Patent Publication Number: US-2023146050-A1

Title: Apparatus for transporting groups of consumables between vertically spaced holding shelves

Description:
CROSS REFERENCE OF RELATED APPLICATION 
     This application is a continuation of U.S. application Ser. No. 16/811,772, filed Mar. 6, 2020, now pending, which claims the benefit of U.S. Provisional Application No. 62/815,184, filed Mar. 7, 2019, the contents of each of which applications are hereby incorporated by reference herein. 
    
    
     FIELD OF THE DISCLOSURE 
     This disclosure relates to systems and methods for transporting and holding a supply of consumables to be provided to a processing instrument within which the consumables will be moved or otherwise manipulated. 
     BACKGROUND 
     Instruments for performing multiple parallel and/or sequential discrete processes often require various consumables used in the performance of each discrete process. Such consumables may be used one time for each individual process—or for different steps of the process—and then discarded. Accordingly, a sufficient supply of such consumables must be provided to the instrument to enable the processes to be performed. For example, an analyzer for performing biological, chemical, biochemical, or other multi-step analytical processes on sample materials may perform numerous discrete procedures over a period of time. For example, the Panther® and Panther Fusion® systems available from Hologic, Inc. (Marlborough, Mass.) can process up to 320 samples in 8 hours and up to 750 samples in 15.2 hours. Multiple, different samples may be processed in parallel and/or sequentially, and multiple processes—e.g., tests—may be performed on each sample processed. A separate reaction vessel—such as a test tube—is typically required for each process performed on each sample that is tested by the analyzer, and, in some instances, a separate reaction vessel—such as a test tube—may be required for different steps of the process. 
     It is often desirable to maximize the throughput of the processing instrument by performing as many processes as are possible over a given period of time, and, to that end, it is likewise desirable that the instrument be operated continuously, or nearly continuously, with minimal interruptions. Accordingly, to avoid interruptions in instrument operation due to the need to periodically reload consumables, such as reaction vessels on an automated molecular analyzer, it is desirable to have an ample supply of consumables on the instrument. Moreover, the consumables must be provided in such a manner that they are accessible to the instrument for use in processing samples, i.e., the consumables are not merely stored on the instrument in large quantities, requiring operator intervention to feed the consumables to the instrument in smaller batches. Throughput can be further improved if additional consumables may be loaded onto the instrument while the instrument is operating and without interrupting processing by the instrument. 
     SUMMARY 
     A system and method as disclosed herein enable a user to load a sufficient number of consumables—such as reaction vessels—onto an instrument to support prolonged operation of the instrument, e.g., 4, 6, 8, 10, 12 hours or more, without requiring further interaction from the operator. Thus, the system and method as disclosed herein represent an improvement over existing systems that require an operator to periodically return to the instrument to load additional consumables. Moreover, the system and method disclosed herein enable all consumables of an extended supply of consumables to be accessed by the instrument for processing, and further, where even more prolonged operation of the instrument is desired, the system and method as disclosed herein enable the user to load additional consumables onto the instrument without interrupting instrument operation. 
     The following presents a simplified summary in order to provide a basic understanding of some aspects described herein. This summary is not an extensive overview of the claimed subject matter. It is intended to neither identify key or critical elements of the claimed subject matter nor delineate the scope thereof. Its sole purpose is to present some concepts in a simplified form as a prelude to the more detailed description that is presented later. 
     Aspects of the disclosure are embodied in an apparatus for transporting groups of consumables between a plurality of vertically spaced holding shelves. The apparatus comprises a support chassis disposed at a laterally-spaced position with respect to the plurality of holding shelves, a transport elevator coupled to the support chassis for moving the support chassis in a vertical direction between the plurality of holding shelves, a lift platform, and a scissors actuator connecting the lift platform to the support chassis and configured to translate the lift platform laterally with respect to the support chassis between a first position laterally aligned with the support chassis at the laterally-spaced position with respect to the plurality of holding shelves and a second position laterally displaced from the support chassis and laterally aligned with one of the holding shelves. 
     According to other aspects, the apparatus further comprises a carrier configured to be carried on the lift platform and to be placed on any of the plurality of holding shelves. 
     According to other aspects, the carrier comprises a base, a pair of support rails for slidably supporting the consumables thereon, and a resilient tab located at an end of each support rail and configured to releasably retain the consumables on the support rails. 
     According to other aspects, each resilient tab is disposed at the end of a serpentine spring that is attached to or contiguous with a portion of the respective support rail. 
     According to other aspects, the transport elevator comprises two drive belts, each drive belt being attached to a portion of the support chassis, a drive pulley for each drive belt, a motor coupled to the drive pulleys, and an idler pulley for each drive belt. 
     According to other aspects, the apparatus further comprises an elevator home sensor configured to detect a locator flag extending from the support chassis. 
     According to other aspects, the scissors actuator comprises a first arm having first and second ends and a second arm having first and second ends. The first and second arms are rotatably connected to each other at intermediate positions between their respective first and second ends, the first arm is pivotably attached at its first end to the support chassis and is pivotably and translatably attached at its second end to the lift platform, and the second arm is pivotably and translatably attached at its first end to the support chassis and is pivotably attached at its second end to the lift platform. 
     According to other aspects, the first and second arms are rotatably connected to each other by a slewing ring having an inner ring and an outer ring, where the inner and outer rings are rotatable with respect to each other, and where the first arm is attached to the inner ring at its respective intermediate position, and the second arm is attached to the outer ring at its respective intermediate position. 
     According to other aspects, the second end of the first arm is pivotably and translatably attached to the lift platform by a slide that is slidably disposed within a linear slot formed in the lift platform, where the slide is rotatably attached to the second end of the first arm. 
     According to other aspects, the apparatus further comprises a roller bearing disposed within the slide that rolls against a side of the slot during lateral translation of the lift platform. 
     According to other aspects, the scissors actuator further comprises a motor coupled to the first end of the first arm to effect powered pivoting movement of the first arm. 
     According to other aspects, the scissors actuator is configured to translate the lift platform in either of two opposed lateral directions with respect to the support chassis. 
     According to other aspects, the apparatus further comprises a carrier detection sensor associated with each holding shelf and configured to detect the presence of a carrier on the associated holding shelf. 
     Aspects of the disclosure are embodied in an apparatus comprising a plurality of vertically spaced holding shelves, a transporter for transporting groups of consumables between the plurality of holding shelves, and a transport elevator coupled to the support chassis for moving the support chassis in a vertical direction between the plurality of holding shelves. The transporter comprises a support chassis disposed at a laterally-spaced position with respect to the plurality of holding shelves, a lift platform, and a scissors actuator connecting the lift platform to the support chassis and configured to translate the lift platform laterally with respect to the support chassis between a first position laterally aligned with the support chassis at the laterally-spaced position with respect to the plurality of holding shelves and a second position laterally displaced from the support chassis and laterally aligned with one of the holding shelves. 
     According to other aspects, the apparatus further comprises a carrier configured to hold the consumables, to be carried on the lift platform, and to be placed in any of the plurality of holding shelves. 
     According to other aspects, each holding shelf includes a carrier detection sensor configured to detect the presence of a carrier on the corresponding holding shelf. 
     According to other aspects, the carrier comprises a base, a pair of support rails for slidably supporting the consumables thereon, and a resilient tab located at an end of each support rail and configured to releasably retain the consumables on the support rails. 
     According to other aspects, each resilient tab is disposed at the end of a serpentine spring that is attached to or a part of the respective support rail. 
     According to other aspects, the carrier includes at least one opening formed in the bottom thereof, and each holding shelf includes at least one carrier locator pin protruding from the holding shelf for engaging the opening formed in the carrier. 
     According to other aspects, the transport elevator comprises two drive belts, each drive belt being attached to a portion of the support chassis, a drive pulley for each drive belt, a motor coupled to the drive pulley, and an idler pulley for each drive belt. 
     According to other aspects, one of the holding shelves comprises a carrier support configured to be moveable in a lateral direction between a first position accessible by the transporter and a second position accessible by a user to load a plurality of consumables into the carrier support. 
     According to other aspects, the apparatus further comprises a carrier configured to be carried on the lift platform and to be placed in any of the plurality of holding shelves, where one of the holding shelves comprises a carrier support configured to be moveable in a lateral direction between a first position accessible by the transporter and a second position accessible by a user to load a plurality of consumables into the carrier support. The carrier support comprises a carrier locking mechanism configured to lock the carrier within the carrier support when the carrier support is moved to the second position and to release the carrier when the carrier support is moved to the first position to permit the transporter to remove the carrier from the carrier support. 
     According to other aspects, the carrier locking mechanism comprises a pivoting latch configured to pivot between a first position not engaged with a portion of the carrier and a second position engaged with a portion of the carrier, and a slide latch configured to translate linearly between a first position not engaged with a portion of the carrier and a second position engaged with a portion of the carrier. 
     According to other aspects, the apparatus further comprises a torsional spring coupled to the pivoting latch to bias the pivoting latch to its respective second position engaged with a portion of the carrier, and a linear spring coupled to the slide latch to bias the slide latch to its respective second position engaged with a portion of the carrier. 
     According to other aspects, the pivoting latch includes an upper end that engages a portion of a carrier on the carrier support when the carrier support is in the second position and the pivoting latch is in the second position and a lower end that contacts a hard stop when the carrier support is moved from the second position thereof to the first position thereof, thus causing the pivoting latch to rotate from the second position to the first position, thereby releasing the carrier supported on the carrier support. The slide latch engages a portion of a carrier on the carrier support when the carrier support is in the second position and the slide latch is in the second position, and the slide latch contacts a hard stop that pushes slide latch into the first position when the carrier support is moved from the second position thereof to the first position thereof, thereby releasing the carrier supported on the carrier support. 
     According to other aspects, the carrier is longer than the lift platform so that first and second ends of the carrier extend beyond first and second ends of the lift platform, and each holding shelf comprises first and second shelf portions spaced apart by at least the length of the lift platform. The transporter is configured and controlled to transport a carrier supported on the lift platform from the lift platform to one of the plurality of holding shelves by moving the support chassis with the transport elevator to a vertical position at which the lift platform is above the holding shelf, moving the lift platform laterally with the scissors actuator into a position at which the first and second ends of the carrier are aligned with the first and second shelf portions of the holding shelf, and lowering the support chassis with the transport elevator to move the lift platform between the first and second shelf portions until the first and second ends of the carrier are supported on the first and second shelf portions. 
     According to other aspects, each of the consumables comprises a multi-receptacle unit including a plurality of receptacles connected to each other in a side-by-side arrangement, and the apparatus further comprises a carrier configured to be carried on the lift platform and to be placed in any of the plurality of holding shelves. The carrier comprises a base, a pair of parallel support rails for slidably supporting the multi-receptacle units thereon with at least one of the receptacles of each multi-receptacle unit disposed between the support rails, and a resilient tab located at an end of each support rail and configured to releasably retain the multi-receptacle units on the support rails. One of the holding shelves comprises an input module configured to hold the carrier therein, the input module comprising a pusher configured to push one or more multi-receptacle units supported on the carrier toward an end of the carrier. 
     According to other aspects, the input module is disposed on one side of the support chassis, and one or more of the remaining holding shelves are disposed on an opposed side of the support chassis, where the scissors actuator is configured to translate the lift platform in either of two opposed lateral directions with respect to the support chassis. 
     According to other aspects, each of the consumables comprises a multi-receptacle unit including a plurality of receptacles connected to each other in a side-by-side arrangement, and the apparatus further comprises a carrier configured to be carried on the lift platform and to be placed in any of the plurality of holding shelves. The carrier comprises a base, a pair of parallel support rails for slidably supporting the multi-receptacle units thereon with at least one of the receptacles of each multi-receptacle unit disposed between the support rails, and a stop flange located at an end of each support rail. 
     According to other aspects, at least one of the holding shelves comprises a packing mechanism configured to move with respect to the carrier held in the holding shelf and to push the multi-receptacle units carried on the carrier until an end-most one of the multi-receptacle units is pushed off the support rails. 
     According to other aspects, the apparatus further comprises a packing mechanism position sensor configured to detect a stop position of the packing mechanism at which the end-most one of the multi-receptacle units is pushed off the support rails and to determine the number of multi-receptacle units carried on the carrier based on the detected stop position. 
     According to other aspects, the apparatus further comprises position sensor mechanisms for detecting a vertical position of the support chassis and a lateral position of the lift platform, and a controller for controlling the transport elevator and the scissors actuator and in communication with the positon sensor mechanisms. The controller is configured to record a position of each holding shelf by moving the lift platform with respect to each holding shelf until the lift platform contacts a positioning tab of the holding shelf and recording the vertical position of the support chassis and the lateral position of the lift platform detected by the position sensor mechanisms at which the lift platform contacts the positioning tab. 
     Aspects of the disclosure are embodied in a carrier support for holding a carrier, where the carrier is configured to hold a plurality of receptacles, and where the carrier support is configured to be moveable between a first position and a second position. The carrier support comprises a carrier locking mechanism configured to lock the carrier with respect to the carrier support when the carrier support is moved to the second position and to release the carrier when the carrier support is moved to the first position to permit the carrier to be moved with respect to the carrier support when the carrier support is in the first position. The carrier locking mechanism comprises a pivoting latch configured to pivot between a first position not engaged with a portion of the carrier and a second position engaged with a portion of the carrier, and a slide latch configured to translate linearly between a first position not engaged with a portion of the carrier and a second position engaged with a portion of the carrier. 
     According to other aspects, the carrier further comprises a torsional spring coupled to the pivoting latch to bias the pivoting latch to its respective second position engaged with a portion of the carrier, and a linear spring coupled to the slide latch to bias the slide latch to its respective second position engaged with a portion of the carrier. 
     According to other aspects, the pivoting latch includes an upper end that engages a portion of a carrier on the carrier support when the carrier support is in the second position and the pivoting latch is in the second position and a lower end that contacts a hard stop when the carrier support is moved from the second position thereof to the first position thereof, thus causing the pivoting latch to rotate from the second position to the first position, thereby releasing the carrier supported on the carrier support. The slide latch engages a portion of a carrier on the carrier support when the carrier support is in the second position and the slide latch is in the second position, and the slide latch contacts a hard stop that pushes the slide latch into the first position when the carrier support is moved from the second position thereof to the first position thereof, thereby releasing the carrier supported on the carrier support. 
     Aspects of the disclosure are embodied in an input module comprising a carrier shelf for receiving and supporting a carrier holding a plurality of receptacles, a retrieval dock adjacent the carrier shelf and configured to receive one receptacle from a carrier supported on the carrier shelf and present the receptacle for removal from the input module by a receptacle transport apparatus, and a pusher configured to push one or more receptacles held on the carrier supported on the carrier shelf to one end of the carrier and to push one receptacle at a time off the end of the carrier and onto the retrieval dock. 
     According to other aspects, the pusher comprises a pusher carriage coupled to a pusher track and configured to translate bi-directionally along the track, and a pusher arm projecting from the pusher carriage. 
     According to other aspects, the pusher arm comprises an upright portion extending upwardly from the pusher carriage, a lateral portion extending laterally from an end of the upright portion, and a contact portion extending downwardly from the lateral portion. 
     According to other aspects, a carrier supported on the carrier shelf includes a pair of parallel support rails for slidably supporting a plurality of receptacles thereon with at least a portion of each receptacle disposed between the support rails, and the contact portion is aligned with a gap between the support rails so that as the pusher translates along the pusher track, the contact portion moves between the support rails and contacts the portion of the receptacle that is disposed between the support rails. 
     According to other aspects, the receptacle comprises a plurality of cylindrical tubes connected to one another by a connecting rib structure defining a downwardly facing shoulder, where at least one of the cylindrical tubes is disposed between the support rails and a portion of the downwardly-facing shoulder is supported on top of the support rails. 
     According to other aspects, the pusher further comprises a pusher drive belt attached to the pusher carriage, and a pusher motor coupled to the pusher drive belt for effecting powered translation of pusher carriage along the pusher track. 
     According to other aspects, the input module further comprises a sensor configured to detect when one of the receptacles has been pushed onto the retrieval dock. 
     According to other aspects, the input module further comprises a guide plate adjacent the retrieval dock and configured to align the receptacle on the retrieval dock with a receptacle transport apparatus. 
     According to other aspects, the input module further comprises at least one carrier locator pin protruding from the carrier shelf for engaging an opening formed in a carrier supported by the carrier shelf and to restrict relative movement between the carrier shelf and the carrier supported thereby. 
     According to other aspects, the input module further comprises a position encoder for detecting a longitudinal position of the pusher, and a controller configured to receive longitudinal position data from the position encoder and to determine the number of receptacles supported by a carrier supported on the carrier shelf when the pusher is positioned in contact with an end-most receptacle of one or more receptacles held on the carrier. 
     According to other aspects, the input module further comprises a pusher home sensor configured to detect when the pusher has moved to a home position. 
     According to other aspects, a processing instrument comprises the input module as previously described and a receptacle transport apparatus configured to remove a receptacle from the retrieval dock of the input module and transport the receptacle within the processing instrument. 
     Aspects of the disclosure are embodied in a carrier for holding a plurality of multi-receptacle units, each multi-receptacle unit including a plurality of receptacles connected to each other in a side-by-side arrangement. The carrier comprises a pair of parallel support rails for slidably supporting the multi-receptacle units thereon with at least one of the receptacles of each multi-receptacle unit disposed between the support rails, and a resilient tab associated with each support rail and configured to releasably retain the multi-receptacle units on the support rails. 
     According to other aspects, each resilient tab is disposed at the end of a serpentine spring. 
     According to other aspects, each serpentine spring is an integral portion of each associated support rail. 
     According to other aspects, the support rails are made from spring steel. 
     According to other aspects, the carrier further comprises a carrier base comprising a first end, a second end, and a connecting portion extending between the first end and the second end, where the connecting portion is generally narrower than the first and second ends. 
     According to other aspects, the support rails are attached to opposed edges of the connecting portion. 
     According to other aspects, the carrier further comprises a carrier base with one or more locator holes formed in the bottom of the carrier base. 
     According to other aspects, the carrier further comprises one locator hole at a first end of the carrier base and a locator slot at a second end of the carrier base. 
     According to other aspects, the carrier further comprises two locator holes at a first end of the carrier base and two locator slots at a second end of the carrier base. 
     Aspects of the disclosure are embodied in a scissors actuator configured to translate a support platform in either of opposed lateral directions with respect to a base frame. The scissors actuator comprises a first arm having first and second ends, a second arm having first and second ends, where the first and second arms are rotatably connected to each other at intermediate positions between their respective first and second ends, where the first arm is pivotably attached at its first end to the base frame and the second arm and is pivotably attached at its second end to the support platform, a first slide disposed within a first linear track formed in the support platform and including a bearing protruding from a side of the first slide for rolling contact with a side of the first linear track formed in the support platform, where the first arm is pivotably and translatably attached at its second end to the support platform by the first slide, and a second slide disposed within a second linear track formed in the base frame and including a bearing protruding from a side of the second slide for rolling contact with a side of the second linear track formed in the base frame, where the second arm is pivotably and translatably attached at its first end to the base frame by the second slide. 
     According to other aspects, the first and second arms are rotatably connected to each other by a slewing ring having an inner ring and an outer ring, where the inner and outer rings are rotatable with respect to each other, and where the first arm is attached to the inner ring at its respective intermediate position, and the second arm is attached to the outer ring at its respective intermediate position. 
     According to other aspects, the scissors actuator further comprises a motor coupled to the first end of the first arm to effect powered pivoting movement of the first arm. 
     According to other aspects, the scissors actuator further comprises an encoder coupled to the motor or to the first arm. 
     According to other aspects, the scissors actuator is configured to translate the support platform in either of two opposed lateral directions with respect to the base frame. 
     Aspects of the disclosure are embodied in a method for automatically transferring a receptacle carrier between a holding shelf and a lift platform of a transporter. The method comprises the steps of a) with a transport elevator for effecting vertical movement of the transporter, positioning the transporter at an approximate vertical location of the holding shelf, b) after step a), effecting relative movement between the lift platform and a positioning structure associated with the holding self, c) during step b), detecting contact between the lift platform and the positioning structure, d) recording data relating to the position of the lift platform at which contact is detected in step c), and e) transferring a receptacle carrier between the holding shelf and the lift platform by controlling movement of the lift platform in accordance with the data recorded at step d). 
     According to other aspects, step b) comprises one or both of (1) effecting vertical movement of the lift platform with respect to the holding shelf with the transport elevator and (2) effecting lateral movement of the lift platform with a lateral actuator. 
     According to other aspects, step a) comprises positioning the transporter such that the vertical position of the lift platform is below an expected vertical location of the positioning structure, and step b) comprises b-1) moving the lift platform laterally with the lateral actuator until the lift platform is positioned below an expected location of the positioning structure, and b-2) after step b-1), raising the transporter and lift platform with the transport elevator until contact is detected in step c). 
     According to other aspects, step a) comprises positioning the transporter such that the vertical position of the lift platform is above an expected vertical location of the positioning structure, and step b) comprises b-1) moving the lift platform laterally with the lateral actuator until the lift platform is positioned above an expected location of the positioning structure, and b-2) after step b-1), lowering the transporter and lift platform with the transport elevator until contact is detected in step c). 
     According to other aspects, step a) comprises positioning the transporter such that the vertical position of the lift platform is the same as an expected vertical location of the positioning structure, and step b) comprises moving the lift platform laterally with the lateral actuator until contact is detected in step c). 
     According to other aspects, step e) comprises transferring a receptacle carrier from the lift platform to the holding shelf by supporting the receptacle carrier on the lift platform with opposed ends of the receptacle carrier extending beyond opposed ends of the lift platform, with the transport elevator, and using the data recorded at step d), positioning the transporter at a vertical position so that the lift platform is above the holding shelf, effecting lateral movement of the lift platform with a lateral actuator and using the data recorded at step d) so that the lift platform is disposed within an open area between a first shelf portion and a second shelf portion of the holding shelf and the opposed ends of the receptacle carrier are positioned above the first and second shelf portions, and with the transport elevator, lowering the lift platform until the opposed ends of the receptacle carrier are supported on the first and second shelf portions, and the receptacle carrier is not supported on the lift platform. 
     According to other aspects, step e) comprises transferring a receptacle carrier from the holding shelf to the lift platform by supporting opposed ends of the receptacle carrier on a first shelf portion and a second shelf portion of the holding shelf, with the transport elevator, and using the data recorded at step d), positioning the transporter at a vertical position so that the lift platform is below the holding shelf, effecting lateral movement of the lift platform with a lateral actuator and using the data recorded at step d) so that the lift platform is aligned with an open area between the first and second shelf portions, and with the transport elevator, raising the lift platform until the receptacle carrier is supported on the lift platform with the opposed ends of the receptacle carrier extending beyond opposed ends of the lift platform and the opposed ends of the receptacle carrier are lifted off the first and second shelf portions. 
     Aspects of the disclosure are embodied in a method for determining the number of receptacles supported by a carrier. The method comprises a) placing the carrier with one or more receptacles supported thereby on a carrier shelf, b) pushing the one or more receptacles to one end of the carrier with a packer positioned adjacent the carrier shelf, c) detecting a longitudinal position of the packer when the one or more receptacles have been pushed to the one end of the carrier, and d) determining the number of receptacles held on the carrier based on the longitudinal position of the packer. 
     According to other aspects, step a) comprises transferring the carrier from a lift platform to the carrier shelf by supporting the carrier on the lift platform with opposed ends of the carrier extending beyond opposed ends of the lift platform, with a transport elevator, positioning the lift platform above the carrier shelf, effecting lateral movement of the lift platform with a lateral actuator so that the lift platform is disposed within an open area between a first shelf portion and a second shelf portion of the carrier shelf and the opposed ends of the carrier are positioned above the first and second shelf portions, and with the transport elevator, lowering the lift platform until the opposed ends of the carrier are supported on the first and second shelf portions, and the carrier is not supported on the lift platform. 
     According to other aspects, the packer comprises a packer carriage coupled to a packer track and configured to translate bi-directionally along the track, a contact portion projecting from the packer carriage, a packer drive belt attached to the packer carriage, and a packer motor coupled to the packer drive belt for effecting powered translation of the packer carriage along the packer track. 
     According to other aspects, step c) comprises detecting output of the packer motor by a rotary encoder coupled to the packer motor or detecting output of the packer motor by motor steps. 
     Aspects of the disclosure are embodied in a method for packing a plurality of receptacles supported by a carrier. The method comprises a) placing the carrier with a plurality of receptacles supported thereby on a carrier shelf, b) contacting an end-most one of the receptacles with a packer positioned adjacent the carrier shelf, where the packer comprises a packer carriage coupled to a packer track and configured to translate bi-directionally along the track, and a contact portion projecting from the packer carriage, and c) pushing the plurality of receptacles to one end of the carrier with the packer to pack the receptacles in a stack. 
     According to other aspects, a carrier supported on the carrier shelf includes a pair of parallel support rails for slidably supporting a plurality of receptacles thereon with at least a portion of each receptacle disposed between the support rails, and where step c) comprises contacting an end-most one of the receptacles with the packer by aligning the contact portion with a gap between the support rails, so that as the packer carriage translates along the packer track, the contact portion moves between the support rails and contacts the portion of the end-most receptacle that is disposed between the support rails. 
     According to other aspects, the carrier includes a hard stop at an end of each support rail, where step c) comprises pushing the plurality of receptacles against the hard stops. 
     According to other aspects, the receptacle comprises a plurality of cylindrical tubes connected to one another by a connecting rib structure defining a downwardly facing shoulder, where at least one of the cylindrical tubes is disposed between the support rails and a portion of the downwardly-facing shoulder is supported on top of the support rails. 
     According to other aspects, the packer further comprises a horizontal portion that contacts a portion of the end-most receptacle extending above the support rails to keep the receptacles generally perpendicular to a longitudinal direction of the support rails. 
     According to other aspects, the packer further comprises a packer drive belt attached to the packer carriage, and a packer motor coupled to the packer drive belt for effecting powered translation of packer carriage along the packer track. 
     According to other aspects, the method further comprises detecting a longitudinal position of the packer during step c), and determining the number of receptacles held on the carrier based on the longitudinal position of the packer. 
     According to other aspects, the packer further comprises a packer drive belt attached to the packer carriage, and a packer motor coupled to the packer drive belt for effecting powered translation of packer carriage along the packer track, where detecting the longitudinal position of the packer during step c) comprises using a home sensor to detect an initial position of the packer along the packer track and an encoder coupled to the packer motor to detect a number of encoder counts associated with a motorized packer movement from the initial position. 
     Aspects of the disclosure are embodied in a method for presenting multi-receptacle units for retrieval by an automated receptacle distributor of a processing instrument, each multi-receptacle unit including a plurality of receptacles connected to each other in a side-by-side arrangement, The method comprises the steps of a) placing a carrier with one or more multi-receptacle units held thereon on a carrier shelf, where the carrier comprises a pair of parallel support rails for slidably supporting the multi-receptacle units thereon with at least one of the receptacles of each multi-receptacle unit disposed between the support rails, b) contacting an end-most one of the receptacles with a pusher positioned adjacent the carrier shelf, the pusher comprising a contact portion configured to move between the support rails and contact the receptacle disposed between the support rails, and c) pushing the plurality of multi-receptacle units along the support rails toward one end of the carrier with the pusher until an end-most one of the multi-receptacle units is pushed off the support rails and onto a retrieval dock adjacent to the carrier shelf. 
     According to other aspects, the method further comprises detecting when the one of the plurality of multi-receptacle units is pushed off the support rails and onto the retrieval dock, and stopping the pusher from further pushing the one or more multi-receptacle units toward the one end of the carrier. 
     According to other aspects, the method further comprises retrieving the one multi-receptacle unit from the retrieval dock with a receptacle transport mechanism of the processing instrument. 
     According to other aspects, the receptacle transport mechanism comprises an extendible and retractable hook and the multi-receptacle unit comprises a manipulating structure, where retrieving the one receptacle from the retrieval dock with a receptacle transport mechanism comprises extending the hook, engaging the manipulating structure with the extended hook, and retracting the hook to pull the multi-receptacle unit from the retrieval dock into a housing of the receptacle transport mechanism. 
     According to other aspects, the method further comprises during step c), detecting a longitudinal position of the pusher when the multi-receptacle unit is pushed off the support rails, and determining the number of multi-receptacle units held on the carrier based on the longitudinal position of the pusher. 
     According to other aspects, step a) comprises transferring the carrier from a lift platform to the carrier shelf by supporting the carrier on the lift platform with opposed ends of the carrier extending beyond opposed ends of the lift platform, with a transport elevator, positioning the lift platform above the carrier shelf, effecting lateral movement of the lift platform with a lateral actuator so that the lift platform is disposed within an open area between a first shelf portion and a second shelf portion of the carrier shelf and the opposed ends of the carrier are positioned above the first and second shelf portions, and with the transport elevator, lowering the lift platform until the opposed ends of the carrier are supported on the first and second shelf portions, and the carrier is not supported on the lift platform. 
     According to other aspects, the pusher further comprises a pusher carriage coupled to a pusher track and configured to translate bi-directionally along the track, a pusher arm comprising the contact portion and projecting from the pusher carriage, a pusher drive belt attached to the pusher carriage, and a pusher motor coupled to the pusher drive belt for effecting powered translation of pusher carriage along the pusher track. 
     According to other aspects, the method further comprises, prior to step c), retaining the one or more multi-receptacle units on the support rails with spring-biased retainer tabs that releasably engage the end-most one of the multi-receptacle units, where the spring-biased retainer tabs are configured to deflect laterally during step c) to permit the end-most one of the multi-receptacle units to be pushed off the support rails. 
     Other features and characteristics of the subject matter of this disclosure, as well as the methods of operation, functions of related elements of structure and the combination of parts, and economies of manufacture, will become more apparent upon consideration of the following description and the appended claims with reference to the accompanying drawings, all of which form a part of this specification, where like reference numerals designate corresponding parts in the various figures. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated herein and form part of the specification, illustrate various embodiments of the subject matter of this disclosure. In the drawings, like reference numbers indicate identical or functionally similar elements. 
         FIG.  1    is a plan view of a system for transporting and holding consumables comprising a transporter/storage module and an input module as disclosed herein combined with a processing instrument for performing a chemical, biological, or other multi-step analytical process. 
         FIG.  2    is a perspective view of a transporter/storage module in accordance with an embodiment of the disclosure. 
         FIG.  3    is a side elevation view of the transporter/storage module. 
         FIG.  4    is a partial perspective view of the transporter/storage module with an access door in an open position and a loading drawer partially withdrawn from a housing of the module. 
         FIG.  4 A  is a top plan view of a holding shelf with a lift platform positioned within an open area of the holding shelf. 
         FIG.  5    is a partial perspective view of a top end of the transporter/storage module with the access door in a closed position and the loading drawer inserted into the housing. 
         FIG.  6    is a partial side elevation view of the transporter/storage module with the access door in a closed position and the loading drawer inserted into the housing. 
         FIG.  7    is a partial perspective view of the loading drawer inserted into the housing with a carrier disposed in the loading drawer and showing a receptacle packing mechanism. 
         FIG.  7 A  is an end view—in the direction of arrow “ 7 A” in  FIG.  7   —showing a packer of the receptacle packing mechanism in isolation within a linear track. 
         FIG.  8    is a perspective view of the loading drawer removed from the module housing. 
         FIG.  9    is a perspective view of a multi-receptacle unit of a type to be transported and stored in an embodiment of the system. 
         FIG.  10    is a top perspective view of a carrier for consumables to be transported and stored within the system. 
         FIG.  11    is a bottom perspective view of the carrier. 
         FIG.  12    is a partial perspective view of an alternate embodiment of the carrier. 
         FIG.  13    is a top perspective view of the carrier with a plurality of multi-receptacle units supported thereon. 
         FIG.  14    is a bottom perspective view of the carrier with a plurality of multi-receptacle units supported there on. 
         FIG.  15    is a top perspective view of a transporter of the transporter/storage module with a lift platform in a retracted position. 
         FIG.  16    is a top perspective view of the transporter with the lift platform extended to one side of the transporter. 
         FIG.  17    is an exploded perspective view of the transporter with the lift platform extended to the one side of the transporter. 
         FIG.  18    is a top perspective view of the transporter with the lift platform extended to an opposite side of the transporter. 
         FIG.  19    is a bottom perspective view of the transporter with the lift platform extended to the opposite side of the transporter. 
         FIG.  20    is a top perspective view of the transporter with the lift platform extended to one side of the transporter and with a carrier supported on the lift platform. 
         FIG.  21    is a perspective view of a transport elevator of the system. 
         FIG.  22    is a front, right perspective view of an input module of the system for transferring consumables from the transporter/storage module to the processing instrument. 
         FIG.  23    is a back, right perspective view of the input module. 
         FIG.  24    is a front, right perspective view of the input module with a carrier supporting a plurality of multi-receptacle units positioned within the queue. 
         FIG.  25    is a front, left perspective view of the input module with a receptacle distribution head of a receptacle distributor of the processing instrument pulling a multi-receptacle unit from the input module (some components are omitted in this view to allow visibility of relevant mechanisms). 
         FIG.  26    is a partial, perspective view of the transporter illustrating a sensor for detecting the presence of a carrier on the transporter. 
         FIG.  27    is a flowchart illustrating a method (algorithm) for performing a self-teaching process for determining locations within the transporter/storage module and/or the input module. 
         FIG.  28    is a block diagram that schematically illustrates a control architecture of the transporter/storage module. 
     
    
    
     DETAILED DESCRIPTION 
     While aspects of the subject matter of the present disclosure may be embodied in a variety of forms, the following description and accompanying drawings are merely intended to disclose some of these forms as specific examples of the subject matter. Accordingly, the subject matter of this disclosure is not intended to be limited to the forms or embodiments so described and illustrated. 
     Unless defined otherwise, all terms of art, notations and other technical terms or terminology used herein have the same meaning as is commonly understood by one of ordinary skill in the art to which this disclosure belongs. All patents, applications, published applications and other publications referred to herein are incorporated by reference in their entirety. If a definition set forth in this section is contrary to or otherwise inconsistent with a definition set forth in the patents, applications, published applications, and other publications that are herein incorporated by reference, the definition set forth in this section prevails over the definition that is incorporated herein by reference. 
     Unless otherwise indicated or the context suggests otherwise, as used herein, “a” or “an” means “at least one” or “one or more.” 
     This description may use relative spatial and/or orientation terms in describing the position and/or orientation of a component, apparatus, location, feature, or a portion thereof. Unless specifically stated, or otherwise dictated by the context of the description, such terms, including, without limitation, top, bottom, above, below, under, on top of, upper, lower, left of, right of, in front of, behind, next to, adjacent, between, horizontal, vertical, diagonal, longitudinal, transverse, radial, axial, etc., are used for convenience in referring to such component, apparatus, location, feature, or a portion thereof in the drawings and are not intended to be limiting. 
     Furthermore, unless otherwise stated, any specific dimensions mentioned in this description are merely representative of an exemplary implementation of a device embodying aspects of the disclosure and are not intended to be limiting. 
     The use of the term “about” applies to all numeric values specified herein, whether or not explicitly indicated. This term generally refers to a range of numbers that one of ordinary skill in the art would consider as a reasonable amount of deviation to the recited numerical values (i.e., having the equivalent function or result) in the context of the present disclosure. For example, and not intended to be limiting, this term can be construed as including a deviation of ±10 percent of the given numeric value, provided such a deviation does not alter the end function or result of the value. Therefore, under some circumstances as would be appreciated by one of ordinary skill in the art a value of about 1% can be construed to be a range from 0.9% to 1.1%. 
     As used herein, the term “adjacent” refers to being near or adjoining. Adjacent objects can be spaced apart from one another or can be in actual or direct contact with one another. In some instances, adjacent objects can be coupled to one another or can be formed integrally with one another. 
     As used herein, the terms “substantial” and “substantially” refer to a considerable degree or extent. When used in conjunction with, for example, an event, circumstance, characteristic, or property, the terms can refer to instances in which the event, circumstance, characteristic, or property occurs precisely as well as instances in which the event, circumstance, characteristic, or property occurs to a close approximation, such as accounting for typical tolerance levels or variability of the embodiments described herein. 
     As used herein, the terms “optional” and “optionally” mean that the subsequently described component, structure, element, event, circumstance, characteristic, property, etc. may or may not be included or occur and that the description includes instances where the component, structure, element, event, circumstance, characteristic, property, etc. is included or occurs and instances in which it is not included or does not occur. 
     A system and method for transporting and holding consumables in a processing instrument are described herein. The processing instrument may be an analyzer for performing a biological, chemical, biochemical, or other multi-step analytical process, and the consumables may comprise receptacles within which such processes are performed in the analyzer. As shown in  FIG.  1   , aspects of the system and method may include one or both of a transporter/storage module  100  for transporting and holding a supply of consumables to be provided to a processing instrument  400  and an input module  230  configured to receive consumables from the transporter/storage module  100  and to present the consumables for input into the processing instrument  400  by a distributor mechanism within processing instrument  400 . Further details of an exemplary processing instrument  400  are described below. 
     Details of various aspects of the transporter/storage module  100  are shown in  FIGS.  2 - 8   . 
       FIG.  2    is a perspective view of transporter/storage module  100  for transporting and holding a supply of consumables to be provided to a processing instrument, within which the consumables will be moved, processed, or otherwise manipulated.  FIG.  3    is a side elevation view of the transporter/storage module, and  FIG.  6    is a partial side view of the transporter/storage module. Transporter/storage module  100  includes a housing  102  and one or more vertically-spaced holding shelves  104 . An access door  106  may be opened to permit a loading drawer  280  to be withdrawn from housing  102  so that a plurality of consumables may be placed thereon and then provided to transporter/storage module  100  by inserting loading drawer  280  into the housing  102 . The consumables may be supported on carriers configured to be supported on loading drawer  280  or on one of the holding shelves  104 . 
     A transporter  120  is configured to remove the consumables from loading drawer  280  or one of the holding shelves  104 , for example, by removing a carrier on which the consumables are supported from the loading drawer  280  or holding shelf  104 . Transporter  120  is further configured to move a group of consumables, e.g. a carrier supporting the consumables, or an empty carrier to loading drawer  280  or to one of the holding shelves  104 . A vertical transport mechanism is coupled to the transporter  120  and is configured to move the transporter  120  in a vertical direction (up or down) between the loading drawer  280  and holding shelves  104 . In one example, the vertical transport mechanism comprises a transport elevator  210  that moves transporter  120 , and the consumables (and carrier) supported thereon, vertically within the housing  102 . 
     Input module  230  is configured to receive consumables (for example consumables supported on a carrier) transported by transporter  120  from one of the holding shelves  104  into the input module  230 . In an embodiment, the input module  230  may be incorporated into a housing of the processing instrument. From the input module  230 , the consumables are selectively retrieved into the processing instrument  400  and are moved about or otherwise manipulated within the processing instrument. After all the consumables have been removed from the carrier within the input module  230 , the transporter  120  will move the empty carrier from the input module  230  to the loading drawer  280  or one of the holding shelves  104 . Further details of the input module  230  are described below. 
     Relative positions of the transporter/storage module  100 , the transporter  120 , the loading drawer  280  and holding shelves  104 , and the input module  230  with respect to the processing instrument  400  are shown schematically with dashed lines in  FIG.  1   . These relative positions are exemplary and are not intended to be limiting. 
     As shown in  FIG.  1   , processing instrument  400  may include various modules configured to receive one or more receptacles (examples of which are described in more detail below) within each of which may be performed one or more steps of a biological, chemical, biochemical, or other multi-step analytical process. The modules of the processing instrument  400  constitute receptacle-receiving structures configured to receive and hold one or more receptacles. 
     Processing instrument  400  may further include load stations  404 ,  406 ,  408  configured to receive receptacles and within which one or more materials may be added to the receptacles, e.g., by an automated pipettor (not shown), including sample material and various reaction reagents. 
     Processing instrument  400  may further comprise one or more parking stations  410  for holding receptacles containing reaction mixtures prior to subsequent processing within another module of the processing instrument  400 . Parking stations  410  may include magnets for attracting magnetically-responsive solid supports to the inner walls of receptacles, thereby pulling the solid supports out of suspension. An exemplary parking station is described in U.S. Pat. No. 8,276,762. 
     Processing instrument  400  may include one or more incubators  412 ,  414 ,  416  configured to receive a plurality of receptacles and to heat (and/or maintain) the contents of the receptacles at a temperature higher than ambient temperature. The illustrated embodiment includes three incubators  412 ,  414 ,  416 , each of which may be configured to heat and/or maintain the contents of the receptacles at a different temperature. Exemplary incubators are described in U.S. Pat. Nos. 7,964,413 and 8,718,948. 
     Processing instrument  400  may include sample-processing devices, such as magnetic wash stations  418 ,  420 , adapted to separate or isolate a target nucleic acid or other analyte (e.g., immobilized on a magnetically-responsive solid support) from the remaining contents of the receptacle. Exemplary magnetic wash stations are described in U.S. Pat. Nos. 6,605,213 and 9,011,771. 
     Processing instrument  400  may further include a detector  424  configured to receive a receptacle and to detect a signal (e.g., an optical signal, such as fluorescence or chemiluminescence) emitted by the contents of the receptacle. In one implementation, detector  424  may comprise a luminometer for detecting luminescent signals emitted by the contents of a receptacle and/or a fluorometer for detecting fluorescent emissions from the contents of the receptacle. Processing instrument  400  may also include one or more signal detecting devices, such as, for example, fluorometers (e.g., coupled to one or more of incubators  412 ,  414 ,  416 ) configured to detect (e.g., at periodic intervals) signals emitted by the contents of receptacles contained in the incubators while a process, such as nucleic acid amplification, is occurring within the reaction receptacles. Exemplary luminometers and fluorometers are described in U.S. Pat. Nos. 7,396,509 and 8,008,066. 
     The processing instrument  400  further includes a receptacle transport apparatus, which, in the illustrated embodiment, comprises a receptacle distributor  430 . Each of the modules of the processing instrument  400  includes a receptacle transfer portal through which receptacles are inserted into or removed from the respective module. Each module may or may not include an openable door covering its receptacle portal. Receptacle distributor  430  is configured to move receptacles between the various modules and retrieve receptacles from the modules and deposit receptacles into the modules. More specifically, receptacle distributor  430  includes a receptacle distribution head  432  configured to move in an X direction along a transport track  434 , rotate in a theta (Θ) direction, and move receptacles in an R direction into and out of the receptacle distribution head  432  and one of the modules of processing instrument  400 . The receptacle distributor  430  may further be configured to remove receptacles, one-at-a-time, from the input module  230  described herein. 
     In operation, receptacle distribution head  432  moves in the X direction along the transport track  434  to a transfer position with respect to one of the modules or the input module  230 . The distribution head then rotates in the  0  direction to place the distribution head in a receptacle transfer orientation with respect to the receptacle transfer portal of the module or the input module  230 . A receptacle moving mechanism, e.g. a linearly-actuated hook, moves in an R direction with respect to the distribution head  432  to move a receptacle from the distribution head  432  into the module or to retrieve a receptacle from the module or input module  230  into the distribution head  432 . In an embodiment, receptacle distributor  430  further includes means for effecting vertical (Z-axis, normal to the page of  FIG.  1   ) position adjustment of the distribution head  432  to accommodate variations in vertical position of the receptacle transfer portals of the various modules. Receptacle distributor  430  may include structural elements and associated control logic for opening a door that is covering a receptacle transfer portal before inserting a receptacle into the module or removing the receptacle from the module. 
     An exemplary receptacle transport apparatus, exemplary receptacle transfer portal doors, and mechanisms for opening the doors are described in U.S. Pat. No. 8,731,712. 
     Exemplary processing instruments with which transporter/storage module  100  may be used include analyzers described in U.S. Pat. Nos. 8,731,712 and 9,732,374 and International Patent Application No. PCT/US2018/041472, as well as the Panther® and Panther Fusion® systems available from Hologic, Inc. (Marlborough, Mass.). 
     Exemplary consumables that may be transported and stored within module  100  and provided to the processing instrument by input module  230  may include receptacles for holding volumes of substances, such as a multi-receptacle unit  160  shown in  FIG.  9   . As shown in  FIG.  9   , a multi-receptacle unit (“MRU”)  160  comprises a plurality of individual receptacles  162  (five in the illustrated embodiment). In alternate embodiments, an MRU may include more or less than five receptacles  162 . In the illustrated example, receptacles  162  are in the form of cylindrical tubes (e.g., test tubes) with open top ends and closed bottom ends and are connected to one another by a connecting rib structure  164  which defines a downwardly facing shoulder extending longitudinally along either side of MRU  160 . In other examples, receptacles having configurations other than cylindrical tubes are contemplated. The receptacles may have the same or different sizes and/or shapes. 
     In an embodiment, an arcuate shield structure  169  is provided at one end of MRU  160 . An MRU manipulating structure  166  extends from the shield structure  169 . The manipulating structure is adapted to be engaged by a receptacle distributor of the processing instrument, such as receptacle distributor  430  of processing instrument  400  described above, for withdrawing MRU  160  from the input module  230  and for moving MRU  160  between different locations of the processing instrument  400 . MRU manipulating structure  166  comprises a laterally extending plate  168  extending from shield structure  169  with a vertically extending piece  167  on the opposite end of the plate  168 . A gusset wall  165  extends downwardly from lateral plate  168  between shield structure  169  and vertical piece  167 . 
     Shield structure  169  and vertical piece  167  have mutually facing convex surfaces. MRU  160  may be engaged by a distributor (e.g., distributor  430 ), by moving an engaging member (e.g., a hook) laterally into the space between shield structure  169  and vertical piece  167 . The convex surfaces of shield structure  169  and vertical piece  167  provide for wider points of entry for an engaging member moving laterally into the space. 
     A label-receiving structure  174  having a flat label-receiving surface  175  is provided on an end of MRU  160  opposite the shield structure  169  and MRU manipulating structure  166 . MRU  160  may also include tiplet holding structures  176  adjacent the open mouth of each respective receptacle  162 . Each tiplet holding structure  176  provides a cylindrical orifice within which is received a conduit, such as contact-limiting tiplet  170 , that is adapted to be placed onto the end of an aspirating tube (not shown). An exemplary multi-receptacle unit is described in U.S. Pat. No. 6,086,827. 
     Carrier 
     A carrier for holding consumables to be transported and stored in module  100  is indicated by reference number  300  in  FIG.  10   , which is a top perspective view of the carrier  300 , and in  FIG.  11   , which is a bottom perspective view of the carrier  300 . In an example, carrier  300  may comprise a type of rack that includes a carrier base  302  that, in various embodiments, comprises a first end  304 , a second end  306 , and a connecting portion  308  extending between first end  304  and the second end  306  and being generally narrower than the first and second ends  304 ,  306 . 
     A pair of parallel support rails  312 ,  314  extend substantially the entire length of carrier base  302  and are attached to carrier base  302  by, for example, fasteners or fastener elements  324  attaching support rails  312 ,  314  to opposed edges of the connecting portion  308  so that the spacing between support rails  312 ,  314  is defined by the width of the connecting portion  308 . Support rails  312 ,  314  and carrier base  302  may be made of any suitable material having sufficient strength and rigidity. Ideally, carrier  300  is constructed of lightweight materials to enable rapid movement of the carrier. In one example, support rails  312 ,  314  are made from spring steel, and the carrier base  302  is made from aluminum. Fastener elements  324  may be welds or any suitable mechanical fasteners, such as, screws, rivets, or bolts, or a combination thereof. 
     As shown in  FIG.  11   , carrier base  302  includes a shelf locator hole  340  and a lift platform locator hole  344  formed in the bottom of the carrier base near the first end  304 . The carrier base  302  further includes a lift platform locator slot  346  and a shelf locator slot  342  formed in the bottom of the carrier base adjacent the second end  306 . 
     The support rails  312 ,  314  include hard stops  316 ,  318 , respectively. In the illustrated example, hard stops  316 ,  318  comprise stop flanges extending transversely with respect to the support rails  312 ,  314 , and each hard stop  316 ,  318  is supported at its bottom end by the second end  306  of the carrier base  302  to provide lateral stability to the corresponding support rail. 
     Each support rail  312 ,  314  includes a retainer tab  320 ,  322 , respectively. Retainer tab  320  is disposed at the end of a serpentine spring  330 , and retainer tab  322  is disposed at the end of a serpentine spring  332 . The serpentine springs  330 ,  332  permit lateral flexing of the retainer tabs  320 ,  322 , respectively. In an embodiment, the springs  330 ,  332  are contiguous with and cut from the support rails  312 ,  314  (e.g., by laser cutting), which, as noted above, may be formed from spring steel. In another embodiment (not shown), the retainer tabs  320 ,  322  may be disposed at the ends of serpentine springs that are distinct from, but attached to, the support rails  312 ,  314 . 
     In the embodiment of the rail  300  shown in  FIGS.  10  and  11   , tabs  320  and  322  are located below ends  334 ,  336 , of support rails  312 ,  314 , respectively. In an alternate embodiment shown in  FIG.  12   , carrier  600  includes retainer tabs  620 ,  622  at the ends of serpentine springs  630 ,  632 , respectively, and which are not positioned beneath, but are longitudinally aligned with the ends  634 ,  636 , respectively, of support rails  612 ,  614 . In other respects, carrier  600  may be substantially identical to carrier  300 , with a carrier base  602 , including a first end  604  similar to first end  304 , and a connecting portion  608  similar to connection portion  308 , to which support rails  612  and  614  are attached. 
     Carrier  300  shown in  FIGS.  10  and  11   , and carrier  600  shown in  FIG.  12   , are particularly configured to hold a plurality of the MRUs  160  shown in  FIG.  9   , although other carrier configurations may be incorporated. Each MRU  160  is supported on the carrier  300  or  600  with the middle receptacle  162  disposed between the support rails  312 ,  314 , or support rails  612 ,  614 . The portions of the connecting rib structure  164  connecting the middle receptacle  162  to the adjacent receptacles on either side of it are supported on the top edges of the support rails  312 ,  314  or support rails  612 ,  614 . 
       FIGS.  13  and  14    are top and bottom perspective views, respectively, of a carrier  300  holding a plurality of MRUs  160 . When the carrier  300  is fully loaded with MRUs  160 , as shown in  FIGS.  13  and  14   , the front-most (left end in the figures) MRU  160  presses against the hard stops  316 ,  318 , which prevents the MRU from sliding off the left ends of the support rails  312 ,  314 . The retainer tabs  320 ,  322  are each bent laterally outwardly so that the tabs contact the receptacles  162  on either side of the center receptacle disposed between the support rails  312 ,  314 . Alternatively, the retainer tabs  320 ,  322  can be bent laterally inwardly so that the tabs contact the center receptacle  162  disposed between the support rails  312 ,  314 . 
     The retainer tabs  320 ,  322  provide resistance against the end-most (right end in the figures) MRU  160  sliding off the right ends of the support rails  312 ,  314 , e.g., to prevent the MRUs  160  from “walking” off the ends of the support rails  312 ,  314 —when in a horizontal orientation—due to ambient vibrations. Because the retainer tabs  320 ,  322  are disposed at the ends of their respective serpentine springs  330 ,  332 , each tab may flex inwardly for outwardly bent retainer tabs  320 ,  322  or may flex outwardly for inwardly bent retainer tabs  320 ,  322 , so that a nominal force applied to the end-most MRU  160 , e.g. by pushing the entire stack of MRUs to the right, will overcome the resistance generated by the retainer tabs  320 ,  322 , so that the end-most MRU  160  can be forced off the right ends of the support rails  312 ,  314 . 
     Features of a holding shelf  104  are shown in  FIG.  4 A , which is a top plan view of a holding shelf with a lift platform positioned within an open area of the holding shelf. Holding shelf  104  includes a first shelf portion  112  and a second shelf portion  114  with a connecting portion  118  extending between the first and second shelf portions  112 ,  114  and an open area  116  between the first and second shelf portions  112 ,  114 . A holding shelf positioning tab  108  extends laterally from the connecting portion  118 . A first locator pin  110  protrudes above the first shelf portion  112 , and a second locator pin  111  protrudes above the second shelf portion  114 . 
     When the carrier  300  is supported on the holding shelf  104 , the first locator pin  110  is received in the shelf locator hole  340  and the second locator pin  111  is received in the shelf locator slot  342 . The locator pins  110 ,  111  and the shelf locator hole  340  and shelf locator slot  342  formed in the carrier base  302  facilitate accurate positioning of the carrier  300  on the holding shelf  104  and prevent lateral sliding of the carrier  300  within the holding shelf. To accommodate machining and manufacturing tolerances, the carrier  300  is positioned within the holding shelf  104  by the locator hole  340  at one end of the carrier  300  and the locator slot  342  at the other end of the carrier  300 , the elongated slot accommodating variations in the distance between the first and second locator pins  110 ,  111 . 
     In an alternate embodiment, locator pins may be provided on the carrier and locator holes may be provided on the holding shelf. For example, carrier  300  may include downwardly-projecting locator pins at the positions of shelf locator hole  340  and shelf locator slot  342  that engage locator holes (e.g., one locator hole and one locator slot) formed in the holding shelf  104  at the positions of first and second locator pins  110 ,  111 . In another embodiment, the carrier includes more or less than two locator holes/slots or locator pins that align with a corresponding number of locator pins or locator holes/slots, respectively, on the holding shelf. 
     The holding shelf  104  may include a sensor, such as carrier detection sensor  115  shown in  FIG.  6   , for detecting when a carrier  300  is positioned on the holding shelf  104 . Details of an exemplary optical sensor are described below. 
     Loading Drawer 
     Various exemplary features of a loading drawer  280  are shown in  FIGS.  5 - 8   . Loading drawer  280 , which may also function as a holding shelf for holding a carrier  300 ,  600 , comprises a support for the carrier—and thus may also be referred to as a carrier support—that is movable in a lateral direction with respect to the housing  102  between a first position (shown in  FIGS.  2 ,  3 ,  5 , and  6   ) accessible by the transporter  120  and a second position accessible by a user to load a plurality of consumables into the drawer (shown in  FIG.  4   , which is a partial perspective view of the transporter/storage module  100  with the access door  106  in an open position and the loading drawer  280  partially withdrawn from the housing  102  of the module  100 ). Loading drawer  280  may be supported within the housing  102  on a linear track  281  (see  FIG.  7   ), such as a linear bearing, enabling the loading drawer  280  to be moved between the first position (also referred to as the closed position) and second position (also referred to as the closed position). A sensor  299 , which may comprise an optical sensor, within the housing  102  (see  FIGS.  5  and  7   ) may be provided to detect when the loading drawer  280  is in the closed position inserted into the housing  102 . 
     Features of loading drawer  280  are shown in  FIG.  8   . Loading drawer  280  includes a sidewall  284  extending substantially the length of the drawer, a handle  282 , a first shelf  286 , and a second shelf  292  with an open space  298  between first shelf  286  and second shelf  292 . A pair of stops  283  extend above the first shelf  286  and prevent any MRUs  160  from falling off an end of a carrier  300  (or  600 ) supported on the loading drawer  280 , especially as the loading drawer  280  is moved from the open position to the closed position or when a user is loading MRUs  160  onto the carrier. A first locator pin  288  protrudes above first shelf  286 , and a second locator pin  294  protrudes above second shelf  292 . First shelf  286  includes a pivoting latch  290 , and second shelf  292  includes a slide latch  296 . Loading drawer  280  is supported within module housing  102  by one or more slides, tracks (such as linear track  281 ), rollers, or a combination thereof for sliding movement of loading shelf  280  into and out of an access port formed in module housing  102  at access door  106 . A loading drawer positioning tab  276  extends laterally from housing  102  at a position adjacent the loading drawer  280 . 
     Loading drawer  280  is configured to support a carrier  300  (or  600 ) on first shelf  286  and second shelf  292 . As shown in  FIGS.  6  and  7   , carrier  300  is supported on loading drawer  280  with first end  304  of carrier base  302  supported on first shelf  286  and second end  306  of carrier base  302  supported on second shelf  292 . A sensor  297 , which may comprise an optical sensor, within the housing  102  (see  FIG.  5   ) may be provided to detect the presence of a carrier  300  (or  600 ) within the loading drawer  280 . 
     When carrier  300  is supported in loading drawer  280 , the first locator pin  288  of loading drawer  280  is received in shelf locator hole  340  and the second locator pin  294  of loading drawer  280  is received in shelf locator slot  342 . The locator pins  288 ,  294  and the shelf locator hole  340  and shelf locator slot  342  formed in the carrier base  302  facilitate accurate positioning of the carrier  300  in the loading drawer  280  and prevent lateral sliding of the carrier  300  with respect to the loading drawer  280 . To accommodate machining and manufacturing tolerances, the carrier  300  is positioned within the loading drawer  280  by shelf locator hole  340  at one end of the carrier  300  and shelf locator slot  342  at the other end of the carrier  300 , the shelf locator slot  342  being elongated to accommodate variations in the distance between first and second locator pins  288 ,  294 . 
     In an alternate embodiment, locator pins may be provided on the carrier and locator holes may be provided on the loading drawer. For example, carrier  300  may include downwardly-projecting locator pins at the positions of shelf locator hole  340  and shelf locator slot  342  that engage locator holes (e.g., one locator hole and one locator slot) formed in the loading drawer  280  at the positions of first and second locator pins  288 ,  294 . In another embodiment, the carrier includes more or less than two locator holes/slots or locator pins that align with a corresponding number of locator pins or locator holes/slots, respectively, on the loading drawer. 
     In various embodiments, when loading drawer  288  is pulled to the open position (i.e., extended from the housing  102 ) so that MRUs  160  (or other consumables that a different carrier is configured to hold) can be loaded onto carrier  300 , it is preferred that carrier  300  not be removed or removable from loading drawer  280 . Conversely, when loading drawer  288  is in the closed position (i.e., inserted into module housing  102 ), it is necessary that carrier  300  is removable from loading drawer  280  so that carrier  300  can be removed from loading drawer  280  by transporter  120  and moved to one of the holding shelves  104  or to the input module  230 . Accordingly, loading drawer  280  includes locking mechanisms that lock carrier  300  to loading drawer  280  when the drawer  280  is in the open position and release carrier  300  from loading drawer  280  when drawer  280  is in the closed position. 
     In an embodiment, the locking mechanisms are provided by pivoting latch  290  and slide latch  296 . Pivoting latch  290  is configured to pivot with respect to first shelf  286  between a locking position disposed over a portion of first end  304  of carrier base  302  and a released position not extended over any portion of carrier base  302 . Slide latch  296  is configured to slide into and out of a receptacle  295  between an extended, or locking, position disposed over a portion of second end  306  of carrier base  302  and a retracted, or released, position that is not extended over any portion of carrier base  302 . 
     Pivoting latch  290  is spring biased, for example, by a torsional spring or the like, into the locking position, and slide latch  296  is biased, for example, by a linear spring, into the extended position. Thus, without any external agencies or forces to overcome the biases of pivoting latch  290  and slide latch  296 , carrier  300  will be locked into loading drawer  280  by latches  290  and  296 . This will be the state when loading drawer  280  is in the open or withdrawn position. When loading drawer  280  is in the closed position, as shown in  FIG.  6   , a lower end of pivoting latch  290  contacts a hard stop inside module  100 , causing pivoting latch  290  to rotate (counterclockwise in the illustrated embodiment) from the locking position to the released position, thereby releasing first end  304  of carrier base  302 . Similarly, when loading drawer  280  is in the closed position, slide latch  296  will contact a hard stop that pushes slide latch  296  into the retracted position within receptacle  295 , thereby releasing second end  306  of carrier base  302 . Thus, when loading drawer  280  is fully inserted into module housing  102 , carrier  300  will be released from loading drawer  280  and can be moved by transporter  120  to some other location within module  100  or input module  230 . 
     A receptacle packer  350  is configured to push the MRUs  160  held on a carrier  300  (or  600 ) that is supported within input loading shelf  280  toward the second end of carrier  300  at which hard stops  316 ,  318 , are located to pack the MRUs  160  into a relatively tight pack of MRUs (i.e., the MRUs  160  are pushed together so that adjacent MRUs  160  contact each other). Receptacle packer  350  includes a packer  360  (see also  FIG.  7 A ) that is comprised of a packer carriage  362  coupled to a packer track  356  (e.g., a linear bearing attached to a top panel  103  of housing  102 ) and is configured to translate (e.g., slide or roll) bi-directionally along the track  356 . The packer carriage  362  is attached to a packer drive belt  368  that is coupled to a packer motor  352 , which may be a stepper motor, for effecting powered translation of packer  360  along packer track  356 . 
     In other examples, the packer  360  may be automatically moved in a linear manner by other means, such as a rack and pinion, drive screw, hydraulic or pneumatic piston, etc. 
     As shown in  FIG.  7 A , in various embodiments, packer  360  further comprises a horizontal portion  364  connected to the packer carriage  362  and a contact portion  366  extending downwardly from horizontal portion  364 . In an embodiment shown in  FIG.  7   , the contact portion  366  is aligned with a gap between the support rails  312 ,  314  of the carrier  300  that is disposed within the loading shelf  280 . As the packer  360  moves along the packer track  356 , the contact portion  366  moves between the support rails  312 ,  314  and contacts a middle receptacle  162  of the MRU  160  that is disposed between the support rails  312 ,  314  and packs the MRUs against the hard stops  316 ,  318 . Contact portion  366  may also be arranged to pass between the pair of stops  283 . Horizontal portion  364  of the packer  360  contacts the end most MRU  160  above the support rails  312 ,  314  and keeps the MRUs  160  square on the support rails  312 ,  314  (i.e., keeps the MRUs  160  generally perpendicular to the longitudinal direction of the sup-port rails  312 ,  314 ) while the MRUs  160  are being pushed to prevent the MRUs  160  from getting crooked and binding on the support rails  312 ,  314 . 
     A position encoder, such as rotary encoder  354  operatively coupled to the packer motor  352 , detects the longitudinal position of packer  360  relative to a home position detected by a home sensor  355 , which may comprise an optical sensor as described below. For example, a longitudinal position of the packer  360  may be determined by the number of encoder counts executed in a motorized movement of the packer  360  from a detected home position. In an embodiment, the home position may be a position at which the packer  360  is fully retracted, for example, as shown in  FIG.  7   . Alternatively, if packer motor  352  is a stepper motor, the longitudinal position of packer  360  may be determined by counting motor steps. The packing mechanism  350  may be calibrated to determine the number of MRUs  160  held on the carrier  300 , based on the longitudinal position of that packer  360  at which the MRUs are packed together and the width of the MRUs  160 . A position at which the MRUs are packed together may be determined, for example, by a threshold resistance detected by the packer motor  352 , 
     Input Module 
     In the illustrated example, the input module  230  comprises a receptacle dispenser station configured to receive a carrier holding one or more receptacles and to present the receptacles for input into the instrument. 
     Details of input module  230  are shown in  FIGS.  22 - 25   . Input module  230  is configured to hold a carrier (e.g., carrier  300  or carrier  600 ) loaded with one or more consumables (e.g., MRUs  160 ) within, or adjacent to, a processing instrument (e.g., processing instrument  400 ) and to present the consumables for retrieval into the instrument by a distributor mechanism (e.g., distributor  430 ) within the instrument. 
       FIGS.  22  and  23    are front, right and back, right perspective views, respectively, of input module  230  without carrier  300  or  600  contained therein.  FIG.  24    is a right, side perspective view of input module  230  with carrier holding a plurality of MRUs  160 .  FIG.  25    is a front, left perspective view of the input module  230  with the receptacle distribution head  432  of the receptacle distributor  430  of the processing instrument  400  pulling an MRU  160  from the input module  230 . 
     As noted above, the input module  230  may be a component of the instrument to which the transporter/storage module  100  is coupled with transporter  120  disposed between the processing instrument (e.g., analyzer  400 ) and input module  230  on one side of transporter  120  and the holding shelves  104  and loading drawer  280  on an opposite side of transporter  120 . See also  FIG.  1   . 
     Referring to  FIGS.  22  and  23   , input module  230  includes a first carrier shelf  232  for supporting first end  304  of carrier base  302  of a carrier  300  (or first end  604  of carrier  600 ). A carrier locator pin  234  protrudes above first carrier shelf  230  and is received within shelf locator hole  340  formed in the bottom of carrier base  302  of carrier  300 . Referring to  FIG.  23   , input module  230  further includes a second carrier shelf  236  for supporting second end  306  of carrier base  302  of carrier  300 . A carrier locator pin  238  protrudes above second carrier shelf  236  and is received within shelf locator slot  342  formed in the bottom of carrier base  302  of carrier  300 . First carrier shelf  232  and second carrier shelf  236  are spaced apart so as to define an open gap  235  therebetween. 
     In an alternate embodiment, locator pins may be provided on the carrier and locator holes may be provided on the first and second carrier shelves. For example, carrier  300  may include downwardly-projecting locator pins at the positions of shelf locator hole  340  and shelf locator slot  342  that engage locator holes (e.g., one locator hole and one locator slot) formed in the first and second carrier shelves  232 ,  236  at the positions of carrier locator pins  234 ,  238 . In another embodiment, the carrier includes more or less than two locator holes/slots or locator pins that align with a corresponding number of locator pins or locator holes/slots, respectively, on the first and second carrier shelves. 
     Input module  230  may include a sensor, such as carrier detection sensor  264  shown in  FIG.  23   , for detecting when a carrier  300  has been placed in the input module  230 . Details of an exemplary optical sensor are described below. 
     In some examples, input module  230  includes a housing  270  with an input module positioning tab  256  extending therefrom. 
     A pusher  240  is configured to push the MRUs  160  held on a carrier  300  (or  600 , all references to carrier  300  are likewise applicable to carrier  600 , whether explicitly stated or not, and unless otherwise noted) deposited within input module  230  toward the first end of carrier  300  at which retainer tabs  320 ,  322  (or  620 ,  622 ) are located to pack the MRUs  160  into a relatively tight pack of MRUs (i.e., the MRUs  160  are pushed together so that adjacent MRUs  160  contact each other). In this regard, the pusher  240  functions as a packing mechanism. Pusher  240  includes a pusher carriage  248  coupled to a pusher track  250  and is configured to translate (e.g., slide or roll) bi-directionally along the track  250 . The pusher carriage  248  is attached to a pusher drive belt  254  that is coupled to a pusher motor  252 , which may be a stepper motor and/or may be operatively coupled to a rotary encoder  253 , for effecting powered translation of pusher carriage  248  along pusher track  250 . In various embodiments, pusher  240  further comprises a pusher arm extending from the pusher carriage  248  and may comprise an upright portion  242  extending upwardly from pusher carriage  248 , a lateral portion  244  extending laterally from upright portion  242 , and a contact portion  246  extending downwardly from lateral portion  244 . In an embodiment shown in  FIG.  25    the contact portion  246  is aligned with a gap between the support rails  612 ,  614  of the carrier  600  disposed within the input module  230  so that as the pusher  240  moves along the pusher track  250 , the contact portion  246  moves between the support rails  612 ,  614  and contacts a middle receptacle  162  of the MRU  160  that is disposed between the support rails  612 ,  614 . 
     To permit a carrier  300  with one or more MRUs  160  supported thereon to be placed in input module  230 , pusher  240  is moved to a standby position (at the far left end of housing  270  in the embodiment shown in  FIGS.  22 - 24   ) to permit carrier  300  to be placed in the input module  230 . A pusher home sensor may be provided to detect when the pusher  240  is in the standby position and provide a confirmatory signal. In one example, the home sensor comprises a slotted optical sensor  249  (see  FIG.  25   ) that detects a tab  243  extending from the pusher  240  when the pusher  240  is in the standby position. Other types of sensors may be used for the home sensor, including contact sensors or proximity sensors. After carrier  300  is placed into input module  230 , as shown in  FIG.  24   , pusher  240  is activated to translate laterally against MRUs  160  supported on carrier  300 . The force of pusher  240  on MRUs  160  slides the MRUs along support rails  312 ,  314  toward the retainer tabs  320 ,  322  and pushes the right-most MRU  160  past flexing retainer tabs  320 ,  322  of the support rails  312 ,  314  and into a retrieval dock  260 , where the MRU can be retrieved by a distributor within the instrument. A contact sensor  258  (see  FIG.  22   ) detects when one of the MRUs  160  has been pushed into the retrieval dock  260 , thereby causing the pusher  240  to stop translating and thus stop applying a force to the MRUs. A pushdown mechanism  262 , which may comprise a flexible metal tab attached at one end to the housing  270  and extending laterally therefrom above the retrieval dock  260 , is contacted by the top of the MRU  160  as the MRU is pushed into the retrieval dock  260 . When contacted by the MRU  160 , the pushdown mechanism  262  bends upwardly, and the resilience of the mechanism creates a force pushing the MRU  160  down into the loading dock  260 . 
     An upright guide plate  268  (see  FIG.  22   ) is positioned adjacent to the retrieval dock  260  and is spaced apart from and generally parallel to a guide panel  274 . 
     As shown in  FIG.  25   , when an MRU  160  is pushed off the carrier  600  and onto the retrieval dock  260 , the MRU  160  can be pulled off the retrieval dock  260  and into the processing instrument (e.g. processing instrument  400 ) by the receptacle distribution head  432  of receptacle distributor  430 . Specifically, in the illustrated example, the receptacle distributor head  432  is moved on the transport track  434  to a position adjacent the retrieval dock  260  and rotated into a position operatively aligned with respect to the MRU  160 . Translation of the receptacle distributor head  432  to this “pick-up” position may be activated by the MRU  160  contacting the contact sensor  258 . Once the receptacle distributor head  432  is at the pick-up position, a distribution head hook  436  is extended from a distribution head housing  438  and engaged with the MRU manipulating structure  166  of the MRU  160  positioned on the retrieval dock  260 . The distribution head hook  436  then retracts into the distribution head housing  438  to pull the MRU  160  off the retrieval dock  260  and into the housing  430 . As the MRU  160  is pulled from the retrieval dock  260 , the MRU  160  passes between the guide plate  268  and guide panel  274  (see  FIG.  22   ) to align the MRU  160  with an opening (not shown) into the distribution head housing  438 . A leading edge  272  of the guide plate  268  may be outwardly flared to redirect an MRU  160  that is misaligned with the space between the guide plate  268  and the guide panel  274 . In addition, by packing the MRUs with the pusher  240 , the MRUs are less likely to tip or twist on the carrier  300  and are thereby properly positioned for depositing on and retrieval from the retrieval dock  260 . 
     As shown in  FIG.  25   , no MRUs  160  remain on the carrier  600 , and the pusher  240  has moved back to the standby position. Had there been one or more MRUs remaining on the carrier  600 , the pusher  240  would have remained in a position in contact with (or closely adjacent to) the end-most MRU remaining on the carrier  600 . After an MRU  160  is pulled off the retrieval dock  260 , as indicated by the contact sensor  258  no longer being in contact with an MRU, the pusher  240  would be activated to push another MRU off the carrier  600  and onto the retrieval dock  260 . 
     A position encoder, such as rotary encoder  253  operatively coupled to the pusher motor  252 , detects the longitudinal position of pusher  240  when an MRU contacts the sensor  258  based on rotational output of the pusher motor  252  (alternatively, if pusher motor  252  is a stepper motor, the longitudinal position of pusher  240  may be determined by counting motor steps), and input module  230  may be calibrated to determine the number of MRUs  160  currently held on the carrier  300 , based on the longitudinal position of pusher  240  and the width of the MRUs  160 . After the instrument retrieves an MRU  160  from the retrieval dock  260 , the sensor  258  detects the absence of the MRU  160 , thereby activating the pusher  240  to push the next MRU off the carrier  300  and onto the retrieval dock  260 . In an alternate example, the next MRU may not be pushed off the carrier and onto the retrieval dock  260  until the instrument signals that the next MRU is needed. 
     Transporter/Elevator 
     Features of transporter  120  are shown in  FIGS.  15 - 20   . In an embodiment, transporter  120  includes a transporter chassis  122  comprising a horizontally oriented base frame  124 , a first upright  126  attached to a first end of the base frame  124 , and a second upright  128  attached to a second end of the base frame  124 . Note that the first and second uprights  126 ,  128  are not shown in  FIG.  17   , which is an exploded view of the transporter  120 . A lift platform  180  (also referred to as a carrier support platform or a support platform) is carried by and coupled to support chassis  122  by a lateral actuator. In an example, the lateral actuator comprises a scissors actuator  140  configured to translate lift platform  180  laterally in with respect to the support chassis  122  in a first direction—direction “D”—to one side of support chassis  122 , as shown in  FIG.  16   , or in a second direction—direction “E”—to an opposite side of support chassis  122 , as shown in  FIG.  18   . Thus, the lateral actuator is configured to translate the lift platform  180  laterally from a position aligned with the support chassis  122  (as shown in  FIG.  15   ) to a first laterally displaced position shown in  FIG.  16   , which is laterally aligned with one of the holding shelves  104  (the holding selves  104  are not shown in  FIG.  16   ), or to a second laterally displaced position shown in  FIG.  18   , which is laterally aligned with first carrier shelf  232  and second carrier shelf  236  of input module  230  (the first and second carrier shelves  232 ,  236  are not shown in  FIG.  18   ). 
     In an embodiment, a vertical guide rod extends through a bore  127  formed through first upright  126  of support chassis  122 , and a vertical guide rod extends through a bore  129  formed through the second upright  128  of the support chassis  122 .  FIG.  2    (and  FIG.  21   ) show a first guide rod  156  extending through first upright  126 . A similar guide rod  158  (see  FIG.  21   ) extends through second upright  128 . 
     As shown in  FIG.  21   , transporter  120  is coupled to transport elevator  210 , which is configured to move transporter  120  in a vertical direction, up or down in direction “B”, within housing  102  of transporter/storage module  100 . Referring to  FIG.  21   , transport elevator  210  includes first and second drive pulleys  216 ,  217  connected to each other by a connecting shaft  218 . An elevator drive motor  212 , which may be a stepper motor and/or be operatively coupled to a rotary encoder  213 , is coupled to drive pulleys  216 ,  217  and connecting shaft  218  by a drive belt  214 . A first elevator belt  220  is trained around first drive pulley  216  and a first idler pulley  224 . Similarly, a second elevator belt  222  is trained around second drive pulley  217  and a second idler pulley  225 . First elevator belt  220  is connected to first upright  126  of support chassis  122 , for example by clamps  134 ,  135 . Similarly, second elevator belt  222  is connected to second upright  128  of support chassis  122 , for example by clamps  136 ,  137 . In various embodiments, a counterweight  228  may be attached to first and second elevator belts  220 ,  222 . 
     It can be appreciated from  FIG.  21    that powered rotation of connecting shaft  218  and drive pulley  216 ,  217  in direction “C” by elevator drive motor  212  and drive belt  214  will result in a vertical translation of transporter  120  up or down in accordance with the direction of rotation of pulleys  216 ,  217 . 
     In other examples, motive means other than drive belts and drive pulleys are contemplated for effecting vertical translation of the transporter  120 . For example, transporter  120  could be moved up or down by a lead screw mechanism comprising one or more vertically-oriented, power-driven lead screws operatively coupled to a screw follower that is attached or otherwise coupled to the support chassis  122  of the transporter  120 . 
     In various embodiments, a locator flag  130  extends laterally from one of the uprights, such as upright  126 . The locator flag  130  is used by one or more sensors (not shown) located within the housing  102  along the vertical path of the transporter  120  to detect a vertical position of the transporter  120 —for example, by detecting when the locator flag  130  passes between an emitter and a receiver of an optical detector. Accordingly, the flag  130  and an associated optical sensor may be used as home sensor for detecting a specified location of the transporter based on the position of the sensor. In other embodiments, more than one sensor may be employed to detect multiple transporter positions, each corresponding to a different sensor location. 
     Referring to  FIGS.  15 - 18   , lift platform  180  includes first and second carrier locator pins  190 ,  191 , respectively, and is configured to support a carrier  300  (or  600 ), as shown in  FIG.  20   . When carrier  300  is supported on lift platform  180 , first carrier locator pin  190  is received in lift platform locator hole  344  and second carrier locator pin  191  is received in lift platform locator slot  346 . The locator pins  190 ,  191  and the lift platform locator hole  344  and lift platform locator slot  346  formed in carrier base  302  facilitate accurate positioning of carrier  300  with respect to lift platform  180  and prevent lateral sliding of carrier  300  on the lift platform  180 . 
     In an alternate embodiment, locator pins may be provided on the carrier and locator holes may be provided on the lift platform. For example, carrier  300  may include downwardly-projecting locator pins at the positions of lift platform locator hole  344  and lift platform locator slot  346  that engage locator holes (e.g., one locator hole and one locator slot) formed in the lift platform  180  at the positions of first and second locator pins  190 ,  191 . In another embodiment, the carrier includes more or less than two locator holes/slots or locator pins that align with a corresponding number of locator pins or locator holes/slots, respectively, on the lift platform. 
     A carrier detection sensor  204  (see  FIG.  19   ) may be provided to detect a carrier  300  supported on lift platform  180  when the lift platform is moved to the retracted position. Details of an exemplary carrier detection sensor, which may be an optical sensor, are shown in  FIG.  26   . In an embodiment, the carrier detection sensor  204  is attached to the second upright  128  of the support chassis  122  and comprises an L-shaped bracket comprising an upright portion  206  and a lateral portion  208 . An optical emitter is disposed at a distal end of one of the upright and lateral portions  206  and  208  and an optical receiver is disposed at the distal end of the other of the upright and lateral portions  206  and  208 . An optical beam, represented by line  209 , is directed between the optical emitter and receiver at the distal ends of the upright and lateral portions  206  and  208 . The ends of a carrier  300  (or  600 ) supported on the lift platform  180  extend over the ends of the lift platform  180 . Thus, when the lift platform  180  is moved to the retracted position shown in  FIG.  15   , one of the over-extending ends of the carrier  300  passes over the lateral portion  208  of the L-shaped bracket and interrupts the beam  209  between the emitter and the receiver of the sensor to generate a signal indicating the presence of the carrier on the lift platform. 
     Other optical detection sensors described herein, such as the carrier detection sensor  115  of the holding shelf  104  shown in  FIG.  6   , the packer home sensor  355  shown in  FIG.  7   , the carrier detection sensor  297  of the loading drawer  280  shown in  FIG.  5   , the drawer closed sensor  299  shown in  FIGS.  5  and  7   , and the carrier detection sensor  264  of the input module  230  shown in  FIG.  23   , may have the same configuration and functionality as the carrier detection sensor  204  shown in  FIG.  26   . 
     Scissors Actuator 
     Details of the scissors actuator  140  are shown in  FIGS.  16 - 20   . 
     The scissors actuator  140  comprises a powered arm  142  comprising first and second parts  142   a ,  142   b . The powered arm  142  is pivotably attached to support chassis  122  (base frame  124 ) at a pivot shaft  152  and attached to the lift platform  180  and is translatably attached to the support chassis  122  at a slide  184  disposed in a platform slide track  182 . The second part  142   a  of the powered arm  142  may be attached to the slide  184  by a pivot shaft  143  extending into a bearing  186  disposed within the slide  184  and protruding from one or both sides of the slide  184  so that the bearing  186  rolls against a side of the slide track  182  as the slide  184  translates along the track  182 . 
     Scissors actuator  140  further comprises a follower arm  144  comprising first and second parts  144   a ,  144   b  and attached to the base frame  124  at a post  155  protruding from a follower arm slide  154  disposed in a base frame track  132  and attached to the lift platform  180  by a post  149  and a pivot connection  188 . Post  155  may extend into a bearing disposed within the slide  154  and protruding from one or both sides of the slide  154  so that the bearing rolls against a side of the slide track  132  as the slide  154  translates along the track  132 . 
     First part  142   a  and second part  142   b  of the powered arm  142  are fixedly couple to each other at a coupling  146 , first part  144   a  and second part  144   b  of the follower arm  144  are fixedly coupled to each other at the coupling  146 , and the powered arm  142  and the follower arm  144  are rotatably coupled to each other at the coupling  146 . As shown in  FIG.  17   , in one example, coupling  146  comprises a slewing ring (sometimes referred to as a slewing bearing) having an inner ring  146   a  and an outer ring  146   b  that is rotatable with respect to the inner ring  146   a . Exemplary slewing rings include Iglide® PRT slewing rings available from Igus®. First part  142   a  of powered arm  142  is attached to second part  142   b  by fasteners  141   a ,  141   b  (e.g., pins, screws, or bolts) extending through the inner ring  146   a  of the coupling  146 . First part  144   a  of follower arm  144  is attached to second part  144   b  by fasteners  147  (e.g., pins, screws, or bolts) extending through a ring  145   b  of the second part  144   b , the outer ring  146   b  of the coupling  146 , and a ring  145   a  of the first part  144   a.    
     Referring to  FIG.  19   , a scissors drive motor  192 , e.g., a stepper motor, attached to the base frame  124  includes a drive pulley  194  coupled, via a drive belt  196 , to a drive pulley  198  couple to the pivot shaft  152 . An encoder  202  maybe couple to the pivot shaft  152  for monitoring rotational position of the shaft. 
     Referring to  FIG.  16   , powered, clockwise rotation of the powered arm  142 , via scissors drive motor  192 , drive belt  196 , and pivot shaft  152 , will cause lateral translation of the lift platform  180  in a first direction, “D”. Conversely, as shown in  FIG.  18   , counterclockwise rotation of the powered arm  142 , via the scissors drive motor  192 , drive belt  196 , and pivot shaft  152 , causes lateral translation of the lift platform  180  in an opposite direction, “E”. 
     A sensor  148 , which may be a slotted optical sensor, is disposed adjacent the first part  142   a  of the powered arm  142  and detects a sensor flag  150 , comprising a lateral flange extending from the end of the powered arm  142  adjacent the pivot shaft  152 . In one embodiment, sensor  148  detects the edge of the sensor flag  150  to determine a “home” position of the powered arm  142  (and thus, the home position of the scissors actuator  140 ). Other positions of the powered arm  142  relative to the home position are determined by encoder  202 . 
     The transporter  120  is configured to transport carriers  300  (all references to carrier  300  are likewise applicable to carrier  600 , whether explicitly stated or not, and unless otherwise noted) between different holding shelves  104 , between the loading drawer  280  and one of the holding shelves  104 , between one of the holding shelves  104  and input module  230  or between the loading drawer  280  and the input module  230 . The transporter  120  performs this transport operation by lifting the carrier  300  from the loading drawer  280  or a holding shelf  104  with the lift platform  180 , moving the transporter  120  with the transport elevator  210  to a different holding shelf  104 , the loading drawer  280 , or the input module  230 , and then placing the carrier in the new location with the lift platform. 
     More specifically, to transport a carrier  300  from a first one of the holding shelves  104  to a second one of the holding shelves  104 , the transport elevator  210  positions the transporter  120  and lift platform  180  adjacent to the first holding shelf  104  at which the carrier  300  to be moved is positioned. Sensors may be used to indicate the position of the transporter  120  relative to a desired holding shelf  104 . In an embodiment, a sensor adjacent the desired holding shelf  104  detects the locator flag  130 . Alternatively, or in addition, an encoder coupled to the elevator drive motor  212 , such as rotary encoder  213 , is used to control the vertical positioning of the transporter  120  relative to a home position detected by a sensor (not shown) detecting the locator flag  130 . 
     The lift platform  180  is initially in the retracted position with respect to the support chassis  122  as shown in  FIG.  15   . Once the lift platform  180  is positioned adjacent to the first holding shelf  104 , the lift platform  180  is extended by the scissors actuator  140  in a first direction with respect to the support chassis  122 , as shown in  FIG.  16   , to a position beneath the carrier  300 . In an embodiment, the encoder  202  coupled to the pivot shaft  152  detecting the rotation of the power arm  142  of the scissors actuator  140  is used to control the amount of lateral translation of the lift platform  180 . 
     As shown schematically in  FIG.  4 A , the length of the lift platform  180  is less than the length of the open area  116  between the first shelf portion  112  and the second shelf portion  114  of the holding shelf  104 . As shown in  FIG.  11   , the lift platform locator hole  344  and the lift platform locator slot  346  formed in the bottom of the carrier base  302  are located in-board of the shelf locator hole  340  and the shelf locator slot  342  formed in the bottom of the carrier base. And, as shown in  FIG.  4 A , the first and second carrier locator pins  190 ,  191  of the lift platform  180  are similarly located in-board of the first and second locator pins  110 ,  111  of the holding shelf  104 . 
     Once the lift platform  180  is positioned beneath the carrier  300  held in the holding shelf  104  (i.e., the lift platform is laterally aligned with the carrier  300  and the holding shelf  104 ), the transporter  120  is raised by the transport elevator  210  until the lift platform  180  enters the open area  116  and contacts the bottom of the carrier  300 . The transport elevator  210  continues to raise the transporter  120  and the lift platform  180 , and the first carrier locator pin  190  and the second carrier locator pin  191  enter the lift platform locator hole  344  and the lift platform locator slot  346 , respectively, formed in the bottom of the carrier base  302 . The transport elevator  210  continues to raise the transporter  120  until the lift platform  180  lifts the carrier  300  off of the holding shelf  104  and the first and second locator pins  110 ,  111  are fully clear of the shelf locator hole  340  and the shelf locator slot  342  of the carrier  300 . In one example, the vertical position at which lift platform  180  contacts carrier  300  in a particular holding shelf  104  is known—e.g., by a system self-teaching process described below—and thus, the additional elevation of the lift platform  180  required to lift the carrier  300  off the first and second locator pins  110 ,  111  is determinable from the height of the first and second locator pins  110 ,  111 . 
     With the carrier  300  supported on the lift platform  180 , as shown in  FIG.  20   , the lift platform is retracted by the scissors actuator  140  to the retracted position shown in  FIG.  15    (the carrier  300  is not shown in  FIG.  15   ). The carrier detection sensor  204  (see  FIG.  19   ) may be provided to detect a carrier  300  supported on the lift platform  180  when the lift platform is moved to the retracted position. The transporter  120  is then raised or lowered by the transport elevator  210  to a different holding shelf  104 . To place the carrier in a holding shelf  104 , the lift platform  180  is extended by the scissors actuator  140  to a position above the holding shelf  104  (i.e., the lift platform  180  is laterally aligned with the holding shelf  104 ). Again, in an embodiment, the encoder  202  coupled to the pivot shaft  152  is used to control the amount of lateral translation of the lift platform  180 . The transport elevator  210  then lowers the transporter  120  until the carrier  300  is supported on the first shelf portion  112  and the second shelf portion  114  of the holding shelf  104 . As the lift platform  180  is lowered, the first and second locator pins  110 ,  111  of the first shelf portion  112  and second shelf portion  114 , respectively, enter the shelf locator hole  340  and the shelf locator slot  342  formed in the bottom of the carrier base  302 . When the lift platform has been lowered sufficiently so that the carrier pins  190 ,  191  of the lift platform  180  are clear from the lift platform locator hole  344  and the lift platform locator slot  346  formed in the bottom of the carrier base  302 , the lift platform  180  is retracted by the scissors actuator  140  to the retracted position shown in  FIG.  15   , and the carrier  300  remains supported on the new holding shelf  104 . 
     To transport a carrier  300  from the loading drawer  280  to one of the holding shelves  104 , the transport elevator  210  positions the transporter  120  and lift platform  180  adjacent to the loading drawer  280 . In an embodiment, a sensor adjacent the desired holding shelf  104  detects the locator flag  130 . Alternatively, or in addition, an encoder coupled to the elevator drive motor  212  is used to control the vertical positioning of the transporter  120  relative to a home position detected by a sensor (not shown) detecting the locator flag  130 . 
     Lift platform  180  is then extended laterally by scissors actuator  140  to a position beneath the carrier  300  held in the loading drawer  280 . In an embodiment, the encoder  202  coupled to the pivot shaft  152  is used to control the amount of lateral translation of the lift platform  180 . The transporter  120  is then raised by the transport elevator  210  until the lift platform  180  enters the open area  298  between first shelf  286  and second shelf  292  and contacts the bottom of the carrier  300 . The transport elevator  210  continues to raise the transporter  120  and the lift platform  180 , and the first carrier locator pin  190  and the second carrier locator pin  191  enter the lift platform locator hole  344  and the lift platform locator slot  346 , respectively, formed in the bottom of the carrier base  302 . The transport elevator  210  continues to raise the transporter  120  until the lift platform  180  lifts the carrier  300  off of the loading drawer  280  and the first and second locator pins  288 ,  294  are fully clear of the shelf locator hole  340  and the shelf locator slot  342  of the carrier  300 . In one example, the vertical position at which lift platform  180  contacts carrier  300  at the loading drawer  280  is known—e.g., by a system self-teaching process described below—and thus, the additional elevation of the lift platform  180  required to lift the carrier  300  off the first and second locator pins  288 ,  294  is determinable from the height of the first and second locator pins  288 ,  294 . 
     With the carrier  300  supported on the lift platform  180 , as shown in  FIG.  20   , the lift platform is retracted by the scissors actuator  140  to the retracted position shown in  FIG.  15    and then transported to one of the holding shelves  104 , as described above or to the input module  230  as described below. 
     Similarly, to transport a carrier  300  to the holding drawer  280 , the transport elevator  210  positions the transporter  120  and lift platform  180  with a carrier  300  supported thereon adjacent to the loading drawer  280 . The lift platform  180  is then extended by the scissors actuator  140  to a position above the loading drawer  280 , and the transporter  120  is then lowered by the transport elevator  210  until the lift platform  180  enters the open area  298  between the first shelf  286  and the second shelf  292 . The transport elevator  210  continues to lower the transporter  120  until the carrier  300  is supported on the first shelf  286  and the second shelf  292  and the first and second locator pins  288 ,  294  of the loading drawer enter the shelf locator hole  340  and the shelf locator slot  342  of the carrier  300 . The transport elevator  210  continues to lower the transporter  120  and the lift platform  180  until the first carrier locator pin  190  and the second carrier locator pin  191  are clear of the lift platform locator hole  344  and the lift platform locator slot  346 , respectively, formed in the bottom of the carrier base  302 . With the carrier  300  supported on the loading shelf  280 , the lift platform  180  is retracted by the scissors actuator  140  to the retracted position shown in  FIG.  15   . 
     To transport a carrier from the loading drawer  280  or a holding shelf  104  to the input module  230 , the carrier  300  is first removed from the loading drawer  280  or holding shelf  104 , as the case may be, using the transporter  120  as described above. With the carrier  300  supported on the lift platform  180 , as shown in  FIG.  20   , the lift platform is retracted by the scissors actuator  140  to the retracted position shown in  FIG.  15   . The transporter  120  is then raised or lowered, as necessary, by the transport elevator  210  to input module  230 . To place the carrier  300  into the input module  230 , the lift platform  180  is extended by the scissors actuator  140  into the input module  230  to a position above the first and second carrier shelves  232 ,  236 , with the lift platform  180  disposed within the gap  235  between the first and second carrier shelves  232 ,  236 . The transport elevator  210  then lowers the transporter  120  until the carrier  300  is supported on the first and second carrier shelves  232 ,  236  of the input module  230 . As the lift platform  180  is lowered, the first and second carrier locator pins  234 ,  238  of the first and second carrier shelves  232 ,  236 , respectively, enter the shelf locator hole  340  and the shelf locator slot  342  formed in the bottom of the carrier base  302 . When the lift platform has been lowered sufficiently so that the carrier pins  190 ,  191  of the lift platform  180  are clear from the lift platform locator hole  344  and the lift platform locator slot  346  formed in the bottom of the carrier base  302 , the lift platform  180  is retracted by the scissors actuator  140  to the retracted position shown in  FIG.  15   , and the carrier  300  remains supported within the input module  230 . 
     To remove a carrier  300  from the input module  230 , the lift platform  180  is positioned in the gap  235  between the first and second carrier shelves  232 ,  236  beneath the carrier  300 . The lift platform is then raised by the transport elevator  210  until the lift platform  180  contacts the bottom of the carrier  300 . The transport elevator  210  continues to raise the transporter  120  and the lift platform  180 , and the first carrier locator pin  190  and the second carrier locator pin  191  enter the lift platform locator hole  344  and the lift platform locator slot  346 , respectively, formed in the bottom of the carrier base  302 . The transport elevator  210  continues to raise the transporter  120  until the lift platform  180  lifts the carrier  300  off of the first and second carrier shelves  232 ,  236  and the first and second carrier locator pins  234 ,  238  are fully clear of the shelf locator hole  340  and the shelf locator slot  342  of the carrier  300 . The scissors actuator  140  then retracts the lift platform  180  and carrier  300  to the retracted position shown in  FIG.  15   . 
     Control System 
       FIG.  28    is a block diagram that schematically illustrates s control architecture for the transporter storage module  100 . An exemplary control architecture may include a controller  550 , which monitors, communicates with, and controls aspects of transporter storage module  100 , including the holding shelves  104 , the loading drawer  280 , the input module  230 , the transport elevator  210 , and the scissors actuator  140 . The pusher motor  252  of the input module  230 , the elevator drive motor  212  of the transport elevator  210 , and the scissors drive motor  192  of the scissors actuator  140  are coupled to and controlled by the controller  550 , which is also connected to a power supply  460  that is controllable by the controller  550 . Controller  550  provides power and operational control signals to the motors  252 ,  212 , and  192 . Controller  550  may also receive data from the motors  252 ,  212 , and  192  in the form of rotary encoder counts from encoders  253 ,  213 , and  202 , respectively, as well as other feedback sensor signals. 
     Controller  550  may comprise a computer system for executing software (which may include firmware) that effects operation, control, and monitoring of the transporter storage module  100 . Controller  550  may be implemented via one or more logic elements, e.g., a computer, embedded controller, programmable gate array, application specific integrated circuit, programmable logic device, etc., and may include or access data storage memory  552 , which may include random access memory (RAM), read only memory (ROM), flash memory, and other types of memory now known or later developed. Controller  550  may also include additional memory, including, for example, a hard disk drive and/or a removable storage drive, representing a magnetic tape drive, an optical disk drive, USB slot, memory card interface, internet memory, cloud-based memory, or any storage medium or format now known or later developed. Memory devices and storage units used herein may comprise any storage medium for persistent and/or volatile storage of electronic data now known or later developed. Such data may be stored within the storage medium in a database, which may comprise any data structure and format now known or later developed, including, for example, a relational database, an object database, a flat file, list, and so on, or some combination thereof. 
     In alternative embodiments, some or all of the memory may include other similar means for allowing computer programs or other instructions to be loaded into a computer system. Such means can include, for example, a removable storage unit and an interface. Examples of such can include a memory stick and memory stick interface, a secure digital card and interface, and other portable media and interfaces which allow software and data to be transferred to controller  550 . 
     Software comprises instructions stored on non-transitory computer-readable media which, when executed by the logic element(s) of the controller  550 , cause the control and computing hardware to perform one or more automated or semi-automated processes. 
     The computer system of controller  550  may also include a communications interface, which allows information (e.g., power, control and feedback signals, software, data, etc.) to be transferred between controller  550  and external devices. Examples of communications interfaces can include a modem, a network interface (such as an Ethernet card), a communications port, a PCMCIA slot and card, a USB-port, a Firewire port, Bluetooth, or any interface now known or later developed. Information transferred via a communications interface is in the form of signals which can be electronic, electromagnetic, optical, or other signals capable of being received by the communications interface. 
     The computer system of controller  550  can also include one or more input devices, such as a touch screen, stylus, keyboard, mouse or other pointing device, microphone, data scanners (e.g., barcode, RFID, etc.), and so on. Various output devices may also be included in the computer system, including indicator lights, a display, printer, tactile (e.g., vibratory) indicators, and audio speakers. 
     In this document, terms such as “computer program medium,” “computer-readable medium,” “computer usable medium,” and the like are used to generally refer to media, such as removable storage units, a hard disk installed in hard disk drive, and other means for providing software and data to controller  550 . 
     Computer programs (also called computer control logic) are stored in one or more portions of the memory  552  that is part of or accessed by controller  550 . Computer programs can also be received via a communications interface. Such computer programs may include algorithms, such as the algorithm illustrated in  FIG.  27   , that, when executed, enable the computer system of controller  550  to control the operation of the transporter storage module  100  in accordance with aspects disclosed herein. 
     In an embodiment in which aspects of the subject matter disclosed herein are implemented using software, the software may be stored in a computer program product and loaded into the computer system of controller  550  using a removable storage drive, a hard drive, an interface, and/or a communications interface. The control logic (software), when executed by the processor of the controller  550 , causes the processor to perform functional aspects of the subject matter as described herein via the systems, devices, apparatuses, sensors, encoder, etc. described above. An operating system may perform basic tasks such as recognizing input from an input device, sending output to an output device, managing files and system resources, and managing the various processes embodying computer programs running on the computer system. 
     Controller  550  may comprise a stand-alone system dedicated to the transporter storage module  100 , or one or more components of controller  550 —e.g., processor, memory, interfaces, input/output devices, etc.—may be a shared part of a global controller that controls one or more components of an instrument or laboratory of which the transporter storage module  100  is a component, in addition to the transporter storage module  100 . 
     As shown schematically in  FIG.  28   , with respect to each holding shelf  104 , controller  550  receives signals from carrier detection sensor  115  to indicate whether or not a carrier  300 ,  600  is held one the shelf  104 . 
     With respect to the loading drawer  280 , controller  550  may receive signals from carrier detection sensor  297  to indicate whether or not a carrier  300 ,  600  is held within the loading drawer  280 . Controller  550  may also receive signals from drawer position sensor  299  to indicate whether or not the loading drawer  280  is in the closed position. Controller  550  may also receive signals from a door position sensor  293  to indicate a position—opened or closed (or closed or not closed)—of the door  106 . 
     Controller  550  may further receive signals from the packer motor  352  and/or encoder  354  to detect a position of the packer  360 . Controller  550  may also send control (power) signals to the packer motor  352  to effect selective operation of the packer motor  352 . 
     Controller  550  may further receive signals from the packer home sensor  355 , e.g., an optical sensor, to detect if the packer  360  is in the home, or standby, position, and may generate control signals, such as signals effecting operation and control of the packer motor  352 , based on signals received from the packer home sensor. 
     Controller  550  may receive signals from drawer position sensor  299  to detect when the drawer  280  has been closed, and then send a control signal to the packer motor  352  to cause the packer  360  to translate and pack the MRUs  160  on the carrier  300  after the drawer  280  has been detected in the closed position. In another embodiment, controller  550  may receive signals from the packer motor  352  and/or encoder  354  from which the controller  550  can determine the position of the packer  360  with respect to a home position to compute the number of MRUs  160  held on the carrier  300 . 
     With respect to input module  230 , controller  550  receives signals from carrier detection sensor  264  to indicate whether or not a carrier  300 ,  600  is held in the input module  230 . 
     Controller  550  may further receive signals from the motor  252  and/or encoder  253  to detect a position of the pusher  240 . Controller  550  may also send control (power) signals to the pusher motor  252  to effect selective operation of the motor  252 . 
     Controller  550  may further receive signals from the pusher home sensor, e.g., optical sensor  249 , to detect if the pusher  240  is in the home, or standby, position, and may generate control signals, such as signals effecting operation and control of the motor  252 , based on signals received from the pusher home sensor. 
     Controller  550  may further receive signals from contact sensor  258  to detect when one of the MRUs  160  has been pushed into the retrieval dock  260 , and then send a control signal to the pusher motor  252  to cause the pusher  240  to stop translating and thus stop applying a force to the MRUs. Alternatively, controller  550  may receive signals from contact sensor  258  to detect when one of the MRUs  160  has been removed from the retrieval dock  260 , and then send a control signal to the pusher motor  252  to cause the pusher  240  to translate and push the next MRU from the carrier onto the retrieval dock  260 . In another embodiment, when a signal from the contact sensor  258  indicates one of the MRUs  160  has been pushed into the retrieval dock  260 , controller  550  may receive signals from the motor  252  and/or encoder  253  from which the controller can determine the position of the pusher  240  with respect to a home position to compute the number of MRUs  160  remaining on the carrier  300 . If, as a result of that computation, it is determined that no MRUs remain on the carrier, a signal is provided by the controller  550  to the pusher motor  252  to move the pusher  240  to the standby position, and movement of the pusher  240  to the standby position will be confirmed by a signal to the controller  550  from the optical sensor  249 . 
     With respect to transport elevator  210 , controller  550  may receive signals from the elevator drive motor  212  and/or encoder  213  to detect a vertical position of the transporter  120  relative to a home position detected by an elevator home sensor  215  detecting the locator flag  130 . Controller  550  may also send control (power) signals to the elevator drive motor  212  to effect selective operation of the motor  212 . 
     With respect to scissors actuator  140 , controller  550  may receive signals from carrier detection sensor  204  to indicate whether or not a carrier  300 ,  600  is held on the lift platform  180  when the lift platform is moved to the retracted position. 
     Controller  550  may receive signals from the scissors drive motor  192  and/or encoder  202  to detect a position of the lift platform  180 . Controller  550  may also send control (power) signals to the scissors drive motor  192  to effect selective operation of the motor  192 . 
     Controller  550  may further receive signals from sensor  148  to detect if the scissors actuator  140  (and thus the lift platform  180 ) is in the home, or retracted, position, and may generate control signals, such as signals effecting operation and control of the scissors drive motor  192 , based on signals received from the platform home sensor. 
     Positional Self-Teaching 
     It should be evident that operation of transport/storage module  100  requires accurate and repeatable positioning of the transporter  120  and the lift platform  180  with respect to the loading drawer  280 , the holding shelves  104 , and the input module  230  to transfer consumables and carriers between the various locations within transport/storage module  100 . Although the locations of the loading drawer  280 , the holding shelves  104 , and the input module  230  will be substantially the same from one transport/storage module  100  to the next, in some embodiments, manufacturing tolerances and/or installation variances may result in variations in the final positions of the loading drawer  280 , the holding shelves  104 , and the input module  230  after the transport/storage module  100  is attached to a processing instrument, such as processing instrument  400 . 
     In an embodiment, the module  100  has a self-teaching capability whereby, after transport/storage module  100  is attached to a processing instrument, such as processing instrument  400 , transport/storage module  100  automatically determines and stores the proper position of the transporter  120  and the lift platform  180  for each of the holding shelves  104 , the loading drawer  280 , and the input module  230 . 
       FIG.  27    is a flowchart illustrating a method (algorithm)  500  by which a computer controller, such as controller  550 , in communication with the various position sensors, encoders, and motors within the module  100  performs this self-teaching process. 
     In step  502 , the transporter  120  is moved by the transport elevator  210  to a vertical position adjacent to the expected location of the loading drawer  280 . The vertical position of the transporter may be determined and controlled by the controller  550  by signals sent to the elevator drive motor  212  and signals received from the rotary encoder  213  for detecting a vertical position of the transporter  120  relative to a home position detected by a sensor  215  (see  FIG.  28   ) detecting the locator flag  130 . 
     In step  504 , the loading drawer positioning tab  276  is contacted with the lift platform  180 . The processor  550  controls contact of the lift platform  180  with the positioning tab  276  in any of a number of ways. 
     In one embodiment, the transporter  120  is positioned by the transport elevator  210  at height that is known to be above the approximate, expected position of the loading drawer  280  (or above the approximate position of the loading drawer positioning tab  276 ), and the scissors actuator  140  extends the lift platform  182  to a position beyond the approximate, expected position of the end of the loading drawer positioning tab  276 . The transporter  120  is then lowered in step increments until the lift platform  180  contacts the positioning tab  276 . Contact by the lift platform  180  with the positioning tab  276  can be detected in a number of ways, such as by capacitance or by completing a circuit that generates a contact signal upon contact between the lift platform and the positioning tab  276 . Alternatively, contact can be determined by an increase in the load experienced by elevator drive motor  212  beyond a specified threshold as the transport elevator  210  attempts to continue to lower the lift platform  180  after the lift platform contacts the positioning tab  276 . Alternatively, contact by the lift platform  180  with the positioning tab  276  can be detected by detecting motor stall by comparing commanded motor steps to the encoder position. 
     In another embodiment, the transporter  120  is positioned by the transport elevator  210  at height that is known to be below the approximate, expected position of the loading drawer  280  (or below the approximate position of the loading drawer positioning tab  276 ), and the scissors actuator  140  then extends the lift platform  182  to a position beyond the approximate, expected position of the end of the loading drawer positioning tab  276 . The transporter  120  is then raised in step increments until the lift platform  180  contacts the positioning tab  276 . Contact by the lift platform  180  with the positioning tab  276  can be detected in a number of ways, such as by capacitance or by completing a circuit that generates a contact signal upon contact between the lift platform and the positioning tab  276 . Alternatively, contact can be determined by an increase in the load experienced by elevator drive motor  212  beyond a specified threshold as the transport elevator  210  attempts to continue to raise the lift platform  180  after the lift platform contacts the positioning tab  276 . Alternatively, contact by the lift platform  180  with the positioning tab  276  can be detected by detecting motor stall by comparing commanded motor steps to the encoder position. 
     In another embodiment, the transporter  120  is positioned by the transport elevator  210  at height that is known to be at the approximate position of the loading drawer  280 . The scissors actuator  140  then extends the lift platform  182  until the lift platform  182  contacts the end of the loading drawer positioning tab  276  or until the lift platform has moved more than a predetermined lateral distance without contacting the loading drawer positioning tab  276 . If the scissors actuator  140  extends the lift platform  182  for more than a predetermined lateral distance without contacting the loading drawer positioning tab  276 , the scissors actuator retracts the lift platform  180 , the transport elevator  210  adjusts the height of the transporter  120  up or down, and the scissors actuator  140  extends the lift platform  182  until the lift platform  182  contacts the end of the loading drawer positioning tab  276  or until the lift platform has moved more than a predetermined lateral distance without contacting the loading drawer positioning tab  276 . The process is repeated in an iterative fashion until the lift platform  182  contacts the end of the loading drawer positioning tab  276 . Contact by the lift platform  180  with the loading drawer positioning tab  276  can be detected in a number of ways, such as by capacitance or by completing a circuit that generates a contact signal upon contact between the lift platform and the positioning tab  276 . Alternatively, contact can be determined by an increase in the load experienced by scissors drive motor  192  beyond a specified threshold as the scissors actuator  140  attempts to continue to move the lift platform  180  laterally after the lift platform contacts the positioning tab  276 . Alternatively, contact by the lift platform  180  with the positioning tab  276  can be detected by detecting motor stall by comparing commanded motor steps to the encoder position. 
     After step  504 , in step  506 , the vertical position of the transporter  120  and the lateral extension of the lift platform  180  at which the loading drawer positioning tab  276  was contacted by the lift platform  180  are recorded and stored for future reference in positioning the lift platform  180  with respect to the loading drawer  280 . 
     In an alternative embodiment, the self-teaching process with respect to the loading drawer  280  is performed by contacting a positioning structure other than positioning tab  276 , such as, for example, a portion of the loading drawer  280  or some other protruding structure at a known position with respect to the holding shelf loading drawer  280 . 
     In step  508 , the transporter  120  is moved by the transport elevator  210  to a position adjacent to the expected location of a holding shelf  104 . In step  510 , the holding shelf positioning tab  108  is contacted with the lift platform  180 . The processor controls contact of the lift platform  180  with the holding shelf positioning tab  108  in any of the number of ways described above for controlling contact with the loading drawer positioning tab  276 . 
     After step  510 , in step  512 , the vertical position of the transporter  120  and the lateral extension of the lift platform  180  at which the holding shelf positioning tab  108  was contacted by the lift platform  180  are recorded and stored for future reference in positioning the lift platform  180  with respect to the holding shelf  104 . 
     In step  514 , steps  508  to  512  are repeated for all holding shelves  104 . 
     In an alternative embodiment, the self-teaching process with respect to each of the holding shelves  104  is performed by contacting a positioning structure other than positioning tab  108 , such as, for example, a portion of the holding shelf  104  or some other protruding structure at a known position with respect to the holding shelf  104 . 
     In step  516 , the transporter  120  is moved by the transport elevator  210  to a position adjacent to the expected location of the input module  230 . In step  518 , the input module positioning tab  256  is contacted with the lift platform  180 . The processor controls contact of the lift platform  180  with the input module positioning tab  256  in any of the number of ways described above for controlling contact with the loading drawer positioning tab  276 . 
     After step  518 , in step  520 , the vertical position of the transporter  120  and the lateral extension of the lift platform  180  at which the input module positioning tab  256  was contacted by the lift platform  180  are recorded and stored for future reference in positioning the lift platform  180  with respect to the input module  230 . 
     In an alternative embodiment, the self-teaching process with respect to the input module  230  is performed by contacting a positioning structure other than positioning tab  256 , such as, for example, a portion of the input module  230  or some other protruding structure at a known position with respect to the holding shelf input module  230 . 
     EMBODIMENTS 
     Embodiment 1. An apparatus for transporting groups of consumables between a plurality of vertically spaced holding shelves, the apparatus comprising: 
     a support chassis disposed at a laterally-spaced position with respect to the plurality of holding shelves; 
     a transport elevator coupled to the support chassis for moving the support chassis in a vertical direction between the plurality of holding shelves; 
     a lift platform; and 
     a scissors actuator connecting the lift platform to the support chassis and configured to translate the lift platform laterally with respect to the support chassis between a first position laterally aligned with the support chassis at the laterally-spaced position with respect to the plurality of holding shelves and a second position laterally displaced from the support chassis and laterally aligned with one of the holding shelves. 
     Embodiment 2. The apparatus of embodiment 1, further comprising a carrier configured to be carried on the lift platform and to be placed on any of the plurality of holding shelves. 
     Embodiment 3. The apparatus of embodiment 2, wherein the carrier comprises a base, a pair of support rails for slidably supporting the consumables thereon, and a resilient tab located at an end of each support rail and configured to releasably retain the consumables on the support rails. 
     Embodiment 4. The apparatus of embodiment 3, wherein each resilient tab is disposed at the end of a serpentine spring that is attached to or contiguous with a portion of the respective support rail. 
     Embodiment 5. The apparatus of any one of embodiments 1 to 4, wherein the transport elevator comprises: 
     two drive belts, each drive belt being attached to a portion of the support chassis; 
     a drive gear for each drive belt; 
     a motor coupled to the drive gears; and 
     an idler gear for each drive belt. 
     Embodiment 6 The apparatus of any one of embodiments 1 to 5, further comprising an elevator home sensor configured to detect a locator flag extending from the support chassis. 
     Embodiment 7. The apparatus of any one of embodiments 1 to 6, wherein the scissors actuator comprises a first arm having first and second ends and a second arm having first and second ends, wherein the first and second arms are rotatably connected to each other at intermediate positions between their respective first and second ends, wherein the first arm is pivotably attached at its first end to the support chassis and is pivotably and translatably attached at its second end to the lift platform, and wherein the second arm is pivotably and translatably attached at its first end to the support chassis and is pivotably attached at its second end to the lift platform. 
     Embodiment 8. The apparatus of embodiment 7, wherein the first and second arms are rotatably connected to each other by a slewing ring having an inner ring and an outer ring, wherein the inner and outer rings are rotatable with respect to each other, and wherein the first arm is attached to the inner ring at its respective intermediate position, and the second arm is attached to the outer ring at its respective intermediate position. 
     Embodiment 9. The apparatus of embodiment 7 or embodiment 8, wherein the second end of the first arm is pivotably and translatably attached to the lift platform by a slide that is slidably disposed within a linear slot formed in the lift platform, and wherein the slide is rotatably attached to the second end of the first arm. 
     Embodiment 10. The apparatus of embodiment 9, further comprising a roller bearing disposed within the slide that rolls against a side of the slot during lateral translation of the lift platform. 
     Embodiment 11. The apparatus of any one of embodiments 8 to 10, wherein the scissors actuator further comprises a motor coupled to the first end of the first arm to effect powered pivoting movement of the first arm. 
     Embodiment 12. The apparatus of any one of embodiments 1 to 11, wherein the scissors actuator is configured to translate the lift platform in either of two opposed lateral directions with respect to the support chassis. 
     Embodiment 13. The apparatus of any one of embodiments 1 to 12, further comprising a carrier detection sensor associated with each holding shelf and configured to detect the presence of a carrier on the associated holding shelf. 
     Embodiment 14. An apparatus comprising: 
     a plurality of vertically spaced holding shelves; 
     a transporter for transporting groups of consumables between the plurality of holding shelves, the transporter comprising: 
     a support chassis disposed at a laterally-spaced position with respect to the plurality of holding shelves; 
     a lift platform; and 
     a scissors actuator connecting the lift platform to the support chassis and configured to translate the lift platform laterally with respect to the support chassis between a first position laterally aligned with the support chassis at the laterally-spaced position with respect to the plurality of holding shelves and a second position laterally displaced from the support chassis and laterally aligned with one of the holding shelves; and 
     a transport elevator coupled to the support chassis for moving the support chassis in a vertical direction between the plurality of holding shelves. 
     Embodiment 15. The apparatus of embodiment 14, further comprising a carrier configured to hold the consumables, to be carried on the lift platform, and to be placed in any of the plurality of holding shelves. 
     Embodiment 16. The apparatus of embodiment 15, wherein each holding shelf includes a carrier detection sensor configured to detect the presence of a carrier on the corresponding holding shelf. 
     Embodiment 17. The apparatus of embodiment 15 or 16, wherein the carrier comprises a base, a pair of support rails for slidably supporting the consumables thereon, and a resilient tab located at an end of each support rail and configured to releasably retain the consumables on the support rails. 
     Embodiment 18. The apparatus of embodiment 17, wherein each resilient tab is disposed at the end of a serpentine spring that is attached to or a part of the respective support rail. 
     Embodiment 19. The apparatus of any one of embodiments 15 to 18, wherein the carrier includes at least one opening formed in the bottom thereof, and each holding shelf includes at least one carrier locator pin protruding from the holding shelf for engaging the opening formed in the carrier. 
     Embodiment 20. The apparatus of any one of embodiments 14 to 17, wherein the transport elevator comprises: 
     two drive belts, each drive belt being attached to a portion of the support chassis; 
     a drive gear for each drive belt; 
     a motor coupled to the drive gear; and 
     an idler gear for each drive belt. 
     Embodiment 21. The apparatus of any one of embodiments 14 to 20, wherein one of the holding shelves comprises a carrier support configured to be moveable in a lateral direction between a first position accessible by the transporter and a second position accessible by a user to load a plurality of consumables into the carrier support. 
     Embodiment 22. The apparatus of embodiment 14, further comprising a carrier configured to be carried on the lift platform and to be placed in any of the plurality of holding shelves, wherein one of the holding shelves comprises a carrier support configured to be moveable in a lateral direction between a first position accessible by the transporter and a second position accessible by a user to load a plurality of consumables into the carrier support, and wherein the carrier support comprises a carrier locking mechanism configured to lock the carrier within the carrier support when the carrier support is moved to the second position and to release the carrier when the carrier support is moved to the first position to permit the transporter to remove the carrier from the carrier support. 
     Embodiment 23. The apparatus of embodiment 22, wherein the carrier locking mechanism comprises: 
     a pivoting latch configured to pivot between a first position not engaged with a portion of the carrier and a second position engaged with a portion of the carrier; and 
     a slide latch configured to translate linearly between a first position not engaged with a portion of the carrier and a second position engaged with a portion of the carrier. 
     Embodiment 24. The apparatus of embodiment 23, further comprising: 
     a torsional spring coupled to the pivoting latch to bias the pivoting latch to its respective second position engaged with a portion of the carrier; and 
     a linear spring coupled to the slide latch to bias the slide latch to its respective second position engaged with a portion of the carrier. 
     Embodiment 25. The apparatus of embodiment 23 or embodiment 24, wherein the pivoting latch includes an upper end that engages a portion of a carrier on the carrier support when the carrier support is in the second position and the pivoting latch is in the second position and a lower end that contacts a hard stop when the carrier support is moved from the second position thereof to the first position thereof, thus causing the pivoting latch to rotate from the second position to the first position, thereby releasing the carrier supported on the carrier support; and 
     wherein the slide latch engages a portion of a carrier on the carrier support when the carrier support is in the second position and the slide latch is in the second position, and the slide latch contacts a hard stop that pushes slide latch into the first position when the carrier support is moved from the second position thereof to the first position thereof, thereby releasing the carrier supported on the carrier support. 
     Embodiment 26. The apparatus of any one of embodiments 15 to 19, wherein the carrier is longer than the lift platform so that first and second ends of the carrier extend beyond first and second ends of the lift platform, wherein each holding shelf comprises first and second shelf portions spaced apart by at least the length of the lift platform, and wherein the transporter is configured and controlled to transport a carrier supported on the lift platform from the lift platform to one of the plurality of holding shelves by: 
     a) moving the support chassis with the transport elevator to a vertical position at which the lift platform is above the holding shelf; 
     b) moving the lift platform laterally with the scissors actuator into a position at which the first and second ends of the carrier are aligned with the first and second shelf portions of the holding shelf; and 
     c) lowering the support chassis with the transport elevator to move the lift platform between the first and second shelf portions until the first and second ends of the carrier are supported on the first and second shelf portions. 
     Embodiment 27. The apparatus of embodiment 14, wherein each of the consumables comprises a multi-receptacle unit including a plurality of receptacles connected to each other in a side-by-side arrangement, wherein the apparatus further comprises a carrier configured to be carried on the lift platform and to be placed in any of the plurality of holding shelves and comprising a base, a pair of parallel support rails for slidably supporting the multi-receptacle units thereon with at least one of the receptacles of each multi-receptacle unit disposed between the support rails, and a resilient tab located at an end of each support rail and configured to releasably retain the multi-receptacle units on the support rails, and wherein one of the holding shelves comprises an input module configured to hold the carrier therein, the input module comprising a pusher configured to push one or more multi-receptacle units supported on the carrier toward an end of the carrier. 
     Embodiment 28. The apparatus of embodiment 27, wherein the input module is disposed on one side of the support chassis, and one or more of the remaining holding shelves are disposed on an opposed side of the support chassis, and wherein the scissors actuator is configured to translate the lift platform in either of two opposed lateral directions with respect to the support chassis. 
     Embodiment 29. The apparatus of embodiment 14, wherein each of the consumables comprises a multi-receptacle unit including a plurality of receptacles connected to each other in a side-by-side arrangement, and wherein the apparatus further comprises a carrier configured to be carried on the lift platform and to be placed in any of the plurality of holding shelves and comprising: a base, a pair of parallel support rails for slidably supporting the multi-receptacle units thereon with at least one of the receptacles of each multi-receptacle unit disposed between the support rails, and a stop flange located at an end of each support rail. 
     Embodiment 30. The apparatus of embodiment 29, wherein at least one of the holding shelves comprises a packing mechanism configured to move with respect to the carrier held in the holding shelf and to push the multi-receptacle units carried on the carrier until an end-most one of the multi-receptacle units is pushed off the support rails. 
     Embodiment 31. The apparatus of embodiment 30, further comprising a packing mechanism position sensor configured to detect a stop position of the packing mechanism at which the end-most one of the multi-receptacle units is pushed off the support rails and to determine the number of multi-receptacle units carried on the carrier based on the detected stop position. 
     Embodiment 32. The apparatus of any one of embodiments 14 to 31, further comprising: 
     position sensor mechanisms for detecting a vertical position of the support chassis and a lateral position of the lift platform; and 
     a controller for controlling the transport elevator and the scissors actuator and in communication with the positon sensor mechanisms; 
     wherein the controller is configured to record a position of each holding shelf by moving the lift platform with respect to each holding shelf until the lift platform contacts a positioning tab of the holding shelf and recording the vertical position of the support chassis and the lateral position of the lift platform detected by the position sensor mechanisms at which the lift platform contacts the positioning tab. 
     Embodiment 33. A carrier support for holding a carrier, wherein the carrier is configured to hold a plurality of receptacles, wherein the carrier support is configured to be moveable between a first position and a second position, and wherein the carrier support comprises a carrier locking mechanism configured to lock the carrier with respect to the carrier support when the carrier support is moved to the second position and to release the carrier when the carrier support is moved to the first position to permit the carrier to be moved with respect to the carrier support when the carrier support is in the first position, wherein the carrier locking mechanism comprises: 
     a pivoting latch configured to pivot between a first position not engaged with a portion of the carrier and a second position engaged with a portion of the carrier; and 
     a slide latch configured to translate linearly between a first position not engaged with a portion of the carrier and a second position engaged with a portion of the carrier. 
     Embodiment 34. The carrier support of embodiment 33, further comprising: 
     a torsional spring coupled to the pivoting latch to bias the pivoting latch to its respective second position engaged with a portion of the carrier; and 
     a linear spring coupled to the slide latch to bias the slide latch to its respective second position engaged with a portion of the carrier. 
     Embodiment 35. The carrier support of embodiment 33 or embodiment 34, wherein the pivoting latch includes an upper end that engages a portion of a carrier on the carrier support when the carrier support is in the second position and the pivoting latch is in the second position and a lower end that contacts a hard stop when the carrier support is moved from the second position thereof to the first position thereof, thus causing the pivoting latch to rotate from the second position to the first position, thereby releasing the carrier supported on the carrier support; 
     and 
     wherein the slide latch engages a portion of a carrier on the carrier support when the carrier support is in the second position and the slide latch is in the second position, and the slide latch contacts a hard stop that pushes the slide latch into the first position when the carrier support is moved from the second position thereof to the first position thereof, thereby releasing the carrier supported on the carrier support. 
     Embodiment 36. An input module comprising: 
     a carrier shelf for receiving and supporting a carrier holding a plurality of receptacles; 
     a retrieval dock adjacent the carrier shelf and configured to receive one receptacle from a carrier supported on the carrier shelf and present the receptacle for removal from the input module by a receptacle transport apparatus; and 
     a pusher configured to push one or more receptacles held on the carrier supported on the carrier shelf to one end of the carrier and to push one receptacle at a time off the end of the carrier and onto the retrieval dock. 
     Embodiment 37. The input module of embodiment 36, wherein the pusher comprises: 
     a pusher carriage coupled to a pusher track and configured to translate bi-directionally along the track; and 
     a pusher arm projecting from the pusher carriage. 
     Embodiment 38. The input module of embodiment 37, wherein the pusher arm comprises: 
     an upright portion extending upwardly from the pusher carriage; 
     a lateral portion extending laterally from an end of the upright portion; and 
     a contact portion extending downwardly from the lateral portion. 
     Embodiment 39. The input module of embodiment 38, wherein a carrier supported on the carrier shelf includes a pair of parallel support rails for slidably supporting a plurality of receptacles thereon with at least a portion of each receptacle disposed between the support rails, and wherein the contact portion is aligned with a gap between the support rails so that as the pusher translates along the pusher track, the contact portion moves between the support rails and contacts the portion of the receptacle that is disposed between the support rails. 
     Embodiment 40. The input module of embodiment 39, wherein the receptacle comprises a plurality of cylindrical tubes connected to one another by a connecting rib structure defining a downwardly facing shoulder, wherein at least one of the cylindrical tubes is disposed between the support rails and a portion of the downwardly-facing shoulder is supported on top of the support rails. 
     Embodiment 41. The input module of any one of embodiments 37 to 40, wherein the pusher further comprises: 
     a pusher drive belt attached to the pusher carriage; and 
     a pusher motor coupled to the pusher drive belt for effecting powered translation of pusher carriage along the pusher track. 
     Embodiment 42. The input module of any one of embodiments 36 to 41, further comprising a sensor configured to detect when one of the receptacles has been pushed onto the retrieval dock. 
     Embodiment 43. The input module of any one of embodiments 36 to 42, further comprising a guide plate adjacent the retrieval dock and configured to align the receptacle on the retrieval dock with a receptacle transport apparatus. 
     Embodiment 44. The input module of any one of embodiments 36 to 43, further comprising at least one carrier locator pin protruding from the carrier shelf for engaging an opening formed in a carrier supported by the carrier shelf and to restrict relative movement between the carrier shelf and the carrier supported thereby. 
     Embodiment 45. The input module of any one of embodiments 36 to 44, further comprising: 
     a position encoder for detecting a longitudinal position of the pusher; and 
     a controller configured to receive longitudinal position data from the position encoder and to determine the number of receptacles held on a carrier supported on the carrier shelf when the pusher is positioned in contact with an end-most receptacle of one or more receptacles held on the carrier. 
     Embodiment 46. The input module of any one of embodiments 36 to 45, further comprising a pusher home sensor configured to detect when the pusher has moved to a home position. 
     Embodiment 47. A processing instrument comprising: 
     the input module of any one of embodiments 36 to 46; and 
     a receptacle transport apparatus configured to remove a receptacle from the retrieval dock of the input module and transport the receptacle within the processing instrument. 
     Embodiment 48. A carrier for holding a plurality of multi-receptacle units, each multi-receptacle unit including a plurality of receptacles connected to each other in a side-by-side arrangement, wherein the carrier comprises: 
     a pair of parallel support rails for slidably supporting the multi-receptacle units thereon with at least one of the receptacles of each multi-receptacle unit disposed between the support rails, and 
     a resilient tab associated with each support rail and configured to releasably retain the multi-receptacle units on the support rails. 
     Embodiment 49. The carrier of embodiment 48, wherein each resilient tab is disposed at the end of a serpentine spring. 
     Embodiment 50. The carrier of embodiment 49, wherein each serpentine spring is an integral portion of each associated support rail. 
     Embodiment 51. The carrier of any one of embodiments 48 to 50, wherein the support rails are made from spring steel. 
     Embodiment 52. The carrier of any one of embodiments 48 to 51, further comprising a carrier base comprising a first end, a second end, and a connecting portion extending between the first end and the second end, wherein the connecting portion is generally narrower than the first and second ends. 
     Embodiment 53. The carrier of embodiment 52, wherein the support rails are attached to opposed edges of the connecting portion. 
     Embodiment 54. The carrier of any one of embodiments 48 to 51, further comprising a carrier base with one or more locator holes formed in the bottom of the carrier base. 
     Embodiment 55. The carrier of embodiment 54, comprising one locator hole at a first end of the carrier base and a locator slot at a second end of the carrier base. 
     Embodiment 56. The carrier of embodiment 54 or embodiment 55, comprising two locator holes at a first end of the carrier base and two locator slots at a second end of the carrier base. 
     Embodiment 57. A scissors actuator configured to translate a support platform in either of opposed lateral directions with respect to a base frame, the scissors actuator comprising: 
     a first arm having first and second ends; 
     a second arm having first and second ends, wherein the first and second arms are rotatably connected to each other at intermediate positions between their respective first and second ends, wherein the first arm is pivotably attached at its first end to the base frame and the second arm and is pivotably attached at its second end to the support platform; 
     a first slide disposed within a first linear track formed in the support platform and including a bearing protruding from a side of the first slide for rolling contact with a side of the first linear track formed in the support platform, wherein the first arm is pivotably and translatably attached at its second end to the support platform by the first slide, and 
     a second slide disposed within a second linear track formed in the base frame and including a bearing protruding from a side of the second slide for rolling contact with a side of the second linear track formed in the base frame, wherein the second arm is pivotably and translatably attached at its first end to the base frame by the second slide. 
     Embodiment 58. The scissors actuator of embodiment 57, wherein the first and second arms are rotatably connected to each other by a slewing ring having an inner ring and an outer ring, wherein the inner and outer rings are rotatable with respect to each other, and wherein the first arm is attached to the inner ring at its respective intermediate position, and the second arm is attached to the outer ring at its respective intermediate position. 
     Embodiment 59. The scissors actuator of embodiment 57 or embodiment 58, further comprising a motor coupled to the first end of the first arm to effect powered pivoting movement of the first arm. 
     Embodiment 60. The scissors actuator of embodiment 59, further comprising an encoder coupled to the motor or to the first arm. 
     Embodiment 61. The scissors actuator of any one of embodiments 57 to 60, wherein the scissors actuator is configured to translate the support platform in either of two opposed lateral directions with respect to the base frame. 
     Embodiment 62. A method for automatically transferring a receptacle carrier between a holding shelf and a lift platform of a transporter, the method comprising: 
     a) with a transport elevator for effecting vertical movement of the transporter, positioning the transporter at an approximate vertical location of the holding shelf; 
     b) after step a), effecting relative movement between the lift platform and a positioning structure associated with the holding self; 
     c) during step b), detecting contact between the lift platform and the positioning structure; 
     d) recording data relating to the position of the lift platform at which contact is detected in step c); and 
     e) transferring a receptacle carrier between the holding shelf and the lift platform by controlling movement of the lift platform in accordance with the data recorded at step d). 
     Embodiment 63. The method of embodiment 62, wherein step b) comprises one or both of (1) effecting vertical movement of the lift platform with respect to the holding shelf with the transport elevator and (2) effecting lateral movement of the lift platform with a lateral actuator. 
     Embodiment 64. The method of embodiment 63, wherein step a) comprises positioning the transporter such that the vertical position of the lift platform is below an expected vertical location of the positioning structure, and step b) comprises: 
     b-1) moving the lift platform laterally with the lateral actuator until the lift platform is positioned below an expected location of the positioning structure; and 
     b-2) after step b-1), raising the transporter and lift platform with the transport elevator until contact is detected in step c). 
     Embodiment 65. The method of embodiment 63, wherein step a) comprises positioning the transporter such that the vertical position of the lift platform is above an expected vertical location of the positioning structure, and step b) comprises: 
     b-1) moving the lift platform laterally with the lateral actuator until the lift platform is positioned above an expected location of the positioning structure; and 
     b-2) after step b-1), lowering the transporter and lift platform with the transport elevator until contact is detected in step c). 
     Embodiment 66. The method of embodiment 63, wherein step a) comprises positioning the transporter such that the vertical position of the lift platform is the same as an expected vertical location of the positioning structure, and step b) comprises moving the lift platform laterally with the lateral actuator until contact is detected in step c). 
     Embodiment 67. The method of any one of embodiments 62 to 66, wherein step e) comprises transferring a receptacle carrier from the lift platform to the holding shelf by: 
     supporting the receptacle carrier on the lift platform with opposed ends of the receptacle carrier extending beyond opposed ends of the lift platform; 
     with the transport elevator, and using the data recorded at step d), positioning the transporter at a vertical position so that the lift platform is above the holding shelf; 
     effecting lateral movement of the lift platform with a lateral actuator and using the data recorded at step d) so that the lift platform is disposed within an open area between a first shelf portion and a second shelf portion of the holding shelf and the opposed ends of the receptacle carrier are positioned above the first and second shelf portions; and 
     with the transport elevator, lowering the lift platform until the opposed ends of the receptacle carrier are supported on the first and second shelf portions, and the receptacle carrier is not supported on the lift platform. 
     Embodiment 68. The method of any one of embodiments 62 to 66, wherein step e) comprises transferring a receptacle carrier from the holding shelf to the lift platform by: 
     supporting opposed ends of the receptacle carrier on a first shelf portion and a second shelf portion of the holding shelf; 
     with the transport elevator, and using the data recorded at step d), positioning the transporter at a vertical position so that the lift platform is below the holding shelf; 
     effecting lateral movement of the lift platform with a lateral actuator and using the data recorded at step d) so that the lift platform is aligned with an open area between the first and second shelf portions; and 
     with the transport elevator, raising the lift platform until the receptacle carrier is supported on the lift platform with the opposed ends of the receptacle carrier extending beyond opposed ends of the lift platform and the opposed ends of the receptacle carrier are lifted off the first and second shelf portions. 
     Embodiment 69. A method for determining the number of receptacles supported by a carrier, the method comprising: 
     a) placing the carrier with one or more receptacles supported thereby on a carrier shelf; 
     b) pushing the one or more receptacles to one end of the carrier with a packer positioned adjacent the carrier shelf; 
     c) detecting a longitudinal position of the packer when the one or more receptacles have been pushed to the one end of the carrier; and 
     d) determining the number of receptacles held on the carrier based on the longitudinal position of the packer. 
     Embodiment 70. The method of embodiment 69, wherein step a) comprises transferring the carrier from a lift platform to the carrier shelf by: 
     supporting the carrier on the lift platform with opposed ends of the carrier extending beyond opposed ends of the lift platform; 
     with a transport elevator, positioning the lift platform above the carrier shelf; 
     effecting lateral movement of the lift platform with a lateral actuator so that the lift platform is disposed within an open area between a first shelf portion and a second shelf portion of the carrier shelf and the opposed ends of the carrier are positioned above the first and second shelf portions; and 
     with the transport elevator, lowering the lift platform until the opposed ends of the carrier are supported on the first and second shelf portions, and the carrier is not supported on the lift platform. 
     Embodiment 71. The method of embodiment 69 or embodiment 70, wherein the packer comprises: 
     a packer carriage coupled to a packer track and configured to translate bi-directionally along the track; 
     a contact portion projecting from the packer carriage; 
     a packer drive belt attached to the packer carriage; and 
     a packer motor coupled to the packer drive belt for effecting powered translation of the packer carriage along the packer track. 
     Embodiment 72. The method of embodiment 71, wherein step c) comprises detecting output of the packer motor by a rotary encoder coupled to the packer motor or detecting output of the packer motor by motor steps. 
     Embodiment 73. A method for packing a plurality of receptacles supported by a carrier, the method comprising: 
     a) placing the carrier with a plurality of receptacles supported thereby on a carrier shelf; 
     b) contacting an end-most one of the receptacles with a packer positioned adjacent the carrier shelf, wherein the packer comprises a packer carriage coupled to a packer track and configured to translate bi-directionally along the track; and a contact portion projecting from the packer carriage; and 
     c) pushing the plurality of receptacles to one end of the carrier with the packer to pack the receptacles in a stack. 
     Embodiment 74. The method of embodiment 73, wherein a carrier supported on the carrier shelf includes a pair of parallel support rails for slidably supporting a plurality of receptacles thereon with at least a portion of each receptacle disposed between the support rails, and wherein step c) comprises contacting an end-most one of the receptacles with the packer by aligning the contact portion with a gap between the support rails so that as the packer carriage translates along the packer track, the contact portion moves between the support rails and contacts the portion of the end-most receptacle that is disposed between the support rails. 
     Embodiment 75. The method of embodiment 74, wherein the carrier includes a hard stop at an end of each support rail, and wherein step c) comprises pushing the plurality of receptacles against the hard stops. 
     Embodiment 76. The method of embodiment 74 or embodiment 75, wherein the receptacle comprises a plurality of cylindrical tubes connected to one another by a connecting rib structure defining a downwardly facing shoulder, wherein at least one of the cylindrical tubes is disposed between the support rails and a portion of the downwardly-facing shoulder is supported on top of the support rails. 
     Embodiment 77. The method of embodiment 76, wherein the packer further comprises a horizontal portion that contacts a portion of the end-most receptacle extending above the support rails to keep the receptacles generally perpendicular to a longitudinal direction of the support rails. 
     Embodiment 78. The method of any one of embodiments 73 to 77, wherein the packer further comprises: 
     a packer drive belt attached to the packer carriage; and 
     a packer motor coupled to the packer drive belt for effecting powered translation of packer carriage along the packer track. 
     Embodiment 79. The method of any one of embodiments 73 to 77, further comprising 
     detecting a longitudinal position of the packer during step c); and 
     determining the number of receptacles held on the carrier based on the longitudinal position of the packer. 
     Embodiment 80. The method of embodiment 79, wherein the packer further comprises a packer drive belt attached to the packer carriage; and a packer motor coupled to the packer drive belt for effecting powered translation of packer carriage along the packer track, and wherein detecting the longitudinal position of the packer during step c) comprises using a home sensor to detect an initial position of the packer along the packer track and an encoder coupled to the packer motor to detect a number of encoder counts associated with a motorized packer movement from the initial position. 
     Embodiment 81. A method for presenting multi-receptacle units for retrieval by an automated receptacle distributor of a processing instrument, each multi-receptacle unit including a plurality of receptacles connected to each other in a side-by-side arrangement, the method comprising: 
     a) placing a carrier with one or more multi-receptacle units held thereon on a carrier shelf, wherein the carrier comprises a pair of parallel support rails for slidably supporting the multi-receptacle units thereon with at least one of the receptacles of each multi-receptacle unit disposed between the support rails; 
     b) contacting an end-most one of the receptacles with a pusher positioned adjacent the carrier shelf, the pusher comprising a contact portion configured to move between the support rails and contact the receptacle disposed between the support rails; and 
     c) pushing the plurality of multi-receptacle units along the support rails toward one end of the carrier with the pusher until an end-most one of the multi-receptacle units is pushed off the support rails and onto a retrieval dock adjacent to the carrier shelf. 
     Embodiment 82. The method of embodiment 81, further comprising: 
     detecting when the one of the plurality of multi-receptacle units is pushed off the support rails and onto the retrieval dock; and 
     stopping the pusher from further pushing the one or more multi-receptacle units toward the one end of the carrier. 
     Embodiment 83. The method of embodiment 81 or embodiment 82, further comprising retrieving the one multi-receptacle unit from the retrieval dock with a receptacle transport mechanism of the processing instrument. 
     Embodiment 84. The method of embodiment 83, wherein the receptacle transport mechanism comprises an extendible and retractable hook and the multi-receptacle unit comprises a manipulating structure, and wherein retrieving the one receptacle from the retrieval dock with a receptacle transport mechanism comprises extending the hook, engaging the manipulating structure with the extended hook, and retracting the hook to pull the multi-receptacle unit from the retrieval dock into a housing of the receptacle transport mechanism. 
     Embodiment 85. The method of any one of embodiments 81 to 84, further comprising: 
     during step c), detecting a longitudinal position of the pusher when the multi-receptacle unit is pushed off the support rails; and 
     determining the number of multi-receptacle units held on the carrier based on the longitudinal position of the pusher. 
     Embodiment 86. The method of any one of embodiments 81 to 85, wherein step a) comprises transferring the carrier from a lift platform to the carrier shelf by: 
     supporting the carrier on the lift platform with opposed ends of the carrier extending beyond opposed ends of the lift platform; 
     with a transport elevator, positioning the lift platform above the carrier shelf; 
     effecting lateral movement of the lift platform with a lateral actuator so that the lift platform is disposed within an open area between a first shelf portion and a second shelf portion of the carrier shelf and the opposed ends of the carrier are positioned above the first and second shelf portions; and 
     with the transport elevator, lowering the lift platform until the opposed ends of the carrier are supported on the first and second shelf portions, and the carrier is not supported on the lift platform. 
     Embodiment 87. The method of any one of embodiments 81 to 86, wherein the pusher further comprises: 
     a pusher carriage coupled to a pusher track and configured to translate bi-directionally along the track; 
     a pusher arm comprising the contact portion and projecting from the pusher carriage; 
     a pusher drive belt attached to the pusher carriage; and 
     a pusher motor coupled to the pusher drive belt for effecting powered translation of pusher carriage along the pusher track. 
     Embodiment 88. The method of any one of embodiments 81 to 87, further comprising, prior to step c), retaining the one or more multi-receptacle units on the support rails with spring-biased retainer tabs that releasably engage the end-most one of the multi-receptacle units, wherein the spring-biased retainer tabs are configured to deflect laterally during step c) to permit the end-most one of the multi-receptacle units to be pushed off the support rails. 
     While the subject matter of this disclosure has been described and shown in considerable detail with reference to certain illustrative embodiments, including various combinations and sub-combinations of features, those skilled in the art will readily appreciate other embodiments and variations and modifications thereof as encompassed within the scope of the present disclosure. Moreover, the descriptions of such embodiments, combinations, and sub-combinations are not intended to convey that the claimed subject matter requires features or combinations of features other than those expressly recited in the claims. Accordingly, the scope of this disclosure is intended to include all modifications and variations encompassed within the scope of the following appended claims.