Communications: electrical – Wellbore telemetering or control – Diagnostic monitoring or detecting operation of...
Reexamination Certificate
2000-03-29
2001-03-20
Trieu, Van T. (Department: 2736)
Communications: electrical
Wellbore telemetering or control
Diagnostic monitoring or detecting operation of...
C340S309160, C340S309300, C709S232000, C455S067700
Reexamination Certificate
active
06204776
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a communication abnormality detecting/coping device and a vacuum pump remote monitor control device, and more particularly to a communication abnormality detecting/coping device and a vacuum pump remote monitor control device, which are capable of detecting the presence/absence of an abnormality in data communication and reducing an influence of the abnormality on a system device when detecting the abnormality.
2. Description of the Related Art
FIG. 3
is a diagram showing the entire structure of a magnetic floatation type turbo-molecular pump
10
. Referring to
FIG. 3
, a rotor
1
is axially floated by an axial electromagnet
3
, and radial position control thereof is conducted by radial electromagnets
5
A and
5
B. Then, the rotor
1
is rotated by a motor
7
. A plurality of rotating blades
9
are axially formed in the rotor
1
. A plurality of fixed blades
11
are disposed at the rotating blades with a gap therebetween. One ends of the fixed blades
11
are supported between a plurality of fixed wing spacers
13
which are stacked one on another.
In the turbo-molecular pump
10
thus structured, gas molecules are struck by the rotating blades
9
during its rotation so as to be moved axially, thereby exhausting a gas. The turbo-molecular pump
10
of this type is, for example, used to exhaust the gas from a chamber of an etching device for manufacturing semiconductor (hereinafter referred to as “system device
30
”). A gas is always supplied to the chamber to process the semiconductor, and the supplied gas is exhausted by the turbo-molecular pump
10
.
In the case where the turbo-molecular pump
10
is controlled by the system device
30
, on/off signals using a relay have been employed as input/output signals from/to the turbo-molecular pump
10
up to now.
However, in the case where the relay is used, multiple wirings are arranged to cause an increase in cost and an increase in size. Also, there arises such a problem that analog information of r.p.m. or the like cannot be inputted or outputted.
To cope with the above problem, serial communication control using an RS 232 cable
21
or the like is recently increasingly implemented as shown in FIG.
4
. Referring to
FIG. 4
, the turbo-molecular pump
10
is connected to a bus
25
through a drive circuit
23
. The bus
25
is connected with switches such as a stop switch
29
or a start switch
31
through a switch I/F circuit
27
.
The bus
25
is connected with a liquid crystal display
33
. The bus
25
is also connected with a communication circuit
35
and the system device
30
through the RS232 cable
21
. A turbo-molecular pump control device
20
enclosed by a dotted line in
FIG. 4
is thus formed with the driver circuit
23
, the switch I/F circuit
27
, the liquid crystal display
33
, the communication circuit
35
, a CPU
37
and so on.
By the way, in a conventional case where data communication is conducted between the turbo-molecular pump control device
20
and the system device
30
through the RS232 cable
21
or the like, there may arise the following problems.
FIG. 5
illustrates data communication between the turbo-molecular pump control device
20
and the system device
30
. In
FIG. 5
, data communication in a normal operation is shown. For example, a command
41
such as a start command is transmitted to the turbo-molecular pump control device
20
from the system device
30
. The turbo-molecular pump control device
20
returns an acknowledgement signal
43
(hereinafter referred to as “ACK
43
”) indicative of the reception of the command
41
to the system device
30
and simultaneously starts the turbo-molecular pump
10
.
Then, in the case where, for example, r.p.m. data is required in the system device
30
, a data request signal
45
is transmitted to the turbo-molecular pump control device
20
by the system device
30
. The turbo-molecular pump control device
20
transmits r.p.m. data
47
to the system device
30
in response to the data request signal
45
. The system device
30
transmits an ACK
49
which is an acknowledgement signal indicative of the reception of the r.p.m. data
47
to the turbo-molecular pump control device
20
.
Thereafter, in the case where a trouble (program runaway) on the part of the system device
30
, the disconnection of the cable, falling-out of a connector or the like occurs while the turbo-molecular pump
10
is rotating, communication is hung up. In this situation, because the turbo-molecular pump control device
20
is of a slave, it cannot acknowledge the communication state with the system device
30
which is of a master. As a result, even in the case where the turbo-molecular pump
10
must stop, it continues to rotate, and an energy is unnecessarily consumed.
Also, depending on the operating state, there is a fear that a trouble may be caused in a process on the system device
30
side by stoppage of the turbo-molecular pump
10
immediately after the disenablement of the data communication.
SUMMARY OF THE INVENTION
The present invention has been made in view of the above problems with the conventional device, and therefore an object of the present invention is to provide a communication abnormality detecting/coping device and a vacuum pump remote monitor control device, which are capable of detecting the presence/absence of an abnormality in data communication and reducing an influence of the abnormality on a system device when detecting the abnormality.
In order to achieve the above object, according to the present invention, there is provided a communication abnormality detecting/coping device comprising:
a system device;
a control/display device for conducting data communication with the system device;
a first message transmission means for periodically transmitting a first message to the system device from the control/display device;
a second message transmission means for periodically transmitting a second message to the control/display device from the system device;
a communication system abnormality judging means for measuring an elapsed period of from a time of transmission of the first message by the first message transmission means to a time of reception of the second message transmitted from the second message transmission means and received by the control/display device to judge whether the measured elapsed period exceeds a preset period, or not; and
a warning/coping means for warning the abnormality of a communication system or coping with the abnormality of the communication system when the communication system abnormality judging means judges that the measured elapsed period exceeds the preset period, characterized in that
one of the second message transmission means and the first message transmission means sends an operation acknowledgement message for acknowledging that data communication is enabled between the system device and the control/display device, and the other thereof sends a reply message indicative of the acknowledgement of the operation acknowledgement message.
The first message transmission means periodically transmits the first message to the system device from the control/display device. The second message transmission means periodically transmits the second message to the control/display device from the system device.
The communication system abnormality judging means measures the elapsed period of from a time of transmission of the first message by the first message transmission means to a time of reception of the second message transmitted from the second message transmission means by the control/display device. Then, the communication system abnormality judging means judges whether the measured elapsed period exceeds a preset period, or not.
One of the second message transmission means and the first message transmission means sends an operation acknowledgement message for acknowledging that data communication is enabled between the system device and the control/display device, and the other thereof sends a reply messa
Adams & Wilks
Seiko Seiki Kabushiki Kaisha
Trieu Van T.
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