Patent Application
20050066084
Not applicable.
Not applicable.
1. Field of the Invention
The present invention relates to devices, systems, and processes useful for signal conditioning.
2. Brief Description of the Related Art
Control systems automate our world. From assembly lines to home heating and cooling systems, sensors detect various conditions, and report those conditions with discrete signals to a controller. The controller is programmed to keep the system running by feeding back commands determined by the various signals it receives. The processor feeds command signals back to controllers to operate equipment that perform work. Input/Output (I/O) devices feed information between sensors and controllers. To send discrete signals back and forth through the system, signal conditioning must be performed.
One problem found in control system design is integrating different discrete signal formats. Many different types of sensors may be used in a system. For example, a mail processing system may have optical character recognition scanners, and scales, along with other types of sensors, to sort mail. These sensors are manufactured by different companies, and have different discrete signal formats. Thus, the problem of integrating discrete signal formats is continuously present in control systems.
Another problem in designing control systems is encountered when bridging the gap between existing, or legacy, technology, and current computer architecture. Particularly, control systems have moved towards a distributed architecture, where a single controller controls signal discretes (“discretes”) that are distributed along a common FieldBUS (Device-Level Network). Legacy systems typically have several central processing units (CPUs) controlling various subsystems and accessing discrete signals locally, with a custom format, rather than a common architecture. Increased performance of CPU's has enabled and driven the migration towards distributed I/O systems. If the legacy system cannot be interfaced with a distributed system, the user is faced with purchasing and testing a completely new automation system. This complete replacement is often too costly and time consuming to be feasible.
Discrete signals must be conditioned when interfacing the legacy and distributed systems. If the signals are compatible, the discrete may be left alone. Otherwise, the discrete may need to be interrupted, redirected, or over-ridden. In current systems, conditioning legacy discretes has typically been approached in two ways. One approach has been to place a communications link between the legacy controller and the distributed system controller, and allow this new controller to make requests from the legacy system. This approach, however, does not give the distributed system real-time control. Another approach to conditioning legacy discretes has been to alter the existing hardware, effectively generating a new discrete signal format. This approach, however, again requires custom alteration to the existing system, requiring testing and equipment replacement.
Various devices, systems and methods are known for conditioning signals in control systems. U.S. Pat. No. 6,392,557 to Kreuter, issued May 21, 2002, describes an output over-ride board 10 releasably mounted to a programmable logic controller 12 (PLC) that controls an output of the PLC 12. The over-ride board is particularly used for over-riding the output signal from a PLC so that the PLC can be modified at the installation sight (col. 4, 11. 23-28.)
U.S. Pat. No. 5,947,748 to Licht, et al., issued Sep. 7, 1999, for a connector to a PLC. The interface connector board 16 evenly distributes thermocouple wires providing input to the PLC. A plurality of dielectrically isolated interconnection points permits the user to custom design components used for signal conditioning (col. 3, 11. 5-30).
Although prior systems, methods, and devices generally functioned well and provided advantages over prior systems, methods, and devices, they do not provide a simple, efficient, and cost-effective manner of conditioning legacy discrete signals interfaced with a distributed system architecture.
A circuit card assembly provides signal conditioning for signal discretes in control systems integrating a legacy, distributed processing architecture and a distributed I/O control system. Signal conditioning functions are determined, and the necessary physical circuits to perform the signal conditioning functions are incorporated into a circuit card. The Integrated Signal Conditioning Circuit Card Assembly is installed within the control system between legacy controllers and distributed I/O modules. The Integrated Signal Conditioning Circuit Card Assembly may leave any discrete signal unaltered or otherwise condition discretes with interrupt, interrupt on demand, over-ride, and monitor circuits. The centralized processor accesses and controls the conditioned discretes transmitted over a common hardware connection for use in system feedback and control.
The invention of the present application will now be described in more detail with reference to preferred embodiments of the apparatus and method, given only by way of example, and with reference to the accompanying drawings, in which:
Referring to the drawing figures, like reference numerals designate identical or corresponding elements throughout the several figures.
The Master CPU 20 is electrically connected to the various subsystems 10, 12, 14 and to the legacy controllers 22, 24, 26. The Master CPU 20 runs the control system and has sufficient flash memory to store instructions when the system is powered down. When the system is powered up, the Master CPU 20 downloads high-level instructions to each legacy controller 22, 24, 26. During system operation, subsystems 10, 12, 14 transmit data read for sorting flats 5 to the Master CPU 20.
Flats 5 are transferred from the processing area 1, to the sorting area 3 via the mail transport mechanism 16. In the sorting area, mail diverters 30a, 30b, 30c, 32a, 32b, 32c can either transport the flats 5 downstream or divert the flats 5, as illustrated by diverter 30b, for sortation. Swivels 40, 42 are connected to chutes 60, 62 that direct flats 5 into trays 50, 52 for eventual transfer onto take-away conveyor 17.
Diverters 30a, 30b, 30c, 32a, 32b, 32c, re-position flats 5 as operated by legacy controllers 24, 26 when flats are in the sorting area 3. As a flat 5 moves along the transport 16, the information detected by the subsystems 10, 12 and 14 in the processing area 1, are transmitted to various processors (further described below) that control the sorting system. For example, all flats 5 weighing less than 5 ounces and going to zip code 22314 may belong in tray 50. The controller 24 for diverter 30b is signaled to operate diverter 30b to sort flat 5 off the transport 16. At the same time, the controller 24 activates swivel 40 to open chute 60, allowing the flat 5 to enter chute 60 and fall into its proper tray 50. Each legacy controller 22, 24, & 26 is given high-level instructions regarding activities to take place in their sections from the Master CPU 20. As different actions along the sorting or processing areas happen, control signals are received and sent between sensors and controllers to provide information about and operate the system.
Referring to
The Legacy I/O Cards 501, 502, 503 are designed and manufactured according to the type of discrete signals to be processed. One of skill in the art determines the type of signal conditioning function needed to convert the discrete to the proper format for the distributed architecture. The Legacy I/O Cards 501, 502, 503 accept legacy input signals and transmit legacy output signals through pinned connectors and wires, as known by one of ordinary skill in the art. Preferably, the Legacy I/O Cards 501, 502, 503 operate on a direct current format. It will be appreciated that other formats may be accommodated. Preferably, from 5 to 30 volt direct current format, or less than 250 volts alternating current. By accepting and conditioning the legacy discretes having different signal formats, The Legacy I/O Cards 501, 502, 503, provide an opportunity for the legacy controllers to operate compatibly with a new distributed I/O processing architecture. For example, where a legacy system sensor monitors the position of a mail diverter, and a controller in a modern distributed I/O tray handling system needs to read the same signal providing status of the diverter, one of ordinary skill would determine that a monitor circuit would be needed to interface the legacy signal to the modern distributed I/O tray handling system. Once the design determination is made, an Integrated Signal Conditioning Circuit Card Assembly may now be manufactured to accept and condition the discrete signal inputs.
Referring to
Discrete signals 72, 73, 82, 83 originate from legacy controller 24 (as illustrated in
In the exemplary mail sorting system illustrated in
It will be appreciated by one of ordinary skill in the art that signal-conditioning circuits are well-known, and a variety of circuit types and structures may be used to format signals within an Integrated Signal Conditioning Circuit Card Assembly without departing from the scope of the present invention. For example, monitor, interrupt, interrupt-on-demand, over-ride, and pass-through functions can be provided as constants or on-demand by altering the conditioning circuit structure. Further, though a specific number of discrete signals are illustrated in the exemplary embodiment, it will be appreciated by one of ordinary skill in the art that the Integrated Signal Conditioning Circuit Card Assembly of the present invention may be manufactured to accept as many discrete signals as can be contained on a circuit card. Preferably, the Integrated Signal Conditioning Circuit Card Assembly accepts between 1-32 discrete signals, and more preferably, 32 discrete signals. However, it will be appreciated by one of ordinary skill in art that circuit cards may be fabricated for conditioning more than 32 discretes. Conditioned signals are then available to the new control system for further processing and control. The legacy controller continues to provide feedback to the Master CPU through the communications network for system operation, not necessarily even aware of the discrete signal conditioning that has taken place.
While the control system illustrates a single signal conditioning circuit card assembly associated with each legacy controller, it will be appreciated by one of ordinary skill in the art that multiple signal conditioning circuit card assemblies can be incorporated into each CPU to accommodate multiple signal formats. Likewise, multiple Integrated Signal Conditioning Circuit Card Assemblies may be used, throughout legacy control system architectures, in accordance with the present invention.
While the present invention is described in the context of a mail sorting system, it will be appreciated by one of ordinary skill in the art that an Integrated Signal Conditioning Circuit Card Assembly in accordance with the present invention may be used in any type of control system environment.
While the invention has been described in detail with reference to preferred embodiments thereof, it will be apparent to one skilled in the art that various changes can be made, and equivalents employed, without departing from the scope of the invention.
