceivable component or methodology for purposes of describing these aspects. One of ordinary skill in the art may recognize that further combinations or permutations may be possible. Various methodologies or architectures may be employed to implement the subject invention, modifications, variations, or equivalents thereof. Accordingly, all such implementations of the aspects described herein are intended to embrace the scope and spirit of subject claims. Furthermore, to the extent that the term “includes” is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term “comprising” as “comprising” is interpreted when employed as a transitional word in a claim.
