Automated materials storage system and method

A system and method for automatically storing and retrieving loads of materials from a high-rise storage warehouse including providing for electronic identification of materials at a remote storage operator station and thereafter activating a CPU to (a) electronically verify the acceptability of the materials, (b) assign a transaction code to the data bit representation of the identification of the load, and (c) select an address in the high-rise storage warehouse for the load. The load is accompanied by the transaction code in machine-readable form and then moved to a pickup station adjacent the high-rise storage warehouse. Proper alignment of the load is then electronically verified and the transaction code is communicated to the CPU to identify which materials are on the pickup station. A storage-retrieval (S/R) machine is dispatched at the command of the CPU to move the load to its CPU-assigned address in the high-rise storage warehouse. In retrieving the goods, a request is entered at the storage operator station and the CPU scans all inventory to identify materials which will match the request. Then the CPU identifies the address in the high-rise storage warehouse of the requested materials and dispatches the S/R machine to retrieve the materials and place the load upon the pickup station. As soon as a lift truck is available to remove the load, the CPU is asked for a move-ticket which is then printed in man-readable form by the CPU, the move-ticket identifying the pickup and deposit station where the load is located and such other information as may be desirable. When the load is taken from the pickup and deposit station, the load description is deleted from CPU memory automatically.

BACKGROUND 
1. Field of the Invention 
This invention relates to automated materials storage systems and methods 
and more particularly to a system and method for storing and retrieving 
unit storage loads through utilization of computer-controlled 
in-processing and out-processing. 
2. The Prior Art 
The problems with materials handling are well known in the art. 
Particularly where the conventional warehousing and storge systems are 
used, it is common for a forklift or the like to move materials from a 
truck or train dock into a warehouse where the goods are stored in an area 
generally designated for the type of goods received. The storage location 
of the goods is dependent upon the availability of warehousing space and 
accessibility requirements. It is well known that this technique consumes 
an enormous amount of time, space and records. It is also well known that 
this system tends to create many errors in the retrieval of goods. 
Even where mechanized warehousing systems are used, it is conventional for 
a variety of lift truck drivers to each assume the responsibility for 
identifying the goods to be stored and for placing the thus identified 
goods into the mechanized storage system. Using a number of people to 
perform the identification function significantly increases the risk that 
the goods will be erroneously identified and stored in an improper 
location. Subsequently, when retrieval of the goods is attempted, they 
cannot be found. 
Through conventional prior art systems, it is also well known that a single 
pickup and deposit station cannot be used both for input and output of 
goods from the storage warehouse because of the high risk that incoming 
and outgoing goods will be confused and mixed up. 
BRIEF SUMMARY AND OBJECTS OF THE INVENTION 
The present invention significantly advances the art of automated high-rise 
storage systems by combining the accuracy of computerized management of 
materials handling with the utility and lower cost of forklift trucks for 
moving materials to and from the high-rise storage area. 
The high incidence of error in describing goods being stored in the system 
is avoided in the present invention by providing for identification and 
description of the goods by a specialized operator at a control location, 
the description being transmitted to a computer whereupon a transaction 
code is identified to the goods. A physical ticket bearing the transaction 
code accompanies the goods in transit. The goods are accepted for storage 
only when the transaction code is submitted to the computer for 
acceptance. Goods are retrieved from storage upon request from a 
specialized operator and the computer keeps track of the goods and issues 
instructions to pick up the goods at a specified pickup station thereby 
minimizing risk of human error in obtaining the goods. 
It is, therefore, a primary object of the present invention to provide an 
improved system and method for identifying, storing and retrieving goods 
with a minimum of human error. 
It is another primary object of the present invention to provide the 
accuracy of a computer-managed storage system while retaining the lower 
cost and utility of using forklift trucks to and from the high-rise 
storage area. 
It is another valuable object of the present invention to provide efficient 
computer management of materials flow into and out of a high-rise storage 
system. 
Another valuable object of the present invention is to provide a novel and 
useful method whereby the need for separate input and output stations is 
eliminated. 
It is another valuable object of the present invention to provide system 
and method for generating a transaction code in machine-readable form to 
accompany goods in transit to a high-rise storage warehouse. 
Another object of the present invention is to provide system and method for 
verifying alignment of the load of goods prior to storage in the high-rise 
warehouse. 
One still further valuable object of the present invention is to provide 
system and apparatus for storing a library of descriptions of acceptable 
goods and comparing each load of incoming goods with the library to 
determine the acceptability of the incoming goods. 
Another object of the present invention is to provide system and method for 
electronically ascertaining the status of goods, whether incoming or 
outgoing to permit a single station to be used for receiving and 
discharging goods. 
It is another object of the present invention to provide system and method 
for electronically preparing instructions for the pickup of ordered goods 
at a specified location as the goods become available for pickup. 
These and other objects and features of the present invention will become 
more fully apparent from the following description and appended claims 
taken in conjunction with the accompanying drawing.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Reference is now made to figures illustrating presently preferred 
embodiments of the system and the method of the invention. 
THE AUTOMATED WAREHOUSING SYSTEM 
Until relatively recent times, inefficiency in areas where goods were 
warehoused and stored was grudgingly accepted. Picking errors, pilferage, 
slow service, wasted space, and employee turnover were simply regarded as 
inherent characteristics of warehouse operations, large and small. 
More recently, however, automated pallet storage has been used to improve 
space utilization, inventory control, production speedup and efficiency. A 
pallet storage system, sometimes referred to as a unit load system, is 
characterized by its capacity to store and retrieve a load of goods 29 as 
a single unit. In this specification, the unit load of goods 29 may be a 
single container or a pallet upon which one or more containers of goods 
are stacked. This system is distinguished from a small parts storage 
system where parts are placed in an open bin which is stocked and picked 
as required. 
A modified unit load system comprises part of the illustrated embodiment of 
the present invention schematically illustrated in FIG. 1. With reference 
to FIG. 1, a high-rise storage warehouse assembly 32 is schematically 
illustrated. The high-rise storage assembly 32 comprises an array of 
vertically stacked bays 33. Each bay is arranged in a horizontal tier. 
Each bay 33 corresponds to a computer address representing its location in 
the high-rise storage assembly 32. Each high-rise storage assembly 32 is 
mounted back-to-back with another similar high-rise storage assembly 32 so 
as to face outwardly. Accordingly, the face 35 of each high-rise storage 
assembly 32 projects toward an aisle generally designated 37. 
A storage-retrieval (S/R) machine generally designated 30 is mounted upon 
tracks schematically illustrated at 39 for longitudinal movement up and 
down each aisle 37. For ease of illustration, only one S/R machine is 
illustrated in FIG. 1. The S/R machine has a chassis 43 with wheels (not 
shown) which engage the tracks 39. An upstanding mast 45 is mounted upon 
the chassis and is typically associated with an overhead guide rail 47. A 
lift plate shuttle 41 is mounted upon the mast 45 and is vertically 
movable thereon. As will be hereinafter more fully described, the S/R 
machine is electronically commanded to move to an address in the high-rise 
storage 32 and moves up and down the aisles 37 to the addressed vertical 
array whereupon the lift plate shuttle 41 is elevated to the addressed 
tier. The lift plate shuttle then automatically moves the unit load of 
goods 29 into or out of the appropriate bay 33 upon command. 
Representative of the apparatus accomplishing the described result are 
U.S. Pat. Nos. 3,632,001 and 3,784,791, herein incorporated by reference. 
With continued reference to FIG. 1, each high-rise storage assembly 32 is 
provided with a pickup and delivery station (P and D station) generally 
designated 26 and 27. In the embodiment illustrated in FIG. 1, P and D 
stations 26 are shown with a unit load 29 thereon while P and D stations 
27 are illustrated empty. The P and D stations employed with the presently 
preferred embodiment of the invention are more fully illustrated in FIG. 2 
and will be hereinafter more fully described. 
The S/R machine 30 has the capacity to remove the unit load 29 from either 
of the P and D stations on the right or left of the aisle 37. Typically, 
the S/R machine will remove a load from one P and D station, take the load 
to its computer-assigned address in the high-rise storage assembly 32 and 
deposit the load in the appropriate bay 33. An order for a load stored in 
another bay 33 in the high-rise storage assembly 32 will be communicated 
to the S/R machine which will retrieve the ordered load and return it to 
the empty P and D station. A suitable S/R machine which will perform the 
described tasks is manufactured by Kenway Inc. of Salt Lake City, Utah 
under the name Kenway Unit Load S/R Machine. 
In the embodiment of FIG. 1, an aisle input-output terminal (I/O terminal) 
24 is located in each aisle 37. Each aisle terminal 24, each P and D 
station 26 or 27 and each S/R machine 30 is connected to a central 
computer (CPU) 22 through electrical cables 33-35. Furthermore, the CPU 22 
is connected by an electrical cable 38 to a station operator console 
generally designated 12. The operator station 12 is equipped with a 
conventional computer terminal 14 comprising a keyboard and cathode-ray 
tube (CRT), a card reader 16 and a ticket printer 20. A line printer 19, 
connected through cable 17 has also been found desirable. The line printer 
19 makes possible a variety of management reports concerning the goods in 
storage and transit. For example, it may be desirable to print reports on 
the quantity of goods in storage, age of goods and utilization of 
equipment. Also of interest is the location of empty storage bays, the 
content of each bay, receipts and disbursals and a list of part numbers or 
description of materials in storage. The printer 19 is preferable on line 
with the CPU and may be controlled through the terminal 14 or time 
initiated, as desired, to print selected contents of the CPU memory 40, 
hereinafter more fully described. 
The interaction of the CPU with the various peripheral devices and the 
purpose of each of the peripheral devices is best understood by reference 
to FIG. 3. 
The storage operator station 12 provides one central location where a 
single skilled operator can electronically enter information describing 
incoming or outgoing material to the CPU 22. The CPU 22 has a memory 40 
having segregated files, for convenience designated retrieval file 42, 
storage inventory file 44, part number file 46, in-processing transaction 
file 48 and out-processing transaction file 49. The files 42, 44, 46, 48 
and 49 in memory 40 are used by the CPU in identifying and keeping track 
of the physical location of the goods while both in storage and in transit 
into or out of the high-rise storage warehouse 32. The part number file 46 
contains an established listing of descriptions of goods, such as part 
numbers of all goods acceptable for storage within the high-rise storage 
warehouse 32. This file 46 is used by the CPU in comparing and verifying 
the correctness of part numbers or other descriptions entered at the 
storage operator station 12. The transaction files 48 and 49 are used by 
the CPU to keep track of which goods are in transit, either coming into or 
going out of the high-rise storage assembly 32, by storing information 
describing which goods are on the pickup and deposit station 26 at any 
given time. The storage inventory file 44 contains a listing and the 
computer-assigned addresses of all goods in storage within the high-rise 
storage assembly 32. The retrieval file 42 includes a queue used by the 
CPU to temporarily store information describing orders for outgoing goods. 
The CPU compares the information stored in the retrieval file 42 with the 
information in the storage inventory file 44 in determining whether the 
order can be filled from the inventory on hand. The label and move-ticket 
printer 20 is a device through which the CPU can print, in man-readable 
form, labels to be attached to the goods or instructions for picking up 
goods at assigned pickup stations. Goods in transit can be identified by 
the CPU at the operator station 12 by assigned transaction cards 18. The 
code carried by the cards 18 being recognized when transmitted from an 
aisle I/O terminal 24. The aisle I/O terminal 24 provides a way in which 
the CPU is informed of the transaction code of the goods located on the P 
and D station for pickup. The P and D station monitor generally designated 
51 (see also FIG. 2) monitors the availability of pickup and deposite 
stations and the alignment of loads on the station and communicates the 
monitored information to the CPU. Finally, the CPU controls the physical 
storage or retrieval of goods from the high-rise storage units 32 with the 
S/R machine 30. Having described the purpose of the various peripheral 
devices utilized within the automated storage system, attention is now 
turned to the method and preferred mode of operation of the system. 
IN-PROCESSING AND STORAGE 
The broken-line path 10 represents the general movement of the materials by 
forklift operators. The method for in-processing and storage begins when a 
forklift operator brings a load of materials to the operator station 12. 
Of course, any suitable mode of transporting the goods other than with 
forklifts could be used. Referring now to FIGS. 3 and 4, a trained storage 
operator will examine goods brought to the storage operator station 12 by 
the forklift driver (not shown) and the operator will enter information 
such as the part number and quantity of the goods or materials into the 
CPU from the CRT keyboard 14 at the operator station 12. one of the 
principal problems encountered in materials handling relates to entering 
the wrong description of materials into the CPU 22 at the storage operator 
station. Entry of the wrong description or part number through 
inadvertence will make subsequent retrieval of the goods difficult or 
impossible because the computer will remember the goods only as they have 
been incorrectly described to the CPU 22. In order to minimize the 
potential error in describing the goods to the CPU, the CPU is provided 
with a part number file 46 as part of the CPU memory. The part number file 
46 contains a permanent listing of all part numbers or other suitable 
description of acceptable mateials to be stored in the high-rise warehouse 
32. 
When the trained storage operator enters the part number and quantity of 
goods brought to the storage operator station 12 into the CPU 22, the CPU 
will compare the submitted part number with the part numbers listed in the 
part number file 46 of the CPU memory 40. If the part number received from 
the operator station 12 does not match any number in the list stored in 
file 46, the CPU 22 will send to the operator station 12 a request that 
the part number of the incoming materials be rechecked. If the part number 
received from the operator station 12 matches a description found in the 
file 46, the CPU will then accept a transaction code for assignment to the 
load of goods. 
In order to uniquely identify the described goods to the CPU in the 
illustrated embodiment, a transaction card 18 is fed into the card reader 
16 which in turn enters a transaction code into the in-processing file 48 
of CPU 22. The transaction code associated with the goods identified to 
the CPU 22 permits the CPU 22 to store the precise description of the 
goods without human error at the time the goods are accepted by the S/R 
machine. Human error is eliminated by transmitting the transaction code 
from the aisle I/O terminal 24 to the CPU 22 at the time the goods are 
accepted by the S/R machine 30. Note that no human interpretation of the 
goods description is necessary at the P and D station 26. Significantly, 
error in transmitting the transaction code to the CPU is minimized by 
obtaining the code in machine-readable form at the storage operator 
station 12 and physically associating the code with the goods prior to 
movement of the goods along the path 10 (FIG. 1) to the pickup and 
deposite station 26. 
Alternatively, error in transmitting the transaction code may be minimized 
by printing the code in man-readable form and including as part of the 
code at least one check digit. The check digit technique is a well-known 
method of verifying the accuracy of a particular number sequence. The 
check digit may, for example, be electronically verified from a 
mathematical operation on the transaction code. When the code has been 
transmitted, the CPU 22 can verify the accuracy of the transaction code by 
performing the mathematical operation and comparing the result thereof 
with the check digit. 
The assignment of the transaction code could be accomplished in any one of 
several alternative ways. For example, the CPU may select a number from 
the in-processing transaction file 48 and print the code on a transaction 
card at the storage operator station 12 (FIG. 1). The transaction code is 
then stored in the transaction number file 48 of the CPU memory 22 (FIG. 
3). The transaction code is later used to identify the load while it is 
still is transit before being stored. At this point it should be noted 
that the transaction code assigned to a given load can only be assigned at 
the storage operator station 12. This eliminates the need for more than 
one skilled operator. Furthermore, the transaction code is only assigned 
after the CPU 22 has verified and identified the incoming goods. This will 
greatly reduce the possibility of incorrectly identifying the goods at the 
P and D station 26 as will be hereinafter more fully described, since a 
forklift operator merely reenters the assigned transaction code which the 
CPU uses to automatically identify the goods waiting at the P and D 
station 26. 
After the CPU 22 has associated the transaction code with the load of goods 
in memory 40, a physical form of the transaction code is attached to the 
load of goods as described above. This attachment may, for example, 
include placing the transaction card 18 with the goods. The card may, if 
desired, be secured by taping, tying or otherwise suitably attaching the 
card to the load 29. Alternatively, it may be desirable to have the CPU 22 
print a transaction code from the file 48. The CPU then causes the ticket 
printer (not shown) at the storage operator station 12 to generate a 
man-readable label which is secured to the load. This label may include 
descriptive information in man-readable form to enable personnel to read 
the part number and quantity of material on the load. The load 29, with 
both the label and the transaction card is next moved in the general 
direction of path 10 (shown in FIG. 1) by a forklift operator to a pickup 
and deposit station 26. 
Pickup and deposit stations 26 and 27 are illustrated in FIG. 1. A more 
schematic representation of the pickup and deposit stations are 
illustrated in FIG. 2. Referring now to FIG. 2, it is observed that each 
pickup and deposit station 26 has four load supports 52 spaced so as to 
receive a pallet 21 illustrated in broken lines in FIG. 2. If desired, the 
supports 52 may be provided with flanges (not shown) which guide the 
pallet 21 toward an alignment position as the pallet 21 is lowered upon 
the supports 52. The pallet 21 is illustrated as supporting a load 29 also 
illustrated in broken lines. 
Desirably, the pickup and deposit station 26 is provided with an alignment 
verification and pickup and delivery station monitor system generally 
designated 51. The purpose for the monitor 51 is to ensure that the load 
29 will fit properly into the bays 33 (FIG. 1) when the load 29 is 
inserted therein by the S/R machine 30. The pallet 21 is selected to be 
the appropriate size to fit within the bays 33. Accordingly, it is of 
primary concern that the load 29 not exceed the height of the bay 33 and 
that the load not be twisted on the pallet 21 so that a corner of the load 
would catch as the load is inserted into the bay. The alignment 
verification system 51 is an example of a suitable structure for detecting 
the described alignment difficulties. 
Each alignment verification system 51 has three vertical cylindrical posts 
50 which contain photocells 53. When two P and D stations are side by 
side, the alignment system 51 can cover both with four posts 50 as 
illustrated in FIG. 2. The photocells 52 are positioned in such a manner 
that if the load is twisted at an angle or if the load is too tall the 
light beams produced by the photocells will be interrupted, thereby 
generating a signal which is communicated to the CPU and notifying the CPU 
that the load is improperly aligned. Alignment of the load 29 is verified 
by creating a light beam 54 diagonally along the back of the load 29 
between opposed photocells 53. A similar light beam 56 traverses the side 
of the load 29 diagonally between opposed photocells 53. If the load is 
twisted or otherwise improperly aligned, at least one of the light beams 
54 or 56 will be broken by the load. The broken light beam will be 
detected by the P and D station monitor 51 (FIG. 3) and the misalignment 
communicated to the CPU 22. A light beam 55 traverses the top of the load 
29 from corner to corner as illustrated in FIG. 2. If the light beam 55 is 
broken, the P and D station monitor 51 (FIG. 3) will communicate to the 
CPU that the load is too tall to be received in the bays 33. 
If the load of goods 29 is made up of a plurality of stacked packages, the 
described diagonal light beams 54 and 56 may be inadequate to detect a 
package protruding undesirably from the load. Accordingly, it may be 
desirable to substitute the illustrated diagonal light beams with a 
plurality of parallel beams which form a light curtain for detecting 
protruding packages. 
The pickup and delivery station 26 is also provided with structure for 
sensing the presence of the load 29 and pallet 21 on the pickup and 
delivery station. It is particularly important that the CPU be apprised of 
the presence or absence of goods 29 at the pickup and delivery station so 
that the CPU can direct the S/R machine 30 as to whether a load is to be 
picked up or delivered at the particular station. The presence of the 
pallet 21 and load 29 is detected by light beam 57 diagonally directed 
across the load 29 at pallet-height between opposed posts 50. The height 
of the beam 57 is selected so that if a pallet is brought to rest upon the 
supports 52, the beam will be broken and the P and D station monitor 51 
will communicate the presence of the load 29 on the particular P and D 
station to the CPU 22. If the beam is not broken, as illustrated on the 
right side of FIG. 2, the CPU is instructed that the pickup and delivery 
station is available for deposit of goods 29. 
If the goods 29 have been placed upon the station 26 but the alignment is 
improper either because the goods are twisted on the station 26 or because 
the height of the goods exceeds the acceptable limit, the CPU will cause a 
signal to be sent to the aisle I/O terminal 24 instructing the forklift 
operator to realign the load upon the station 26 or to shorten the load, 
as required. 
After the proper alignment of a load has been verified, the forklift 
operator inserts the transaction card bearing a machine-readable code into 
the aisle terminal 24. If the code is in man-readable form, the code is 
manually entered into the I/O terminal 24. The CPU then searches the 
transaction file 48 of the CPU memory until it finds the proper 
transaction code. Since this transaction code was previously associated 
with the part number and quantity of goods to be stored at the operator 
station, the CPU automatically knows the part number and quantity of the 
goods at the pickup and deposit station 26. If for some reason the CPU is 
unable to find the transaction code in the transaction file 48 of the CPU 
memory 40 which was entered at the aisle terminal 24, the CPU returns a 
message to the aisle terminal requesting that the load be returned to the 
operator station 12. 
After the transaction number entered at the aisle terminal 24 has been 
properly identified by the CPU 22 as resident in its transaction file 48, 
the CPU then monitors the availability of the S/R machines 30. If there 
are no S/R machines 30 available, the CPU holds the information for a 
predetermined length of time and then rechecks availability. As soon as 
the S/R machine 30 is available, the CPU 22 automatically commands the S/R 
machine 30 to pick up the load 29 and store it at a CPU-selected bay 33 
within the high-rise warehouse 32. When the S/R machine 30 has completed 
storing the load 29 within the bay 33, the CPU 22 then stores the load 
description including part number and quantity in the storage inventory 
file 44. Since the information pertaining to part number and quantity has 
now been entered into the storage inventory file 44, which is a listing of 
all goods stored within the system, the transaction number is then deleted 
from the information of the stored goods 29 so that the number may be 
reassigned to another incoming load of materials. 
Several advantages of the automatic high-rise system and in-processing and 
storage method described above should be noted. For example, the need for 
highly skilled operators is minimized through the use of one central 
operator station 12 from which all goods 29 are processed into and out of 
the automatic high-rise storage 32. Furthermore, the potential error for 
mislabeling or retrieving the wrong materials is minimized through the use 
of transaction codes and the transaction file 48 contained in the CPU 
memory 40. Since the transaction code is associated with the load of 
materials only at one location (i.e. the operator station 12) and since 
the transaction code is in machine-readable or check digit man-readable 
form and only assigned to the goods 29 after the goods 29 have properly 
been identified, the incoming materials cannot be improperly identified to 
the CPU at the pickup and deposit station 26. This serves to ensure that 
when a load of materials is placed at a deposit station 26 to be stored in 
the high-rise warehouse 32 and the transaction code is entered into the 
CPU from the aisle terminal 24, the CPU will know what materials are on 
that deposit station so that it can properly direct the S/R machine 30 in 
storing those materials at the CPU-assigned address. 
OUT-PROCESSING AND RETRIEVAL 
Attention is now directed to FIG. 3 in conjunction with FIG. 5 relative to 
out-processing and retrieval of load 29 of materials from the automatic 
high-rise storage system 32. An order for materials to be shipped is first 
sent to the operator station 12 (FIGS. 1 and 3). Information, e.g. 
describing the part number, quantity of materials required and destination 
is then sent to the CPU 22 by means of the computer terminal keyboard 14 
at the operator station 12 (FIG. 1). Alternatively, orders may be 
communicated to the CPU with one or more cards with the required order 
information punched thereon or by magnetic tape or other commonly used 
computer generated or machine-readable media. The CPU then searches the 
storage inventory file 44 (FIG. 3) of the CPU memory 40 which contains a 
listing of all materials stored in the high-rise warehouse 32. 
If the CPU is unable to fully satisfy the order as requested from the 
operator station 12, the CPU returns a message to the operator station by 
means of the CRt 14 stating that the order as requested cannot be filled. 
However, if the CPU is able to locate in the storage inventory file 44 the 
goods meeting the requested order, the CPU then checks to see whether an 
S/R machine 30 is available to retrieve the materials. If a machine 30 is 
not available, the CPU holds the information in a queue for a 
predetermined length of time and then rechecks availability. When an S/R 
machine 30 is available, the CPU 22 next determines whether or not a 
pickup and deposit station 26 or 27 is available. This is determined 
through means of the P and D station monitor 51 described above. When it 
is determined that the machine 30 is available and that the P and D 
station 26 or 27 is empty, the CPU commands the S/R machine 30 to retrieve 
the load 29 from its bay 33 and deposit the load on the P and D station. 
The CPU then deletes from the storage inventory file 44 (FIG. 3) those 
materials which have been retrieved from the high-rise storage warehouse 
32 and assigns an out-processing transaction code from the out-processing 
transaction file 49 to the load 29 which has been set down at the P and D 
station 26. The out-processing transaction code accompanies the order 
information keyed in at the operator station 12, including part number, 
quantity and destination. The computer terminal 14 at the operator station 
12 is monitored by the CPU 22 until a request for a move-ticket printout 
is sent to the CPU from the operator station 12. The move-ticket printout 
will be requested when a forklift is available to remove the outbound load 
29 from the P and D station 26. 
Upon receiving a request for a move-ticket printout, the CPU then takes the 
next out-processing transaction code in sequence in the transaction file 
49 and causes the ticket printer 20 (FIG. 1) at the operator station 12 to 
print a move-ticket. This ticket contains the information in man-readable 
form associated with the out-processing transaction code keyed in with the 
order and in addition the particular P and D station 26 or 27 upon which 
the outbound load 29 is waiting. This move-ticket is then taken by a 
forklift operator who proceeds to pick up the materials from the station 
designated on the move-ticket. The CPU then monitors the station 26 or 27 
through the P and D station monitor 51 as described above to determine 
when the load has been picked up. When the load 29 has been removed from 
the P and D station, the out-processing transaction code is deleted and 
can be reassigned to another outgoing load of materials. 
The invention may be embodied in other specific forms without departing 
from its spirit or essential characteristics. The described embodiments 
are to be considered in all respects only as illustrative and not 
restrictive and the scope of the invention is, therefore, indicated by the 
appended claims rather than by the foregoing description. All changes 
which come within the meaning and range of equivalency of the claims are 
to be embraced within their scope.