Abstract:
Systems and methods for accepting and producing various I/O. The systems can include a plurality of input connectors and/or output connectors integral to a board, a circuit to disable the output connectors, and a programmable logic controller modular to the board and electrically coupled to the plurality of input connectors and the plurality of output connectors. The programmable logic controller can be associated with a computer readable medium that incorporates instructions executable by the programmable logic controller to configure one or more of the input and/or output connectors, and/or to at least partially control an output timeout state.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     The present application claims priority to U.S. Provisional Pat. App. No. 60/368,504, entitled PLC I/O SYSTEM FOR PROCESSING MAIL filed on Mar. 29, 2002. The entirety of the aforementioned U.S. provisional patent application is incorporated herein by reference for all purposes. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to systems and methods for processing and distributing mail, and in particular to systems and methods for processing I/O. 
     Mail processing in a large consumer service provider is a cumbersome endeavor. Systems and methods for automatically processing the mail have been developed. Such systems and methods have reduced the necessity for manually processing mail for distribution and have provided significant efficiencies. Such systems and methods, however, require processing of significant input/output (I/O) signals. To date, I/O processing capabilities are limited in various ways that make implementation of the automatic systems and methods more complex. 
     Further, production of prototype circuit boards, such as I/O processing boards, can be both cumbersome and expensive. For example, hundreds of leads from semiconductor chips must be soldered to a board. This can be very labor intensive and often damages the board. Alternatively, a solder stencil may be made, and the boards populated and soldered in an automatic soldering machine. However, such a process involves significant non-recurring engineering expenses. 
     Thus, there is a need in the art for advanced I/O processing capabilities, and methods for manufacturing such capability. 
     BRIEF SUMMARY OF THE INVENTION 
     Among other things, the present invention provides systems and methods related to processing I/O. In some embodiments, the systems and methods include a circuit board for processing I/O and methods for manufacturing such circuit boards. 
     Various embodiments of the present invention provide systems for accepting and producing various I/O. The systems include a plurality of input connectors and/or output connectors integral to a board. In one particular instance, the plurality of input connectors and the plurality of output connectors are configurable to be either inputs or outputs. The systems further include a programmable logic controller modular to the board and electrically coupled to the plurality of input connectors and the plurality of output connectors. The programmable logic controller is associated with a computer readable medium that comprises instructions executable by the programmable logic controller to output a timer clock signal associated with the plurality of output signals. 
     In various instances, the plurality of output connectors include a power source, that is individually fused to each of the plurality of output connectors. In other cases, the computer readable medium further comprises instructions to configure at least one of the plurality of input connectors to drive an output, and to drive the output, and/or instructions to configure at least one of the plurality of output connectors to receive an input, and to receive an input signal therefrom. In yet other instances, a hardware circuit is included to disable the plurality of output connectors when the timer clock signal goes inactive for a period, which in some cases is approximately 650 milliseconds. In certain cases, the period is a first period, and the system includes a hardware circuit to maintain the output connectors in the disabled state for a second period after the timer clock signal becomes active again. In some cases, the second period is more than the time required to reset the programmable logic controller. In particular cases, the computer readable medium further comprises instructions to maintain the output connectors in the disabled state for a second period after the timer clock signal becomes active again, and to activate the output connectors after the second period has expired. 
     In other cases, the computer readable medium further comprises instructions to disable an input connector that has been configured as an output. The input connector is disabled when the timer clock signal goes inactive for a period, and stays inactive for another period. 
     Other embodiments provide methods for receiving and driving I/O in a mail processing system. The methods include providing a set of configurable I/O ports, wherein each I/O port in the set of configurable I/O ports can be configured to be an I/O selected from a group consisting of an input and an output. The methods further include providing a configuration processor modularly coupled to the set of configurable I/O ports, programming the configuration processor to configure a first I/O port of the set of I/O ports as an input and a second I/O port of the set of I/O ports as an output, disabling the output when a timer associated with the configuration processor goes inactive for a first period, and enabling the disabled output when the timer associate with the configuration processor resumes activity for a second period. Further, in some cases, a fuse is provided in relation to each of the set of configurable I/O ports. Also, the methods can include resetting the processor after the first period. 
     In yet other embodiments, methods for preparing circuits are provided. The methods include preparing an I/O circuit board where the I/O circuit board has lead lines and at least a first I/O port and a second I/O port. The I/O board is populated with one or more semiconductor chips touching the lead lines, and a bead of solder is placed in proximity to the one or more semiconductor chips near locations where the one or more semiconductor chips touch the lead lines. The I/O board is baked until the bead of solder melts, thus adhering the semiconductor chips to the lead lines. A processor is attached to the I/O circuit board, and programmed to configure a first I/O port as an input and the second I/O port as an output, disable the output when a timer associated with the processor goes inactive for a first period, and enable the disabled output when the timer associate with the configuration processor resumes activity. In some cases, programming the timer to disable the outputs includes selecting circuitry to define a time-out period. 
     This summary provides only a general outline of the embodiments according to the present invention. Many other objects, features and advantages of the present invention will become more fully apparent from the following detailed description, the appended claims and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A further understanding of the nature and advantages of the present invention may be realized by reference to the figures which are described in remaining portions of the specification. In the figures, like reference numerals are used throughout several figures to refer to similar components. In some instances, a sub-label consisting of a lower case letter is associated with a reference numeral to denote one of multiple similar components. When reference is made to a reference numeral without specification to an existing sub-label, it is intended to refer to all such multiple similar components. 
         FIGS. 1 , and  1 - 1  through  1 - 18  are a schematic diagram of an embodiment of the present intention; 
         FIG. 2  is a flow diagram of a method for processing I/O in accordance with embodiments of the present invention; 
         FIG. 3  illustrates elements that can be used in manufacturing circuit boards in accordance with various embodiments of the present invention; and 
         FIG. 4  is a flow diagram of a method in accordance with embodiments of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One embodiment of the present invention includes an addressable I/O board for extending I/O for one or more Programmable Logic Controllers (PLC) that are insertable into the board.  FIG. 1  illustrates a sectional assembly of Figures TBD into an overall schematic of the embodiment. The discussion that follows the sections of the schematic. 
     As illustrated in  FIGS. 1-1  through  1 - 3 , the board includes sixty digital input lines (I 1 -I 60 ). Each of the digital input lines are associated with a light emitting diode (LED) (D 61 -D 120 ) and biased with a input voltage through a resistor (R 61 -R 120 ). The bias is such that an LED associated with the particular input lights when the input is grounded. In addition, the board includes sixty analog input lines (I 1 ,J 1 A-A 15 ,J 1 A, I 1 ,J 1 B-I 15 ,J 1 B; I 1 ,J 2 A-A 15 ,J 2 A; and I 1 ,J 2 B-I 15 ,J 2 B). The analog inputs are accepted via an associated 15 pin D connector (J 1 ,A and B; J 2 , A and B) 
     As illustrated in  FIGS. 1-4  through  1 - 7 , the inputs are isolated via a group of opto-isolators (U 1 -U 16 ). The outputs from the opto-isolators (U 1 -U 16 ) are multiplexed using a series of muxes (U 17 -U 24 ). Using the muxes (U 17 -U 24 ), one of the eight mux inputs are selected for output. The selection is provided by AIN 0 -AIN 2  from a PLC (U 26 ) as described hereinafter. Alternatively, the mux outputs are selected using an optional PLC (U 40 ) as described hereinafter. 
     The mux outputs (DIN 1 -DIN 8 ) form the data input for PLC (U 26 ), or optionally, PLC (U 40 ). As illustrated in  FIGS. 1-9  and  1 - 14 , the mux outputs (DIN 1 -DIN 8 ) are electrically connected to PLC (U 26 ) at Port A (PA 0 -PA 7 ). In one particular embodiment, PLC (U 26 ) is a BL1800 series PLC offered by ZWORLD, Inc. 
     Alternatively or in addition, the mux outputs (DIN 1 -DIN 8 ) are electrically connected to PLC (U 40 ) at Port B (PB 2 -PB 5 ). In embodiments, PLC (U 40 ) is optionally populated and can be a core microprocessor module offered as RCM2100 again offered by ZWORLD, Inc. 
     Outputs (DOUT 1 -DOUT 7 ) are output from port E of PLC (U 26 ) and/or optionally from port A of PLC (U 40 ). In addition, PLC (U 26 ) provides input address selection lines (AIN 0 -AIN 2 ) via port D, and PLC (U 40 ) provides the same address lines using a combination of ports D and E. Address out (AOUT 0 -AOUT 2 ) lines are provided using the same ports. 
     As previously mentioned, the address in lines (AIN 0 -AIN 2 ) are used to control the muxes (U 17 -U 24 ) in determining which of a variety of input signals to drive the PLC(s). In one case, the address lines are cycled to make an eight bit parallel input into an eight bit serial stream. Thus, for example, inputs (I 1  and I 9 ) can be selected through the mux (U 17 ) and carried serially thereafter as DIN 1  to the PLC(s). 
     Similarly, the address out signals (AOUT 0 -AOUT 2 ) control the signals provided to the outputs as described further below. Thus, as just one example, the same DIN 1  signal can be transferred to DOUT 1  as a serial signal, and clocked out as parallel output signals. Referring to  FIG. 1-8 , high current latches (U 27 -U 34 ) are used to accept the serial DOUT signals from the PLC(s), latch the distinct signals carried thereon, and provide the signals as outputs ( 1 ,J 3 A- 15 ,J 3 A;  1 ,J 3 B- 15 ,J 3 B;  1 J 4 A- 15 ,J 4 A; and  1 J 4 B- 15 ,J 4 B). The high current latches are capable of driving up to 350 mA per output, but each of the outputs are fused at 250 mA using fuses (F 1 -F 60 ). 
     Of note, each of the I/O are individually fused. This is contrary to the approach known in the art where the I/O would typically be controlled by a common fuse to reduce costs. In contrast, however, it has been found that down time on one or more mail processing machines to which the I/O are related can be considerable and costly. By adding individual fuses, a failing circuit can be quickly identified by determining the failing fuse, and can then be repaired. Such an approach can reduce down time of the mailing machines, and increase productivity. Further, lower value fuses can be selected to provide additional isolation. 
     As illustrated in  FIGS. 1-15  through  1 - 16 , the sixty outputs ( 1 ,J 3 A- 15 ,J 3 A;  1 ,J 3 B- 15 ,J 3 B;  1 J 4 A- 15 ,J 4 A; and  1 J 4 B- 15 ,J 4 B) are each attached to an LED (D 1 -D 60 ) biased to light when the individual outputs are at a low voltage, and to turn off when the outputs are at a high voltage potential. Each of the outputs are accessible via an associated 15 pin D connector (J 3 , A and B; J 4 , A and B). 
     Address in lines, address out lines, the data in and out lines, and the associated clock and control signals are all under control of software operating on PLC(s) (U 26 , U 40 ). In some cases, the input and output connectors are designed to logically control related items. For example D-connector J 1 ,A may receive input from a particular set of potentiometers associated with a mail processing line, and D-connector J 3  may be associated with a related set of solenoids associated with the same mail processing line. Thus, the logical arrangement of the I/O interfaces makes programming PLC(s)(U 26 , U 40 ) more efficient and easily accomplished. 
     More particularly, in one embodiment, a single address select input from one D-connector and provides output from another D-connector. Thus, a programmer need only use one address to access input from a related group of inputs (e.g., potentiometers), and the same address to provide outputs to a related group of outputs (e.g., solenoids). 
     The circuit additionally includes a failsafe mechanism which can drive the outputs to an inactive state upon failure of either or both of the PLCs. In operation, the failsafe circuit monitors one or more clocks from the PLC(s). When a clock goes inactive for more than 650 ms, then all of the outputs are driven to an inactive state and the PLC(s) are reset. If the clocks never again reactivate, the outputs remain in the inactive state. On the other hand, once the clocks begin operation anew, the PLC drives the outputs to a default state and then ultimately back to an operational state under software control. 
     In some instances, the analog inputs are zero through five volt inputs used to detect voltage information obtained from linear potentiometers. Such linear potentiometers can be used to detect the thickness of a stack of mail being processed in a mail processing system. 
     In various aspects of the present invention, one or more of the previously described circuit boards can be daisy chained to create additional I/O capacity. Additional failsafe features may be included to detect the presence of failures of upstream boards. Such failures can be detected by the absence of clock activity and result in the inactivation of outputs on all boards (or a portion of boards) in the daisy chain. 
     The board is programmable through use of the PLC(s). The I/O speed of the board can be directly controlled by the clock driving the PLC. Thus, in some cases, boards with I/O speed up to that of the PLC can be developed. In various embodiments, the address lines only have to be set once to provide for use of the board in relation to a mail processing system. This reduces the complexity of any related software running on the PLC(s). 
     Referring to  FIG. 2 , a flow diagram  250  illustrates a method in accordance with the present invention for operating the circuit board illustrated in  FIGS. 1 , and  1 - 1  through  1 - 18 . Following flow diagram  250 , the input and output ports of the circuit board are configured (block  255 ). Such configuration can include asserting the proper address signals to select the desired inputs and/or outputs. Once all of the inputs and/or outputs are configured, the outputs are enabled and driven by PLC (U 26 ), and the inputs are received at PLC (U 26 ) (blocks  260 ,  265 ). A timer is monitored (block  270 ). In some cases, the timer indicates the active status of PLC (U 26 ). Where the timer is active (block  270 ) operation of the inputs and outputs continues as previously described. Alternatively, where the timer is inactive (block  270 ) it is determined how long the timer has been inactive (block  275 ). Where the timer has been inactive for less than a predefined period, operation of the inputs and outputs continues as previously described. Alternatively, where the timer has been inactive for more than the predefined period (block  275 ) the output ports are disabled (block  280 ). This prevents outputs from being driven when PLC (U 26 ) has become disabled or damaged. In some cases, the predefined period is approximately 650 milliseconds. In other embodiments, the predefined period is programmable and can be matched to a particular application. For example, in one embodiment, the predefined period is programmed by selecting hardware components, such as resistors and capacitors to be associated with the 74123 parts of  FIG. 1-18 . 
     One embodiment of a timer circuit for performing the methods as previously described is illustrated in  FIG. 1-18 . The PCLOCK signal from PLC (U 26 ) drives the B input of a one millisecond timer (U 39 A). Thus, when PCLOCK is active a series of one millisecond pulses will be driven by one millisecond timer (U 39 A). In contrast, when PCLOCK is inactive, the output of one millisecond timer (U 39 A) will go inactive. The output of one millisecond timer (U 39 A) is driven into a 650 millisecond timer (U 38 A) and resets the 650 millisecond timer. Thus, where PCLOCK goes inactive the output (Qbar) of 650 millisecond timer (U 38 A) will assert high after 650 milliseconds. When the output of 650 millisecond timer (U 38 A) asserts high, it drives the input of another one millisecond timer (U 39 B). This causes the output of one millisecond timer (U 39 B) that is tied to the RESET input of PLC U 26 ) to assert, thus resetting PLC (U 26 ). In addition, an output of one millisecond timer (U 39 B) drives the B input of an eight second timer (U 38 B). When the output from U 39 B is asserted, the output of eight second timer (U 38 B) asserts and disables the outputs of the board by asserting OTCLR. Where PCLOCK becomes active again after the RESET signal is asserted, the outputs of the board remain inactive for the eight second period as 650 millisecond timer will not time out again thus avoiding renewed assertion of the RESET signal. Alternatively, where PCLOCK does not become active after assertion of the RESET signal, 650 millisecond timer (U 38 A) again times out causing one millisecond timer (U 39 B) to assert the RESET signal starting the resent process over. In some embodiments, this reset process repeats indefinitely until the PCLOCK signal becomes active again. 
     In addition to disabling the outputs, PLC (U 26 ) can be reset (block  285 ). Once PLC  285  has completed its reset, the timer again becomes active (block  290 ), and the input and/or output ports are again configured (block  255 ). From this point, the process repeats as previously described. 
     Referring to  FIG. 3 , various elements useful in manufacturing circuit boards, such as that described in relation to  FIG. 1 , and  FIGS. 1-1  through  1 - 18  are illustrated. The elements include a container  205  of solder paste. Such solder paste is commercially available. Other elements include a circuit board  220  including lead lines  225  of a width  235  that are electrically connected to other elements and/or lead lines on circuit board  220  via wire traces  230 . In addition, a commercially available syringe  210  is provided that can be loaded with the solder paste, and which provides an output orifice  240  sufficiently large to dispense the solder paste, yet small enough to assure application of only a limited amount of the solder paste. In some cases, the diameter of orifice  240  is approximately the same as width  235 . In other embodiments, the diameter is slightly less than width  235 . In some embodiments of the present invention, container  205  of solder paste is combined with syringe  210  in a kit with instructions on how to perform the methods as discussed in relation to FIG.  4 . 
     Referring to  FIG. 4 , a flow diagram  400  illustrates a method in accordance with an embodiment of the present invention for manufacturing circuit boards. Following flow diagram  400 , solder paste  205  is loaded into syringe  210  (block  405 ). A surface mount chip is placed on circuit board  220  such that lead lines from the chip touch lead lines  225  (block  410 ). Syringe  210  is used to dispense a bead of solder paste approximately perpendicular across the junction of the chip leads and lead lines  225  (block  415 ). Thus, for example, where seven lead lines  225  exist, a single solder bead crossing the seven lead lines can be dispensed. Circuit board  220 , along with the chip and the applied solder paste is loaded into an oven where it is baked (block  420 ). The temperature and period of the baking process is governed by the type of solder paste used, the width of lead lines  225 , and/or the size of diameter  240 . In one particular embodiment, circuit board  220  is baked for fifteen minutes at 350 degrees Fahrenheit. 
     Once the baking process is completed, circuit board  220  is inspected to determine if the solder paste has melted and adhered to lead lines  225 . In addition, it is determined whether the solder has adhered across lead lines resulting in electrical shorts (block  425 ). Where such shorting is apparent, local heat is applied to the shorted area such that the solder flows to and adheres to individual lead lines (block  430 ). Local heat can be applied to individual leads, or areas of the circuit board using, for example, a soldering iron or heating gun. Otherwise, the process is complete (block  435 ). 
     Using such an approach, a low cost prototype circuit board can be manufactured. Further, the process avoids the commonly used approach of hand soldering that can result in warping of circuit board  220 , and lifting of lead lines  225 . Yet further, the approach limits costs involved in manufacturing prototypes by eliminating the need for a solder mask. One of ordinary skill in the art will recognize the myriad of other advantages afforded through use of the method. Additionally, one of ordinary skill in the art will recognize various modifications that can be made to the method in accordance with the present invention. 
     The invention has now been described in detail for purposes of clarity and understanding. However, it will be appreciated that certain changes and modifications to the previously described embodiment that can be made within the scope of the present invention. Based on the disclosure provided herein, such changes and modifications will be apparent to those of ordinary skill in the art. Thus, the functions of the systems and methods of using such are merely exemplary. Accordingly, it should be recognized that many other systems, functions, methods, and combinations thereof are possible in accordance with the present invention.