Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
WO 91/01020 P~/US90/03887
2~7'`12~ : ;
AtJTO/~A~JlJAL 8!3LI~CT NBANE~
BACXGROUND OF THE INVENTION
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The present invention is general}y directed to
an auto/manual select means for rendering a control
system in either an automatic mode or a manual mode. The
present invention is more particularly directed to such
a sele t means for use in a control system which includes
a processor for controlling at least one external device
wherein the select means is selectable ~or selecting
automatic control of the external device by the processor
or manual control of the external device by an operator
while also providing the processor with information
indicative of the automatic or manual control selection.
Facility management systems are control systems
which generally provide control of the internal
~ environment and security and fire alarm monitoring of,
for example, an office building or plant facility.
}nternal room temperature, humidity, air flow, lighting,
security, and fire alarm are among some of the conditions
controlled and/or monitored by such systems. Such
control is usually provided through the control of
external devices by a system processor. Nany different
types of external devices such as heaters, fan motors,
dampers, humidifiers, and the like, may be employed and
controlled for establishing desired set point conditions.
Processors used to control these devices generally
provide output control signals in a digital format.
Since many different typeC of external devices are
generally employed in a practical system, and since
different types of control signals may be required to
control the different types of external devices,
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interface circuitry is generally required between the
system processor and the external devices to transform
the digital output control signals of the prccessor to
a form which is appropriate to control the various
different types of external devices. The facility
management system disclosed herein employs interface
circuitry for this purpose referred to as output function
modules. Each output function module is adapted to
transform the digital control signals from the system
processor to a form which is adapted to provide suitable
control of the external devicés. For example, in
accordance ~ith one embodiment of the present invention,
an output function module transforms the digital rontrol
signals of the system processor to opened or closed relay
contacts. In aocordance with another preferred
embodiment, an output function module converts the
digital control signals of the system processor to binary
outputs having desired voltage levels. In accordance
with another preferred embodiment, an output function
module converts the digital control signals of the system
.process to an.analog output having the desired voltage
levels. ~
; In addition to the foregoing, it may be
necessary to remove an external device from the automatic
control of the system processor and to -enable the
external device to be controlled manually by an operator.
Such a condition may arise .in the unlikely event of
system malfunction, when an external device is to be
tested,or when some other suitable condition arises which
rQquires manual control of an external device by an
operator.
In the prior art, facility management systems
have provided a selection of either automatic control or
manual contro} of an external device. However, in prior
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art systems,there was no provision for the system
processor to be informed as to whether an external device
was under manual control or automatic control. Such
information would be desirable to be conveyed to the
system processor so that,if an external device is under
manual control,the system processor will annunciate this
condition and react to the condition as defined by the
system software. In this manner, the system processor
will not only be info~med as to the condition of the
external devices which it controls, but in addition,
processing time will be saved because the system
processor need no longer address the external device
under manual control.
SUMMARY OF THE INVENTION
The invention provides an auto/manual select
means for use in a system which includes processing means
for automatically controlling at least one external
device. The auto/manual select means includes manually
selectable means for selecting either-automatic control
of the external device by the processing means or manual
control of the external device by an operator. The
auto/manual select means also includes status means
coupled to the selectable means and to the processing
means ~or providing the processing means with information
denoting the selected condition of the selectable means.
BRIEF_DESCRIPTION OE THE DRAWING~
- Figure 1 is a block diagram of a control system
embodying the present invention. `
Figures 2A and 2B are schematic circuit
diagrams which, when taken together, comprise a ~chematic
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W09l/0l020 PCT/US9QtO3887
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circuit diaqram of a first function ~odule e~bodying the
present invention and which may be utilized in the system
of Figure 1.
Figures 3A and 3B are schematic circuit
S diagrams which, when taken together, comprise a schematic
circuit diagram of a second function modiule embodying the
present invention and which may be utilized in the system
of Figure 1.
DESCRIPTIQN OF THE PREFERRED EMBODIMENT
Referring now to Figure 1, it illustrates a
control system 10 which may utilize the present invention
to advantage, and, more particularly, a facility
management system embodying the present invention. The
system 10 generally includes a main communication bus 12,
which may be an Nl LAN ARCNET bus, a network control
module 14, a digital control module 16, and another bus
18, which may be an N2 0PT4MUX bus interconnecting the
network control module 14 to the digital control module
16. LAN ARCNET and OPTOMUX buses 12 and 18 respectively
are of the type well known in the art. -
As illustrated in Figure 1, the system there
shown includes just one network control module and
digital control module for exemplary purposes, and it
should be un~erstood that additional network control
modules and digital control ~odules may be connected to
the main communication bus 12 in a practical system.
This type o~ control system is referred to as a
"distributed system", wherein each network control module
is on a par with all other network control modules and
communicates with all other network control modules on
the bus 12. -
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The main function of the network conkrol module
is to communicate with the other network control module~
of the system on an equal basis and to control its
associated digital control module under its own assigned
software protocol. Such a protocol may include setting
temperature control set points, heating schedules,
lighting schedules, et cetera. The network control
module, in accordance with its protocol, sends high level
commands to the digital control mo~ule whioh then
executes on those commands by performing closed-loop
operations by issuing suitable control signals at its
outputs responsive to sensed input conditions by its
remote sensors.
The digital control signals issued by the
digital control module are preferably in digital form.
The digital control signals issued by the digital control
module are converted by output function modules to a
format which may be utilized ~or controlling various
different types o~ external devices which may be utilized
within the system. For example, one type of output
function module may convert the digital output signals
to binary signals. Another output function module may
convert the digital control signals to op~ned or closed
contacts of a relay, and still another output ~unction
module may convert the digital control signals to an
analog voltage. The function modules which provide
opened or closed relay contacts may be used to activate
fan motor starting windings or to turn on heaters. An
output function module which provides an analog control
signal can be used to power a damper motor to set a
damper at a desired position. Hence, the digital control
~odule performs -decision-making processes, gathers
information from its remote sensors, digitizes the
information,digitally processes the information, and
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executes control functions to satisfy the high-level
commands of the network control module.
The digital control module 16 thus processes'
digital in~ormation for performing various different
types of closed-loop control operation within the system.
To that end, a digital control module 16 may include ten
output channels identified a~ OCHl through OCHl0. The
outputs OCHl throuqh OC~lO provide the control signals
which are transferred and converted by the output
~unction modules to control the variouls dif~erent types
of control elements of the syst~m, such as relays or
damper motors, to provide the desired control of the
internal environment o~, for example, an office building.
As previously mentioned, output function modules
including relays controlled by the outputs of the digital
contro~l module 16 may, for example, turn on or off fan
motors to establish desired air flow or heaters to
establish desired room temperatures. Damper motors
controlled by analog control signal~ provided by the
output function modules in response to the digital
control signals of the digital control module 16 may be
utilized to set a damper to also control air flow such
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as return air flow within a heating system.
' In order to provide closed-loop "control, the
digital control modules 16 may-include ten input channels
CHl through CHl0. These input channels receive various
different kinds of information from remote sensors within
the system, which remote sensors provide analog input
information of various types indicative of the'con~itions
being sensed by the remote sensors. ' Since the
information provided by the remote sensors is in the form
of analog information, the lnput channel CHl through CHl0
are arranged to rèad analog input information. The
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analog information readable by each of the input channels
is preferably a differential voltage.
Because various types of remote sensors may be
required, the analog information provided by the remote
sensors may be of various di~ferent types of analog
information. For example, a temperaturle sensor may take
the form of a temperature dependant resistance so that
the temperature sensor provides a resistance having a
magnitude which is indicative of the temperature being
sensed. Other types of remote sensors may provide analog
information of the condition being sensed in the form a
voltage magnitude or current magnitude carried through
a two-wire current loop. As a result, the system 10
preferably includes a universal analog input (IAU)_ 24
associated with each input channel CHl through CH10. The
universal analog inputs 24 interface the remote sensors
with the digital control module inputs to convert the
various different types of analog information provided
by the remote sensors to a given type of analog
information, such as a differential voltage which is
readable by the input channels CHl through CH10 of the
digital control module.
: To that end, the control system 10 of Figure
- 1 is illustrated as including a remote sensor 20 which
-- is coupled to the first input channel (CHl) of the
digital control module by an input interface which
includes a terminal bloc~ 22 and a universal analog input
circuit (IAU) 24. Similarly, another remote sensor 26
is shown coupled to the tenth input channel (CH10) by an
identical terminal block 22 and an identical universal
analog input circuit 24. ~ ;
The terminal blocks 22 are adapted for
connecting the re~ote sensors to the control system.
The universal analog input circuit 24 provides an
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wosl/o1o~o PCT/VS90/03887
interfac~d'isposed between the terminal blocks and the
input channels. When the differential voltages at the
input channels (CHl through CH10 are read, these
differential voltages are converted to another analog
voltage having a magnitude indicative of the condition
being sensed which is then received by the inputs of a
data acquisition system within the digil:al control module
16. The data acquisition system thereafter converts the
analog voltage to digital data in a bit-parallel format
for storage in memory and subsequent digital processing
by the digital control module 16.
Since the digital control module includes ten
output channels, it may perform up to ten separate
closed-loop control operations. One such closed~loop
control operation is illustrated in Figure 1 in
connection with the tenth output channe} (OCH10). Output
channel OCH10 is coupled to an output function module 30.
The output function module 30 preferably embodies the
présent invention, and, for purposes of this description,
will be assumed to be the output function module depicted
in Figures 2A and 2B which provides open and closed relay
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contacts. The output function module 30 is coupled to
a heater through a terminal block 34. When the relay of
the output function module 30 closesjthe heater 32 is
turned on for heating an internal space such as a room
of a building.
The temperature of the room may be sensed by
the remote sensor 26 which provides analog information
in the form of a resistancs having a magnitude indicative
o~ the temperature being ~ensed. The resistance analog
information provided by the remote sensor 26 is coupled
to the tenth input channel (CH10) by the terminal block
22 and the universal analog input circuit 24. The
temperature information from the remote sensor 26 is
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converted from a resistance ~agnitude to a differential
:ltage by an interface formed by the texminal block 22
and the universal analog input circuit 24. When the
differential voltage read at the tenth input channel
(CH10) indicates that the room being heated by the heater
32 is at the desired temperature dictated by the high~
level command of the network control module, the digital
control module 16 through output channel OCHlO will open
the relay of the output function module 30 to turn off
the heater 32. When the room temperature falls below the
desired temperature, that condition is sensed by the
remote sensor 26, is converted to a differential voltage
by the input interface including terminal blocX 22 and
. the universal analog input circuit 24 to a differential
voltage, which then causes the digital control module to
close,the relay of the output function module 30 by its
output channel OCHl0. The foregoing closed-loop process
continues until it is interrupted by either an operator,
manually placing the output function module 30 into a
manual mode, or by a command from the natwork control
", module 14 to the digital control.modu}e 16 through the
bus 18. In accordance with the present invention, if the
output function module is placed in the manual mode, it
will provide the digital control module with information
25 , indicative of the manual mode selection.
Referring now to Figures 2A and 2B, these
Figures, when taken together, comprise a schematic
circuit diagram ,of the output function module 30
illustrated in Figure 1 which embodies the present
invention. The output function module 30 generally
includes a bus interface 40, a data register 42, an
output or driver section 44, and an auto/manual select
circuit comprising a first portion 46a and a second
portion 46b. The output function module 30 further
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w091/01020 PCT/US90/03887
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in lude6 three output lines 50, 52, and 54 which are
adapted to be coupled to the external device to be
controlled by the output function module through a
terminal block as illustrated in Figure 1. As described
with respect to Figure l, the output function module 30
is of the type which includes a relay 48 which provides
the external device coupled to the output function module
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with opened or closed contact conditions for controlling
the axternal device. ~ore specifically, when the relay
48 is energized, output lines 50 and 54 are coupled
to~ether and when the relay 48 is de-energized, output
lines 50 and 52 are coupled together.
In general, the bus interface 40 couples the
function module 50 to the digital control module 16 as
illustrated in Figure l. The bus interface 40 is coupled
to the~ data register 42 and permits data to be written
into the data register 42 of the output function moclule
30. The bus interface 40 also permits the digital
control module to read the condition of the auto/manual
select circuit 46a, ~6b at section 46b to enable the
auto/manual select circuit to inform the digital control
module as to whether the output function module 30 is in
the automatic mode or the manual mode'. 'The data register
- 42 is coupled to the output circuit 44 for conveying the
control signals from the ~digital control module to the
output circuit 44 to the end of either energizing or de-
energizing the relay 48 in accordance with the control
signals. Hence, the output function module transfers the
control signals of the digital'control module to the
external device to be controlled and converts tbe digital
control signals to a suitable control' format 'for
controlling the external device.~ ' ' ' '-
When the output function module is placed into
the manual ~ode by the auto/manual select circuit 46a,
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46b, the first portion 46a of the auto/manual select
circuit disconnects the output circuit 44 from t~e output
lines 50, 52, and 54 and is utilized to manually
duplicate the output conditions of the output lines 50,
52, and 54 obtaina~le with the energization or de-
energization of the relay 48. This function will be
described in greater detail hereinafter.
The bus interface 40 is coupled to a plurality
of lines from the digital control module which include
a line 56 which is used to initiate the reading of the
condition of the auto/manual select circ,uit and to enable
the writing of information into the data register ~2, a
line 58 which is utilized by the digital control module
to select the function module 30 for addressing purposes,
a line 60 to provide clock pulses for clocking data into
the data register, and lines 62 and 64 which are by bi-
directional lines which are utilized for conveying data
into the data register from the digital control module
to the function module and for conveying the condition
of the auto/manual select circuit from the function
module to the digital control module. The bus interface
40 includes a HAND gate 66, a NAND gate 68, NOR gate 70,
, NOR gate 72,~and;transistors 74 and 76. NAND gate 66
includes a first~input which is coupled to the line 56
through a resistor 78 and a second input which is coupled
to the output o~ NAND gate 68. NAND gate 68 includeR a
~irst input which is coupled to a positive 15 volt power
supply and a second input which is coupled to line 58
through resistor 80. NOR gate 70 includes a~first input
which is also coupled to the line 58 through a resistor
80 and a second input which is coupled to the autput of
NOR gate 72. NOR gate 72 includes a first input which
is coupled to the line 60 through a resistor 82 and a
second input which is coupled to system ground.
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Transistor 74 includes a collector which is coupled
directly to the line 62 and an emitter which is coupled
to system ground. Similarly, transistor 76 includes a
collector which is coupled directly to line 64 and an
emitter which is coupled to system ground.
The data register 42 includes a pair of ~type
flip-flops 84 and 86. The clock input of flip-flop 84
is coupled to the output of NOR gate 70, the D-input of
flip-flop 84 is coupled to line 62 through a resistor 8~,
and the S-input of flip-flop 84 is coupled to system
ground. The clock input of flip-flop 86 is also coupled
to the output of NOR gate 70, the D-input of flip-~lop
86 is coupled to line 64 through a resistor 90, and the
5-input of flip-flop 86 ls coupled to system ground.
The auto/manual select circuit, as previously
mentioned, includes two portions, 46a and 46b. The
auto/manual select circuit includes a two section, three
position switch comprising a first section 92a and a
second section 92b. The switch sections 92a and 92b are
ganged together. ~ach switch section includes two poles,
switch section 92a including poles 94 and 96 and switch
section 92~ including poles 98 and lOO. When the switch
- is in its firet position as illustrated, pole 94 is in
contact with contact 102, pole 96 is in contact with
contact 104, pole 98 is in contact with contact 106, and
pole lOO is in contact with contact 108. When the switch
is in its second position, pole 94 is in contact with
contact llO, pole 96 is in contact with contact 104, and
poles 98 and lOO are opened as illustrated by`the dashed
lines. ~When the switch is in its third position, pole
94 is in contact with contact llO, pole 96 is in contact
with contac~ 112, pole 9~ is in contact with contact 114,
and pole lOO is in contact with contact 116.
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WO91/01020 PCT/US90/03887
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The auto/manual select circuit portion 46b
includes gate means comprising NOR gates 120 and 122.
NOR gates 120 and 122 are coupled to the second section
92b of the auto/manual select switch and provide the
status information in digital form to the digital control
module in response to intermediate status signals
provided by the second switch section 5i2b. To that end,
NOR gate 120 includes a first input which is coupled to
the output of NAND gate 66 and a second input which is
coupled to contact 106 of switch section 92b and to a
positive 15 volt power supply through a resistor 124.
NOR gate 120 also includes an output which is coupled to
the base of transistor 74 through a resistor 126.
Similarly, NOR gate 122 includes a first input which is
coupled to the output of NAND gate 66, a second input
which~is coupled to contact 116 of switch section 92b and
to a positive 15 volt power supply through a resistor
126, and an output which is coupled to the base of
.transistor 76 through a resistor 128.
The reset inputs of flip-flops 84 and 86 are
coupled to a.power-up reset circuit 130 through a
resistor 132. The power-up reset circuit 130 includes
transistors 134 and.136 which are arranged in a manner
well known in the art. The power-up circuit 130 assures
that when power is first applied to the output function
module 30, the state of the flip-flops 84 and 86 will be
in a kno~n and predetermined condition.
The output circuit 44 includes, in addition to
.relay 48, a transistor 140. The base of transistor 140
.; is coupled to the Q-output of ~lip-flop 84 through a
resistor 142. The emitter of transistor 140 is coupled
to system ground and the collector of transistor 140 is
coupled to one side of the relay coil 144 of relay 48.
The other side of relay coil 144-is coupled to a positive
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15 volt power upp}y through a resistor 146. When
transistor 140 conducts, it completes a circuit ~rom the
power supply through the relay coil 144 and to ground to
cause the relay 48 to be energized. When transistor 140
is back biased, and is thus off, the circuit path is
disconnected for de-energizing the relay 48.
In operation, when data is to be read into the
data register 42, the read-write line 56 goes high and
the select line 58 goes low. Since the first input of
NAND gate is tied to a high lsvel, N.AND gate 68 will
provide a high level at its output which is impressed
upon the second input of NAND gate 66. Since both inputs
of NAND gate 66 are high, it will provide at its output
a low-level which is im~ressed upon the ~irst input of
NOR gate 120. When the auto~manual select switch is in
the automatic position, pole 98 is in contact with
contact 114 so that a high level will be at the second
input of NOR gate 120. This will cause the output of NOR
gate 120 to be low ~or back biasing the transistor 74.
.With trànsistor 74 back biased,the line 62 is available
~or presenting data to the D-input of ~lip-flop 84. At
the next clock pulse, the first input of NOR gate 72 will
. ..;~ be at a high level and together with the low levei:at its
econd input, the output of NOR gate 72 will be low.
Both inputs of NOR gate 70 will be low to cause its
output to go high to present a po~itive going clock pulse
at the clock input of the flip-~lop 84 for clocking the
data on line 62 to the Q-output of flip-flop 84. If the
- data is a high level, the Q-output will go high to causé
transistor 140 to be forward biased, and turned on for
completing the.circuit path fro~ the positive 15 volt
power supply through relay coil 144 and to ground to
energize the relay 48. This causes, as previously
mentioned, output lines 50 and 54 to be coupled togèther.
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WO91/0l020 7 ~ CT/US90/03887
If the data at the D-input of flip-flop 84 was a low
level, the Q-output of flip-flop 84 will be at a low
level which back biases and turns off transistor 140.
This causes the relay to be de-energized and for output
lines 50 and 52 to be coupled togetherO
When the condition of the auto/manual select
means is read by the digital control module in the
automatic mode, the second input of NOR gate 120 is
coupled to a high voltage level as previously described.
Also, when in the automatic mode, pole lOO is in contact
with contact 116. This causes the second input of NOR
gate 122 to be coupled to system ground and provides that
inp~t with a low voltage level. Since the output of NAND
gate 66 is low, both inputs of NOR gate 12 wiil be low
causing its output to be high. The high level at the
output of NOR gate 122 forward biases transistor 76
causing the line 64 to go low. Hence, when the function
module is in the automatic mode, line 62 will be at a
high level and line 64 will be at a low level to enable
the digital control module to be informed that the
function module is in the automatic made.
As previously mentioned, the auto/manual select
switch is a three-position switch.-: The third position
of the switch is for the automatic mode as p~reviously
described. The first position of the switch corresponds
to a manual mode selection referred to as the "hand"
position. In the "hand" position, the auto/manual select ;
switch not only selects a ~anual mode, but in addition,
couples output lines 50 and 54 together as if the relay
48 wera energized. When in the "hand" position, the
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second input cr NOR gate 120 is coupled to system ground
and the second input of NOR gate 122 is coup}ed to the
positive 15 volt power supply. When the condition of the
auto/manual select means is read by the digital control
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module, the output of NAND gate 66 will go low to cause
NOR gate 120 to provide a high-level output at its
output. This high-level forward biases transistor 74
causing the bi-directional line 62 to go low. Also, the
low voltage level from the output of NAND gate ~6 is
impressed upon the first input of NOR gate 122 to cause
NOR gate 122 to provide a low level at its output to back
bias transistor 76 to cause the bi-directional line 64
to be high. Hence, whsn the auto/manual select switch
is in the manual "hand" condition, line 62 will be low
and line 64 will be high. This condition is read by the
digital control module so that the function module
provides information to the digital control module
~ indicative of the manual "hand" condition.
When the auto/manual select switch is in its
second position, the first switch section 92a duplicates
the output conditions of the relay 48 when the relay is
de-energized and causes output line 50 to be coupled to
output line 52. This condition of the auto~manual select
switch may be referred to as the "off" condition. As
previously mentioned, in this condition; the poles 98 and
,100 of the second switch section 92b are not coupled to
;~ any of the contacts of that switch-portion to cause both
of the second inputs of NOR gates 120 and 122 to be
coupled to a high voltage level. When read by the
digltal control module, the output of NAND gate 66 is low
to cause both NAND gates 120 and lZ2 to provide a low
voltaqe level at their outputs for back biasing both
transistors 74 and 76. This results in both lines 62 and
64 being high. Hence, function module 30~, in accordance
with the present invention, is capable of informing the
digital control module as to the condition of the
auto/manual select switch for each of the three separate ~`~
selectable positions of the switch. - As a result, the
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WO91/~1020 2 -~ 7 ~ ~ ~
auto/manual select means of the present invention
includes means for selecting respective di~ferent
operating conditions of the external device connected to
the functio~ module including automatic control of the
external device, a manual on condition of the external
device, or a manual off condition of the external device,
and wherein the auto/manual selection switch second
6ection includes means for providing respective different
intermediate status signals for each of the operating
conditions of the external device. The NOR gates 120 and
122 in response to the intermediate status signals
provide the final status signals to the transistors 74
and 76 to enable the reading o~ those conditions by the
digital control ~odule.
Referring now to figures 3A and 3B, these
figures when taken together comprise a schematic circuit
diagram of another output function module 150 embodying
the present invention. Function module 150 is adapted
to provide a binary output at its outputs 152 and 154
wherein either output may source a current or sink a
current. The function control module 150 includes the.
bus interface 40, the data register 42, and output
circuit 156, and auto/manual select circuit 158. The ~us
interface 40 and data register 42 are identical to the
bus interface and data register described with respect
to Figure 2A and therefore need not be described in
detail herein. As a result, the bus interface 40 is
shown being coupled to the digital control module by the
same plurality of lines 56, 58, 60,62 and 64 as
previou~ly described with respect to Figure 2A. Also,
the data register 42 is coupled to a power-up~reset
circuit 130 as described with respect to Figure 2B.
~he output circuit 156 comprises a pair of
identical output circuit portion~ 156a and 156b. Since
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WO91/01020 %n~ J~ PCI'~US90/03887
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both output clrcuit portions are identical only output
circuit portion 156a will be described in detail herein.
Output circuit portion 156a includes a NAND
gate 160, an invertor 162, an invertor 164, an invertor
166, and output transistors 168 and 170. The first input
of NAND gate 160 is coupled to the Q output of 84 of data
register 42. The output of NAND gate 160 is coupled to
the input of invertor 162. The output of invertor 162 is
coupled to the input of invertor 164 through resistors
172 and 174. The input of invertor 164 is also coupled
to system ground by a capacitor 176 and to a contact of
178 of switch 180 through a diode 182. The switch 180
is a two-position push button switch and is shown in its
open position. When the switch 180 is closed, the pole
182 will be in contact with contact 178. The switch :L80
is utilized when the function module 150 is rendered in
the manual mode as will be described in greater detail
hereinafter.
The output of invertor 164 is coupled to the
~base of transistor 168. The emitter of transistor ~68
is coupled to a constant voltage current fold back power
source circuit 190 which is coupled to a positive lS volt
power~;supply. A diode 186- isolates -the base of
transistor 168 from the power source 190.
The input to invertor 166 is coupled to the
common node of resistors 172 and 174 and to the contact
178 of switch 180 through a resistor 192 and a diode 194.
A capacitor 194 is also provided between the input of
invertor 166 and system ground. The output of invertor
166 is coupled to the base of transistor 170 through a
resistor 196. As will be noted from the figure, the
collectors of -transistors 168 and 170 are coupled
together and to the output line 152 through a fuse 198.
A zener diode is coupled between the collectors of
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WO91/0l020 PCT/US90/03887
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19
transistors 168 and 1~0 and the emitter of transistor
170, which is also coupled to system ground.
When the function module 50 is in the automatic
mode, the second input of NAND gate 160 will be at a high
voltage level. As a result, the output of NAND gate 160
will depend upon the high or low level condition of the
Q output of flip-flop 84. If the Q out:put of flip-flop
84 is at a high level, the output of NAND gate 160 will
be at a low level. The output of invertor 162 will be -
at a high level and the output of invertor 164 will be ~ -~
at a low level. The low level output at the output of
invertor 164-causes transistor 168 to be forward biased.
Since the output of invertor 162 is at a high level, the
output of invertor 166 will be at a low level to back
bias transistor 170. As a result, transistor 168 will
conduct current from the voltage source 190 out line 152
to the terminal blocks.
When the Q output of flip-flop 84 is at a low
level, the output of NAND gate 160 will be high to cause
the output o~ invertor 162 to be low. The output of '!~
invertor 164 wi}l therefore be high and as a result, the
transistor 168 will be back biased. -Because the output
of invertor 162 is low,-the output of ~invertor 166 will
be high to forward bias transistor -170. ~ence,
tran~istor 168 will not conduct but transistor 170 will
conduct. As a result, the output line 152 will be pulled
down to a low voltage level.
The auto~manual select circuit 158 includes an
auto/manual select switch 202, a NOR gate 204 and another
NOR gate 206. The switch 202 is a sing}e pole two
position switch having a pole 208 and contacts 210 and
~212. The contact 210 is coupled to a positive 15 volt
power supply through a resistor 214 and to the second
input of the NOR gate 204. The first input of NOR yate
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wo 9l~0~02~ t~ ?, ~ PCT/US90/03887
204 is coupled to the output o~ NAND gate 66 of the bus
inter~ace 40. The output of NOR gate 204 is coupled to
the base of transistor 74 through the resistor 126. ~he
contact 212 is coupled to a positive 15 volt power source
through a resistor 216 and to the second input of NOR
gate 206. The first input of NOR gate 206 is also
coupled to the output of NAND gate 66 of bus interface
40. As can be noted from the Figures, the contact 210
is also coupled to the second inputs of NAND ~ate 160 and
NAND gate 161 of the output circuit s~cond portion 156b.
The output of NOR gate 206 is coupled to the base of
transistor 76 of the bus interface 40 through the
resistor 128.
When the auto/manual select switch is
}5 positioned to select the automatic modeJ the pole 208 is
in con~tact with contact 212. This causes the second
input of NOR gate 204 to be at a high level and the
second input of NOR gate 206 to be at a low level.
Because a 1QW level is impressed upon the first inputs
of NOR gates 204 and 206 when the condition of the
auto/manual select circuit is conveyed to the digital
control module, the output of NOR gate 204 will be at a
low level and~the output of-NOR gate 206:wilI be at a
high level. These levels cause transistor 74 to be back
biased and transistor 76 to be forward biased. As a
result, the automatic mode is selected,the bi-directional
line 62 will be at a high level and bi-directional line
64 will be at a low level indicative of the automatic
mode selection. In the ma~ual m~de, the auto/manual
select switch 202 is in the position illustrated. This
causes the second input of NOR gate 204 to be at a low
level and the second input of NOR gate 206 to be at a
high level. As a result, the output of NOR gate 20i will
be at a high level and the output of NOR gate 206 will
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WO91/01020 PCT/US90/03887
2~7n~
21
be at a low level~ These level~ cause transistor 74 to
conduct and transistor 76 to be turned off. As a result,
the bi-directional line 62 will be at a low level and bi-
directional 64 to be at a high level indicative of the
manual mode selection.
When the auto/manual se:Lect circuit is
conditioned to select the manual mode, the second inputs
of NAND gates 160 and 161 will be at a low level so that
regardless of the level of the Q outputs of flip-flops
84 and 86 of the data register 42, the binary voltage
level at the outputs 152 ~nd 154 will depend upon the
condition of the switches 180 and 181. For example, if
switch 181 is in the position illustrated, that is, its
open position, then the binary output at output line 152
will be at a low level. This results because the second
input;of NAND gate 160 is at a low level causing its
output to be at a high level. This in turn causes the
output of invertor 162 to be at a low level and the
output of invertor 164 to be at a high leve}. The output
of invertor 166 will also be at a high level so that
transistor 170 will conduct and transistor 168 will be
turned off. This results in the output line 152 being
pulled down to a low level.
When switch 180 is closed and pole 182 contacts
contact 178, a high voltage level will be impressed upon
the inputs to invertors 164 and 166 through resistors 174
and 192 respectively. This causes the outputs of
invertors 164 and 166 to be at a low level to forward
bias transistor 168 and back bias transistor 170. As a
result, current will flow through transistor 168 and out
line 152 to the terminal blocks.
As a result of the foregoing, the function
module 150 of this embodiment provides the selection of
either an automatic or manual mode condition o~ the
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WO91/01020 22 PCT/US~0/03887
2 ~nction module. The function module 150 provides the
digital control module with information indicative of the
manual or automatic mode selection. When in the
automatic mode, line 62 is high and line 64 is low. When
in the manual mode, line 62 is low and line 64 is high.
In addition, when in the manual mode, control of the
external device is removed from the digital control
module by the NAND gates }60 and 161 to place the outputs
under the control of ~he manual switches 180 and 1~1.
~hile particular embodiments of the present
invention have been shown and described, modifications
may be made f and it is intended in the appended claims
to cover all such modifications as may fall within the
true spirit and scope of the invention.
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