Patent Publication Number: US-2021187648-A1

Title: Welding power supplies, wire feeders, and systems to measure a weld cable impedance

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This present application claims the benefit of U.S. Provisional Patent Application Ser. No. 62/950,657 filed Dec. 19, 2019, entitled “WELDING POWER SUPPLIES, WIRE FEEDERS, AND SYSTEMS TO MEASURE A WELD CABLE IMPEDANCE.” The entire content of U.S. Provisional Patent Application Ser. No. 62/950,657 is expressly incorporated herein by reference. 
    
    
     BACKGROUND 
     This disclosure relates generally to welding systems and, more particularly, to welding power supplies, wire feeders, and systems to measure a weld cable impedance. 
     Some welding applications, such as coal-fired boiler repair, shipyard work, and so forth, may position a welding location or workpiece a non-insignificant distance away from a welding power source. Accordingly, in some applications, weld cables may produce a non-negligible voltage drop between the power source and the site of the work (e.g., the wire feeder, the torch). It is therefore desirable for systems and methods to determine the resistance and/or impedance of the weld cables. 
     SUMMARY 
     Welding power supplies, wire feeders, and systems to measure a weld circuit impedance, substantially as illustrated by and described in connection with at least one of the figures, as set forth more completely in the claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows an example welding-type system in accordance with aspects of this disclosure. 
         FIG. 2  is a schematic diagram of the weld circuit of the welding-type system of  FIG. 1 . 
         FIG. 3  is a flowchart illustrating example machine readable instructions which may be executed by the example welding-type power supply of  FIG. 1  to determine a weld cable resistance. 
         FIG. 4  is a flowchart illustrating additional example machine readable instructions which may be executed by the example welding-type power supply of  FIG. 1  to determine a weld cable resistance. 
         FIG. 5  is a flowchart illustrating example machine readable instructions which may be executed by the example welding-type power supply of  FIG. 1  to determine a weld cable inductance. 
         FIG. 6  is a flowchart illustrating example machine readable instructions which may be executed by the example wire feeder of  FIG. 1  to determine a weld cable impedance. 
     
    
    
     The figures are not necessarily to scale. Where appropriate, similar or identical reference numbers are used to refer to similar or identical components. 
     DETAILED DESCRIPTION 
     Disclosed examples perform an impedance (e.g., resistance and/or inductance) measurement of a portion of a weld circuit (e.g., a weld cable). In some examples, the impedance measurement involves closing a switch at a welding device coupled to the weld circuit, to cause short circuiting of a portion of the weld circuit. The impedance measurement also involves generating a first signal at a controlled voltage, where the current of the first signal is limited to a threshold level. The weld circuit voltages and the current may then be used with Ohm&#39;s law to calculate a resistance of the remaining portion of the weld circuit after the weld circuit is shunted. The power supply may use the resistance as an compensation value to generate a weld voltage that is close to a weld voltage setpoint. The power supply may also determine an inductance of a portion of the weld circuit by sampling the current and sampling voltages at points in the weld circuit during a ramp up condition of the test signal. While other methods determine voltage drops between the power supply and the welding device coupled to the power supply, disclosed examples allow the resistance and/or inductance measurement(s) to be taken at any time when the system is not welding (e.g., any time when the power supply is not outputting welding-type power for a welding-type application). 
     Weld cable communications enable components of welding systems, such as a welding power supply and a wire feeder, to communicate via a same cable used to deliver welding current from the power supply to the wire feeder (and to a welding torch attached to the wire feeder). Weld cable communications enable a simplification of a welding system by, for example, removing one or more cables that were conventionally used for control signals. 
     Disclosed example welding-type power supplies include: power conversion circuitry configured to convert input power to welding-type power; a voltage monitor configured to measure a power supply output voltage of the power conversion circuitry; communication circuitry configured to transmit a first communication to a welding device coupled to the weld circuit, where the first communication comprises a command to the welding device to close a switch to complete a measurement circuit, where the measurement circuit comprises a first portion of the weld circuit; and control circuitry configured to control the power conversion circuitry to: output a first signal at a controlled voltage to the measurement circuit; and after the first communication, limit a current of the first signal to a first threshold level; where the communication circuitry is configured to receive, from the welding device, a second communication indicating a welding device voltage measured in response to the first signal; and where the control circuitry is configured to determine a resistance of a second portion of the weld circuit based on the power supply output voltage, the welding device voltage, and the current of the first signal. 
     In some disclosed welding-type power supplies, the switch is configured to open a threshold period of time after closing. 
     Some disclosed welding-type power supplies further include a current monitor configured to measure a current of the measurement circuit. 
     In some disclosed welding-type power supplies, the communication circuitry is configured to send a third communication to the welding device when the current monitor senses that current of the first signal has reached the threshold level, wherein the third communication commands the welding device to open the switch. 
     In some disclosed welding-type power supplies, the communication circuitry is configured to send a third communication to the welding device a threshold period of time after the current monitor senses that the current of the first signal has reached the threshold level, wherein the third communication commands the welding device to open the switch. 
     In some disclosed welding-type power supplies, the control circuitry is configured to determine the resistance of the second portion of the weld circuit based on the measured current of the first signal. 
     In some disclosed welding-type power supplies, a magnitude of the first threshold level is less than a magnitude of the welding-type power current. 
     In some disclosed welding-type power supplies, the control circuitry is configured to control the power conversion circuitry to output the welding-type power based on the determined resistance. 
     In some disclosed welding-type power supplies, the control circuitry is configured to control the power conversion circuitry to output the welding-type power based on the determined resistance and a weld process parameter. 
     In some disclosed welding-type power supplies, the control circuitry is configured to determine the resistance of the second portion of the weld circuit prior to outputting welding-type current. 
     In some disclosed welding-type power supplies, the communications circuitry is configured to transmit a third communication to the welding device, where the third communication includes a command to the welding device to close the switch to complete the measurement circuit; the control circuitry is configured to control the power conversion circuitry to: output a second signal at the controlled voltage to the measurement circuit; and after the third communication, limit a current of the second signal to a second threshold level; the communications circuitry is further configured to receive a fourth communication from the welding device indicating a plurality voltage measurements during the second signal; and the control circuitry is configured to determine an impedance of a portion of the weld circuit based on the determined resistance, a plurality of current measurements, and the plurality voltage measurements. 
     In some disclosed welding-type power supplies, the second signal is output after the first signal. 
     In some disclosed welding-type power supplies, the switch is automatically opened between the first signal and the second signal. 
     In some disclosed welding-type power supplies, the control circuitry is configured to control the power conversion circuitry to output the welding-type power based on the determined impedance. 
     In some disclosed welding-type power supplies, the communications circuitry is configured to communicate with the welding device via the weld circuit. 
     Disclosed example welding devices include: communications circuitry configured to communicate with a welding-type power supply; a switch configured to selectively complete a measurement circuit, wherein the measurement circuit comprises a portion of a weld circuit; control circuitry configured to control the switch to complete the measurement circuit in response to a first communication from the welding-type power supply; and a voltage monitor configured to measure a voltage of a first signal received via the measurement circuit in response to detecting the first signal following reception of the first communication, the communications circuitry configured to transmit a second communication to the welding-type power supply based on the measured voltage of the first signal. 
     In some disclosed welding devices, the welding device is a wire feeder. 
     Some disclosed welding devices further include a current monitor configured to monitor a current of the first signal, and the control circuitry is configured to control the switch to open the measurement circuit in response to the current monitor determining that the current of the first signal has reached a threshold magnitude. 
     Some disclosed welding devices further include a current monitor configured to monitor a current of the first signal, and the control circuitry is configured to control the switch to open the measurement circuit a threshold period of time after the current monitor determines that the current of the first signal has reached a threshold magnitude. 
     In some disclosed welding devices, the control circuitry is configured to control the switch to open the measurement circuit a threshold period of time after receiving the first communication. 
     As used herein, the term “welding-type power” refers to power suitable for welding, plasma cutting, induction heating, CAC-A and/or hot wire welding/preheating (including laser welding and laser cladding). As used herein, the term “welding-type power supply” refers to any device capable of, when power is applied thereto, supplying welding, plasma cutting, induction heating, CAC-A and/or hot wire welding/preheating (including laser welding and laser cladding) power, including but not limited to inverters, converters, resonant power supplies, quasi-resonant power supplies, and the like, as well as control circuitry and other ancillary circuitry associated therewith. 
     As used herein, a “weld voltage setpoint” refers to a voltage input to the power conversion circuitry via a user interface, network communication, weld procedure specification, or other selection method. 
     As used herein, the terms “circuit” and “circuitry” refer to physical electronic components (i.e. hardware) and any software and/or firmware (“code”) which may configure the hardware, be executed by the hardware, and or otherwise be associated with the hardware. As used herein, for example, a particular processor and memory may comprise a first “circuit” when executing a first one or more lines of code and may comprise a second “circuit” when executing a second one or more lines of code. 
     The terms “control circuit” and “control circuitry,” as used herein, may include digital and/or analog circuitry, discrete and/or integrated circuitry, microprocessors, digital signal processors (DSPs), and/or other logic circuitry, and/or associated software, hardware, and/or firmware. Control circuits may include memory and a processor to execute instructions stored in memory. Control circuits or control circuitry may be located on one or more circuit boards, that form part or all of a controller, and are used to control a welding process, a device such as a power source or wire feeder, motion, automation, monitoring, air filtration, displays, and/or any other type of welding-related system. 
     As used, herein, the term “memory” and/or “memory device” means computer hardware or circuitry to store information for use by a processor and/or other digital device. The memory and/or memory device can be any suitable type of computer memory or any other type of electronic storage medium, such as, for example, read-only memory (ROM), random access memory (RAM), cache memory, compact disc read-only memory (CDROM), electro-optical memory, magneto-optical memory, programmable read-only memory (PROM), erasable programmable read-only memory (EPROM), electrically-erasable programmable read-only memory (EEPROM), flash memory, solid state storage, a computer-readable medium, or the like. 
     As used herein, the term “weld circuit” includes any and all components in an electrical path of a welding operation, regardless whether the welding operation is underway. For example, the weld circuit is considered to include any or all of: power conversion and/or conditioning component(s), weld cable conductor(s), weld torch(es), consumable or non-consumable welding electrode(s), workpiece(s), work clamp(s), ground cable(s) (return cables), and/or weld cable connections (e.g., weld studs that connect a welding power supply to a weld cable). As used herein, the “weld circuit” does not include components or conductors that do not conduct weld current at any time (e.g., that are not in the electrical path of the weld current). For example, the weld circuit does not include separate control cables that transmit data but do not transmit weld current. 
     As used herein, the term “filtering,” as it applies to voltage and/or current values, refers to generating one or more representative values from a larger set of values. For example, a set of voltage values or measurements may be filtered to obtain an average voltage, a root-mean-square value of the voltage values, or any other representative or derivative value(s). 
     Welding operation, as used herein, includes both actual welds (e.g., resulting in joining, such as welding or brazing) of two or more physical objects, an overlaying, texturing, and/or heat-treating of a physical object, and/or a cut of a physical object) and simulated or virtual welds (e.g., a visualization of a weld without a physical weld occurring). 
     Turning now to the drawings,  FIG. 1  is a block diagram of an example welding system  100  having a welding-type power supply  102 , a wire feeder  104 , and a welding torch  106 . The welding system  100  powers, controls, and supplies consumables to a welding application. In some examples, the power supply  102  directly supplies input power to the welding torch  106 . The welding torch  106  may be a torch configured for shielded metal arc welding (SMAW, or stick welding), tungsten inert gas (TIG) welding, gas metal arc welding (GMAW), flux cored arc welding (FCAW), based on the desired welding application. In the illustrated example, the power supply  102  is configured to supply power to the wire feeder  104 , and the wire feeder  104  may be configured to route the input power to the welding torch  106 . In addition to supplying an input power, the wire feeder  104  may supply a filler metal to a welding torch  106  for various welding applications (e.g., GMAW welding, flux core arc welding (FCAW)). While the example system  100  of  FIG. 1  includes a wire feeder  104  (e.g., for GMAW or FCAW welding), the wire feeder  104  may be omitted and/or replaced by any other type of remote accessory device, such as a stick welding and/or TIG welding remote control interface that provides stick and/or TIG welding consumables to the welding application. 
     The power supply  102  receives primary power  108  (e.g., from the AC power grid, an engine/generator set, a battery, or other energy generating or storage devices, or a combination thereof), conditions the primary power, and provides an output power to one or more welding devices in accordance with demands of the system  100 . The primary power  108  may be supplied from an offsite location (e.g., the primary power may originate from the power grid). The power supply  102  includes power conversion circuitry  110 , which may include transformers, rectifiers, switches, and so forth, capable of converting the AC input power to AC and/or DC output power as dictated by the demands of the system  100  (e.g., particular welding processes and regimes). The power conversion circuitry  110  converts input power (e.g., the primary power  108 ) to welding-type power based on weld parameter setpoint(s) (e.g., a voltage setpoint, a current setpoint, etc.) and outputs the welding-type power via a weld circuit. 
     In some examples, the power conversion circuitry  110  is configured to convert the primary power  108  to both welding-type power and auxiliary power outputs. However, in other examples, the power conversion circuitry  110  is adapted to convert primary power only to a weld power output, and separate auxiliary conversion circuitry  111  is provided to convert primary power to auxiliary power. In some other examples, the power supply  102  receives a converted auxiliary power output directly from a wall outlet. Any suitable power conversion system or mechanism may be employed by the power supply  102  to generate and supply both weld and auxiliary power. 
     The power supply  102  includes control circuitry  112  to control the operation of the power supply  102 . The power supply  102  also includes a user interface  114 . The control circuitry  112  receives input from the user interface  114 , through which a user may choose a process and/or input desired parameters (e.g., voltages, currents, particular pulsed or non-pulsed welding regimes, and so forth). The user interface  114  may receive inputs using any input device, such as via a keypad, keyboard, buttons, touch screen, voice activation system, wireless device, etc. Furthermore, the control circuitry  112  controls operating parameters based on input by the user as well as based on other current operating parameters. Specifically, the user interface  114  may include a display  116  for presenting, showing, or indicating, information to an operator. The control circuitry  112  may also include interface circuitry for communicating data to other devices in the system  100 , such as the wire feeder  104 . For example, in some situations, the power supply  102  wirelessly communicates with other welding devices within the welding system  100 . Further, in some situations, the power supply  102  communicates with other welding devices using a wired connection, such as by using a network interface controller (NIC) to communicate data via a network (e.g., ETHERNET, 10baseT, 10base100, etc.). In the example of  FIG. 1 , the control circuitry  112  communicates with the wire feeder  104  via the weld circuit via communications circuitry  118 , as described below. 
     The control circuitry  112  includes at least one controller or processor  120  that controls the operations of the power supply  102 . The control circuitry  112  receives and processes multiple inputs associated with the performance and demands of the system  100 . The processor  120  may include one or more microprocessors, such as one or more “general-purpose” microprocessors, one or more special-purpose microprocessors and/or ASICS, and/or any other type of processing device. For example, the processor  120  may include one or more digital signal processors (DSPs). 
     The example control circuitry  112  includes one or more storage device(s)  123  and one or more memory device(s)  124 . The storage device(s)  123  (e.g., nonvolatile storage) may include ROM, flash memory, a hard drive, and/or any other suitable optical, magnetic, and/or solid-state storage medium, and/or a combination thereof. The storage device  123  stores data (e.g., data corresponding to a welding application), instructions (e.g., software or firmware to perform welding processes), and/or any other appropriate data. Examples of stored data for a welding application include an attitude (e.g., orientation) of a welding torch, a distance between the contact tip and a workpiece, a voltage, a current, welding device settings, and so forth. 
     The memory device  124  may include a volatile memory, such as random access memory (RAM), and/or a nonvolatile memory, such as read-only memory (ROM). The memory device  124  and/or the storage device(s)  123  may store a variety of information and may be used for various purposes. For example, the memory device  124  and/or the storage device(s)  123  may store processor executable instructions  125  (e.g., firmware or software) for the processor  120  to execute. In addition, one or more control regimes for various welding processes, along with associated settings and parameters, may be stored in the storage device  123  and/or memory device  124 , along with code configured to provide a specific output (e.g., initiate wire feed, enable gas flow, capture welding current data, detect short circuit parameters, determine amount of spatter) during operation. 
     In some examples, the welding power flows from the power conversion circuitry  110  through a weld cable  126  to the wire feeder  104  and the welding torch  106 . The example weld cable  126  is attachable and detachable from weld studs at each of the power supply  102  and the wire feeder  104  (e.g., to enable ease of replacement of the weld cable  126  in case of wear or damage). Furthermore, in some examples, welding data is provided with the weld cable  126  such that welding power and weld data are provided and transmitted together over the weld cable  126 . The communications circuitry  118  is communicatively coupled to the weld cable  126  to communicate (e.g., send/receive) data over the weld cable  126 . The communications circuitry  118  may be implemented based on various types of power line communications methods and techniques. For example, the communications circuitry  118  may utilize IEEE standard P1901.2 to provide data communications over the weld cable  126 . In this manner, the weld cable  126  may be utilized to provide welding power from the power supply  102  to the wire feeder  104  and the welding torch  106 . Additionally or alternatively, the weld cable  126  may be used to transmit and/or receive data communications to/from the wire feeder  104  and the welding torch  106 . The communications circuitry  118  is communicatively coupled to the weld cable  126 , for example, via cable data couplers  127 , to characterize the weld cable  126 , as described in more detail below. The cable data coupler  127  may be, for example, a voltage or current sensor. 
     The example communications transceiver  118  includes a receiver circuit  121  and a transmitter circuit  122 . Generally, the receiver circuit  121  receives data transmitted by the wire feeder  104  via the weld cable  126  and the transmitter circuit  122  transmits data to the wire feeder  104  via the weld cable  126 . As described in more detail below, the communications circuitry  118  enables remote configuration of the power supply  102  from the location of the wire feeder  104  and/or compensation of weld voltages by the power supply  102  using feedback information transmitted by the wire feeder  104 . 
     Example implementations of the communications circuitry  118  are described in U.S. Pat. No. 9,012,807. The entirety of U.S. Pat. No. 9,012,807 is incorporated herein by reference. However, other implementations of the communications transceiver  118  may be used. 
     The example wire feeder  104  also includes communications circuitry  119 , which may be similar or identical in construction and/or function as the communications circuitry  118  of the power supply. 
     In some examples, a gas supply  128  provides shielding gases, such as argon, helium, carbon dioxide, and so forth, depending upon the welding application. The shielding gas flows to a valve  130 , which controls the flow of gas, and if desired, may be selected to allow for modulating or regulating the amount of gas supplied to a welding application. The valve  130  may be opened, closed, or otherwise operated by the control circuitry  112  to enable, inhibit, or control gas flow (e.g., shielding gas) through the valve  130 . Shielding gas exits the valve  130  and flows through a cable  132  (which in some implementations may be packaged with the welding power output) to the wire feeder  104  which provides the shielding gas to the welding application. In some examples, the welding system  100  does not include the gas supply  128 , the valve  130 , and/or the cable  132 . 
     In some examples, the wire feeder  104  uses the welding power to power the various components in the wire feeder  104 , such as to power wire feeder control circuitry  134 . As noted above, the weld cable  126  may be configured to provide or supply the welding power. The power supply  102  may also communicate with communications circuitry  119  of the wire feeder  104  using the weld cable  126  and the communications circuitry  118  disposed within the power supply  102 . In some examples, the communications circuitry  119  is substantially similar to the communications circuitry  118  of the power supply  102 . The wire feeder control circuitry  134  controls the operations of the wire feeder  104 . In some examples, the wire feeder  104  uses the wire feeder control circuitry  134  to detect whether the wire feeder  104  is in communication with the power supply  102  and to detect a current welding process of the power supply  102  if the wire feeder  104  is in communication with the power supply  102 . 
     A contactor  135  (e.g., high amperage relay) is controlled by the wire feeder control circuitry  134  and configured to enable or inhibit welding power to continue to flow to the weld cable  126  for the welding application. In some examples, the contactor  135  is an electromechanical device. However, the contactor  135  may be any other suitable device, such as a solid state device. The wire feeder  104  includes a wire drive  136  that receives control signals from the wire feeder control circuitry  134  to drive rollers  138  that rotate to pull wire off a spool  140  of wire. The wire is provided to the welding application through a torch cable  142 . Likewise, the wire feeder  104  may provide the shielding gas from the cable  132  through the cable  142 . The electrode wire, the shield gas, and the power from the weld cable  126  are bundled together in a single torch cable  144  and/or individually provided to the welding torch  106 . 
     The welding torch  106  delivers the wire, welding power, and/or shielding gas for a welding application. The welding torch  106  is used to establish a welding arc between the welding torch  106  and a workpiece  146 . A work cable  148  couples the workpiece  146  to the power supply  102  (e.g., to the power conversion circuitry  110 ) to provide a return path for the weld current (e.g., as part of the weld circuit). The example work cable  148  attachable and/or detachable from the power supply  102  for ease of replacement of the work cable  148 . The work cable  148  may be terminated with a clamp  150  (or another power connecting device), which couples the power supply  102  to the workpiece  146 . 
     The example wire feeder  104  of  FIG. 1  includes a voltage monitor  152  coupled to the weld circuit (e.g., electrically connected to the weld cable  126 ) and to the workpiece  146  via a clamp  154  and a work sense lead  156 . The example voltage monitor  152  may be coupled to the weld circuit via a cable data coupler  127 . The voltage monitor  152  measures a voltage at the wire feeder  104 . 
     The voltage monitor  152  captures one or more measurements (e.g., samples) of the wire feeder voltage. In some examples, the voltage monitor  152  assigns time stamps to the measurements for use in performing calculations, compensation, and/or matching of measurements to other measurements. 
     The example voltage monitor  152  and/or the control circuitry  134  may perform filtering (e.g., analog and/or digital filtering) to determine a representative value of the voltage over a designated time period. The representative value may be a filtered voltage value based on the measurements captured by the voltage monitor  152 , such as an average voltage over the designated time period or a root-mean-square voltage over the designated time period. For example, the voltage monitor  152  and/or the control circuitry  112  or the control circuitry  134  may calculate an average wire feeder voltage for an N second time period based on a corresponding number of measurements captured by the voltage monitor  152  at a designated rate. In some examples, the time period for filtering is selected based on the switching frequency of the power conversion circuitry  110  and/or a processing frequency used by the control circuitry  134  and/or the processor(s)  120 . 
     The example control circuitry  134  stores the average weld voltage(s) and/or the voltage measurement(s) as voltage feedback information. The communications circuitry  119  transmits the wire feeder voltage feedback information to the power supply  102  via the weld circuit (e.g., via the weld cable  126 ). 
     In some examples, the voltage feedback information includes a characteristic of the weld cable  126  such as a model number or other identifier of the weld cable  126  that can be used to accurately compensate the weld voltage for the drop over the weld cable  126 . For example, if a model of weld cable has a determinable impedance without measurements, the control circuitry  112  can use the identification of that weld cable to compensate the output from the power conversion circuitry  110 . 
     When the power supply  102  receives the voltage measurements, the power supply  102  may execute an algorithm to determine the impedance of the weld cable  126 , and may control the power conversion circuitry  110  based in part on the determined impedance. 
     The example power supply  102  includes a voltage monitor  160  that measures an actual power supply output voltage. The actual power supply output voltage is an approximation that is substantially equal to, but may be slightly different (e.g., a negligible difference) than, the real voltage that is output from the power supply  102  to the weld cable  126 . In some examples, the voltage monitor  160  is included in the power conversion circuitry  110 . In some examples, the voltage monitor  160  assigns time stamps to the measurements for use in performing calculations, compensation, and/or matching of measurements to other measurements. 
     In some examples, the power supply  102  may include a current monitor  168 . Current measurements generated by the current monitor  168  may be filtered to determine, for example, an average current, a peak current, and/or an RMS current. In some examples, the current monitor  168  assigns time stamps to the measurements for use in performing calculations, compensation, and/or matching of measurements to other measurements. 
     The wire feeder  104  may include an energy storage device, such as an energy storage capacitor  162 , isolated from the weld circuit through a diode bridge  164 , such that no current flows when the weld circuit voltage is lower than the energy storage device charge voltage. Energy from the energy storage device  162  may be used to supply power to the control circuitry  134  and other circuits of the wire feeder  104 . The wire feeder  104  may also include a switch  170 . The switch  170  may be, for example an IGBT or a MOSFET. When closed, the switch  170  completes a measurement circuit, where the measurement circuit is a portion of the weld circuit. The measurement circuit bypasses the torch  106 . When the switch  170  is closed, a diode  166  prevents current from flowing from the capacitor  162  to the measurement circuit. When the switch  170  is closed, the control circuitry  134  does not receive power from the weld circuit. The switch  170  is controlled by control circuitry  134  of the wire feeder  104 . The communications circuitry  119  may receive a communication from the power supply  102  commanding the switch  170  to close, and the control circuitry  134  commands the switch  170  to close after receiving the communication from the power supply. As described below, the switch  170  may be closed to measure the weld cable  126  resistance and/or impedance. 
     As mentioned above, the weld cable  126  between the power supply  102  and the wire feeder  104  causes a voltage drop. The voltage drop caused by the weld cable  126  (V cabledrop ) can be expressed as a difference between a voltage measured at the power supply output (e.g., V stud , measured across the power supply output studs or ports) and a voltage measured at the wire feeder  104  (e.g., V feeder ), as expressed in Equation 1 below. The V feeder  term is received as the voltage feedback information, such as a weld voltage measurement and/or average weld voltage determined by the wire feeder  104  and communicated via the weld cable  126 . 
         V   cableDrop   =V   stud   −V   feeder   Equation 1
 
     Adjusting the voltage output by the power conversion circuitry  110  (e.g., V stud ) by the voltage drop in the weld cable  126  (e.g., V cableDrop ) effectively raises the voltage at the wire feeder  104  (e.g., V feeder ). Thus, the example control circuitry  112  may adjust the power (e.g., voltage and/or current) output by the power conversion circuitry  110  to cause the voltage at the wire feeder  104  (e.g., effectively the weld voltage or arc voltage) to substantially match a voltage setpoint. The example control circuitry  112  may adjust the voltage setpoint (e.g., V cmd ) to determine an adjusted voltage setpoint V adjustedcmd  (e.g., an adjusted voltage command). 
     In some examples, the example control circuitry  112  may determine a weld cable  126  resistance and/or inductance (e.g., via V cableDrop  and measurement circuit current). The example control circuitry  112  may then determine an adjusted output based on the determined weld cable  126  resistance and/or inductance (e.g., impedance). 
     Prior to performing welding, the example power supply  102  may not have a reliable measure of the weld cable  126  resistance. To better reflect the selected weld parameters at the arc, the example system  100  of  FIG. 1  determines an initial estimate of the resistance and/or inductance of the weld cable  126 . The control circuitry  112  may then control the output of the power conversion circuitry  110  based on the determined resistance and/or inductance, such as adjusting the output of the power conversion circuitry  110  to compensate for the determined resistance and/or inductance. 
     The control circuitry  112  communicates to the control circuitry  134 , via communications circuitry  118  and communications circuitry  119 , a command to close the switch  170 . In response to the command, the control circuitry  134  controls the switch  170  to close. The communication may include a message that the system  100  will conduct a weld cable resistance/inductance measurement test. When the switch  170  is closed, the measurement circuit includes a portion of the weld circuit, including the power conversion circuitry  110 , the weld cable  126 , the switch  170 , the voltage sense lead  156 , the clamp  154 , the workpiece  146 , and the work cable  148 . 
     The control circuitry  112  then commands the power conversion circuitry  110  to output a test signal at a controlled voltage via the measurement circuit. The control circuitry  112  controls the power conversion circuitry  110  to limit the current of the test signal to a threshold level. In the example of  FIG. 1 , the current and/or voltage levels of the test signal are less than the current and/or voltage levels of typical welding-type power. For example, the current limit of the test signal may between 100 mA and 200 A. The voltage monitor  160  measures the actual output voltage (e.g., the voltage output by the power conversion circuitry  110 , the output voltage at the output terminals of the power supply  102 , etc.) while outputting the test signal (e.g., a filtered voltage, a voltage at a specific time after the signal is initiated, a voltage at a time when the current threshold is satisfied). The voltage monitor  152  measures the voltage (e.g., a filtered voltage, a voltage at a time when the current threshold is satisfied) at the wire feeder  104  while the test signal is being output by the power supply  102 . 
     The communications circuitry  119  transmits the wire feeder voltage measured by the voltage monitor  152  in response to the test signal to the communications circuitry  118 . The transmitted voltage may be a sampled voltage, a filtered voltage, and/or any other voltage representative of the wire feeder voltage measured by the voltage monitor  152 . The control circuitry  112  then compares the voltage at the wire feeder  104  V feeder  to the actual output voltage V stud  to determine the weld cable  126  voltage drop V cableDrop . The control circuitry  112  determines the weld cable  126  resistance by dividing V cableDrop  by the weld current. The weld current may be a current measured by the current sensor  168  (e.g., a filtered current, a current measured at a specific time after the signal is initiated) or the current threshold. The control circuitry  134  may command the switch  170  to open after the power conversion circuitry  110  ceases outputting the test signal. For example, the control circuitry  134  may control the switch  170  to open a set amount of time after the test signal is initiated, after receiving a communication from the welding power supply  102  commanding the switch  170  to open, or after the voltage monitor  152  senses the test signal has ended. 
     When the resistance measurement is determined by the control circuitry  112 , the power supply  102  may use the measured resistance as the initial value for determining a weld cable voltage drop and control the primary power conversion circuitry  110  to increase an output voltage from a voltage setpoint and/or further refine the weld cable voltage drop measurement as disclosed in U.S. patent application Ser. No. 15/238,585 and U.S. patent application Ser. No. 15/238,589. The entireties of U.S. patent application Ser. No. 15/238,585 and U.S. patent application Ser. No. 15/238,589 are hereby incorporated by reference. 
     After the weld cable  126  resistance is determined, an inductance measurement test may be conducted. An inductance measurement test includes closing the switch  170 , and outputting a test signal similarly to the resistance measurement. To determine inductance, the voltage monitor  152  samples the voltage at the feeder, the voltage monitor  160  samples the actual output voltage, and the current monitor  168  samples the current of the test signal, at several points during ramp up of the current when the test signal is output. The voltage of the weld cable V cableDrop  can then be determined at several points during ramp up of the current when the test signal is output. The inductance of the weld cable is then determined by equation 2. The resistance and the inductance of the weld cable together encompasses the weld cable impedance. 
     
       
         
           
             
               
                 
                   
                     
                       V 
                       
                         cable 
                          
                         
                             
                         
                          
                         Drop 
                       
                     
                     × 
                     
                       dt 
                       di 
                     
                   
                   = 
                   
                     L 
                     cable 
                   
                 
               
               
                 
                   Equation 
                    
                   
                       
                   
                    
                   2 
                 
               
             
           
         
       
     
     In some examples, the control circuitry  112  may be configured to perform a weld cable resistance and/or weld cable inductance test prior to any welding operation. In some examples, the control circuitry  112  may be configured to perform a weld cable resistance and/or weld cable inductance test any time the welding power supply  102  is powered on and a wire feeder is first attached or re-attached to the power supply  102 . The resistance of the work cable  148  could also be determined by similarly measuring the voltage at the workpiece  146  via another voltage monitor and comparing the voltage at the workpiece to the measured voltage at the opposite terminal of the welding power supply  102 . 
       FIG. 2  is a schematic diagram of the weld circuit of the system  100 . When the switch  170  is open, as in normal operation, the power conversion circuitry  110  converts input power received from a primary power source  108  to welding-type power. The welding-type current is output to the wire feeder  104  via the weld cable  126 . The wire feeder  104  includes the energy storage device (e.g., a capacitor)  162 , which is isolated from the weld circuit through a diode bridge  164 , such that no current flows from the energy storage device  162  to the weld circuit when the weld circuit voltage is lower than the energy storage device charge voltage. Energy from the energy storage device  162  is used to supply power to the control circuitry  134  and other circuits of the wire feeder  104 . Welding-type current flows from the wire feeder  104  to the torch  106 . The welding-type current arcs from the torch  106  to the workpiece  146 , and returns to the power conversion circuitry  110  via the work cable  148 . 
     The weld cable  126  and the work cable  148  each have a resistance and an inductance. The switch  170  may be closed in order to measure the weld cable  126  resistance and/or inductance. The diode  166  prevents current from flowing from the capacitor  162  to the measurement circuit when the switch  170  is closed. When the switch  170  is closed, current output by the power conversion circuitry  110  flows through the diode bridge  164 , the switch  170 , the voltage sense lead  156 , and then returns to the power conversion circuitry  110  via the work cable. Thus, closing the switch  170  completes the measurement circuit by bypassing the torch cable  142  and the torch  106 . 
       FIG. 3  is a flowchart illustrating example machine readable instructions  300  which may be executed by the example control circuitry  112  of the welding-type power supply  102  of  FIG. 1  to determine a resistance of the weld cable  126 . 
     At block  302 , the control circuitry  112  of the power supply  102  controls the power conversion circuitry  110  to turn off output. At block  304 , the control circuitry  112  transmits a command, via the communications circuitry  118 , to the wire feeder  104  to close the feeder switch  170 . The command may be a communication indicating that the power supply  102  will perform a weld cable resistance measurement test. The control circuitry  134  of the wire feeder  104  controls the switch  170  to close after receiving the command. 
     At block  306 , the control circuitry  112  controls the power conversion circuitry  110  to output a voltage-controlled current-limited signal in order to determine the resistance of the weld cable  126 . The power level of the signal is less than the power level of welding-type power. In other words, the magnitude of the current and/or the voltage of the signal is less than the magnitude of the current and/or voltage of welding-type power. 
     At block  308 , after a predetermined duration of time T after the command was sent (block  304 ), the voltage monitor  160  measures the actual output voltage of the power conversion circuitry  110 . The duration T is selected to have consistent output from the power conversion circuitry  110  and short enough in duration to reduce or prevent inaccuracies resulting from heating of the weld cable  126  by the current. At block  310 , after the duration T after the command, the current monitor  168  measures the output current of the power conversion circuitry  110 . At block  312 , the control circuitry  112 , receives from wire feeder via the communications circuitry  118 , a feeder voltage measurement. The feeder voltage measurement is measured after the duration T after the command by the voltage monitor  152 , and transmitted by the wire feeder  104  via the communications circuitry  119 . In some examples, the voltage measurement taken by the voltage sensor  160  and the current measurement taken by current sensor  168  are timestamped. The wire feeder  104  may transmit an array of sampled timestamped voltages at block  314 . The control circuitry  112  may select the voltage measurement in the array having a timestamp that corresponds to the timestamped voltage and/or current measurements taken at blocks  308  and  310 . 
     At block  314 , the control circuitry  112  determines the voltage drop across the weld cable  126 , V cableDrop . V cableDrop  is equal to the received feeder voltage (received at block  312 ) subtracted from the actual output voltage (measured at block  308 ). At block  316 , the control circuitry  112  determines the weld cable  126  resistance. The weld cable resistance is equal to the determined V cableDrop  (block  314 ) divided by the measured output current (block  310 ). In some examples, a current monitor  168  is not used, and instead the current limit is used to determine the weld cable  126  resistance. 
     At block  318 , the control circuitry  112  commands the power conversion circuitry  110  to turn off the test signal. At block  320 , the control circuitry  112  transmits, via the communications circuitry  118 , a command to open the switch  170 . The control circuitry  134  then commands the switch  170  to open. In some examples, the control circuitry  134  is configured to automatically open the switch  170  at a predetermined period of time after receiving the communication to close the switch rather than waiting for a command from the power supply  102  to open the switch  170  (block  304 ). 
     The determined resistance may be displayed via the user interface  114  (e.g., via the display  116 ). In some examples, if the determined resistance exceeds a threshold, the user interface  114  may display an error. In some examples, if the determined resistance exceeds a threshold, the control circuitry  112  may prevent the power conversion circuitry  110  from outputting welding-type power. For example, the control circuitry  112  may prevent the power conversion circuitry  110  from outputting welding-type power until another resistance measurement test is run in which the determined resistance is less than the threshold. In some examples, the threshold may be stored in memory  124 . In some examples, the threshold resistance may correspond to a selected welding application. 
     The control circuitry  112  may control the power conversion circuitry  110  to output welding-type power for welding applications based on the determined resistance. U.S. Patent Application Publication No. 2018/0257162 by Nathan W. Johnson and Brian L. Ott, titled “Welding Power Supplies, Wire Feeders, And Systems to Measure a Weld Circuit Resistance Via Communications Over the Weld Circuit” disclose methods for controlling the output of a welding-type power source based on a cable resistance. U.S. Patent Application Publication No. 2018/0257162 is hereby incorporated by reference in its entirety. 
     In some examples the instructions  300  may be executed on command (e.g., an operator may command the system  100  to perform a resistance measurement test via the user interface  114 ). In some examples, the instructions  300  may be automatically executed when the power supply  102  is turned on and connected to a wire feeder  104  via cables  126  and  148 . In some examples, the instructions  300  may be automatically executed when a welding application is selected (e.g., prior to the power supply outputting welding-type power for the selected welding application). 
       FIG. 4  is a flowchart illustrating another example machine readable instructions  400  which may be executed by the example control circuitry  112  of the welding-type power supply  102  of  FIG. 1  to determine a resistance of the weld cable  126 . 
     At block  402 , the control circuitry  112  of the power supply  102  controls the power conversion circuitry  110  to turn off output. At block  404 , the control circuitry  112  transmits a command, via the communications circuitry  118 , to the wire feeder  104  to close the feeder switch  170 . The command may be a communication indicating that the power supply  102  will perform a weld cable resistance measurement test. The control circuitry  134  of the wire feeder  104  controls the switch  170  to close. 
     At block  406 , the control circuitry  112  controls the power conversion circuitry  110  to output a voltage-controlled current-limited signal in order to determine the resistance of the weld cable  126 . The power level of the signal is less than the power level of welding-type power. 
     At block  408 , the control circuitry  112  checks if the output current (measured by the current monitor  168 ) satisfies a threshold (e.g., has reached the current limit). If the current satisfies the threshold (block  408 ), then the method proceeds to block  412 . If the current does not satisfy the threshold (block  408 ), then at block  410 , the control circuitry  112  checks if the time since the communication was sent (block  404 ) satisfies a threshold. If the time does not satisfy the threshold (block  410 ), then the method returns to block  408 . If the time does satisfy the threshold (block  410 ) then the method proceeds to block  412 . At block  412  the control circuitry  112  measures the actual output voltage via the voltage monitor  160 . The actual output voltage may be an instantaneous voltage or may be a filtered voltage (e.g., average voltage) of the voltage measured since the communication (block  404 ). At block  414  the control circuitry  112  measures the output current via the current monitor  168 . The measured current may be an instantaneous current or may be a filtered (e.g, average current) of the current measured since the communication (block  404 ). At block  416 , the control circuitry  112  receives from the wire feeder  104  via the communications circuitry  118  a communication including the measured voltage at the wire feeder  104 . The measured voltage at the feeder, measured by the voltage monitor  152 , may be an instantaneous voltage or may be a filtered voltage (e.g, average voltage) of the voltage measured since the communication (block  404 ). 
     At block  418 , the control circuitry  112  determines the voltage drop across the weld cable  126 , V cableDrop . V cableDrop  is equal to the received feeder voltage (received at block  416 ) subtracted from the actual output voltage (measured at block  412 ). At block  420 , the control circuitry  112  determines the weld cable  126  resistance. The weld cable resistance is equal to the determined V cableDrop  (block  418 ) divided by the measured output current (block  414 ). In some examples, a current monitor  168  is not used, and instead the current limit is used to determine the weld cable  126  resistance. 
     At block  422 , the control circuitry  112  commands the power conversion circuitry  110  to turn off the test signal. At block  424 , the control circuitry  112  transmits, via the communications circuitry  118 , a command to open the switch  170 . The control circuitry  134  then commands the switch  170  to open. In some examples, the control circuitry  134  is configured to automatically open the switch  170  at a predetermined period of time after receiving the communication to close the switch  170  (block  404 .) 
       FIG. 5  is a flowchart illustrating example machine readable instructions  500  which may be executed by the example control circuitry  112  of the welding-type power supply  102  of  FIG. 1  to determine an inductance of the weld cable  126 . 
     At block  502 , the control circuitry  112  of the power supply  102  controls the power conversion circuitry  110  to turn off output. At block  504 , the control circuitry transmits a command, via the communications circuitry  118 , to the wire feeder  104  to close the feeder switch  170 . The command may be a communication indicating that the power supply  102  will perform a weld cable inductance measurement test. The control circuitry  134  of the wire feeder  104  controls the switch  170  to close. 
     At block  506 , the control circuitry  112  controls the power conversion circuitry  110  to output a voltage-controlled current-limited signal in order to determine the inductance of the weld cable  126 . The power level of the signal is less than the power level of welding-type power. 
     At block  508 , the voltage monitor  160  measured the actual output voltage, and the control circuitry  112  saves and timestamps the actual voltage measurement. At block  510 , the current monitor  168  measures the output current, and the control circuitry  112  saves and timestamps the actual current measurement. At block  512 , the control circuitry  112  determines whether the last measured current satisfies a threshold. If the last measured current does not satisfy the threshold (block  512 ), then the method returns to block  508  and takes additional measurements. If the measured current satisfies the threshold (block  512 ), then the method proceeds to block  514 . At block  514 , the control circuitry  112  receives from the wire feeder  104 , via communications circuitry  118 , timestamped voltage measurements measured by the voltage monitor  152  (e.g., an array of feeder voltage measurements). 
     At block  516 , the control circuitry  112  determines the weld cable  126  inductance based on the array of received feeder voltage measurements, the array of stored measured actual output voltage measurements, and the array of current measurements. As explained above with respect to equation 2, 
     
       
         
           
             
               
                 V 
                 
                   cable 
                    
                   
                       
                   
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               . 
             
           
         
       
     
     Accordingly, the control circuitry  112  can determine the inductance of the weld cable  126  L cable  based on the timestamped received feeder voltage, actual output voltage, and output current arrays. 
     At block  518 , the control circuitry  112  commands the power conversion circuitry  110  to turn off the test signal. At block  520 , the control circuitry transmits, via the communications circuitry  118 , a command to open the switch  170 . The control circuitry  134  then commands the switch  170  to open. In some examples, the control circuitry  134  is configured to automatically open the switch at a predetermined period of time after receiving the communication to close the switch  170  (block  304 .) In some examples the control circuitry  134  is configured to control the switch  170  to open the measurement circuit in response to the current monitor  168  determining that the current of the first signal has reached a threshold magnitude. 
     The determined inductance may be displayed via the user interface  114 . In some examples, if the determined inductance exceeds a threshold, the user interface  114  may display an error. In some examples, if the determined inductance exceeds a threshold, the control circuitry  112  may prevent the power conversion circuitry  110  from outputting welding-type power. For example, the control circuitry  112  may prevent the power conversion circuitry  110  from outputting welding-type power until another inductance measurement test is run in which the determined inductance is less than the threshold. In some examples, the threshold may be stored in memory  124 . In some examples, the threshold inductance may correspond to a selected welding application. The control circuitry  112  may control the power conversion circuitry  110  to output welding-type power for welding applications based on the determined inductance. 
     In some examples the instructions  500  may be executed on command (e.g., an operator may command the system  100  to perform a resistance measurement test via the user interface  114 ). In some examples, the instructions  500  may be automatically executed when the power supply  102  is turned on and connected to a wire feeder  104  via cables  126  and  148 . In some examples, the instructions  300  may be automatically executed when a welding application is selected (e.g., prior to the power supply outputting welding-type power for the selected welding application). In some examples, the instructions  500  are automatically executed after the control circuitry  112  determines the resistance (e.g., via executing instructions  300  or  400 ). Accordingly, in some examples, the impedance of the weld cable  126  (e.g., the resistance and the inductance) may be automatically determined by the control circuitry  112 . The control circuitry  112  may control the output of the power conversion circuitry  110  based on the determined impedance and a voltage setpoint. 
       FIG. 6  is a flowchart illustrating example machine readable instructions  600  which may be executed by the example control circuitry  134  of the wire feeder  104  of  FIG. 1  during an impedance measurement test. 
     At block  602 , the control circuitry  134  receives, via the communications circuitry  119 , a command to close the switch  170 . The command may be a communication indicating that the power supply  102  will perform a weld cable resistance or inductance measurement test. At block  604 , the control circuitry  134  controls the switch  170  to close. At block  606 , the control circuitry measures the wire feeder voltage via the voltage sensor  152 , timestamps the voltage measurement, and saves the measurement in memory  124 . 
     At block  608 , the control circuitry  134  determines whether the time since receiving the command (block  602 ) satisfies a threshold. If the time satisfies the threshold (block  608 ), the control circuitry  134  proceeds to block  612 . If the time does not satisfy the threshold (block  608 ), then the control circuitry  134  proceeds to block  610 . At block  610 , the control circuitry  134  checks if the control circuitry  134  has received an end command from the power supply  102  via the communications circuitry  119 . If the control circuitry  134  has not received an end command (block  610 ), then the control circuitry  134  returns to block  606  and takes and saves another timestamped voltage measurement. If the control circuitry receives an end command (block  610 ), then the control circuitry proceeds to block  612 . 
     At block  612 , the control circuitry  134  transmits the saved voltage measurement(s) to the power supply  102  via the communications circuitry  119 . In some examples, the control circuitry  134  transmits the most recent voltage measurement. In some examples, the control circuitry  134  transmits all saved and timestamped voltage measurements taken during the impedance measurement test. In some examples, the control circuitry transmits a filtered (e.g., an average) voltage measurement. At block  614 , the control circuitry  134  controls the switch  170  to open. 
     In some examples, rather than opening the switch  170  between test signals (e.g., between a resistance measurement test and an inductance measurement test, the control circuitry  112  may control the power conversion circuitry  110  to adjust the current limit of the test signal. For example, rather than opening the switch, the control circuitry  112  may change the current limit to zero amps after a resistance measurement test (e.g., at block  320  of the instructions  300  or block  424  of the instructions  400 , the control circuitry  112  may change the current limit of the test signal output by the power conversion circuitry  110  to zero amps instead of transmitting a command to open the switch  170 ) Likewise, if the switch  170  is already closed after a resistance measurement test, the control circuitry  112  does not send a command to close the feeder switch  170  in a subsequent inductance measurement test (e.g., the control circuitry  112  may skip block  504  of the instructions  500 , and then at block  506 , the control circuitry may then increase the current limit to a test signal level). 
     In some examples, to conduct an inductance measurement test after a resistance measurement test, the control circuitry changes the current limit of the test signal without opening the switch  170  or changing the current limit to zero amps. As 
     
       
         
           
             
               
                 
                   V 
                   
                     cable 
                      
                     
                         
                     
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                 × 
                 
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                 cable 
               
             
             , 
           
         
       
     
     inductance of the cable  126 , L cable , may be determined based on a change in the measurement circuit current. Therefore, the inductance of the cable  126  may be determined by adjusting the current limit of the test signal, which causes a change in the current in the measurement circuit. As described with respect to  FIG. 5 , the timestamped voltage and current measurements taken at the welding power supply  102  and the wire feeder  104  during the time when the measurement circuit current is changing after the current limit is adjusted may then be used to determine the inductance of the cable  126 , based on the equation 
     
       
         
           
             
               
                 V 
                 
                   cable 
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     While the examples of  FIGS. 3-6  disclose measuring the circuit current at the power supply  102 , the current may additionally or alternatively be measured at the wire feeder  104 . The current measurements and/or filtered current measurements may be communicated to the power supply  102 . 
     In some examples, the control circuitry  134  of the wire feeder  104  may determine the resistance, inductance, and/or impedance of the weld cable. For example, the control circuitry  134  of the wire feeder  102  may transmit a command via the communications circuitry  119  to the power supply  102  commanding the power supply  102  to conduct a weld cable resistance and/or inductance measurement test. The control circuitry  134  may then command the switch  170  to close, and then measure the feeder voltage via the voltage monitor  152  when the power supply  102  provides a voltage-controlled current-limited test signal. The control circuitry  134  may then receive from the power supply  102  via the communications circuitry  119  a measured actual output voltage measured by the voltage monitor  160  and a measured current measured by the current monitor  168 . In some examples, the wire feeder  104  may include a current monitor. The control circuitry  134  may then determine the resistance and/or inductance of the weld cable  126  based on the feeder voltage, the actual output voltage, and the measured current, as described above. The control circuitry  134  may then transmit the determined resistance and/or inductance to the control circuitry  112  of the power supply  102  via the communications circuitry  119  and  118 . 
     The present methods and systems may be realized in hardware, software, and/or a combination of hardware and software. The present methods and/or systems may be realized in a centralized fashion in at least one computing system, or in a distributed fashion where different elements are spread across several interconnected computing systems. Any kind of computing system or other apparatus adapted for carrying out the methods described herein is suited. A typical combination of hardware and software may include a general-purpose computing system with a program or other code that, when being loaded and executed, controls the computing system such that it carries out the methods described herein. Another typical implementation may comprise an application specific integrated circuit or chip. Some implementations may comprise a non-transitory machine-readable (e.g., computer readable) medium (e.g., FLASH drive, optical disk, magnetic storage disk, or the like) having stored thereon one or more lines of code executable by a machine, thereby causing the machine to perform processes as described herein. As used herein, the term “non-transitory machine-readable medium” is defined to include all types of machine readable storage media and to exclude propagating signals. 
     As utilized herein the terms “circuits” and “circuitry” refer to physical electronic components (i.e. hardware) and any software and/or firmware (“code”) which may configure the hardware, be executed by the hardware, and or otherwise be associated with the hardware. As used herein, for example, a particular processor and memory may comprise a first “circuit” when executing a first one or more lines of code and may comprise a second “circuit” when executing a second one or more lines of code. As utilized herein, “and/or” means any one or more of the items in the list joined by “and/or”. As an example, “x and/or y” means any element of the three-element set {(x), (y), (x, y)}. In other words, “x and/or y” means “one or both of x and y”. As another example, “x, y, and/or z” means any element of the seven-element set {(x), (y), (z), (x, y), (x, z), (y, z), (x, y, z)}. In other words, “x, y and/or z” means “one or more of x, y and z”. As utilized herein, the term “exemplary” means serving as a non-limiting example, instance, or illustration. As utilized herein, the terms “e.g.,” and “for example” set off lists of one or more non-limiting examples, instances, or illustrations. As utilized herein, circuitry is “operable” to perform a function whenever the circuitry comprises the necessary hardware and code (if any is necessary) to perform the function, regardless of whether performance of the function is disabled or not enabled (e.g., by a user-configurable setting, factory trim, etc.). 
     While the present method and/or system has been described with reference to certain implementations, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the present method and/or system. For example, block and/or components of disclosed examples may be combined, divided, re-arranged, and/or otherwise modified. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the present disclosure without departing from its scope. Therefore, the present method and/or system are not limited to the particular implementations disclosed. Instead, the present method and/or system will include all implementations falling within the scope of the appended claims, both literally and under the doctrine of equivalents.