Abstract:
A chainable I/O termination block system for connecting a programmable logic controller (PLC) or other controller to I/O signals such as sensors and control relays in an automatic tooling environment. A number of modular termination blocks ( 20 ) can be conveniently chained together to provide the required number of I/O points ( 28 ) at the appropriate location on the automated tool while simultaneously providing a single connection to the PLC ( 10 ). Chainable termination blocks ( 20 ) can be connected together directly or can be distributed over the required distance using block-to-block cabling ( 13 ). An autoshifting arrangement within each chainable termination block ( 20 ) determines the bit position at the controller ( 10 ) of each I/O signal ( 28 ). Each termination block ( 20 ) has at least one termination connector ( 21 ) for making the I/O connections to the automated tool, a PLC-side chaining connector ( 26 ) for connecting to the PLC ( 10 ) or to termination blocks ( 20 ) closer in the chain to the PLC ( 10 ), and an I/O-side chaining connector ( 24 ) for connecting to additional termination blocks ( 20 ) further down the chain away from the PLC ( 10 ). In each chainable termination block ( 20 ) remote signal lines are to be shifted and replaced by local signal lines while ground and power lines remain unshifted.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of the U.S. application Ser. No. 09/219,659, now U.S. Pat. No. 6,077,125, by Emery, filed Dec. 23, 1998, titled “Versatile Input/Output Control and Power Distribution Block for Use With Automated Tooling”, which is in turn a continuation of U.S. application Ser. No. 08/783,852, now U.S. Pat. No. 5,897,399, by Emery, filed Jan. 16, 1997, titled “Versatile Input/Output Control and Power Distribution Block for Use With Automated Tooling”. This application also relates to the subject matter disclosed in the co-pending U.S. application Ser. No. 09/556,507, by Emery et al., filed concurrently herewith, titled “Submersible Sensor Output Inverter”. All of these applications are assigned to the assignee of the present invention and are hereby incorporated by reference in their entirety. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates generally to automated tooling, and pertains more particularly to a versatile input/output control and power distribution block for use with automated tooling. 
     BACKGROUND OF THE INVENTION 
     When using automated tooling, a programmable logic controller or computer is often required to send output control signals to, and receive input sensor signals from, a number of automated tools. Typically the connection to each automated tool consists of three wires: a wire which carries a ground signal, a wire which carries a power signal, and a wire which carries an input/output (I/O) signal which either is a control signal that is output from the controller to the automated tool, or a sensor signal from the automated tool that is input to the controller. 
     The connections from the automated tools are typically terminated at a termination block. At the termination block, the ground signals and the power signals connected to the automated tools are combined respectively. The termination block passes the control signals and the sensor signals between the programmable logic controller or computer and the individual automated tools. 
     The three individual wires from each automated tool sensor or control, grouped together in a cable, have typically been connected to a terminator block using wire leads held in individual wire receptacles. However, when automation tools are used in production, this mechanical arrangement frequently results in the sensor cables being subject to repetitive motion. Over the course of time, this can result in the wires within the cables becoming intermittently or permanently defective. In addition, replacement of I/O cables with wire leads held in individual wire receptacles can be time consuming. 
     To alleviate this problem, some manufacturers have utilized I/O cables with connectors which can be plugged into a termination block. This has provided for an easier replacement of defective cables. However, existing units which utilize these types of connectors typically can connect to no more than eight I/O connector cables, and are not backward compatible with automated tools which require the use of pull-up/down resistors or which have wires with flying leads. 
     In addition, programmable logic controllers typically provide a number of input/output lines, frequently sixteen, packaged in a single I/O module. As a result, it would be most efficient to connect a single I/O cable from the controller to a termination block of the corresponding size. However, it is not infrequent that an automated tool occupies a relatively large physical area, such as a number of different bays of equipment, with clusters of input/output connections of fewer than sixteen lines spaced dozens or even hundreds of feet away from each other. As a result, in order to make full use of all the lines in the controller&#39;s I/O module, a number of separate wires will need to run a relatively long distance to the proper area of the tool. It would be a far more robust arrangement with more optimal interconnect wiring the appropriate I/O connections could be provided in the desired areas of the tool, while still allowing simple and reliable cabling from the controller to the termination block. 
     SUMMARY OF THE INVENTION 
     In a preferred embodiment, the present invention provides a modular, distributable termination system for an automated tooling arrangement that is easy to wire and physically robust. The termination system has at least one chainable termination puck with at least one termination connector which provides a total of (L) local signal lines for connection to I/O devices of the automated tooling. The puck also has an I/O-side chaining connector with a total of (N−L) remote signal lines, and a PLC-side chaining connector with a total of (N) lines which is electrically connected to the (L) local signal lines and the (N−L) remote signal lines. The signals are arranged on the two chaining connectors such that the remote signal lines are shifted in position on the PLC-side chaining connector relative to the I/O-side chaining connector by the number (L) of local signal lines, and replaced in position by the local signal lines. In the preferred embodiment, N=16, and L=2, 4, or 8. The I/O-side chaining connector of one chainable termination puck is electrically engageable with the PLC-side chaining connector of an additional chainable termination puck, thus providing the desired modularity in terms of the number of I/O connections. The two chaining connectors are complementary such that they can be mechanically mated with each other when additional I/O points are required in the same area, or they can be connected using an electrical cable assembly so that the I/O points can be distributed to the areas of the tool that require them. In the preferred embodiment, the termination connector is a DIN connector, while the two chaining connectors are the same type of connector having the same number of pins but a different gender, typically mail and female  25  pin female D-sub connectors. The puck also has power and ground lines on the first and second chaining connectors and the termination connectors which are used to supply power from the controller to I/O devices connected to the termination connectors. 
     An alternate embodiment of the termination system includes a termination block puck which has two chaining connectors and multiple I/O device connectors, of a type different from the termination connectors. The termination block puck also has multiple switches for selecting either a line from the chaining connector or a line from one of the I/O device connectors to be electrically connected to a line of the second main connector. 
     The present invention may also be implemented as a method for distributing a linearly ordered group of input/output lines from a controller to input/output devices. Such a method includes receiving a first linearly ordered group, connecting the lines in a local subgroup adjacent a first end of the first linearly ordered group to at least one termination connector, shifting the lines in a remote subgroup comprising the remaining input/output lines in a direction toward the first end so as to form a second linearly ordered group, and providing the second linearly ordered group to an external device. Both linearly ordered groups have the same number of lines. Some embodiments further include electrically connecting the first termination puck to the controller, and electrically connecting the first termination puck to a second termination puck. The first linearly ordered group can be received at a PLC-side connector adapted for connection to the controller, and the second linearly ordered group can be provided to an I/O-side connector adapted for connection to the second termination puck. Since the second linearly ordered group has more lines than the remote subgroup, no connections are made to the extra lines in the second group. 
    
    
     Other aspects and advantages of the present invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, which illustrate by way of example the principles of the invention. 
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a chainable termination puck, also referred to as a chainable termination block, according to the present invention. 
     FIG. 2 is a schematic diagram of exemplary electrical chaining interconnections between a programmable logic controller and four chainable termination pucks of FIG. 1, illustrating the automatic shifting of the input/output line groups between two chaining connectors on each termination pucks when the pucks are chained together. 
     FIG. 3 is a schematic diagram of the internal electrical wiring of the chainable termination puck of FIG.  1 . 
     FIG. 4 is a perspective view of a flying-lead termination block, also referred to as a termination block puck, usable with the chainable termination block of FIG.  1 . 
     FIG. 5 is a perspective view of a non-chainable termination puck usable with the chainable termination puck of FIG.  1 . 
     FIGS. 6A-6C are schematic representations of exemplary distributed input/output line interconnection schemes for an automated tool using the chainable termination puck of FIG.  1 . 
     FIG. 7 is a flowchart of a method for distributing input/output lines from a programmable logic controller or other control device to input/output devices using the chainable termination puck of FIG.  1 . 
     FIG. 8 is a schematic representation of the operation of the flowchart of FIG.  7 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, and more particularly to FIGS. 1 and 2, there is illustrated a chainable input/output (I/O) termination puck  20  constructed in accordance with the present invention which provides a robust, distributed, and convenient wiring system for connecting sensors and other input/output devices to a programmable logic controller (PLC)  10  or other types of computers or controllers. A number of pucks  20 , such as pucks  20   a-d , can be electrically chained together and connected to the PLC  10 . Each puck  20  includes one or more termination connectors  21  for making connections to a corresponding one or more input/output devices, an I/O-side chaining connector  24 , and a PLC-side chaining connector  26 . 
     Each termination connector  21  is preferably an 8 millimeter DIN connector having three female pins for carrying electrical signals. A first pin  27  provides a power source 32 to the I/O device. A second pin  28  connects to the signal input or output of the I/O device. A third pin  29  provides a reference voltage (ground)  31  to the I/O device. The preferred embodiment of the puck  20  has four termination connectors  21 , although the invention is usable with pucks having different numbers of connectors  21 , and pucks with different numbers of termination connectors  21  can be chained together. The second pins  28  of the set of termination connectors  21  on a puck  20  collectively provide local signal lines  2 . As will be discussed subsequently, the pucks  20  have internal wiring which route the local signal lines  2  to pins on the PLC-side chaining connector  26 . 
     Each I/O-side chaining connector  24 , such as connectors  24   a-d  for the corresponding pucks  20   a-d , is preferably a 25-pin female D-subminiature connector which can be used to electrically chain a puck (such as puck  20   b ) to a subsequent puck (such as puck  20   c ) farther down the chain (i.e., away from the PLC  10 ). The I/O-side connector  24   b  has pins for connecting to remote signals  23  from the subsequent puck  20   c . The I/O-side chaining connector  24   b  can be directly plugged into the PLC-side chaining connector  26   c , or a cable assembly can be used to interconnect the I/O-side  24   b  and PLC-side  26   c  connectors. 
     Each PLC-side chaining connector  26 , such as connectors  26   a-d  for the corresponding pucks  20   a-d , is preferably a 25-pin male D-subminiature connector which is usable to electrically chain the puck  20   b  to a previous puck  20   a  located nearer to the PLC  10  in the chain. The PLC-side connector  26   b  can be directly plugged into the I/O-side connector  24   a , or a cable assembly can be used to interconnect the I/O-side  24   a  and PLC-side  26   b  connectors. Alternatively, the PLC-side connector  26  can be connected directly to the PLC  10  via a cable assembly, as is illustrated for connector  26   a . Each PLC-side connector  26  has pins for connecting both the local signal lines  2  and the chained signals  23  of the I/O-side connector  24  to the previous puck  20  or to the PLC. 
     Considering now the internal wiring of the pucks  20  that interconnects the local signal lines  2  and the chained signals  23  to the PLC-side connector  26 , and as best understood with reference to FIGS. 2 and 3, chained signals  23  received at I/O side connector  24  are connected to remote signal lines  3  inside puck  20 . The wiring of remote signal lines  3  is arranged such that the pin position on the PLC-side connector  26  of each individual one of the remote signal lines  3  is shifted from its corresponding position on the I/O-side connector by the number of signals contained in the local signal lines  2 . The local signal lines  2  are then connected to the pins on the PLC-side connector  26  whose pin positions were vacated by the remote signal lines, resulting in a merged set of local and remote signal lines at the PLC-side connector  26 . Because the number of chained signals  23  on both connectors  24 ,  26  is the same, some of the chained signals  23  present on I/O-side connector  24  are not passed through to PLC-side connector  26 ; the number of chained signals  23  omitted equals the number of local signal lines  2  in the puck  20 . Expressed generally, for a group of N chained signals  23  applied to the I/O-side connector  24  and L local signal lines  2 , N−L of the chained signals  23  will be connected to the PLC-side connector  26  along with the L local signal lines  2 . 
     Considering now the remaining internal wiring connections of the puck  20 , power and ground are supplied from the PLC  10  to the arrangement of chained pucks  20  via the PLC-side  26  and I/O-side  24  connectors. In the preferred embodiment, there are four power and four ground pins, located in the same pin positions on all connectors. Power and ground are supplied  20  to the sensors and other I/O devices via the first pin  27  and the third pin  29  of termination connector  21 . Table I summarizes the wiring of the puck  20 . The connector pin numbers are as illustrated on FIG.  3 . 
     
       
         
               
               
               
               
             
           
               
                 TABLE I 
               
               
                   
               
               
                   
                 Pin #s on 
                 Pin #s on 
                 Pin # on 
               
               
                   
                 I/O-side 
                 PLC-side 
                 Termination 
               
               
                 Signals 
                 Connector 24 
                 Connector 26 
                 Connectors 21 
               
               
                   
               
             
             
               
                 Local Signals 2 
                 n/c 
                 1-4 
                 2 
               
               
                 Remote Signals 3 
                  1-12 
                  5-16 
                 (no connection) 
               
               
                 Power 
                 22-25 
                 22-25 
                 1 
               
               
                 Ground 
                 18-21 
                 18-21 
                 3 
               
               
                   
               
             
          
         
       
     
     Considering now the programming interface between the PLC  10  and I/O devices connected to a chain of pucks  20 , and as best understood with reference to the exemplary system configuration of FIG. 2 having four pucks  20   a - 20   d  each providing four termination connectors, the puck  20   a  is typically connected to PLC  10  via a cable with flying leads. This flying lead cable defines which pins on the PLC-side connector  26   a  of puck  20   a  are connected to which programmable I/O signals on the PLC  10 . The chain of connections between pucks  20   a - 20   d  determines which termination connectors&#39; signals appear on which pins of PLC-side connector  26   a  for communication with the PLC  10 . The four local signals A 1 -A 4  of puck  20   a  are connected to bits # 1  through # 4 . The four local signals B 1 -B 4  of puck  20   b  are shifted four bit positions as they chain through puck  20   a , and thus are connected to bits # 5  through # 8 . The programmatic effect to insert the local signals A 1 -A 4  into the set of remote signals, bit-shift the chained remote signals  23 , and eliminate four chained remote signals which originated from the furthest location in the chain. 
     Similarly, local signals C 1 -C 4  of puck  20   c  are connected to bits # 9  through # 12  of PLC  10 , and local signals D 1 -D 4  of puck  20   d  are connected to bits # 13  through # 16  of PLC  10 . In the preferred embodiment, which uses a 25-pin connector to chain sixteen lines of I/O signals, local signals of any additional pucks connected to the I/O-side connector  24   d  of puck  20   d , such as those represented by chained signals E, F, and G, will not be connected to the PLC  10 . Pucks  20  having other numbers of termination connectors  21 , such as two or eight, can also be connected together in the same chain with pucks  20  having four connectors  21 . To fully utilize the programmable I/O signals on the PLC  10 , each puck  20  will preferably bit-shift the chained signals  23  it receives on its I/O-side connector  24  by the same number of bits as the number of termination connectors  21  on the puck  20 . Expressed generally, for a group of N chained signals  23  applied to the I/O-side connector  24  and L local signal lines  2  on the puck  20 , the N−L remote signal lines  3  connected to bit positions between 1 and N−L on the I/O-side connector  24  will be shifted by L bits to the corresponding bit position between L+1 and N on the PLC-side connector  26 . 
     Considering now cable assemblies usable with the puck  20 , eight millimeter cord sets compatible with termination connectors  21  are available from a variety of places, for example, from Turck, Inc., having a business address of 3000 Campus Drive, Minneapolis, Minn. 55441. These cord sets have a male DIN connector on one end and a female DIN connector on the other end. The cord sets are available in both straight and 90 degree orientations on the sensor end. The cord sets come in various lengths (e.g., 0.3 meters, 0.6 meters, 0.9 meters, 1.2 meters, 1.5 meters and 1.8 meters) which can be plugged together to make custom lengths. There is also available a termination connector  21  to Euro 0.5 meter adapter cable for sensors that have a 12 millimeter (Euro) connector. For valve termination, type “A” and “B” valve DIN connector cables are available, both in 0.6 meter and 0.9 meter lengths. In the preferred embodiment, puck  20  is capable of handling two amps total, and 500 milliamps per connector. 
     Chainable pucks  20  are also usable in conjunction with a termination block puck (TBP)  40  illustrated in FIG.  4 . TBP  40  can be utilized when pull-up/down resistors are used or when sensors with flying leads are used. Wire receptacles  44 ,  45 ,  46 ,  47 ,  48  and  49  are used to receive and secure wire leads to TBP  40 . Wire receptacles  44  and  47  receive wire lines to be connected to ground. Wire receptacles  45  and  48  receive wire lines to be connected to power. Wire receptacles  46  and  49  receive wire lines to be connected to I/O devices. A connector  42  is a 25 pin female D-sub connector, which mates to PLC-side connector  26 . Connector  42  is a 25 pin male D-sub connector which is used to connect TBP  40  to PLC  10  via a cable assembly. This allows TBP  40  to be connected to puck  20  and utilized only when necessary. When TBP  40  and puck  20  are used together, a DIP switch groups  51 - 54  are used to select for each I/O device whether a sensor cable is connected to a termination connector  21  of a puck  20  in the chain, or whether a wire connection is made to TBP  40  instead. 
     Chainable pucks  20  can replace or be used in conjunction with the non-chainable puck  20 ′ of FIG.  5 . Non-chainable puck  20 ′ has a plurality of termination connectors  21 ′ identical to connectors  21  of chainable puck  20 , and a PLC-side connector  26 ′ identical to PLC-side connector  26  of chainable puck  20 . Input/output signals, power, and ground are provided at the same pins of connector  26 ′ of non-chainable puck  20 ′ as of connector  26  of chainable puck  20 . As a result, non-chainable puck  20 ′ can be used at the end of a chain of chainable pucks  20 , and one or more chainable puck  20  can replace non-chainable puck  20 ′ in a PLC system. 
     The chainable pucks  20  according to the present invention can be interconnected with each other, with a non-chainable puck  20 ′, and with a termination block puck  40  in a variety of different ways so as to form modular termination systems, as illustrated in the exemplary schematic diagrams of FIGS. 6A-6C. FIG. 6A shows a PLC  10  connected by a flying-lead cable to a first puck  20   a  having termination connectors  21  for I/O signals # 1 -# 4 . A cable assembly  13  having a 25-pin D-subminiature cable on each end connects pucks  20   a - 20   b , thus allowing them to be located at a distance from each other as the wiring to the tool bays require. Pucks  20   b - 20   c  are directly plugged together without use of a cable, then pucks  20   c - 20   d  are connected using another cable assembly  13 . A total of  16  I/O connections are thus presented to the PLC  10 . 
     FIG. 6B illustrates a second exemplary modular termination system using a termination block puck  40  with chainable puck  20   a - 20   b . Chainable puck  20   a  is directly plugged into termination block  40  without the use of a cable. The two pucks  20   a - 20   b  present a total of 8 I/O connections to the PLC  10 ; other I/O connections can be made via flying-lead connections to the termination block puck  40  using cable  15 . 
     FIG. 6C illustrates a third exemplary modular termination system using a non-chainable puck  20 ′ with chainable puck  20 . Puck  20  provides four termination connectors  21  for I/O signals # 1 -# 4 , while non-chainable puck  20 ′ provides sixteen termination connectors  21  for I/O signals # 5 -# 16 . I/O signals for four of the termination connectors  21  on non-chainable puck  20 ′ will not be transmitted through the flying-lead cable  11  to PLC  10  due to the bit-shifting operation and sixteen-signal capacity of chainable puck  20 . 
     The present invention may also be implemented as a novel method for distributing linearly ordered group of input/output lines from a controller to input/output devices. As best understood with reference to FIGS. 7 and 8, the method begins with a block  80  which electrically connects a PLC  10  to the PLC-side connector  26  of a chaining termination puck  20 . Typically a cable  11  capable of carrying N signals is used for this connection. At  81 , the puck  20  receives at the PLC-side connector  26  a first linearly ordered group of I/O lines  90 . At  82 , a local subgroup  91  of (L) I/O lines adjacent a first end  92  of the first linearly ordered group  90  is connected to at least one I/O termination connector  21  adapted for connection to I/O devices  93 . At  83 , a remote subgroup  94  made up of the (N−L) unconnected I/O lines is shifted toward the first end  92  so as to form a second linearly ordered group  95  having the same number of I/O lines as the first linearly ordered group  90 . At  84 , no connection is made to those (L) extra lines  96  in the second linearly ordered group  95  which have no connection from the remote subgroup. At  85 , the second linearly ordered group  95  is provided at an I/O-side connector  24  which is adapted for connection to a second termination block  20 . If there are no more I/O devices to connect (“No” branch of  86 ), the method ends. If there are more I/O devices to connect (“Yes” branch of  86 ), the second termination block  20  is electrically connected to the first termination block, and the method continues at  81 . 
     From the foregoing it will be appreciated that the chaining I/O termination apparatus and methods provided by the present invention represent a significant advance in the art. Although several specific embodiments of the invention have been described and illustrated, the invention is not to be limited to the specific methods, forms, or arrangements of parts so described and illustrated. In particular, the invention has application beyond the field of automated tooling, and may be used, for instance, in general purpose data acquisition systems and in automated electronic test equipment. The invention is limited only by the claims.