DESCRIPTION
Title of Invention: PROCESS CONTROL SYSTEM, PROCESS CONTROL
DEVICE, AND PROCESS CONTROL METHOD
Technical Field
[0001]
The present invention relates to a process control system,
a process control device, and a process control method.
Background Art
[0002]
Conventionally, process control is important in a factory
(for example, an automobile factory), and various methods
related to process control are considered. For example, PTL
1 discloses a production control system which appropriately
controls adjustment of a product production plan and progress
of an actual product production operation.
[0003]
Specifically, the production control system described in
PTL 1 includes a database registering the number of used
components, an operation time, a mechanical operation time, and
a testing time necessary for producing one product and includes
information from component procurement to production
completion. The database is updated at any time based on new
spec information and product renewal information, and a stress
3
process (an overload operation process or an operation process
which is not completed as planned) is controlled based on the
database. Further, the production control system visually
controls an estimation and a result of the stress process by
displaying them on a screen, sends a notification to related
departments by e-mail, and replans automatically.
Citation List
Patent Literature
[0004]
PTL 1: JP 2011-90595 A
Summary of Invention
Technical Problem
[0005]
Various devices are installed in a factory and are
connected to a programmable logic controller (PLC). An example
of the various devices includes a sensor for detecting that a
vehicle passes through on a production line.
[0006]
This sensor is installed at each point on a manufacturing
line, and when detecting that a vehicle passes through the
manufacturing line, the sensor sends a passing signal to a PLC.
When receiving the passing signal from the sensor, the PLC
stores the signal in a register included in the PLC as device
information and also appropriately controls the various devices
4
based on the stored device information.
[0007]
Further, the PLC is connected to the various devices and
also connected to a host device such as a client and a server.
In connection between the PLC and the host device, a
communication standard called OLE for process control (OPC) is
used. The OPC is for communicating by mutually connecting the
host device and the PLC regardless of a vendor of the PLC.
Communication by OPC is called OPC communication.
[0008]
By this OPC communication, the host device can
appropriately obtain device information stored in a register
of the PLC. The host device can perform process control by
grasping delay in a manufacturing process or like by analyzing
the device information obtained from the PLC.
[0009]
However, in the case where the host device communicates
with PLCs of different vendors by OPC communication, various
settings are needed for each of the PLCs of different vendors
on the host device side, and complicated operations are needed.
Further, in the case where device information from the PLCs is
analyzed in the host device, a specialized expertise for
analysis is needed.
[0010]
Further, even if the host device obtains an analysis
5
result that a manufacturing process is delayed, since a tact
time is different for each vehicle component, it is difficult
to determine whether the delay obtained as the analysis result
is actually within an allowable range, the delay is out of the
allowable range, but not significant, or the delay is
significant.
[0011]
Specifically, there is a first issue that complicated
setting operations are needed in the case where the host device
and the PLC are communicatively connected by OPC communication.
Further, there is a second issue that a specialized expertise
is needed for analysis in the case where the host device analyses
device information obtained by the OPC communication. Even if
the information can be analyzed, there is a third issue that
process control is not properly performed in the case where an
analysis result is not appropriate.
[0012]
The prevent invention is in view of the above issues, and
proposes a process control system, a process control device,
and a process control method in which device information can
be simply obtained without complicated setting operations and
appropriate process control can be performed based on the
obtained device information.
Solution to Problem
6
[0013]
To solve the above issues, according to the present
invention, a process control system includes a controller and
a process control device. The controller controls a device
installed in a factory. The process control device is
communicatively connected to the controller by OPC
communication. The controller includes a register for storing
device information provided from the device. The process
control device includes a storage unit and a monitoring
communication unit. The storage unit stores, as definition
information, a tag associated with a storage region of the
register. The monitoring communication unit monitors the
device information by periodically accessing the storage region
of the register associated with the tag by referring to the
definition information.
[0014]
Further, to solve the above issues, according to the
present invention, a process control device is communicatively
connected, by OPC communication, to a controller for
controlling a device installed in a factory. The controller
includes a register for storing device information provided
from the device. The process control device includes a storage
unit and a monitoring communication unit. The storage unit
stores, as definition information, a tag associated with a
storage region of the register. The monitoring communication
7
unit monitors the device information by periodically accessing
the storage region of the register associated with the tag by
referring to the definition information.
[0015]
To solve the above issues, according to the present
invention, in a process control method for a process control
system including a controller to control a device installed in
a factory and a process control device communicatively
connected to the controller by OPC communication, the process
control method includes three steps. A first step is that the
controller stores device information provided from the device.
A second step is that the process control device stores, as
definition information, a tag associated with a storage region
of a register. A third step is for monitoring the device
information by periodically accessing the storage region of the
register associated with the tag by referring to the definition
information.
Advantageous Effects of Invention
[0016]
According to the present invention, device information
can be easily obtained without complicated setting operations,
and appropriate process control can be performed based on the
obtained device information.
8
Brief Description of Drawings
[0017]
[FIG. 1] FIG. 1 is an overall configuration diagram of
a process control system.
[FIG. 2] FIG. 2 is a schematic diagram of difference
information.
[FIG. 3] FIG. 3 is a schematic diagram of result
information.
[FIG. 4] FIG. 4 is a schematic diagram of process
information.
[FIG. 5] FIG. 5 is a schematic diagram of definition
information.
[FIG. 6] FIG. 6 is a screen configuration diagram.
[FIG. 7] FIG. 7 is a schematic diagram for describing an
outline of processing according to an embodiment described
herein.
[FIG. 8] FIG. 8 is a schematic diagram indicating a normal
distribution.
[FIG. 9] FIG. 9 is a flowchart indicating monitor
communication processing.
[FIG. 10] FIG. 10 is a flowchart indicating previous value
comparison processing.
[FIG. 11] FIG. 11 is a flowchart indicating process result
comparison processing.
9
Description of Embodiments
[0018]
An embodiment of the present invention will be described
below with reference to drawings.
[0019]
(1) Overall Configuration
FIG. 1 illustrates an overall configuration of a process
control system 1 according to the embodiment. The process
control system 1 includes a programmable logic controller (PLC)
10, a process control device 20, and an OPC (OLE for process
control) server 30, a monitor 40, and a host process 50.
[0020]
The PLC 10 is a controller installed in a factory (for
example, an automobile factory) and includes a central
processing unit (CPU) 11, a register 12, and a communication
unit 13. When receiving a signal from various devices (not
illustrated) installed in the factory, the CPU 11 stores the
received signal in the register 12 as device information. An
example of the various devices installed in the factory includes
a sensor for detecting that a vehicle passes through on a
manufacturing line. Further, if the device is the sensor, the
CPU 11 stores a passing signal from the sensor in the register
12 as device information.
[0021]
The register 12 stores the device information from the
10
various devices. Further, in the case where the register 12
receives new device information from the device of which the
device information is already stored, the register 12 stores
the new device information by overwriting the past device
information.
[0022]
The communication unit 13 is connected the OPC server 30
and sends device information stored in the register 12 to the
OPC server 30. The device information sent to the OPC server
30 is sent to the process control device 20 and held by the
process control device 20. On the other hand, the communication
unit 13 receives control information from the OPC server 30.
The control information received herein is information to
control an operation of the various devices. The received
control information is sent to the various devices after being
converted into a control signal by the CPU 11.
[0023]
The process control device 20 includes a CPU 21, a hard
disk drive (HDD) 22, a communication unit 23, and an operation
display unit 24. The CPU 21 integrally controls operations of
the process control device 20 based on various programs of the
monitoring communication unit 211, the previous value
comparison unit 212, and the process result comparison unit 213
and various information stored in the HDD 22.
[0024]
11
The process of various programs of the monitoring
communication unit 211, the previous value comparison unit 212,
and the process result comparison unit 213, included in the CPU
21 will be described later in detail (FIGS. 9 to 11). The CPU
21 can perform appropriate process control by performing the
process of the various programs.
[0025]
The HDD 22 includes difference information 221, result
information 222, process information 223, and definition
information 224. The difference information 221, the result
information 222, the process information 223, and the
definition information 224 will be described later in detail
(FIGS. 2 to 4). The difference information 221 is information
indicating a difference between an estimated time for obtaining
device information (a process time) and a time at which the
device information is actually obtained (a result time). The
result information 222 is device information actually obtained
at a certain time (a result value). The process information
223 is device information to be obtained (a process value). The
definition information 224 is information defined to the
various devices including such as an address of the register
12.
[0026]
The communication unit 23 is connected to the OPC server
30 and sends, to the OPC server 30, control information for
12
controlling an operation of the various devices installed in
a factory. The control information sent to the OPC server 30
is sent to the various devices by being converted into a control
signal by the PLC 10. On the other hand, the communication unit
23 receives device information from the OPC server 30. The
received device information is stored in the HDD 22 by the CPU
21.
[0027]
The operation display unit 24 includes an operation unit
such as a keyboard and a mouse and a display unit such as a liquid
crystal display (LCD).
[0028]
The OPC server 30 is connected to the communication units
13 and 23 via a local area network (LAN). For the connection,
a communication standard called OPC is used. Herein, the OPC
server 30 is independently installed, but it is not limited
thereto. The OPC server 30 may be integrally formed with the
process control device 20 and incorporated into the process
control device 20.
[0029]
The monitor 40 is a display unit installed in a factory.
The monitor 40 displays a visualized product (vehicle) such that
the progress of a manufacturing process can be grasped at a
glance. A display mode in the monitor 40 will described later
(FIG. 6).
13
[0030]
The host process 50 is a server which is connected to a
host side of the process control device 20 and integrally
controls process control.
[0031]
(2) Details of Each Information
Each information including the difference information
221, the result information 222, the process information 223,
the definition information 224, and the like stored in the HDD
22 of the process control device 20 will be described with
reference to FIGS. 2 to 5.
[0032]
FIG. 2 is a schematic configuration of the difference
information 221. The difference information 221 includes a tag
column 2211 and a delay second column 2212. The tag column 2211
stores identification information of a tag associated with a
device. The delay second column 2212 stores a process time and
delay in seconds from the process time.
[0033]
Therefore, FIG. 2 indicates that, for example, a device
of which identification information is associated with a tag
of “PI01” starts an operation when a process time is “13:00:00”
(delay in seconds is “0”) and does not obtain device information
when the process time is “13:00:05”. Therefore, the device
information is actually obtained “3” seconds behind.
14
Specifically, the device in which a tag is “PI01” actually
obtains the device information at 13:00:08 (a result time).
[0034]
Further, the device of “PI01” does not intend to obtain
the device information when the process time is “13:00:10”
(delay in seconds is a blank) and obtains the device information
again when the process time is “13:00:15”. This indicates that
the device information is obtained “2” seconds behind at this
time.
[0035]
FIG. 3 illustrates a schematic configuration of the
result information 222. The result information 222 includes
a tag column 2221 and a device information column 2222. The
tag column 2221 stores identification information of a tag
associated with a device. Further, the device information
column 2222 stores device information (a result value) actually
obtained from the device at a certain time.
[0036]
Therefore, FIG. 3 indicates that, for example, a device
of which identification information is associated with a tag
of “PI01” obtains information at a certain time that the device
information (a result value) is “000F”.
[0037]
FIG. 4 illustrates a schematic configuration of the
process information 223. The process information 223 includes
15
a tag column 2231 and a device information column 2232. The
tag column 2231 stores identification information of a tag
associated with a device. Further, the device information
column 2232 stores device information (a process value) to be
obtained from the device for each process time.
[0038]
Therefore, FIG. 4 indicates that, for example, a device
of which identification information is associated with a tag
of “PI01” intends to obtain device information of “0000” when
a process time is “13:00:00” and intends to obtain device
information of “000F” at “13:00:05” which is 5 seconds later.
The difference information 221 in FIG. 2 indicates that the
device information of “000F” is obtained “3” seconds behind.
[0039]
FIG. 5 illustrates a schematic configuration of the
definition information 224. The definition information 224
includes an item column 2241 and an information column 2242.
The item column 2241 stores an item to be defined to a device.
Further, the information column 2242 stores information defined
to the device.
[0040]
Therefore, FIG. 5 indicates that, for example, “1”, “2”,
and “3” are stored in items of “NUMBER” and definition
information of total three devices is stored as the definition
information 224. Regarding a device of NUMBER “1”, for example,
16
identification information “PI01” is defined as “TAG”, and the
name of a device type called “Device001” is defined as “DEVICE
TYPE”.
[0041]
Further, as “MONITORING CYCLE”, “5” seconds are defined,
and it is indicated that this device of “PI01” obtains device
information at intervals of five seconds. Furthermore, as
“DRAWING NECESSITY”, “1” is defined, and it is indicated that
drawing is necessary. When drawing is performed, a position
of “192” pixel in a “DRAWING POSITION X” direction on a screen
is a drawing start position, and a position of “168” pixel in
a “DRAWING POSITION Y” direction on the screen is a drawing start
position.
[0042]
(3) Screen Configuration
FIG. 6 illustrates an example of a screen configuration
displayed on the monitor 40. Images G1 and G2 are displayed
on the monitor 40. A vehicle ID and a time are displayed on
the images G1 and G2, and also the images G1 and G2 display such
that a state of the vehicle corresponding to the vehicle ID and
the time can be grasped at a glance.
[0043]
Therefore, according to FIG. 6, the image G1 illustrates
a state of a vehicle of the vehicle ID “00001” on a manufacturing
line at “18:00:00”. As illustrated in the image G1, it is easily
17
grasped that a wheel is not assembled to the vehicle at
“18:00:00”.
[0044]
On the other hand, the image G2 illustrates a state of
the vehicle of the vehicle ID “00001” on a manufacturing line
at “18:00:30”. The vehicle illustrated in the image G2 has the
same vehicle ID as the vehicle illustrated in the image G1 and
therefore indicates a state of the vehicle illustrated in the
image G1 after the lapse of thirty seconds. As illustrated in
the image G2, it is easily grasped that a wheel G21 is assembled
to the vehicle when the time is at “18:00:30”.
[0045]
In the case where trouble such as delay occurs in a process
for assembling the wheel G21, the wheel G21 may be displayed
while being identified by changing a color and a display mode
from other components. For example, only the wheel G21 may be
displayed in red or displayed by flashing. In this case, it
is easily grasped that the trouble such as delay occurs in a
process of the wheel G21.
[0046]
(4) Outline of Processing
FIG. 7 indicates an outline of processing according to
the embodiment. According to the embodiment, the process
control device 20 can obtain device information from the PLCs
10, in which vendors are different, without a complicated
18
setting operation and can perform appropriate process control
based on the obtained device information.
[0047]
First the PLC 10 receives a signal from the various devices
(not illustrated) installed in a factory and stores the received
signal in the register 12 in the PLC 10 as device information.
In the register 12, a storage region in which the device
information is stored is provided in each device. For example,
device information of a sensor A1 is stored in a storage region
A11, and device information of the sensor B1 is stored in a
storage region B11.
[0048]
The monitoring communication unit 211 periodically
monitors the register 12 of the PLC 10 via the OPC server 30
by referring to the definition information 224. A tag
associated with a device and an arbitrary storage region of the
register 12 associated with the tag are stored in the definition
information 224, and also a monitoring cycle is set to the tag.
Therefore, the monitoring communication unit 211 can
periodically monitor the arbitrary storage region of the
register 12 at a predetermined monitoring cycle by referring
to a tag in the definition information 224.
[0049]
When detecting that device information is stored or
overwritten in a storage region of the register 12, the
19
monitoring communication unit 211 sends the stored or
overwritten device information to the previous value comparison
unit 212.
[0050]
When receiving the device information from the monitoring
communication unit 211, the previous value comparison unit 212
stores the received device information to the HDD 22 as the
result information 222. Further, the previous value
comparison unit 212 refers to the result information 222,
compares the device information received this time and the
device information received previous time, and determines
whether there is a difference therebetween.
[0051]
In the case where there is a difference, specifically in
the case where the device information is updated, the previous
value comparison unit 212 notifies the process result
comparison unit 213 that the device information is updated and
also performs display on the monitor 40 in a mode in which an
updated component is grasped at a glance.
[0052]
When receiving the notification from the previous value
comparison unit 212, the process result comparison unit 213
refers to the process information 223, calculates whether there
is a difference between a time in which a device actually obtains
device information (a result time) and an estimated time to
20
obtain the information (a process time), and stores delay in
seconds obtained as a calculation result in the difference
information 221.
[0053]
The process result comparison unit 213 confirms a delay
level in the case where the delay is detected at a result time.
Specifically, the process result comparison unit 213
approximates to a distribution of a difference between a past
result time and a process time as a normal distribution (FIG.
8) and determines to be abnormal in the case where significant
difference recognized as sufficient delay occurs. The process
result comparison unit 213 performs display on the monitor 40
such that the abnormal portion (a delayed component) can be
grasped at a glance and also notifies the abnormal portion to
the host process 50.
[0054]
FIG. 8 illustrates a normal distribution F(X) calculated
based on a difference between a result time and a process time.
In the case where delay is recognized in the result time, the
normal distribution F(X) is used to determine whether the delay
is within an allowable range or the delay is out of the allowable
range and abnormal delay and indicates a probability in which
the delay in seconds becomes X. The normal distribution F(X)
is calculated by the following formula 1.
[0055]
21
[Mathematical Formula 1]
X = this delay in seconds
m = average of past delays in seconds
σ = standard deviation
[0056]
An average m of past delays in seconds and a standard
deviation σ are calculated by the following formulas 2 and 3
in the case where the past five delays in seconds are X1, X2,
X3, X4, and X5.
[0057]
[Mathematical Formula 2]
[0058]
[Mathematical Formula 3]
[0059]
In the case where delay is recognized in a result time,
the process result comparison unit 213 calculates a probability
of the occurrence of this delay in seconds by substituting this
delay in seconds to the normal distribution F(X). The process
result comparison unit 213 determines that this delay in seconds
22
is out of an allowable range and an abnormal delay in the case
where a probability obtained as a calculation result is 5% or
less when a significance level is set to 5%.
[0060]
(5) Details in Processing
With reference to FIGS. 9 to 11, details in processing
by the monitoring communication unit 211, the previous value
comparison unit 212, and the process result comparison unit 213
described in FIGS. 7 and 8 will be described.
[0061]
FIG. 9 illustrates details of processing by the
monitoring communication unit 211. This processing starts,
for example, when the monitoring communication unit 211
receives an execution instruction from the operation display
unit 24 or when the process control device 20 is powered on.
[0062]
First, the monitoring communication unit 211 refers to
the definition information 224 and reads various information
associated with each tag (SP1). Specifically, the tag is
associated with a storage region, a monitoring cycle, drawing
necessity, and drawing information (a drawing position and a
drawing image) of the register 12, and the monitoring
communication unit 211 read the various information associated
with the tags.
[0063]
23
Next, the monitoring communication unit 211 refers to the
monitoring cycle in the various read information and determines
whether there is a tag of a timing for reading device information
from a storage region of the register 12 (SP2). After obtaining
a negative result in the determination in step SP2, the
monitoring communication unit 211 refers to the smallest
monitoring cycle in the monitoring cycles associated with tags
and calculates a time until the nearest timing for reading
device information (SP3).
[0064]
The monitoring communication unit 211 determines again
whether there is a tag for reading timing (SP2) after waiting
for a time obtained as a calculation result (SP4). After
obtaining a positive result in the determination in step SP2,
the monitoring communication unit 211 reads device information
from a storage region of the register 12 appointed by a reading
timing tag (SP5), and finishes this processing.
[0065]
After step SP5, the monitoring communication unit 211
sends the read device information to the previous value
comparison unit 212. The device information read by the
monitoring communication unit 211 includes device information
of multiple devices such as sensors A to D.
[0066]
FIG. 10 illustrates details of processing by the previous
24
value comparison unit 212. This processing starts when the
previous value comparison unit 212 obtains device information
from the monitoring communication unit 211.
[0067]
First, the previous value comparison unit 212 generates
one numeric string by connecting all device information read
by the monitoring communication unit 211 (SP11). Next, the
previous value comparison unit 212 generates one numeric string
by connecting all pieces of device information previously read
by the monitoring communication unit 211 (SP12). Then, the
previous value comparison unit 212 calculates an exclusive OR
of the generated two numeric strings (SP13) and determines
whether the exclusive OR is zero (SP14).
[0068]
When obtaining a positive result in the determination in
step SP14, the previous value comparison unit 212 determines
that device information is not updated since there is no
difference and finishes the processing by notifying the process
result comparison unit 213 of the determination result.
[0069]
On the other hand, after obtaining a negative result in
the determination in step SP14, the previous value comparison
unit 212 determines that the device information is updated since
there is a difference, notifies the process result comparison
unit 213 of the determination result, and also sends a tag in
25
which the difference is determined, the device information read
this time, the device information read previous time to the
process result comparison unit 213 (SP15).
[0070]
Next, the previous value comparison unit 212 refers to
drawing necessity associated with the tag in which the
difference is determined and determines whether the tag is a
drawing target tag (SP16). The previous value comparison unit
212 finishes the processing when obtaining a negative result
in the determination in step SP16.
[0071]
On the other hand, the previous value comparison unit 212
obtains drawing information (a drawing position and a drawing
image) stored in the definition information 224 when obtaining
a positive result in the determination in step SP16 (SP17). The
previous value comparison unit 212 sets a drawing flag to ON
(SP18) and finishes the processing.
[0072]
After setting the drawing flag to ON, the previous value
comparison unit 212 may obtain a drawing position and a drawing
image from the definition information 224 and draw them on the
monitor 40. In this case, when an operator can grasp an updated
component when the operator sees the image drawn on the monitor
40.
[0073]
26
FIG. 11 illustrates details of processing by the process
result comparison unit 213. This processing starts when the
process result comparison unit 213 receives a notification
whether there is a difference from the previous value comparison
unit 212.
[0074]
First, the process result comparison unit 213 refers to
the process information 223 and reads the process information
223 in which a process value of each device information at each
time is indicated (SP21). Next, when comparing the device
information (a result value) read from the register 12 and the
process value indicated in the process information 223, the
process result comparison unit 213 initializes an increment
variable N (a gap time N) for comparing by going back in time
subsequently by setting to zero (SP22). Further, the process
result comparison unit 213 determines how much the increment
variable N can be increased, specifically determines the
maximum value M of N (SP23).
[0075]
As a method for determining the maximum value M in step
SP23, herein the following method is used. A gap between a
process time and a result time in the past is accumulated as
a premise. Next, the accumulated gap is approximated to a
normal distribution in assumption that the accumulated gap is
in accordance with the normal distribution, and an average and
27
a dispersion are calculated. In the case where a significance
level is set to 5%, it is determined that the gap time N equal
to or less than the significance level is a significant
difference, and the minimum value of the gap time N which is
a significant difference is determined to M.
[0076]
Next, the process result comparison unit 213 obtains a
time which is the time N before in the time indicated in the
process information 223 and generates a numeric string by
connecting a process value corresponding to the obtained time
(SP24). Then, the process result comparison unit 213
calculates an exclusive OR with the numeric string generated
in step SP11 (SP25) and determines whether the exclusive OR is
zero (SP26).
[0077]
When obtaining a positive result in the determination in
step SP26, the process result comparison unit 213 determines
that there is no process delay and proceeds to step SP35. On
the other hand, when obtaining a negative result in the
determination in step SP26, the process result comparison unit
213 determines that there may be process delay and increments
the increment variable N by +1 (SP27).
[0078]
Next, the process result comparison unit 213 determines
whether the increment variable N is equal to or less than M (SP28).
28
The process result comparison unit 213 proceeds to step SP24
and repeats the above-described processes (SP24 to SP27) when
obtaining a positive result in the determination in step SP28.
[0079]
On the other hand, when obtaining a negative result in
the determination in step SP28, the process result comparison
unit 213 obtains a time just after the current time indicated
in the process information 223 and generates a numeric string
by connecting device information corresponding to the acquired
time, in view of a possibility that the progress actually
exceeds a plan indicated in the process information 223 (SP29).
Then, the process result comparison unit 213 calculates an
exclusive OR with the numeric string generated in step SP11
(SP30) and determines whether the exclusive OR is zero (SP31).
[0080]
When obtaining a positive result in the determination in
step SP31, the process result comparison unit 213 determines
that the progress is not delayed or that the progress is delayed
a little, but is normal, and proceeds to step SP35. On the other
hand, when receiving a negative result in the determination in
step SP31, the process result comparison unit 213 determines
that the progress is delayed, and the delay is abnormal.
[0081]
Next, the process result comparison unit 213 determines
whether a tag of device information determined to be abnormal
29
is a drawing target tag (SP32). The process result comparison
unit 213 proceeds to step SP35 when obtaining a negative result
in the determination in step SP32. On the other hand, when
obtaining a positive result in the determination in step SP32,
the process result comparison unit 213 obtains a drawing
position and a drawing image associated with a tag from the
definition information 224 (SP33) and sets a drawing flag to
ON (SP34).
[0082]
Next, the process result comparison unit 213 determines
whether the drawing flag is set to ON (SP35). The process result
comparison unit 213 finishes the processing when obtaining a
negative result in the determination in step SP35. On the other
hand, when obtaining a positive result in the determination in
step SP35, the process result comparison unit 213 draws a target
component on the monitor 40 based on the acquired drawing
position and drawing image (SP36) and finishes the processing.
[0083]
(6) Advantageous Effects of the Embodiment
As described above, according to the process control
system 1 according to the embodiment, the process control device
20 can access the register 12 of the PLC 10 via the OPC server
30 by referring to the definition information 224. The
definition information 224 can be easily rewritten. Therefore,
by appropriately changing the definition information 224, the
30
process control device 20 can easily access a plurality of PLCs
10 in which vendors are different or the PLC 10 newly added to
the process control system 1 without a complicated setting
operation and compiling a system.
[0084]
The process control device 20 compares the device
information obtained from the register 12 and the device
information obtained previous time, analyzes the device
information in the case where an update is recognized, and
display an updated component on the monitor 40. Accordingly,
the process control device 20 can visualize the progress of a
product on a manufacturing line. Therefore, an operator who
is not a specialist of process control can easily grasp the
progress in processing.
[0085]
Further, the process control device 20 compares the
device information obtained from the register 12 and the device
information indicated in the process information 223. In the
case where delay is recognized, the process control device 20
determines whether the delay is within an allowable range,
identifies and displays a delayed component on the monitor 40,
and accordingly can visualize the delay. Therefore, an
operator who is not a specialist of process control can easily
grasp the delay in processing.
Reference Signs List
31
[0086]
1 process control system
10 PLC
20 process control device
211 monitoring communication unit
212 previous value comparison unit
213 process result comparison unit
221 difference information
222 result information
223 process information
224 definition information
30 OPC server
40 monitor
50 host device

WE CLAIM:
[Claim 1]
A process control system, comprising:
a controller configured to control a device installed in
a factory; and
a process control device communicatively connected to the
controller by OPC communication, wherein
the controller comprises:
a register configured to store device information
provided from the device, and
the process control device comprises:
a storage unit configured to store, as definition
information, a tag associated with a storage region of the
register; and
a monitoring communication unit configured to refer to
the definition information and monitor the device information
by periodically accessing a storage region of the register
associated with the tag.
[Claim 2]
The process control system according to claim 1, wherein
the definition information includes the tag and includes
information on a monitoring cycle, drawing necessity, a drawing
position, and a drawing image, associated with the tag,
the monitoring communication unit monitors the device
information by periodically accessing the storage region of the
33
register based on the monitoring cycle, and
the process control device comprises a previous value
comparison unit configured to visualize an updated portion of
a product on a manufacturing line in a mode in which the updated
part can be grasped at a glance based on the drawing necessity,
the drawing position, and the drawing image in a case where the
device information monitored by the monitoring communication
unit is updated.
[Claim 3]
The process control system according to claim 2, wherein
the monitoring communication unit reads the device information
as well as monitors the device information from the register,
the storage unit stores the device information read this
time with the device information read previous time, and
the previous value comparison unit refers to the device
information stored in the storage unit and determines whether
the device information read this time is updated, by calculating
an exclusive OR between the device information read this time
and the device information read previous time.
[Claim 4]
The process control system according to claim 3, wherein
the storage unit stores a read time of device information read
from the register by the monitoring communication unit as a
result time and stores, as a process time, an estimated time
for reading device information to be read from the register in
34
a predetermined process, and
the process control device comprises a process result
comparison unit configured to determine whether a delay time
is within a predetermined allowable range by referring to the
result time and the process time and to visualize a delayed
component of a product on a product line in a mode in which the
delay can be grasped at a glance in a case where the delay time
is not within allowable range.
[Claim 5]
The process control system according to claim 4, wherein
the process result comparison unit approximates to the delay
time as a normal distribution by referring to the result time
and the process time and determines based on the approximated
normal distribution and a predetermined significance level
whether the delay time is within the predetermined allowable
range.
[Claim 6]
A process control device, wherein a controller configured
to control a device installed in a factory is communicatively
connected to the process control device by OPC communication,
the controller comprises a register configured to store device
information provided from the device, and
the process control device comprises:
a storage unit configured to store, as definition
information, a tag associated with a storage region of the
35
register; and
a monitoring communication unit configured to monitor the
device information by periodically accessing the storage region
of the register associated with the tag by referring to the
definition information.
[Claim 7]
A process control method for a process control system,
the process control system comprising a controller configured
to control a device installed in a factory and a process control
device communicatively connected to the controller by OPC
communication, wherein
the process control method comprises:
a first step in which the controller stores device
information provided from the device;
a second step in which the process control device stores,
as definition information, a tag associated with a storage
region of a register; and
a third step for monitoring the device information by
periodically accessing the storage region of the register
associated with the tag by referring to the definition
information.