Abstract:
A unique cabinet mounted I/O assembly adapted for integration into a control system which allows a block I/O assembly to be mounted in both sides of the cabinet allowing a blind fit of power and signal connections insuring that power will be provided to the block I/O assembly before any application of signals thereto and preventing any mismatching of I/O units to wrong processor blocks in the cabinet by a color matching scheme.

Description:
This application is a division of Ser. No. 08/970,641 filed Nov. 14, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to modular I/O electrical assemblies and more particularly to methods and devices for connecting I/O blocks into an I/O cabinet designed for containing a plurality of such blocks making the cabinet suitable for connection into a control system as one element thereof. 
     2. Description of the Prior Art 
     The prior art I/O cabinetry had block assemblies mounted therein which depended upon markings on the assemblies to insure a proper assembly of the I/O unit to its matching signal and power source in an I/O block cabinet having one side entry thereto. This caused some units to be damaged when they were connected in an improper sequence. Further, these connections were blind in some I/O modules making this sequencing a matter of guesswork. These blind connections were sometimes impossible when there was nonalignment of the I/O module and the power and signal connectors caused by tolerance buildup during the assembly of the case. 
     In prior art systems requiring the assembly of individual parts into a system or element of that system a schematic along with an instructional booklet is used. Such a procedure becomes especially burdensome when you begin assembly of electronic control systems such as block I/O cabinetry. These systems first require the assembly of processor blocks and I/O modules into an I/O assembly according to appropriately co-ordinated identical module functions and a further co-ordination of these modules having the same function for identical type of signal input. As an example, identical digital input-output processor blocks for temperature signals could be mismatched with digital input-output I/O modules for line voltage or pressure signals. The result would be at the least an inoperative system. 
     Similar problems occur in field wiring the processor blocks of I/O modules which can have up to 24 channels which require specific input or output signals co-oordinated to the I/O block which must be not only identified as inputs or outputs but must also be the right type of inputs or outputs as was explained above. 
     Thus an easily accessible I/O cabinet was needed which would provide easy access and mounting of I/O component modules from both sides of the cabinet and which allowed easy and foolproof assembly of such modules into the cabinet while preventing the application of signal inputs to the I/O modules before power was connected to the modules as well as providing such a sequential connection using a blind fit into an I/O module mounting area in the cabinetry. 
     BRIEF SUMMARY OF THE INVENTION 
     The present invention solves the problems associated with prior art devices and others by providing a uniquely designed I/O module mounting cabinet having modules mounted on both sides thereof as well as unique modules which are made in two sections and are color coded for foolproof mounting in said cabinet to insure the proper electrical mount of I/O modules in the cabinet. The modules are also electrically connected therein so that power is first connected to the block I/O unit before any signal connections are made. Also, this connection is made to be a loose fit in the cabinet wall to allow any slight misalignment due to tolerance buildup to be compensated for when the individual units are mated. 
     In view of the foregoing it will be seen that one aspect of the present invention is to provide an I/O module mounting cabinet which allows correct mounting of color coded modules on both sides of the cabinet 
     Another aspect of the present invention is to provide an I/O module mounting cabinet which allows blind mating of a block I/O unit to a cabinet having power and signal connections for the I/O unit. 
     Another aspect of the present invention is to provide an I/O module mounting cabinet which allows the block I/O unit to be electrically connected in the cabinet insuring proper sequencing of power and signal connections. 
    
    
     These and other aspects of the present invention will be more fully understood after a review of the following description of the preferred embodiment when considered with the accompanying drawings. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG.  1 . is a schematic of a distributed process control system using the block I/O system cabinetry of the present invention. 
     FIG.  2 . depicts a block I/O assembly and the connector base and I/O module comprising same. 
     FIG.  3 . is a rear view of the I/O module showing the general pattern of holes found therein for orienting plugs therein according to an identifying pattern. 
     FIG.  4 . is a front view of the I/O module. 
     FIG.  5 . is a front of a control cabinet having a plurality of I/O module assemblies connected therein. 
     FIG.  6 . is a table of abbreviations for various types of I/O modules and color codes for each of these types. 
     FIG.  7 . is a perspective view of the combined processor block showing the color code and functions representation on matching connector base and I/O module making up the processor block 
     FIG.  8 . is a perspective view of the processor block with its door open to reveal the field wiring connections. 
     FIG.  9 . is a front view of a scratch pad label found on the inside of the processor block door of FIG.  8 . 
     FIG.  10 . is a front view of the processor block showing the field wiring channels found therein. 
     FIG.  11 . is a depiction of the labels locatable in a recess between the individual channel connections, identifying the channel number and color code. 
     FIG.  12 . is a disassembled view of the elements of the processor or block of FIG.  8 . 
     FIG.  13 . is an expanded view of the ribbon electrical connection of FIG.  12 . 
     FIG.  14 . shows the assembled relationship of the connectors of FIG. 13 to the FIG. 12 assembly. 
     FIG.  15 . shows the ground plate of the FIG. 12 assembly. 
     FIG.  16 . shows the assembly of the door and channel identification to the FIG. 12 assembly. 
     FIG.  17 . shows terminal redundancy in two processor blocks. 
     FIG.  18 . shows the internal elements of the block I/O unit of FIGS.  2 - 4 . 
     FIG.  19 . is a perspective view of the system cabinet of FIG.  5 . with horizontal supports. 
     FIG.  20 . shows the FIG. 19 cabinet with mounting columns added thereto. 
     FIG.  21 . shows cable carriers in the FIG. 20 cabinet 
     FIG.  22 . shows a plurality of terminal blocks mounted in the FIG. 21 cabinet. 
     FIG.  23 . shows the block I/O&#39;s mounted to the terminal blocks of FIG.  22 . 
     FIG.  24 . is a perspective top view of the electrical connector of the present invention having power and signal connecting holders therein. 
     FIG.  25 . is a perspective bottom view of the power and signal connecting holders of the FIG.  24 . assembly. 
     FIG.  26 . is a top view of the connector shown in FIGS. 24 and 25. 
     FIG.  27 . is a perspective view of a ribbon signal connector which fits into the holder shown in FIGS.  24 - 26 . 
     FIG.  28 . is a perspective view of a power connector which fits into the holder shown in FIGS.  24 - 26 . 
     FIG.  29 . is a side view of the electrical connector of the present invention shown having the power and signal connectors fitted therein shown mounted in a cabinet wall allowing alignment pins on the block I/O connector base to grossly align the holder for mating with the I/O block 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings where the showings are intended to describe preferred embodiment of the invention and not to limit it thereto, FIG. 1 shows a distributed process control system  10 . Process signals are inputted along field wiring lines  12  to a series of local and remote I/O blocs  14 ,  16 . Any of these blocks could be connected to manual/auto stations  18  for allowing operator control of the signals. Since the local D-bus  20  is relatively short (around 50 /meters) a repeater mounting unit  22  (RMU) is connected to the local I/O block for conditioning the signal so it may be transmitted by either fiber optic or twinaxial cable  24  to a remotely located D-bus  26  by way of a second RMU  28  for reconditioning the signal transmitted by the first RMU so it is readable by the I/O blocks  16  connected to the remote D-bus. 
     The various process control signals collected along the local and remote D-bus  20 ,  26  are connected to a multi function control processor  30 . Other processors may be also, connected to these D-buses and their control signals along with that of the processor  30  connected to a controlway  32  which sends the signals to a process control unit  34  for conditioning these signals for use by a control room process unit such as the Elsag Bailey INFI - NET process control system  36 . 
     As is shown in FIGS.  2 - 4 , processor block or the basic I/O block  38  is made up of a terminal block or connector base  40  which serves all these functions and will be referred to herein according to the function being discussed and a I/O module  42 . The Processor Block is the front line controller which houses the electronic and configuration boards. The Terminal Block is used to terminate all field wires and route their signals back to the Processor Block. Each block  38  is specifically programmed or configured for a specific function and is mounted into a cabinet  44  best seen in FIG.  5 . The individual block I/O&#39;s  38  are connected to communicate with each other in the Cabinet  44  as well as providing local access through a laptop computers  45 . 
     The connector base  40  is mounted in a known manner such as by screws or clips to a conductive column  46  found in the cabinet  44  which provides power to the base  40  and  10  therefrom to the assembled I/O blocks  38  as well as providing communication there between. The I/O module  42 - s  connected to the base  40  by pushing it onto guide pins  50  found on the back of the I/O module  42  as seen in FIG.  3 . The module  42  is then locked to the base  40  by pushing a lock handle  54  to extend and lock the mechanism  56  into the base aperture  58 . 
     Each individual I/O block  38  is programmed for a specific function and it is imperative to make sure that the proper module  42  is inserted into the proper base. To insure this ability the base and module are specifically configured to prevent the mating of a module with other than its properly connected base. 
     As best seen in FIGS.  3 - 4 , this is accomplished by either upper and lower holes  60 ,  62  on the back of the module  42  which are alignable through the pegs  50  on the base  40  with complimentary eight upper and lower holes  60 ,  62  on the base  40  matching pins  68 . 
     There are presently 12 different I/O modules being used. The existing I/O block are identified by the 30 following code: 
     I=Input 
     O=Output 
     D=Digital 
     A=Analog 
     C=Control 
     These codes are combined into various combinations some of which may be seen in FIG.  6 . You would then read these combinations as analog output for AO, analog input for AI, control input-output for CI-O, digital input-output for DI-O, digital output for DO and digital input for DI. 
     As best seen in FIG.  5  and FIGS.  20 - 23 , the conductive column  46  has 10, known connectors (not shown) mounted into openings formed in the cabinet  44  which provide power and signal connections  64  and  66  respectively from the cabinet  44  to the I/O module  42 . A pair of alignment pins  50  found on the back of the I/O base or connector unit  40 . When the unit  40  is mounted in the cabinet  44  the alignment pins  50  align the I/O unit through an opening  52  formed therein. An opening  72  matches an opening  74  found on the back of the I/O module  42  which has individual clustered power and signal pins  76 ,  78  which mate with an appropriate known power and signal assembly (not shown) the power pins  78  on the I/O module  42  will be electrically connected to the cabinet  44  before any signal pins  76  are connected to the cabinet by the proper mounting of the module  42  to the connector  40  into the I/O block assembly  38 . 
     Since the present system  10  requires six different processor block  38  categories, six different colors were chosen to represent each category. Thus FIG.  6 . shows a purple color bar P, a blue color bar B, a green color bar G, an orange color bar O, a red color bar R, and a yellow color bar Y as representing each of these six categories. It will be understood that any of these color bars could proceed any of the previously described functional representations shown in FIG. 6., in addition to the ones shown. 
     As may be seen in FIG. 7., the I/O block  38  is thus easily matched to have the appropriate terminal block  40  and I/O module  42  by checking the logo and color bar on both for an identical match. Thus the terminal  40  which as a orange O color bar and digital input-output functional representation DI-O is properly matched only with an I/O module  42  having a red R color bar and digital input-output DI-O representation stamped on each element  40 ,  42 . This identification utilizes a family approach to identification, and as other blocks are added to the system they will follow the same design approach. 
     As is best seen in FIG. 8, the processor block  40  has a door  80  which is supported by hinges  82  to show a plurality of field wiring connectors  84  found therein. 
     A scratch pad label  86  is located inside the hinged door  80  of the Terminal-Block. Its purpose is to both identify the specific wire numbers for each field wiring channel and differentiate between input and output channels. As best seen in FIG.  9 . the scratch pad  86  may have either  24  channels or  16  channels  86   a,    86   b  depending on the installation. The scratch pad  86 ( a ) provides two areas  88 , 90  next to each channel where the wire information can be written on to the label. The information on this label  86  ( a ) is written on by the user at the site. To simplify this procedure, the door  80  swings open 180 degrees and is supported by the Processor Block  42 . In the case of blocks where input  92  and output  94  channels are available, the label  86 ( a ) has been color coded accordingly to the previously described color scheme for each channel and identified with “I”s and “O”s to simplify the wiring of these blocks. This label is manufactured by silk screening on paper stock with an adhesive layer on the back It is located in place by a small recess  95  in the door  80 . The 16 channel scratch pad  86 ( b ) provides 3 areas  96 , 98 , 100  next to each channel where 3 wire installation information is written in by the user. Each scratch pad  86 ( a ),  86  ( b ) has an individually labeled field power connection  102 . 
     As best seen in FIGS.  10 . and  11 ., each field wired channel is physically identified by a label  104  which is mounted on the barrier strip  106  of the Terminal Block  40 . Each channel is individually identified by labels  104 ( a ) and  104 ( b ) for both  16  and  24  channel versions both of which including one for field power. In the case of the input-output blocks  92 , 94  the channel identification label has been similarly color coded though they are not identified with “I”s and “O”s due to space constraints. These labels are manufactured by reverse silk screening on clear plastic with an adhesive layer on the back. They are located in place by a small recess in the plastic barrier strip  106 . 
     Turning next to FIG. 12 it is seen that the terminal block  40  is assembled from the following list of parts and their fabrication method: 
     
       
         
               
               
               
             
           
               
                   
               
               
                 Number of parts 
                 Part Description 
                 Process &amp; Material 
               
               
                   
               
             
             
               
                 1 
                 Terminal strip housing 
                 Injection molded plastic 
               
               
                 1 
                 Backplane cover 
                 Injection molded plastic 
               
               
                 1 
                 Door 
                 Injection molded plastic 
               
               
                 1 
                 Ground plate 
                 Plated sheet steel 
               
               
                 1 
                 Scratch pad label 
                 Silk screened paper stock with 
               
               
                   
                   
                 adhesive 
               
               
                 1 
                 Channel ID label 
                 Reverse silk screened Lexan 
               
               
                   
               
             
          
         
       
     
     As seen in FIG. 13 a ribbon cable assembly  108  has a pair of boards  110 ;  112  attached by an electrical cable  114 . The ribbon cable  114  brings the connected board  112  to the front of the unit  40  to allow easy user access. The board  110  has electrical connector parts  116  which are connected electrically to the field wiring screws  118  seen in FIG.  10 . The board  110  is snapped into a housing  120  and the board into a backplane cover  122  as best seen in FIGS.  12 - 13 . 
     With the circuit boards  110 ,  112  securely in place, a sheet metal ground plate  124  is attached to the plastic housing  120 . This metal part initially snaps to the plastic housing  120  and is then further secured with screws  126 . The ground plate  124  serves three primary functions in the Terminal Block  40 . First and foremost, the metal plate is a bus bar for all ground wires requiring termination to chassis ground. Secondly, it provides the main structure for the Terminal Block itself. This block configuration allows a recess under the terminal strips creating more room for the wiring channel. Lastly, the metal plate  124  protects the ribbon cable  114  that runs from one board to the other. In effect, it traps the cable between the metal and the plastic, eliminating any chance of damage that might occur when installing field wires. 
     As best seen in FIG. 17 horizontal redundancy can be easily achieved with the use of two of the backplane covers snapped to one another. The only new part or addition is the boards required to achieve this application. 
     Vertical redundancy is achieved by placing another termination assembly directly above or below the primary block The two Terminal Blocks are ton attached by a connector that allows them to share the same field signals. 
     Referring now to FIG. 18 it will be seen that the I/O unit  42  provides the main interface between the blocks assemblies and the main operating system. The unit  42  consist of a processor board  128  and an I/O board  130  that provide communication both in and out of the cabinet  44 . It has a simple side cover  130  that snaps into place in a wall plate  132  to hold the boards  128  and  130  there between and has a top and bottom grille  134  which ducts air from the block below to the block above it. 
     Turning next to the cabinet  44 , the assembly thereof, and the placement of the terminal block  40  and I/O blocks  42  therein; FIGS.  19 - 23  show the cabinet  44  having access doors  136  at both ends thereof. A pair of centrally located vertical channels  138  are mounted inside the cabinet  44 . 
     Horizontal Supports  140  is located along the top and the bottom of vertical channel  138 . Some additional Supports  142  are also located in the middle for structural support The system is designed to accommodate up to one Support  142  per I/O Block height 
     With particular reference to FIG.  20 . it will be seen that three columns  46  made from punched and bent sheet metal and finished with Zinc plating are connected to the supports  142 . 
     These columns serve as the fundamental mounting element for the I/O Blocks. Power and communications are distributed to the I/O Blocks via cables that are behind the column. The connectors for these cables are snapped into a connector adapter, which is snapped in holes  45  but which will be described later, which then is in turn mounted from the rear to the column  46 . The Column  46  is longer than the total height of the blocks in order to accommodate an area where the connectors for the ‘start’ of the cabling are mounted. The column  46  is available in various lengths to accommodate 1-7 I/O Blocks. Another variation of the column is for horizontal redundancy, where the column is wider by one Block and also comes in various lengths. 
     As seen in FIG. 21. a series of wire retainers  146  are mounted to the horizontal supports  142  thus making it very easy to accommodate a varying length column  46 . It also makes it very easy for the ultimate user to adapt his system to the cabling environment 
     Next, as is shown in FIG. 22., the terminal block  40  are now fastened securely to the columns  46  with two screws located at the backplane cover area thereof. Next the proper I/O unit  42  is engaged to the proper processor block  40  in a manner described earlier and as best seen in FIG.  23 . 
     As was mentioned, the conductive column  46  has connectors mounted into openings  74  formed on a connector wall thereof which provide power and signal connections respectively from the cabinet  44  to the I/O module  42  of the block I/O assembly  38 . A pair of alignment pins  50  found on the back of the I/O base or connector unit  40 , When the unit  40  is mounted in the cabinet  44  the alignment pins  50  align the I/O unit through an opening  52  formed therein. This opening  52  matches an opening  55  found on the back of the I/O module  42  which has individual dustered power and signal pins  57 ,  59  which mate with an appropriate power and signal connections as will be explained later. The power pins  57  on the I/O module  42  will be electrically connected to the cabinet  44  before any signal pins  59  are connected to the cabinet by the proper mounting of the module  42  to the connector  40  into the I/O block assembly  38 . 
     To provide a blind fit electrical connection of the I/O module  38  which will also provide a sequential connection of the power signals  57  to the module before any signal  59  inputs thereto, a unique power and signal holder assembly  170  is used to mount the I/O block to the power and signal sources  46  in the cabinet  44 . As seen in FIGS.  24 - 29 , the holder assembly  170  is made from polycarbonate material to have a lower signal  59  cable holding area  172  and a power  57  holding area  174  elevated from the signal area  172 . 
     A signal  59  ribbon connector  176  is connected to a end cap  178  which provides electrical conduction from he individual ribbon  176  signal lines to a plurality of electrical connecting openings  180  in a well known manner. The cap  178  has a detented section  182  on both ends. This signal assembly  184  is mounted into the holder  170  section by pressing back a flexible inner wall  186  having a hooked section  188  to allow the detente  182  to slide along a matching protrusion wall  190  inside the section  172  until the hook section  188  snaps back across the bottom of the cap  178  holding the signal assembly firmly therein. Wall sections  192  extend over the cap  178  in the signal area  174  to effectively capture the signal assembly between these wall sections  192  and the hooked area  188 . 
     A power signal assembly  194  has six electrical lead wires  196  individually connected to six electrical apertures  198  formed in a cap assembly  200  to provide electrical conduction from the wires  196  to the apertures  198  in a known manner. The assembly  200  also has a series of extending tips  202 . The power assembly  194  is fitted into the section  174  of the holder  170  by pushing the top of the assembly  194  into the section  174  against the flexible wall section until the sections or teeth  202  of the assembly lock on the top of wall  204 . A rib  206  formed on the back of the assembly  194  then rests against a wall  208  formed in the holder  170  to prevent any further upward movement of the assembly  194  in the area  172 . 
     As best seen in FIG. 29 the holder is mounted into the enlarged opening area  45  formed on a connector wall  210  of the column  46  of the cabinet  44  which provides power and signal connections from the cabinet  44  to the ribbon connectors  176  and the power wires  196 . The holder  170  is mounted to this area by tilting an extended rigid ear section  211  formed on one end of the holder  170  into the opening  209  to extend under the wall section  210  and then snapping a flexible ear sections  212  formed on the end of the holder opposite the ear section  211  through the opening  209  to catch under the wall section  210 . The opening  209  is slightly wider than the connector  170  providing a loose sideways fit. Also, the flexible member  212  by virtue of its flexibility and the width of the extended tip  213  allows lateral movement of the assembly  170  in the opening  209  to thus provide a blind fit of the I/O module which will compensate for tolerance buildup during assembly of the component parts. 
     The holder  170 , also has a pair of enlarged openings  214  formed through wing sections  216  located along the section  172  of the holder  170 . These openings act as alignment holes for a pair of alignment pins  218  found on the back of the I/O base or connector unit  40 . When the unit  40  is mounted to the wall  210  of the cabinet  44  the alignment pins being smaller than the opening  214  will grossly align the holder  170  to be oriented with an opening  220  formed therein. This opening matches an opening  19  found on the back of the I/O module  42  which has individually clustered power and signal pins  76 - 78  which mate with the holes  198 ,  180  found on the cap assemblies  184 ,  194 . Since the power assembly  194  is maintained higher than the signal assembly  184  when both are mounted in the holder  170 , the power pins  224  on the I/O module  42  will be electrically connected to the cabinet before any signal pins  226  are connected to the cabinet by the proper mounting of the module  42  to the connector  40  into the I/O block assembly  38 . 
     It will be understood that certain improvements and additions which would be obvious to one of ordinary skill in this art area have been deleted herein for the sake of conciseness and readability but all such are intended to fall within the scope of the following claim