Abstract:
A power supply booster module for a programmable logic controller system replaces the primary power supply for a number of modules within the system. The power supply booster module allows high power consuming or highly complex modules to be used within a programmable logic controller system. The power supply booster module eliminates the problems present in prior programmable logic controller systems where the primary power supply could not output enough current to adequately power all of the system modules or modules that have a high power requirement.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to power consumption in electronic systems, and more specifically to methods and apparatus for boosting power in programmable logic controller systems. 
     At least one known programmable logic controller system includes a plurality of installed modules, typically referred to as input/output (I/O) modules. The I/O modules consume an amount of power from a primary power supply. However, system configurations change over time and as high complexity or high power I/O modules are added to a programmable logic controller system, capability of the primary power supply is often exceeded. 
     In known systems, available power to a programmable logic controller system is increased by replacing the entire system with another system having a higher capacity power supply. However, a system with a higher capacity power supply is likely to have compatibility problems, for example, programming incompatibility, I/O module configuration differences, and incompatibility with the system to be controlled. 
     BRIEF SUMMARY OF THE INVENTION 
     In an exemplary embodiment, a programmable logic controller system includes a power supply booster module configured to supply power to a number of I/O modules in the programmable logic controller system. The power supply booster module is further configured to electrically interface and mechanically interface to any of a plurality of I/O modules present in the programmable logic controller system. 
     In particular, the power supply booster module increases programmable logic controller primary power supply capacity. More particularly, the power supply booster module provides power in addition to power provided by a primary power supply. The power supply booster module is installed in a programmable logic controller system by separating electrically and mechanically two of a plurality of I/O modules in a system and inserting the power supply booster in between the two I/O modules. Separating I/O modules disconnects the separated I/O modules from the primary power supply since power busses are connected serially through I/O modules. The power supply booster module then supplies power to a subset of a plurality of I/O modules via a second set of power busses created by separating the I/O modules. Specifically, separating the two I/O modules removes primary power supply power from I/O modules not located between the primary power supply and a power supply booster module. The power supply booster module supplies power to the I/O modules located other than between the primary power supply and the power supply booster module. It is possible to use a plurality of power supply booster modules within a programmable logic controller system. 
     The above described power supply booster module allows programmable logic controller power supply capacity to be tailored to requirements of an individual application. The power supply booster module eliminates the need for individual programmable logic controller power supply capacity to be set by worst case conditions. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a schematic illustration of a known programmable logic controller system including eight I/O modules and one primary power supply. 
     FIG. 2 is a schematic illustration of a power supply booster module. 
     FIG. 3 is a schematic illustration of the programmable logic controller system shown in FIG. 1 wherein a power supply booster module has been placed in between two of the eight I/O modules. 
     FIG. 4 is an illustration of an electro-mechanical interface to a known module base. 
     FIG. 5 is a top view of one embodiment of the power supply booster module shown in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a schematic illustration of an existing programmable logic controller system  10 . Programmable logic controller system  10  includes a headend unit  12  and a plurality of modules  14 , which for illustration purposes are numbered # 1  through # 8  and called input/output (I/O) modules. Headend unit  12  includes a primary power supply  16 , a power supply status generator  18 , and a central processing unit (CPU)  20 . I/O modules  14  include module bases  22 , which further include input/output circuits  24  and an application specific integrated circuit (ASIC)  26 . Primary power supply  16  supplies a plurality of voltages to I/O modules  14 . In one embodiment, a 0 volt reference  30 , a +3 volt supply  32 , and a +5 volt supply  34  are supplied by primary power supply  16 . 0 volt reference  30  and +5 volt supply  34  are routed within headend unit  12  to power supply status generator  18 . 
     Headend unit  12  splits the +5 volt supply  34  into a first +5 volt supply  36  and a second +5 volt supply  38 . Headend unit  12  further supplies all voltages (0 volt reference  30 , +3 volt supply  32 , first +5 volt supply  36 , and second +5 volt supply  38 ) to I/O modules  14  as series connected busses. Headend unit  12  also supplies a power supply status signal  40  to all I/O modules  14 . Power supply status signal  40  is also typically electrically connected an output circuit (not shown) that is typically electrically connected to a device (not shown), for example, a light emitting diode (LED) that indicates that the system  10  is functioning properly. 
     In I/O module  14 , second +5 volt supply  38 , +3 volt supply  32 , 0 volt reference  30 , and power supply status signal  40  are routed to input/output circuits  24 . In addition, power supply status signal  40  and first +5 volt supply  36  are routed to ASIC  26 . 
     FIG. 2 illustrates one embodiment of a power supply booster module  50 . Power supply booster module  50  includes a power supply booster base  52  including a booster power supply  54  and a booster power supply status generator  56 . Power supply booster module  50  is electrically connected to an external power source (not shown), for example, 110 Volts AC to supply power to booster power supply  54 . Booster power supply  54  rectifies the external power source to generate supply voltages required by the system to be powered. A 0 volt reference  58  and a first +5 volt supply  60  from a primary power supply (not shown) pass through power supply booster module  50  to I/O modules (not shown) in a programmable logic controller system (not shown). Second +5 volt supply  62 , power supply status signal  64 , and +3 volt supply  66  from the primary power supply are not routed through power supply booster module  50 . Instead, booster power supply  54  supplies a boosted +5 volt supply  68  and a boosted +3 volt supply  70  to booster power supply status generator  56  and to the I/O modules in the system, respectively. 
     FIG. 3 illustrates a programmable logic controller system  80  with a power supply booster module  50  installed. Programmable logic controller system  80  includes a headend unit  82  and a plurality of I/O modules  84 ,  86 , and  88 . I/O module  88  is labeled # 3  through # 8  to represent a plurality of I/O modules and indicates that system  80  is not limited to the I/O module  84  and  86  which are depicted in detail. A power supply booster module  50  has been inserted in between I/O modules  84  and  86 . Headend unit  82  includes a primary power supply  90 , a power supply status generator  92 , and a central processing unit (CPU)  94 . I/O modules  84 ,  86 , and  88  include module bases  96 , which further include input/output circuits  98  and an application specific integrated circuit (ASIC)  100 . Primary power supply  90  supplies a plurality of voltages. In one embodiment, a 0 volt reference  102 , a +3 volt supply  104 , and a +5 volt supply  106  are supplied by primary power supply  90 . 0 volt reference  102  and +5 volt supply  106  are routed within headend unit  82  to power supply status generator  92 . 
     Headend unit  82  splits the +5 volt supply  106  into a first +5 volt supply  108  and a second +5 volt supply  110 . Headend unit  82  further supplies all voltages (0 volt reference  102 , +3 volt supply  104 , first +5 volt supply  108 , and second +5 volt supply  110 ) to I/O module  84  as series connected busses. Headend unit  82  also supplies a power supply status signal  112  to I/O module  84 . Power supply status signal  112  is also typically electrically connected to an output circuit (not shown) which drives a device (not shown), for example, a light emitting diode (LED) that indicates that the system  80  is functioning properly. 
     Second +5 volt supply  110 , +3 volt supply  104 , 0 volt reference  102 , and power supply status signal  112  are routed within input/output module  84 , to input/output circuits  98 . In addition, power supply status signal  112  and first +5 volt supply  108  are routed to ASIC  100 . 
     Referring to power supply booster module  50 , it is seen that power supply status signal  112 , second +5 volt supply  110 , and +3 volt supply  104  from headend unit  82  are supplied to I/O module  84  and are interrupted at power supply booster module  50 . 
     Power supply booster module  50  has been positioned intermediate two I/O modules  84  and  86 . Power supply booster module  50  generates a booster status signal  114 , a boosted +5 volt supply  116 , and a boosted +3 volt supply  118  for supplying successive I/O modules  86  and  88  in order to replace power supply status signal  112 , second +5 volt supply  110 , and +3 volt supply  104  signals that are interrupted by the separation of I/O modules  84  and  86 . The configuration of power supply booster module  50  enables the use of several power supply booster modules  50  within a system. 
     FIG. 4 illustrates power supply booster base  52 , which is mechanically equivalent to module base  96  (shown in FIG.  3 ). Power supply booster base  52  includes control and data connectors  122  and  124 , and booster power supply connector  126 . Specifically, power supply booster base  52  is coupled to CPU  94  (shown in FIG. 3) using control and data connectors  122  and  124  to couple control and data signals to successive I/O modules  86  and  88  (shown in FIG.  3 ). Booster power supply  54  is coupled to power supply booster base  52  and control and data connector  124  via booster power supply connectors  126 . 
     FIG. 5 illustrates one embodiment of power supply booster module  50  including a first light emitting diode (LED)  130  and a second light emitting diode (LED)  132 . First LED  130  is configured to indicate that the voltages supplied for I/O modules  86  and  88  (shown in FIG. 3) by booster power supply  54  located in power supply booster base  52  are within tolerance. First LED  130  thus indicates that, thus the power supply booster module is functioning properly. Second LED  132  indicates that the entire system  80  is functioning properly and is a logical AND of first +5 volt supply  108 , generated by primary power supply  90 , and the voltages generated by booster power supply  54 . Second LED  132  is a substitute for the output circuit (not shown) electrically connected to power supply status signal  112  (shown in FIG. 3) since inserting a power supply booster module  50  (shown in FIG. 3) disconnects a portion of system  80  (shown in FIG. 3) from headend unit  82  including the output circuit (not shown). 
     By using the power supply booster described above, flexibility in selecting combinations of I/O modules and power supply boosters for all applications is achieved without exceeding primary power supply capacity or having to use several different types of systems for varying requirements. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.