Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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4012.232
Improved Switching Control Apparatus For Vending
Machine Al~ernating Current Device Switching
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to improved switching control
apparatus for reducing the number of alternating ~urrent ~AC)
power switching elements for controlling the activation of AC
devices in vending machines, and particularly to a reduction in
the number of such control elements, e.g., the relays used where
a diode matrix arrangement is not practical. One example of such
an arrangement in a vending machine i5 where a plurality of either
AC motors or solenoi~s are employed as vending mechanisms for the
delivery of products.
2. Description of the Prior Art
In simplified terms, vending machines typically include
a selection mechanism which the user uses to communicate a
selection or selections to the vending machine, one or more money
recognition devices, 6uch as a coin validator or a currency
validator for recognizing whether inserted money is acceptable or
not, a plurality of vend delivery devices or vend mechanisms for
deli~ering a selectea item to the vending machine user if adequate
credit has been established and other vend conditions have been
satisfied, and finally a control system for determining whether
all vend conditions have been satisfied and for producing a vend
6ignal if they have been satisfied.
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In older vending machines, there has generally been a
one-to-one correlation between the number of vend delivery devices
and the number of vend control elements used to control the
activation of the delivery devices. The vend control elements
took on several forms. In one known arrangement, each vend
delivery motor had an associated selector switch which was used
to complete the electrical circuit to one side of its associated
vend motor, and the money recognition system via a vend relay
authorized the vend by completing the circuit to the other side
of the motor under the appropriate conditions. See, for example,
U.S. Patent No. 4,220,235. In another known arrangement, a
separate power control device is included in the control system
for each vend delivery device. See, U.S. Patent No. 3,841,456.
These arrangements having a one-to-one correspondence between
control elements and delivery devices are operationally sound but
economically undesirable as they require a large number of costly
control elements where a large number of dispensing devices are
employed.
More recently, control systems have been developed
which include matrix addressing arrangements for addressing a
plurality of vend delivery devices and reducing the number of
control elements employed for the purpose of activating the
delivery devices. See, U.S. Patent No. 4,458,187 assigned to the
assignee of the present invention and U.S. Patent Nos. 4,354,61
and 4,284,206. These arrangements may be described as n x m
matrix arrangements where n is the number of rows in the matrix,
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m is the number of columns in the matrix, and n x m is the number
of vend delivery devices in the apparatus. In these machines,
the number of control elements is reduced to n ~ m or, in other
words, one control element for each of the rows and columns in the
vending machine. Such arrangements are particularly useful where
diodes or some other 6imple means can be used to avoid activation
of undesired vend delivery devices in the matrix. Neither diodes
nor other sufficiently inexpensive means exist for preventing
such undesired activation of alternating current motors or
solenoids wired in a matrix array. Conseguently, matrix arrays
as previously known in the vending field have been inappropriate
where alternating current motors or solenoids are used as deliverv
devices.
SUMMARY OF THE INVENTION
The present invention is an improved switching control
apparatus which does not reguire a one-to-one correspondence
between AC power switching elements and AC devices, and which is
suitable for use with a plurality of delivery devices such as AC
motors and solenoids. Consequently, the present invention
~ addresGes the problem of reducing the number of components
required to control a plurality of delivery devices in a vending
machine, and avoids the problems of undesired activation which
occur if AC motors or solenoids are connected in known vending
delivery device matrix arrays. The invention is generally
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applicable to the problem of switching any AC devices in vending
machines which must be switched on and off with any frequency.
Briefly, improved ~witching control apparatus according
to the present invention uses a reduced number of AC power
switching elements, ~uch as relays, by dividing the AC devices to
be activated into two groups and using one switching element to
select which of the two groups is to be selected, and using an
additional number of AC power switching elements each of which is
connected to one of the AC devices in each of the two groups to
~elect which one of the AC devices is to be activated. This
arrangement reduces the number of AC power switching elements
from the 2N required to switch 2N AC devices where there is a
one-to-one correspondènce, to N + 1. For example, in a prior art
one-to-one arrangement for activating six AC devices, six
switching elements are required.
The arrangement of the present invention employs only
four AC power switching elements, such as relays, to activate
six AC devices such as AC vend motors. According to the
invention, the 6iX vend motors would be divided into two groups
of three in which each group of three motors shares one terminal
in common. Each one of three of the relays is connected to AC
neutral as well as to the other terminal of one motor in each
group so that the position of the wiper blade of each of these
three relays determines which of the two associated motors has
its non-common terminal connected to AC neutral. The fourth
relay i~ connected to an AC hot line or AC power, and both the
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s~
common terminals of the two groups of motors so that the
position of its wiper determines whether AC power is
connected to one group or the other group. This arrangement
in conjunction with suitable control means for controlling
the switching of the relays can be used to simply and
inexpensively activate any one of the six motors. Finally,
preferably, a further AC power switching element is used to
control the flow of power to the group determining, AC power
switching element so that switching transients can ~e
minimized.
In one embodiment the present invention is directed
to an improved switching control apparatus for switching 2N
alternating current ~AC) powered dispensing devices in a
vending machine organized in first and second groups each
having N of said dispensing devices comprising: N + 1 AC
power switching elements of which a first of said N + 1 AC
power switching elements is a group determining element and
is connected to all 2N dispensing devices in a manner so that
said first AC power switching element can control whether AC
power is connected either to a common first terminal of all
of the first group of dispensing devices or to a common first
terminal of all of the second group of dispensing devices,
and each of the remainder of said N + 1 AC power switching
devices is connected to a noncommon second terminal of two
dispensing devices are from each of the two groups to control
whether AC power is connected to the second terminals of its
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corresponding dispensing devices from the first and second
groups of N dispensing devices; and control means for
controlling the switching of the N + 1 AC power switching
elements and thereby controlling which one of the 2N
dispensing devices is activated.
Further features of my invention, its nature, and
various advantages will be more apparent upon consideration
of the attached drawings and the following detailed
description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a simplified schematic diagram
illustrating switching control apparatus according to the
present invention in a rest state in which none of the vend
mechanisms shown in the figure has been selected;
FIG. 2 is a second simplified schematic diagram
illustrating switching control apparatus according to the
present invention in an active state in which one of the
dispensing devices has been selected; and
FIGS. 3A and 3B are a detailed circuit
diagram of a control circuit for use in the preferred
embodiment of the present invention, and in which the
relationship of the control means of
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the switching control apparatus to an overall control system for
a vending machine is illustrated.
While specific types of logic circuits are disclosed in
connection with the embodiments described below in detail, other
logic circuits can be employed to obtain equivalent results
without departing from the invention.
DETAILED DESCRIPTION
Figs. 1 and 2 illustrate the working of a switching
control apparatus 1 having a plurality of AC power switching
elements 10 and vend mechanisms or delivery devices 20 which are
connected as described below. Figs. 1 and 2 illustrate the
connection of ~C power switching elements 10 and vend mechanisms
20 according to the present invention; however~ they do not show
control means for controlling the switching of the elements 10
and detailed discussion of suitable control means is postponed
until the detailed discussion of Figs. ~A and 3B below.
As shown in Fig. 1, the plurality of control elements 10
include seven relays K1-K7, and a power switching device Ql which
is shown as a triac, but could be some other suitable power
switching device such as an additional relay. The plurality of
vend mechanisms 20 includes two columns of six delivery devices
VMAl-VMA6 and VMBl-VMB6 which are designated column ~A~ devices
and column ~B~ devices.
As shown in Fig. 1, a 115V~C line is connected to an
input 11 of triac Ql. A second input 12 of the triac Q1 is
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connected to a means for producing a control signal which is not
sho n in Figs. 1 and 2. When a control ~ignal is present on the
input 12, power flows through the triac Ql and from its output 13
to contact X7A of relay K7 since contact K7A is connected to
output 13 of triac Ql. A second contact K7B of relay K7 is
connected to one terminal of each of the column B delivery devices
VMBl-VMB6. A third contact K7C of relay X7 is connected to one
terminal of each of the column A delivery devices VMA1-~MA6. The
position of relay R7' 6 wiper blade K7W determines whether the
output 13 of triac Q1 is connected to column A or column B. As
shown in Fig. 1, no current is flowing in the coil of the relay
Kl, and consequently triac Q1 is connected to column B. If
current is caused to ~low through the coil of relay K7, then
wiper K7W moves to connect contact K7A to contact X7C and column
A is connected to the triac Ql. Means for controlling the current
in the coil of relay K7 and consequently for controlling the
6witching of the relay K7 is not shown in Figs. 1 and 2.
~ aving described the connection of one terminal of each
of the twelve vend mechanisms 20 to 115 VAC, the connection of
~ the other terminal of each of the vending ~echanisms devices
20 will next be described. Each of the relays K1-K6 also has
three contacts A, B and C and a wiper blade W. Each of the
contacts KlB-K6B is connected to an associated one of the delivery
devices VMA1-VMA6 respectively. For example, contact KlB is
connected to delivery device VMAl. Similarly, each of the
contacts XlC-K6C is connected to an associated one of the delivery
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devices ~MB1-VMB6. For example, contact XlC is connected to
delivery device VMBl. Finally, all the contacts RlA-X6A are
connected to a 115 VAC return line. As for relay X7, control
means which are not shown in Figs. 1 and 2 are provided for
controlling the current in each of the coils of the relays Kl-K6.
This control means determines which of the vend mechanisms are
connected to the 115 VAC return path.
Fig. 1 illustrates a situation in which none of the
vend mechanisms 20 is activated. In this ~tate, the triac Ql is
preferably off. In connection with Fig. 2, the activation of
delivery device VMA2 and operation of the present invention will
be illustrated.
To activate delivery device VMA2, control currents are
produced so that the wiper blades of the relays Kl through K7
take the position ~hown in Fig. 2. In other words, wiper blade
K7W connects contacts K7A and K7C, wiper blades KlW, and K3W-K6W
connect contacts KlA, and K3A-K6A to contacts KlA, and R3C-K6C
respectively. Further, wiper blade X2W connects contacts X2A and
X2B. In a preferred arrangement, a suitable time after these
control currents are produced, triac Ql is turned on by a control
signal at its input 12 and power flows through delivery device
VMA2 thereby activating it and causing a vend to occur so long as
the delivery device VMA2 i6 in proper working order. After
vending is completed, triac Ql i6 turned off and power is removed.
For additional details concerning the preferred timing for
switching power to the triac Q1 and the relays Kl-K7 see the
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disclosure of U.S. Patent No. 4,604,557 issued August 5, 1986
and assigned to the assignee of the present invention.
From the above discussion o~ Figs. 1 and 2, it can be
seen that, rather than controlling a total of 2N delivery devices
with 2N control elements, the present invention allows 2N delivery
devices to be controlled using N+2 AC power switchiny control
elements, or if the triac Ql is eliminated N ~ 1 control elements.
Further, it is apparent that the present switching arrange~ent
does not suffer from deleterious activation of delivery devices
which have not been selected. As a result, substantial component
cost savings are achieved. Additional details of suitable control
means for controlling the ~witching of the AC power switching
elements and of the preferred embodiment are discussed below in
the context of the discussion detailed circuit diagrams of Figs.
3A and 3B.
Figs. 3A and 3B illustrate a control circuit 100 for
ccntrolling the operation of a vending machine (not shown) having
a coin mechanism (not shown), a display (not shown), twelve
selection switches (not shown), twelve vend motors (not shown),
twelve sold out switches (not shown), a cash counter (not shown)
and several machine function switches 170. While the typical
components of a vending machine are not shown in Figs. 3A and 3B,
their proper connection to control circuit 100 is readily apparent
from these figures.
A vending machine with control circuit 100 may have
either one of two different coin mechanisms and may optionally
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include a dollar bill validator. control circuit lOO includes
a dual coin mechanism interface llO and a dollar bill validator
interface lSO for this purpose. Control circuit lOO also includes
the necessary drive circuitry 120 to drive the triac Ql and the
relays Kl-K7 shown in Figs. 1 and 2 as well as Figs. 3A and 3B.
Central to control circuit 100 is a programmed
microprocessor 130 which may 6uita~1y ~e an lntel 8049 chip.
Connected to microprocessor 130 are the dual coin mechanism
interface 110, a display interface 140, the dollar bill validator
10 interface lSO, a cash counter interface 160, the plurality of
~achine ~unction switches 170, a soldout switch interface 180, a
selection switch interface l9O, a vend complete switch interface
200, the triac Ql and the relays Kl-K7. Each of the interfaces
listed above includes the appropriate circuitry necessary for
15 connecting its ass~ciated element, for example, a coin mechanism,
to the microprocessor 130~
The particular dual coin mechanism interface llO shown
in Fig. 3A is for providing the vending machine operator with the
option of connecting either the Mars* MC5000 or the Coinco* C300
20 coin mechanisms sold by Mars Electronics and Coinco respectively.
The particular display interface 140 is for a three digit
alphanumeric LED display which is used to display information
such as the customer credit. The machine function switches 170
preferably include a door switch for monitoring the opening and
25 closing of the vending machine, a free vend switch, coin dispense
switches, and motor or solenoid selection switches. The dollar
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*Trade mark
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bill validator interface 150 shown in Fig. 3A is suitable for
connection with a dollar bill validator sold by Mars Electronics.
The cash counter interface 160 is suitable for connection with a
24 volt electromechanical oash counter. Finally, the particular
control circuit 100 shown in Fig. 3A has interfaces 180, 190 and
200 for connection with 12 selection switches, 12 vend complete
switches and 12 sold out switches whose function and connection
are well known. The operation of the above elements and control
circuit 100 with the exception of how they operate in conjunction
to the control switching of the triac Q1 and relays K1-K7 in
order to activate the appropriate Yend motor selected when a
customer makes a selection using one of the sel~ction switches i5
well known and does not constitute the subject of present
invention. While Figs. 3A and 3B show one particular control
circuit 100 for a particular vending machine with various features
and options, other variations could be made and other options
could readily be provided. For example, the dual coin mechanism
interface 110 could be redesigned for other coin mechanisms, or
for a single coin mechani m and microprocessor 130 could be
readily reprogrammed. Other machine function switches than the
switches 170 shown could be employed, and greater or lesser
numbers of vend motors and consequently different numbers of
selection, sold out and vend complete switches might be employed.
Turning to the details of the microprocessor 130 and its
control of the triac Ql and relays K1-K7, it is seen that
microprocessor 130 has an output pin P24 which controls the gate
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current applied to the triac Ql through the connection of a
buffer-driver U9 and optical-isolator U8 as well as connecting
resistors and capacitors shown within the triac drive circuit
block 120 in Fig. 3A. When triac ~1 is turned on, power flows
from a 115 AC ~ot connection to contact A of relay K7. The
notation ~F~ is used for convenience in drawing Figs. 3A and 3B
and indicates a common point in the two ~igures. This correlation
is also true for notations tA~, tB~, ~C], [D] and any other com~on
notations.
Prior to turning on triac Q1, the microprocessGr 130
must determine that a vend selection has been made by a customer,
that vending conditions have been ~atisfied, and it must set up
the relays Kl-X7 properly 60 that the appropriate vend motor will
vend when power is turned on. Initially, microprocessor 130
monitors the states of all the 6witches connected to the
interfaces 180, 190 and 200. It does this by cyclically
outputting scan pulses via pins P20-22, a serial in/parallel out
~hift register U10 6uch as a National Semiconductor 4094 chip and
a 4-to-16 decoder U13 such as a National Semiconductor 74LS154
chip. When a switch is closed, the microprocessor 130 receives a
return ~ignal on the return lines 135 connected to pins Tl, Pl-0,
and Pl-l of microprocessor 130. In greater detail, switch
scanning is accomplished as follows.
Microprocessor 130 first causes via the 6erial
in/parallel out ~hift register U10 the input pins 20, 21, 22 and
23 of the 4-to-16 decoder U13, to be all low (input pins all low
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0~00=code 00). When its inputs are all low, output o of the
~-~o-16 decoder U13 will be low and all other outputs 1-15 will be
high. The low output 0 of decoder U13 i5 connected through diodes
Dl, D13 and D25 to the first of the sold out, selection and vend
complete switches respectively which are connected to interfaces
180, 190 and 200. These switches it will be recalled are located
off the circuit board which contains the control circuit 100.
The low signal will be returned to the circuit board, if one of
said switches is closed, via the sold out switch input (S0-Input),
the selection switch input (SEL-Input) or the vend complete switch
input (VC-Input) respectively. These three inputs are connected
via appropriate circuitry inclu~ing the three inverters, 132-134,
and the return lines ~35 to pins Tl, Pl-0 and ~1-1 of
microprocessor 130.
If by way of example, the first sold out switch is
closed, input pin 1 of inverter 132 is low, its output pin 2 is
high, and the microprocessor 130 interprets this high at its Tl
input as an indication that the first sold out switch is closed.
If the first sold out switch is not closed, input pin 1 of
' inverter 132 is high or approximately 5 volts as a result of its
connection through the resistor network 136 to ~5V DC.
Consequently, its output pin 2 is low, and microprocessor 130
interprets the low at its T1 input as an indication that the
first sold out switch is not closed, or, in other words, that it
is open and has not been operated. The detection of whether the
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first selection switch and the first vend complete switch are
closed or open occurs in a similar manner.
Once ~icroprocessor 130 has determined whether any of
the first group of three switches is closed or open, it then
causes all but one of the inputs to the 4-to-16 decoder U13 to be
low and one to be high (input pins OOOl=code 01) thereby causing
output 1 of 4-to-16 decoder U13 to go low and all its other
outputs to qo high. Microprocessor 130 now receives inputs on
pins Tl, Pl-O and Pl-l which indicate whether the second switch
in each of the three groups of switches is closed or open. This
process continues until all input values O through 15 (codes=OO
throug~ 15) ha~e been tried a~d then the cyc}e repeats. It should
be noted that outputs 12-15 of 4-to-16 decoder U13 are used for
other purposes than scanning the three groups of switches. For
example, these outputs are used to determine the status of a
dollar bill validator connected to the interface 150 and the
machine function switches 170.
Turning to the activation of the twelve vend mechanisms
connected to vend ~echanism i~terfaces VEND MOTORS FRONT and VEND
MOTO~S REAR shown in Fig. 3B, it is important to note that the
same 4 lines 131 that are the inputs to the 4-to-16 decoder U13
also feed vend mechanism decode circuit 210 shown in Fig. 3B.
Decode circuit 210 includes a 3-to-8 decoder U7, four NAND gates
U18, 2 inverters U14, and six Exclusive-Or gates V16 and U17,
which are connected to control the activation of relays Kl-K7. In
order to prevent the vend mechanism drive relays Kl-K7 from being
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activated during the scanning process, an enable line ENABLE is
provided. During scanning, the enable line ENABLE is kept high
and the vend mechanism decode circuit 210 i5 disabled thereby
preventing activation of the drive relays K1-X7.
Once a closed selection switch has been detected, the
scan stops at the code for that selection (lst switch corresponds
to code 00, 2nd switch corresponds to code 01 etc.) If the code
02 is detected for the third selection switch and all the vend
conditions have been satisfied, microprocessor 130 causes enable
line ENABLE to go low enabling the decoder 210. With the enable
line low, the vend ~echanism decoder 210 will decode the code 02
to select the proper relay ~witch configuration to activate the
vend mechanism corresponding to the closed third selection witch.
Control circuit 100 as explained above is used with a
vending machine having 12 vend mechanisms. These 12 vend
mechanisms can be divided into two groups of six which may be
considered as being in first and second columns VEND MOTORS FRONT
and VEND MOTORS REAR respectively. For purposes of continuing
the discussion of the operation when the third selection switch
is closed, it will be assumed that its associated vend mechanism,
as well as those for the other of the first six selection motor
switches are in the second column VEND MOTORS REAXI and the
remaining six motors are in the first column VEND MOTORS FRONT.
The four NAND gates U18 are connected 60 that if the
scan code is less than six a low output at pin 8 is produced.
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If the ~can code i~ greater than or equal to 06, the NAND gates
U18 produce a high output at pin 8. Since for the third selection
switch, the scan code is 02 which is less than 06, the output at
pin 8 will be low, the input to the inverter U14 connected to pin
8 will be low, the output of inverter U14 will be high, the relay
driver U9 connected to U14 will prevent current from flowing
through the coil of column 6elect relay ~7 and the wiper of relay
K7 will connect contact K7A to contact ~7B of relay X7 as shown
in Fig. 3B. As a result, the rear column o~ vend motors VEND
MOTORS REAR are connected to the point labeled F. When triac Ql
conducts, point F and the rear vend motors are connected through
the triac Ql to 115~AC ~ot. Note, that for a scan code greater
than 06, pin 8 of decoder U18 wi~l produce a high output, inverter
U14 will have a low output, current flows through the coil of
column ~elect relay X7, its wiper connects its contacts X7A and
X7C, and the front vend motors are selected. Also, the six
Exclusive-Or gates U16 and U17 operate to complement the signals
from the 3 to 8 decoder U7 when the code is greater than 06 as
discussed below. Since this particular circuit addresses the
problem of activating two groups of six vend mechanisms, the
3-to-8 decoder U7 is connected as a 3-to-6 decoder. For input
codes 00-05, outputs at lines YO-Y5 are produced and relays X1-X6
are respectively selected. In conjunction with the operation of
relay K7, the rear vend mechanisms are thereby selected. Codes
greater than or equal to 06, select the front mechanlsms. Code
06 produces an output at Y6 which is diode ORed back to the output
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Y4 so that only relay K5 is not activated as discussed further
below. Code 07 produces an output at Y7 which is similarly diode
ORed back to the output Y5 so that only relay K6 is not activated.
Codes 08-11 result in outputs at Y0-Y3 60 that relays Kl-K4 are
respectively not activated.
Returning to the discussion of the activation of the
vend motor associated with the third ~election switch, the code
02 is also decoded by 3-to-8 decoder ~7 which may suitably be a
National Semiconductor 74LS138 chip so that its output pin Y2
produces a low output and its remaining output pins Y0, Yl and
Y3-Y7 all produce a high output. The pins Y0-Y5 are each
connected to one of the six Exclusive-Or gates U16 and U17.
Outputs Y6 and Y7 are`diode ORed to outputs Y4 and Y5 as discussed
above. Since the code 02 is less than 06, each of the
Exclusive-Or gates produces the same output signal as appears at
its input since the circuit pin 8 of the NAND gates U18 produces
a low output. For the code 02, current flows through the coil of
relay K3 and its wiper connects the third motor to 115 V NEUT.
In other words, K3's wiper moves from the position shown in Fig.
3B so that it connects contacts K3A and K3C of relay K3 so that
pin R3 of the interface VEND MOTORS REAR is connected to 115V
NEUT. Current does not flow in the coils of relays Kl, X2 and
K4-K6 and consequently their wipers remain in the position shown
in Fig. 3B.
At this point, the relays Kl-K7 are positioned to
activate the third vend motor which is connected to the pin R3.
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In order to activate this motor, it is only necessary to apply
power to the point F via triac Q1. Before this is done, the
microprocessor 130 is programmed to check the state of the vend
complete switch associated with the third motor to determine if
that motor is in its normal starting or home position. If this
and any other vending conditions are ~atisfied, the microprocessor
130 acti~ates triac Q1 and power is applied to the third ~otor.
~he vend complete switch is monitored ~y the microprocessor 130
to see that the vend mechanism completes a normal cycle. When it
does or after a predetermined preset time, power is removed by
first turning off the triac Ql and then removing the enable signal
from the enable ~ine ENA~LE. ~fter the removal of power, the
microprocessor 130 re`sumes scanning.
Activation of vend mechanisms connected to the interface
VEND MOTORS FRONT, in other words, the activation of those vend
mechanisms having a code greater than 06 is similar to that
explained above, but with the differences noted below. For a
code greater than 06, the output of pin 8 of NAND gates U18 is
high and as a consequence, current ~lows in the coil of relay K7,
K7's wiper connects its contacts K7A and X7C, and the front column
of vend mechanisms are connected to point F. At the same time,
the high output at pin 8 is connected to one input of the
Exclusive-Or gates U16 and U17 and it causes those gates to
complement whatever signal occurs at their other inputs. For
example, if there is a code 07, pin Y7 of 3-to-8 decoder U7 will
produce a low output and the remaining pins YO-Y6 will all produce
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high outputs. The Exclusive-Or gates U16 and U17 will complement
the signal from 3-to-8 decoder U7 so that current will flow in the
coils of relays Kl-K5 and their wiper will connect A and C
thereby preventing the activation of any motor except the one
associated with the code 07 which is connected in the front group
to the line Fl. Current will not flow in the coil of relay K6 so
that its wiper will take the position shown in Fig. 3B thereby
selecting the vend mechanism connected to interface connection
F1.
