Patent Publication Number: US-2005130459-A1

Title: Configurable connectorized I/O system

Description:
This application is a continuation-in-part of U.S. patent application Ser. No. 10/071,870 filed Feb. 8, 2002, which claims the benefit of U.S. Provisional Application Ser. No. 60/269,129 filed Feb. 14, 2001. 
    
    
     BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates generally to cabling and cabling systems, and more particularly to a universal cabling system wherein the requirement for specific wire interconnections between first and second devices is accomplished through use of a programmable I/O module for making connection to the first device, and directing connections from the first device to selected wires of a cable for connection to the second device.  
      2. Description of the Prior Art  
      Complex electrical/electronic systems often require custom cable configurations. Cables are usually special configurations for a particular application. Even in relatively simple systems such as home audio and small computer systems, a number of different cables are typically required. In larger applications, such as industrial control systems, the number of custom cable designs is extensive. In industrial control systems such as those that run automotive plants, etc., interaction is required between control apparatus and sensors and actuators. The apparatus providing the corresponding connections will be referred to as input and output systems. Through the output system, the control system can turn on lights, pumps, valves and other devices. Similarly, through the input system, the control system can sense the state of a pushbutton, whether a switch is on or off, or whether a tank is full or how fast a shaft is turning.  
      In prior art control systems, such as a Programmable Logic Controller (PLC), the user of the control system electrically connects the sensors and actuators to the input/output systems using individual wire connections or via connectorized wire harnesses. A common method of connecting sensors and actuators to industrial control systems is through the use of individual wire connections via terminal blocks. Terminal blocks usually employ a screw-driven clamp. An electrical wire&#39;s insulation is removed from the end, and then the bare wire is slid under the screw-driven clamp. The screw is then tightened to secure the wire under the clamp and effect an electrical connection between the wire and the terminal block. Increasingly, various spring clamps are used to hold the wire, but these are essentially the same as screw-driven clamps.  FIG. 1  shows how individual wires  10  are connected to the input and output Modules  12 ,  14  of a PLC  16  through terminal blocks  18  to three devices, a light bulb  20 , a switch  22  and a proximity switch  24 . A proximity switch is a common type of switch that can detect the presence (typically) of metal, and gives an indication by interrupting or passing electrical current.  
      A disadvantage of the method illustrated in  FIG. 1  is that the terminals  26 ,  28  on the input or output modules of the PLC  16  are not necessarily conveniently arranged for facilitating easy connection of a load, such as a light bulb or switch. As a result, a great deal of custom, hand-wiring must be performed in order to effect the interconnections. In addition the electricity, from a supply  30  to power certain actuators and sensors such as the light bulb or proximity sensor, must be provided on the terminal blocks  18  in order to make connections to the light bulb or switch. In general, the prior art output Modules  12  and  14  do not supply power to the load, they only switch the power. The custom wiring design and implementation illustrated in  FIG. 1  significantly adds to the cost and size of the system.  
      Another method of connecting an industrial control system such as a PLC to a load is via a connectorized wire harness or cable.  FIG. 2  shows one input module  32  and one output module  34  from a PLC  36 . The input/output modules  32  and  34  are equipped with connectors  38  and  40  respectively that allow cables  42  and  44  to be used to make connection with various sensors and actuators. Unfortunately, the cable from the input or output module cannot generally connect directly to the sensor or actuator because the connectors  38  and  40  on the PLC  36  are rarely configured to accept a sensor signal or provide the actuator power. For this reason,  FIG. 3  represents the most common method of connecting a PLC to a sensor or actuator when employing connectors on the PLC. In  FIG. 3 , cables  40  from the PLC input  32  and output  34  modules connect to circuit boards  46  and  48  which contain terminal blocks  50  for making connections to the control system. Therefore, even when connectorized cables are employed, the prior art still requires making connections through use of individual wire connections such as terminal blocks.  
      Making a direct connection between a PLC and a sensor or actuator without individual wire connections is problematical. An example situation is when a PLC must be connected to a device that already is equipped with a connector. The need to connect a PLC to such a device is very common. A typical device is a mass flow controller equipped with a connector for connecting signals that must be connected to the PLC. In this case, the connections are complicated by the fact that the PLC output module contains only outputs and the PLC input module contains only inputs, whereas the mass flow controller connector contains signals that represent both inputs and outputs. To make matters worse, some of the signals are discrete—that is, on/off—and some are continuously varying analog signals. In addition, the mass flow controller also requires application of a power supply voltage and return/ground to the flow controller connector.  
      In general, prior art methods and apparatus require the use of custom cable harnesses designed and built to connect the rigid format of a PLC to the varying formats of the disparate devices such as mass flow controllers and power supplies. The difficulty of designing, fabricating and installing complex wire harnesses is so great that the predominant method of connecting PLC&#39;s to sensors and actuators is via individual wire connections and terminal blocks.  
       FIGS. 4   a  and  4   b  show two examples of typical non-standard cable construction. In  FIG. 4   a  each of wires  52  and  54  connects to a different pin on connector  56  than on connector  58 . The cable of  FIG. 4   b  has two connectors  60  and  62  on one end and a single connector  64  on the other end.  
     SUMMARY  
      It is therefore an object of the present invention to provide a method and apparatus wherein customized connections can be made using standard cables.  
      It is another object of the present invention to provide a method and apparatus that reduces the cable complexity involved in making interconnections in control systems.  
      It is a further object of the present invention to provide a method and apparatus for reducing the number of custom designed cables and individual wire connections in a system.  
      It is an object of the present invention to provide a programmable input/output module for directing signals between apparatus through standard cables.  
      It is another object of the present invention to provide an improved system for testing cables utilizing programmable input/output modules.  
      It is a still further object of the present invention to provide an interlock system for a control system that uses programmable input/output modules and standard cables.  
      Briefly, a preferred embodiment of the present invention includes a system for enabling a system controller to receive a selected signal type from, or apply a selected signal type to any selected one or more of a plurality of cable conductors. An input/output module includes a first connector apparatus for making connection with a first transmission line/cable for conveying signals between the module and the system controller. At least one second connector is provided for connecting to a first end of a second standard cable. A second end of the second standard cable includes a standard cable connector for making connection to a corresponding connector of a device from which data is received or to which a signal is applied. The input/output module is configured to contain programmable logic for enabling the required communication between the controller and the device.  
      An advantage of the present invention is that it minimizes or eliminates hand wired interconnections.  
      A further advantage of the present invention is that it reduces the cost of hand wiring, including related documentation, wire stripping, wire labeling, installation and testing.  
      A still further advantage of the present invention is that it eliminates or minimizes the need for custom cable harnesses.  
      Another advantage of the present invention is that it reduces the time required to design a new system.  
      An advantage of the present invention is that it reduces the quantity of part numbers in a system.  
      A further advantage of the present invention is that it simplifies maintaining systems in the field because a smaller number of cables need to be available to replace damaged or suspected cables.  
      A still further advantage of the present invention is that it aids in making system design changes, because new cable designs are generally not required. 
    
    
     IN THE DRAWING  
       FIG. 1  illustrates a prior art interconnection system using individual wires;  
       FIG. 2  illustrates a prior art interconnection system using cables;  
       FIG. 3  illustrates the prior art use of circuit boards for interconnecting cable wiring to selected devices;  
       FIG. 4   a  shows a typical prior art custom cable arrangement;  
       FIG. 4   b  shows another typical prior art custom cable arrangement;  
       FIG. 5  is a block diagram for illustrating the apparatus and method of the present invention;  
       FIG. 6  is a circuit diagram for illustrating further detail of the module of the connectorized configurable system of the present invention;  
       FIG. 7  is a block diagram illustrating a system for testing cables using the module of the present invention;  
       FIG. 8  is a diagram of a prior art interlock system; and  
       FIG. 9  is a block diagram of an interlock system using the configurable connectorized input/output module of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      Referring now to  FIG. 5  of the drawing, a block diagram is presented for illustration of the method and apparatus of a preferred embodiment of the present invention. The apparatus of the present invention includes a configurable input/output system  65  including an input/output module  66  and one or more cables  68 . All of the cables  68  are preferably identical, but the present invention also includes variations in the cables  68 . Each cable  68  includes one or more conductors. The I/O module  66  according to the present invention includes a microprocessor that is programmable for enabling a particular transmission of a signal between the module  66  and devices  70 , and between the module  66  and a system controller  72 . The module  66  also preferably includes one or more standard connectors  74  for connection to the standard cables  68 . A connector  76  provides connection to a network (preferably Ethernet)  78  for communication between the module  66  and the system controller  72 . The module  66  is programmed/configured by input from the system controller  72 . Alternatively, the module  66  can be configured to be programmed through use of a separate computer (not shown).  
      For example, the module  66  may be programmed to connect a power supply voltage from either an external device such as a device  79  or from a supply built into the module  66 , to any one or more of wires associated with corresponding cables  68  for transmission to corresponding interconnected devices  70 . As another example, the controller  72  may program the module  66  to produce or send a signal on any pin of connector  74 .  
      The module  66  may be programmed to enable transfer of communication data between any one of the devices  70  and the controller  72 , and this may involve any required analog to digital (A/D) or digital to analog (D/A) conversion by the module  66 .  
       FIG. 6  will now be referred to for illustration of further details of the I/O module  66 . The use of the term “standard” as used in the present specification includes any connector and/or cable that is not selected or designed for a particular connection. The term “standard”, in other words is used to distinguish the feature of the present invention that enables the user to direct input to any one of the conductors of a cable without the need to design a special connector or cable wire configuration. The term “standard” as used in this sense may or may not include an “off-the-shelf” connector or cable that may be designed for any of various purposes. Nevertheless, it is a preferred embodiment of the present invention for the method and apparatus to include “standard” connectors and cables in the conventional sense, making wiring less costly, and parts more available.  
      The I/O module  66  as illustrated in  FIG. 6  preferably includes a microprocessor  82  and a power supply  84 . Alternatively the power supply can be externally located with interconnection to I/O module  66  as described in reference to  FIG. 5 . An input line  86  and output line  88  are both shown as required for Ethernet communications between the module  66  and controller  72  according to a preferred embodiment. Other types of interconnections are also included in the present invention according to the type of communications network in use. Line  86  of  FIG. 6  represents the connection apparatus required for network communications between a controller such as controller  72  of  FIG. 5  and the  110  module  66 . Line  88  of  FIG. 6  represents the connection apparatus required for communication to another I/O module, such as  124  in  FIG. 7  between I/O Modules  120  and  122 . In general, the microprocessor  82  is configured/programmed by a controller  72  to receive instruction from the controller as required to sense a particular selected device  96 , which may be for example a pressure sensor, temperature sensor, etc., and provide the corresponding data to the system controller. The microprocessor  82  is also programmed/directed by the controller to cause a particular signal to be applied to any selected one or more of conductors of one or more cables such as cable  94 . In addition, the microprocessor is programmed to respond to direction to send a selected signal type from a device  96  to the system controller.  
      Although  FIG. 6  shows only one line  94  for simplicity of illustration, the present invention includes any number of lines  94 , connectors  114  and devices  96 . The module  66  provides a selection of interconnection devices  98 - 112  for each of any of a plurality of lines  94 . Each set of devices  98 - 112  is dedicated for making a connection to one line  94 . The present invention therefore includes a set of interconnection apparatus such as  98 - 112  and corresponding required programmed logic in the microprocessor  82  for each line  94  leading to each one of the connector pins of connectors  114 , the pins for example as indicated by the circles on connector  114 , for making connection to any corresponding device such as device  96 .  
      As an example of operation of the system  65 , the microprocessor may be programmed to recognize particular input data, included for example in an Ethernet packet on line  86  containing instruction to transmit the data as an analog signal on line  94  to device  96 . The programming in this case would instruct the microprocessor to direct/convert the data through apparatus  98  having a digital to analog converter  116 . Facility for making this connection is symbolized by relay “R1” which would be activated to make the required connection from the device  116  to the device  96 . As another example, if line  94  were to carry  15  volts to the device  96 , the microprocessor would be programmed to respond to a signal from the controller to activate relay R 6 . In this manner, the system  65  allows communication of a selected variety through any line such as  94 , and application of any one of a variety of signals to be sent to any selected line such as  94  and thence to a corresponding device  96 . The cable connecting to the lines such as line  94  can therefor be any cable capable of transmission of the required signals, which as explained above is preferably a conventionally standard cable.  
      The circuit switching apparatus (R 1 -R 8 ) are shown diagrammatically as electromechanical relays. In the preferred embodiment, this switching apparatus is realized in a semiconductor circuit. A semiconductor circuit can be realized far less expensively and can act faster than an electromechanical relay circuit. An electromechanical relay is used in order to show the essence of the invention.  
      As shown in  FIG. 6 , any one of the eight signal paths indicated as  98 - 112  can be interconnected to line  94 .  FIG. 6  shows, for example, four different power supply signals including24V DC, ground, 15V DC and −15V DC. The present invention also includes any quantity or value of signals. As described above, the module  66  is configured with a set of inputs such as  98 - 112  for each line  94  ( FIG. 6 ) in each cable  68  ( FIG. 5 ).  
      The lines and interconnections can carry any signal type. For example, signals can contain frequency information such as that found in feedback from servo motors. Or these signals can represent serial communication carriers handling, for example, RS-232 data or fieldbus data such as Device Net, Profibus or Ethernet.  
       FIG. 6  also illustrates the facility for connection of four non-power signals by paths  98 - 104 . Paths  98  and  100  include A/D and D/A converters, as well as switching apparatus (R 1  and R 2 ), for situations where such conversion is necessary to accommodate different transmission and reception capabilities/requirements of the controller  72  and a device  70  (such as device  96 ). Paths  102  and  104  provide for passage of digital signals in either direction. In further explanation, the controller can direct the module  66  to send a digital signal, which when received by the module  66 , can be sent to a buffer  118 , from which the microprocessor  82  in response to direction from the controller can send the signal to any one of the contacts on connector  114  by activating the required relay in a path such as path  104  to connector  114 , to send the required signal to the desired contact of the desired connector. Again, the routing of the signals is symbolically illustrated as accomplished by closing the associated relay (R 1 -R 8 ). In the case of the aforementioned digital output signal, as shown in  FIG. 6 , relay R 4  would be closed, but relays R 1 -R 3  and R 5 -R 8  would be opened, thus routing the requested digital output to line  94  and the corresponding pin of the standard I/O connector  114 . Similarly, the module  66  can receive a digital signal from a device  72 , such as device  96 , and in response to direction from the controller can send a copy to the controller  72 . In this case, relay R 3  would be closed, while relays R 1 -R 2  and R 4 -R 8  would be opened, thus routing the digital signal from the given pin of the standard I/O connector  114  through path  102 . Paths  98  and  100  accommodate analog to digital conversion as required. Finally, the configurable I/O system  65  can be isolated from a signal such that the signal appears to be disconnected. This disconnection is achieved by opening all relays, R 1 -R 8 .  
      Referring again to  FIG. 5 , a preferred method of the present invention includes the use of the system  65  in a control system wherein a controller  72  receives data from or sends data to one or more devices  70  through an I/O module  66  that is programmed to receive signals from and place signals on any selected conductor of a selected cable to a device  70 . In a preferred embodiment, the device  72  is a system controller in communication with the I/O module  66  through an Ethernet system  78 . Alternatively, the device  72  can be of other configuration, such as a general purpose computer, and the communications line  78  can be of any type, such as a standard computer cable, etc.  
      A further method of the present invention includes the use of the module  66  for testing cables.  FIG. 7  shows a first I/O module  120 , connected to a second I/O module  122  with a cable  124  to be tested. According to a preferred embodiment, a system controller  126  is programmed to direct module  120  to place a particular signal on a selected one of wires  128  in cable  124 . The signal can be for example, a DC supply voltage or other signal type as required for testing the cable  124 . The controller directs the second module  122  to scan the pins  130  of the second module  122 . The results of the scanning are sent to the controller  126 , whereby the controller can know if the correct signal is on the correct pin to determine the condition of the cable. In addition to determining the quality of transmission through a single selected cable conductor, the controller can scan and detect a signal on any pin  130  of the connector of module  122 , and therefore can determine if any of the conductors  128  are shorted to each other, and can determine the level of cross talk between the conductors  128 .  FIG. 7  shows dashed lines  132  and  134  representing communication lines between the system controller  126  and the Modules  120  and  122 .  
      A still further embodiment of the present invention includes a method wherein a module configured to include the features of module  66  is combined with an interlock for providing a safety feature in a system.  FIG. 8  illustrates a prior art interlock system for protecting use of a gas valve  134 . Three relays  136 ,  138  and  140  must conduct current from a 24 VDC supply  142  in order for the gas valve  134  to receive operating power. The electrical windings for operating the relays  136 ,  138  and  140  are symbolized by the circles  142 ,  144  and  146 . The power to each winding is controlled by the sensor units  148 ,  150  and  152 . If any one of the three sensor units is activated and therefore disconnects power to the corresponding winding, the associated relay disconnects/open circuits and shuts off power to the gas valve. The interlock circuit of  FIG. 8  is often built into a custom circuit board requiring custom wiring.  
      An embodiment of a method of the present invention is illustrated in  FIG. 9  wherein configurable connectorized I/O Modules  166 ,  168  and  170 , such as module  66 , are used to minimize or eliminate custom wiring in an interlock system. The Modules  166 ,  168  and  170  may be similar or identical to the module  66  of  FIGS. 5 and 6  with connections to the interlock Modules  180 ,  182  and  184 . The interconnections indicated in  FIG. 9  can all or in part be accommodated with standard connectors and cabling, with the specific direction/routing of signals accomplished by programming the configurable, connectorized I/O modules.  
      The exemplified system  154  of  FIG. 9  includes a system controller  156  for controlling an operation including a device  158  such as a mass flow control, etc. The system  154  includes an interlock system that allows operation of the device  158  only if the state of all three safety sensors  160 ,  162  and  164  indicate that operation conditions are appropriate. The sensors can be of any type for the purpose. The three examples are a proximity switch  160 , a safety interlock  162  and a limit switch  164 .  
      The system controller  156  is connected to each of the three configurable, connectorized I/O Modules  166 ,  168  and  170  which provide the programmable flexibility as described above, to allow standard cables and connectors to be used throughout the system to make the various connections indicated. I/O Modules  166 ,  168  and  170  are shown overlapping the interlock Modules  180 ,  182  and  184  indicating that the interlock Modules  180 ,  182  and  184  plug into the I/O Modules  166 ,  168  and  170 . In the preferred embodiment, the interlock Modules  180 ,  182  and  184  plug into connector  74  of an I/O module such as Module  66  of  FIG. 5  in place of a cable  68 . The interlock Modules  180 ,  182  and  184  each contain a device connector  74  into which a cable  68  plugs for interconnecting the devices  158 - 164 . The interlock Modules  180 ,  182  and  184  therefore reside between the I/O Modules  166 ,  168  and  170  and the devices  158 - 164  to which they attach, including as shown by example in  FIG. 9 a  proximity switch  160 , limit switch  164 , and safety interlock  162 , and device.  158 .  
      The system controller  156  communicates with I/O Modules  166 ,  168  and  170 , and with the interlock processor  172  by way of a network, such as Ethernet as indicated by lines  174 . Apparatus for accomplishing Ethernet communication will be understood to those skilled in the art, and this need not be illustrated in order to reproduce the invention. A power supply  176  is shown with the connections symbolized by lines  178 . An interlock module ( 180 ,  182 ,  184 ) is attached to each of the I/O modules ( 166 ,  168 ,  170 ). Each interlock module ( 180 - 184 ) is attached to the interlock processor  172  through cables/buses as indicated by lines  186 ,  188  and  190 .  
      The interlock system of  FIG. 9  will not be explained in further detail. In general, the system  154  includes interlock modules ( 180 ,  182 ,  184 ) connected to an interlock processor  172  via bus lines ( 186 ,  188 ,  190 ). The Interlock Modules have two functions: (1) The first function, of the Interlock Modules  180  and  182 , is to transmit the state of certain inputs, for example  192 ,  194  and  195  from sensors  160 ,  162  and  164 , such inputs being a subset of all inputs and being called Interlock Inputs, to the Interlock Processor  172  via the Interlock Buses  186  and  188 . Any input ( 192 ,  194 ,  195 ) connected to any interlock module ( 180 - 184 ) can be wired within the interlock module such that the input drives a relay coil, as shown in  FIG. 8 , with relay coils labeled ( 142 ,  144 ,  146 ). When these relay coils are actuated, the associated relay contacts close. These relay coils each activate a contact resulting in a signal being sensed by or sent to the Interlock processor  172  via the interlock buses  186  and  188  to the Interlock Processor  172 . The function of the Interlock Processor will be described shortly. (2) The second function, of the Interlock Module  184 , is to receive one or more interlock signals from the Interlock Processor  172  via the Interlock bus  190 . The Interlock Processor is wired such that the interlock signal or signals that the processor sends on the bus  190  drives a coil of a relay located in the Interlock module  184  whose contacts are in series with an output of the I/O module  170 . This output  197  is therefore interlocked. That is, the I/O module  170  can attempt to turn on an output connected to the device  158 , but that output  197  will be prevented from progressing outside the Interlock Module  184  (that is, interlocked) unless the Interlock Processor  172  drives a signal on the Interlock bus  190  which closes a relay in series with the output  197 . The Interlock Processor  172  is responsive to inputs from the Interlock Modules  180  and  182  by performing Boolean logic upon the inputs to generate one or more interlock outputs on bus  190  that are routed to the Interlock Module  184  and thereby interlock output  197  from the I/O Module  170 . The Interlock Processor  172  preferably does all of its processing using relays. Relays are common in safety circuits since they are simple and reliable. Silicon switches and microprocessors have the reputation for being less reliable and prone to various hardware or software glitches. Nonetheless, nothing in this application precludes the use of silicon processors, switches or logic. The cables  186 ,  188  and  190  are shown making direct connection between each interlock module and the interlock processor.  
      In operation, the proximity switch  160  provides an interlock input  192  that is connected directly to the first interlock module  180 . The safety interlock  162  provides a similar input  194 . These two interlock inputs  192  and  194  are sensed by the system controller  156  by way of connection between the interlock module  180  and the I/O module  166 , and input monitoring communications between the I/O module  166  and system controller  156  by way of network  174 . The interlock module  180  contains one relay for each interlock input  192  and  194 . These relays (not shown) are for driving a signal via the Interlock Bus  186  to the Interlock Processor  172 . The Interlock Processor  172  contains one relay for each interlock input  192  and  194 . The relays are arranged within the Interlock Processor  172  to perform a Boolean operation on the Interlocks  160 ,  162 ,  164  and generate an interlock output that is routed via the Interlock Bus  190  to the Interlock Module  184 . Inside the Interlock Module  184  is one relay (not shown) for each output such as output  197  to be interlocked. In other words, although only one output  197  to one device  158  is shown in  FIG. 9 , the concept of the present invention applies to any number of inputs, outputs and devices. When the Interlock Processor  172  determines that the Interlock inputs  160 ,  162 ,  164  are in their correct states for proper system operation, the Interlock Processor  172  drives a signal via the Interlock bus  190  and causes the relay in the Interlock Module  184  to close, thus allowing an output on line  197  and therefore the device  158  to be enabled or turned on.  
      While a particular embodiment of the present invention has been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from the spirit of the present invention, and therefore the appended claims are to include these changes and alterations as follow within the true spirit and scope of the present invention.