BACKGROUND OF THE INVENTION
Field of the Invention
[0001] The present invention relates to an article recognizing system which is used to automatically
manage and exchange tools of a machine tool, to manage parts and products in a factory,
to identify articles in a physical distribution system and the like.
Description of Prior Art
[0002] In general, in order to mechanize the automatic exchange or management of tools of
a machine tool, discrimination of parts and products on an assembly conveying line
in a factory, or the like, a system to recognize and manage the articles such as tools,
parts, products and the like is necessary. To satisfy this demand, an article recognizing
system has recently been developed. This system comprises a write/read control unit
and a head connected thereto. The write/read control unit is connected to an upper
(superior or host) control apparatus including computer system. On the other hand,
an ID unit having therein a non-volatile memory to store ID data or the like of an
article is attached to the articles which are sent on, e.g., a conveying line. When
a article arrives at the position of the head, data is written into or read out from
the ID unit by the head in a contactless manner under control of the write/read control
unit in response to a command from the upper control apparatus.
[0003] Since the data transmission and reception are executed between the head of the write/read
control unit and the ID unit in a contactless manner, if the distance between the
head and the ID unit is improper, such a situation that data cannot be accurately
written or read out may occur. Therefore, upon installation, the adjustment of the
distance between the head and the ID unit and the positioning thereof become important
and the severe adjusting work is required. On the other hand, after the positioning
adjustment has once been performed, there occurs a case where the distance at which
data can be stably written or read out changes due to the noises, circumstances or
the like, so that a readjustment is required.
[0004] However, the conventional article recognizing system does not have a stable operation
indicator to indicate that the data writing/reading operations can be correctly performed.
Therefore, it is difficult to stably confirm the writing/reading operating range.
Further, since the writing/reading operations for the ID unit are executed in response
to a command from the upper control apparatus, upon adjustment in a field where the
head is installed, the worker must go to the location where the upper control apparatus
is installed and which is away from this field to operate the upper control apparatus.
Thus, there are problems such that the adjusting work is difficult and it takes a
time. In addition, the write/read data cannot be checked or corrected in the field
where the head is located.
[0005] In the article recognizing system, a plurality of write/read control units to be
installed in the field are generally connected to one upper control apparatus.
[0006] The upper control apparatus is connected to a plurality of control units through
transmission lines and gives write/read commands and the like to each of the write/read
control units together with the unit number assigned thereto. If the command given
from the upper control apparatus includes the self No., the write/read control unit
recognizes this command and performs the data transmission and reception with the
ID unit in accordance with this command.
[0007] The write/read control unit returns a response indicating that the command was correctly
executed to the upper control apparatus together with the self No. after completion
of the writing/reading operations. On the contrary, when the command could not be
correctly finished, the write/read control unit returns an error code response indicative
of the kind of error occurred to the upper control apparatus together with the self
No.. When the error code responses are returned, the upper control apparatus stores
the error code data of every write/read control unit and manages the errors.
[0008] In such a conventional system, the error data generated are managed in a lump by
the upper control apparatus. Therefore, when a plurality of write/read control units
are connected to the upper control apparatus, there is a problem such that the load
of the upper control apparatus increases to manage the errors generated.
SUMMARY OF THE INVENTION
[0009] The present invention is made in consideration of the foregoing problem and it is
an object of the invention to provide an article recognizing system for writing/reading
data on the basis of commands from an upper (superior or host) control apparatus,
in which the writing/reading operations for an ID unit can be also executed on the
basis of commands from write/read control units.
[0010] Another object of the invention is to provide an article recognizing system for writing/reading
data on the basis of commands from an upper control apparatus, in which the writing/reading
operations for an ID unit can be also executed based on commands from write/read control
units and can be also continuously performed in a predetermined operating mode.
[0011] Still another object of the invention is to provide an article recognizing system
in which the load of an upper control apparatus is reduced and error data can be also
monitored by each write/read control unit as necessary.
[0012] According to the present invention, there is provided an article recognizing system
comprising a head to perform data transmission and reception in a contactless manner
for an ID unit storing ID data of an article, and a write/read control unit to control
the data transmission and reception through the head in accordance with commands from
an upper control apparatus, wherein the write/read control unit is provided with a
monitor unit having a mode setting device to select either the first mode or the second
mode, key input means for inputting the commands relating to the data transmission
and reception for the ID unit, and a display device. When the first mode is selected,
the write/read control unit is made operative on the basis of the command from the
upper control apparatus, and when the second mode is selected, the write/read control
unit is made operative on the basis of the key input from the monitor unit.
[0013] In this article recognizing system, when the second mode is selected by the mode
setting device in the monitor unit, a write or read command is input to the write/read
control unit by the operation of the key input means in the monitor unit. Thus, data
is written into or read out from the ID unit and the result is displayed on the display
device in the monitor unit.
[0014] According to the invention, the monitor unit having the mode setting device to select
either the first mode (RUN mode) or the second mode (MONITOR mode), key input means
for inputting commands relating to the data transmission and reception for the ID
unit, and display device is provided for the write/read control unit. Therefore, even
if the write/read control unit is disconnected from the upper control apparatus, the
write/read control unit can write/read data into/from the ID unit. In the field where
the head and write/read control unit are installed and which is remote from the upper
control apparatus, the adjustment of the distance between the head and an object and
the check of the write/read data can be easily performed.
[0015] According to the invention, there is provided an article recognizing system comprising
a head to perform data transmission and reception in a contactless manner for an ID
unit storing ID data of an article, and a write/read control unit to control the data
transmission and reception through the head in accordance with commands from an upper
control apparatus, wherein the write/read control unit is provided with a monitor
unit having means for designating a test mode, key input means for inputting commands
relating to the data transmission and reception for the ID unit, and a display device,
and the write/read control unit comprises means for receiving a key input signal from
the monitor unit, means for continuously executing the writing/reading operations
for the ID unit in response to the designation of the test mode, and means for discriminating
whether each of the writing and reading operations has correctly been performed or
not and for displaying the result of the discrimination on the display device of the
monitor unit.
[0016] In this article recognizing system, when the test mode is designated in the monitor
unit, the writing and reading processes are continuously executed after that. A check
is made to see if each of the writing and reading operations has correctly been performed
or not and the result is displayed on the display device of the monitor unit. Therefore,
it is possible to check whether each of the writing/reading operations has correctly
been performed or not at every distance in the test mode designated while making the
ID unit approach or be away from the head, that is, while adjusting the distance between
the ID nit and the head. The distance of the ID unit to the head can be easily adjusted,
thereby enabling the ID unit to be set to the proper distance.
[0017] According to the invention, there is provided an article recognizing system comprising
a head to perform the data transmission and reception in a contactless manner for
an ID unit storing ID data of an article, and a write/read control unit to control
the data transmission and reception through the head in accordance with commands from
an upper control apparatus, wherein the write/read control unit has means for discriminating
whether errors have occurred or not at the data transmission and reception, and error
data memory means for sequentially storing the errors discriminated by the discriminating
means every kind of error. Preferably, the write/read control unit has monitor means
for outputting the error data as necessary.
[0018] In this article recognizing system, when a command is input from the upper control
apparatus, the writing/reading operation is executed in accordance with this command.
The occurrence of errors is discriminated every completion of the writing/reading
operation. If errors occur, they are sequentially stored every kind of error into
the error data memory means. These error data are displayed and output by the monitor
means as necessary.
[0019] Therefore, even when the upper control apparatus manages a plurality of write/read
control units, the error management is executed by each write/read control unit, so
that the load of the upper control apparatus is reduced. When a plurality of write/read
control units are connected to the upper control apparatus, the informaton indicating
in which unit in the system and what kind of error occurred can be known by monitoring
the content stored in the memory means every unit, so that the maintenance of the
system can be easily performed. On the other hand, the cause and frequency of the
errors occurred can be monitored in the field where the unit is installed and a countermeasure
can be rapidly taken.
BRIEF DESCRIPTION OF THE DRAWINGS
[0020]
Fig. 1 is a block diagram showing a schematic arrangement of an article recognizing
system in an embodiment of the present invention;
Fig. 2 is a diagram showing an operation panel of a monitor unit in the article recognizing
system;
Fig. 3 is a diagram for explaining the attachment of the monitor unit to a write/read
control unit;
Fig. 4 is an enlarged diagram of the operation panel of the monitor unit;
Fig. 5 is a block diagram showing a circuit arrangement of the write/read control
unit and monitor nit;
Figs. 6 and 7 are flowcharts for explaining the operation of the article recognizing
system;
Fig. 8 is a flowchart for explaining the operation of the article recognizing system
in another embodiment; and
Fig. 9 is a flowchart for explaining the operation of an article recognizing system
in further another embodiment.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0021] Fig. 1 is a block diagram showing a schematic arrangement of an article recognizing
system in an embodiment of the present invention.
[0022] In the article recognizing system of this embodiment, a write/read control unit 4
writes or reads out data into or from an ID unit 2 attached to an article 1 through
a head 5 by the electromagnetic coupling in response to commands from an upper (superior
or host) control apparatus 6 including a computer and the like. In this system, a
monitor unit 7 is attached to the write/read control unit 4. The monitor unit 7 can
select either a RUN mode or a MONITOR mode, as will be explained hereinafter. When
the RUN mode is selected, the write/read control unit 4 executes the writing or reading
operation of ID data or the like for the ID unit 2 in accordance with a command from
the upper control apparatus 6. On the other hand, when the MONITOR mode is selected,
the upper control apparatus 6 is electrically disconnected from the write/read control
unit 4 and the write/read control unit 4 executes the control of the writing/reading
operation or the like of the ID data or the like for the ID unit 2 in response to
a command from the monitor unit 7.
[0023] Fig. 2 shows an operation panel 7a of the monitor unit 7. A display device 11, a
mode setting device 12 to switch between the RUN mode and the MONITOR mode, and a
group of keys 13 are provided on the operation panel 7a. To clarify these keys, Fig.
4 shows an enlarged diagram of the operation panel 7a. In addition to a test key 31,
a reset key 32, and an error key 33, the group of keys 13 includes the following keys
as typical keys: a read key 41, write keys 42, a clear key 43, a key 44 of an arrow
in the left direction, a key 45 of an arrow in the right direction, a decrement or
decrease (DEC) key 46, an increment increase (INC) key 47, a set key 48, and the like.
These function keys are commonly used as keys to input alphabets such as A, B, C,
etc. and numerals of 0 to 9. The switching between the function keys and the alphabet/numeral
keys is performed by using a predetermined key (for instance, C key).
[0024] As shown in Fig. 3, the monitor unit 7 has a connector 14 on the lower surface. The
monitor unit 7 is assembled onto the write/read control unit 4 such that the connector
14 is fitted into a connector 15 formed on the upper surface of the write/read control
unit 4 and is electrically connected to the connector 15. The control unit 4 further
has a connector 16 to connect to the head 5 and a connector 17 to connect to the upper
control apparatus 6. An LED 25 to display errors is attached to the upper surface
of the write/read control unit 4.
[0025] Fig. 5 shows a circuit arrangement diagram of the write/read control unit 4 and the
monitor unit 7. The control unit 4 comprises: an interface 18 with the upper control
apparatus 6; an MPU (micro processing unit) 19; an RAM 20; a transmission/reception
interface 21 for the ID unit; and an external interface 22 to connect to the monitor
unit 7.
[0026] The monitor unit 7 comprises: key switches SW₁ to SW₁₆ which are turned on by depressing
the keys of the key group 13; the liquid crystal display device (LCD) 11; the mode
setting device (switch) 12; an LCD driver 23; and an expansion port 24.
[0027] The operation of the article recognizing system of the embodiment will now be described
with reference to flowcharts shown in Figs. 6 and 7. The processes in these flowcharts
are executed under the control of the MPU 19.
[0028] When a power source is turned on and the operation is started, the initialization
is first executed (step 1 (hereinafter, referred to as ST 1)). Next, a check is made
to see if the operating mode is the MONITOR mode or not (ST 2). Now, assuming that
the mode setting device 12 is set to the RUN mode and the write/read control unit
4 is connected to the upper control apparatus 6, the answer in ST 2 is NO, so that
ST 3 follows and a check is made to see if command has been sent from the upper control
apparatus 6 or not. In this state, "RUN" is displayed on the LCD 11. This display
indicates that the write/read control unit 4 is in the online state with the upper
control apparatus 6. In this case, even if one of the group of keys 13 of the monitor
unit 7 is operated, nothing is received.
[0029] When a command from the upper control apparatus 6 is received, the answer in ST 3
is YES, so that the received command is analyzed (ST 4). In response to this command,
data is written into or read out from the ID unit 2 through the head 5 (ST 5). After
completion of the process in ST 5, a check is made to see if any error has been generated
in the process or not (ST 6). If no error occurs, a normal end response or read data
is transmitted to the upper control apparatus 6 through the interface 18(ST 7). Then,
the error LED 25 is lit off and the processing routine is returned to ST 2. The presence
or absence of errors is discriminated by reading out the data written in the ID unit
2 and comparing with the write date in the case of the writing mode. On the contrary,
in the case of the reading mode, this discrimination is executed by reading out the
data twice from the same address in the ID unit 2 and comparing them.
[0030] If any error has occurred in ST 6, the cause of the error is analyzed (ST 9). An
error code indicative of the cause of the error is transmitted to the upper control
apparatus 6 (ST 10). The error LED 25 is lit on (ST 11). Then, the processing routine
is returned to ST 2.
[0031] By switching the mode setting device 12 to the MONITOR mode, the worker in the field
where the head 5 is located can write arbitrary data into an arbitrary address in
the memory in the ID unit 2 or can read out data from an arbitrary address by operating
the group of keys 13 of the monitor unit 7.
[0032] When the mode setting device 12 is set to the MONITOR mode, the answer in ST 2 is
YES and a check is then made to see if key input data exists or not (ST 12), thereby
allowing the system to wait until either one of the keys 13 of the monitor unit 7
is operated. In this state, "MONITOR" is displayed on the LCD 11. This display content
means that the group of keys 13 can be subsequently operated. If some of the keys
are operated, an interrupting process shown in Fig. 7 is started and the key matrix
data of the keys operated are fetched (ST 21).
[0033] It is now presumed the case where data is read out of the memory of the ID unit 2.
When the first address to be read out is input by using the address (ADRS) key and
numeral keys, "alF" is displayed on the LCD 11. alF indicates an address. When the
operator operates the READ key 41 to execute the reading operation, the answer in
ST 12 is YES, so that the key input command is analyzed (ST 13). In this case, since
it is presumed that the READ key 41 is operated, "RDalF" is displayed on the LCD 11.
RD denotes a read command and alF represents the address.
[0034] By operating the READ key 41, the reading operation is executed for the ID unit 2
(ST 14). After the reading operation was correctly completed, the answer in ST 15
to check the occurrence of errors becomes NO. Therefore, a normal end code or read
data is displayed on the LCD 11 of the monitor unit 7 (ST 16). In this case, "RDalFd30"
is displayed on the LCD 11. d30 denotes the read data. The read data is displayed
and the error LED 25 is lit off (ST 17). The processing routine is then returned to
ST 2.
[0035] If errors occured in ST 15, the cause of the errors is analyzed (ST 18) and an error
code and an error message are displayed on the LCD 11 of the monitor unit 7 (ST 19).
[0036] For instance, "RDalFE72" is displayed on the LCD 11 in this case. E72 indicates an
error code. On the other hand, the error message "DO NOT" can be alternately displayed
by shifting the display content by using the key 44 or 45. The error is displayed
and the error LED 25 is also lit on (ST 20). Then, the processing routine is returned
to ST 2.
[0037] In the case of writing data into the ID unit 2, the address and data to be first
written are input by using the address (ADRS) key, data (DATA) key and numeral keys,
so that "alFd20" is displayed on the LCD 11. d20 indicates data to be written.
[0038] Next, when the operator operates the WRITE key 42 to execute the writing operation,
the answer in ST 12 becomes YES, so that the key input command is analyzed (ST 13).
For the address in the ID unit 2, "SWalF′ is displayed in the writing operation. SW
denotes a step write command. The display of the data is cleared. After the writing
operation was correctly completed, "SWalFd20" is displayed and the data content written
is again displayed.
[0039] If the writing operation was incorrectly finished, for instance, "SWalFE72" is displayed
on the LCD 11. By pressing the key 44 or 45, e.g., the error message "DO NOT" is displayed.
That is, the error code and error message can be alternately displayed.
[0040] An embodiment in which the processes in the test mode can be performed will now be
described. In this embodiment, the arrangement shown in Figs. 1 to 5 and the processes
in Fig. 7 are applied. The operation of this embodiment, particularly, the processing
procedure by the MPU 19 is shown in Fig. 8 . In this diagram, the same processes as
those shown in Fig. 6 are designated by the same step numbers.
[0041] When the power supply is turned on and the operation is started, the initialization
is first executed (ST 1). Next, a check is made to see if the operating mode has been
set to the MONITOR mode or not (ST 2). If the RUN mode has been set, ST 22 follows
and data is written into or read out from the ID unit 2 on the basis of the command
from the upper control apparatus 6. These processes are the same as those shown in
ST 3 to ST 11 in Fig. 6.
[0042] When the operator sets the MONITOR mode by the mode setting device 12, the answer
in ST 2 is YES, so that a check is then made to see if key input data exists or not
(ST 33). As described in Fig. 7, if any one of the keys is operated, the processing
routine is interrupted and the key matrix data of the operated key is fetched (ST
21). If the fetched key data exists, the answer in ST 33 is YES and the key input
data is analyzed (ST 34). Further, a check is made to see if the operated key is the
TEST key 31 (ST 35) or RESET key 32 (ST 42). The TEST mode is set by the TEST key
31 and reset (test cancelled) by the RESET key 32. If none of the keys 31 and 32 is
not depressed, this means that the process other than the test process has been set,
so that data is written into or read out from the ID unit 2 by using the monitor unit
7 (ST 23). This process corresponds to those shown in ST 13 to ST 20 in Fig. 6.
[0043] When the operator presses the TEST key 31 to adjust the distance between the head
5 and the ID unit 2, the answer in ST 35 becomes YES and a flag indicating that the
test is being executed is set to 1 (ST 36). At this time, "TEST 1-4" is displayed
on the LCD 11. In this display, 1-4 denotes the kind of test. Namely,
1: read
2: write
3: auto-read
4: auto-write
Either one of these kinds of test is designated by pressing a numeral key among the
group of keys 13.
[0044] Thereafter, the test of the designated kind is started. That is, if No in ST 33,
a check is made to see if the test is being executed or not (ST 37). In this case,
since the flag indicating that the test is being executed has already been set to
1, the answer in ST 37 is YES. Next, the reading or writing operation for the ID unit
2 is performed. For example, if No. 1 (read) is selected as the kind of test, the
reading process is executed (ST 38). In this case, "TRD ■" is displayed. TRD denotes
a test command (read) and ■ indicates that the test is being executed. The lower three
digits are provided for error display.
[0045] After the reading operation or the like was executed in ST 38, a check is made to
see if errors have been generated in this process or not (ST 39). The generation of
errors is determined by reading the data in the same address twice and comparing them
in the case of. e.g., the reading process. In the case of the writing process, the
written data is again read out and compared with the data before writing. If no error
is generated, the error LED 25 is lit off (ST 40). If any error occurred, the error
LED 25 is lit on (ST 41) and, for instance, "TRD ■ 9E72" is displayed on the LCD 11.
In this way, after the test key 31 was operated, the command process to read, write,
or the like and the discrimination of the generation of errors are repeated every
second. When the above processes are executed while changing the distance between
the head 5 and the ID unit 2, the writing/reading operation is correctly executed
at the proper distance and no error occurs, where the error LED 25 is not lit on and
the error indication is not displayed on the LCD 11. However, when the distance is
improper, the writing/reading operation is not correctly performed, and if errors
occurred, the error LED 25 is lit on and the error indication is displayed on the
LCD 11. Therefore, the optimum distance can be set by only moving the ID unit 2 while
monitoring the error indication.
[0046] After completion of the test, the RESET key 32 is operated. Thus, the answer in ST
33 is YES, the answer in ST 35 is NO, and the answer in ST 42 to cancel the TEST mode
is YES, so that the flag indicating that the test is being executed is set to 0 (ST
43).
[0047] In the embodiment, although the error LED 25 has been provided in the write/read
control unit 4, it can be also provided for the head 5.
[0048] On the other hand, in the embodiment, the switching between the RUN mode and the
MONITOR mode has been made by the mode setting device. However, when the monitor unit
7 is attached and connected to the write/read control unit 4, the operating mode may
be forcibly set to the MONITOR mode.
[0049] In the embodiment, one write/read control unit 4 has been connected to the upper
control apparatus 6. However, the invention can be also applied to the case where
a plurality of write/read control units 4 are provided and connected to the upper
control apparatus. 6.
[0050] An embodiment which is particularly, effective to the case where a plurality of write/read
control units 4 are provided will now be described in detail. As shown by a broken
line in Fig. 1, a plurality of write/read control units 4 are connected to the upper
control apparatus 6 through a bus or data transmission line. A different ID No. is
assigned to each write/read control unit 4. One or more head 5 is provided for each
write/read control unti 4 and the monitor unit 7 can be attachably and detachably
connected to the control unit 4. The arrangement and constitution shown in Figs. 1
to 5 can be also applied to this embodiment.
[0051] The RAM 20 in the write/read control unit 4 includes a non-volatile memory area.
Errors which are generated when data is written into or read out from the ID unit
2 are encoded every kind and the thirty error data are sequentially stored into this
memory area in accordance with the order from the new data. The MPU 19 in the control
unit 4 has functions to calculate the total number of occurrence times of the respective
errors, the total number of all errors occurred, and the generating ratio of errors
and to store the calculated values into the memory, i.e., RAM 20.
[0052] The operation of the article recognizing system in the embodiment will now be described
with reference to flowcharts shown in Figs. 7 and 9. In these diagrams, the same or
similar processes as those shown in Figs. 6 and 8 are designated by the same reference
numerals.
[0053] When the power supply is turned on and the operation is started, the initialization
is executed (ST 1). Then, a check is made to see if the mode setting device 12 has
been set to the RUN mode or the MONITOR mode (ST 2). It is now assumed that the mode
setting device 12 is set to the RUN mode and the write/read control unit 4 is connected
to the upper control apparatus 6. In this case, the processing routine advances to
ST 3 and a check is made to see if a command from the upper control apparatus 6 has
been received or not. If the self No. has been designated from the upper control apparatus
6 and a command to write or read out data into/from the ID unit 2 is sent, the answer
in ST 3 is YES. The received command is analyzed (ST 4). A check is then made to see
if this command indicates the writing or reading operation for the ID unit 2 or not
(ST 51). In the case of the ordinary writing or reading process as shown in the foregoing
embodiment, data is written into or read out from the ID unit 2 in correspondence
to the command (ST 5). Each time the writing or reading operation is finished, a check
is made to see if errors occurred or not (ST 6). If any error occurred, the error
data is processed (ST 9). That is, the error is encoded every kind of error and stored
into the RAM 20. An error response is returned to the upper control apparatus (ST
10). On the contrary, if no error occurs in ST 6, a normal end response indicating
that the writing or reading operation has correctly been finished is returned to the
upper control apparatus 6 (ST 7). The operation of the error LED 25 is omitted here.
[0054] As the result of the analysis of the command in ST 51, if the command does not indicate
the writing/reading operation for the ID unit, ST 52 follows and a check is made to
see if the error data is monitored or not. If the command from the upper control apparatus
6 indicates to monitor the error date, the error data stored in the memory 20 in the
write/read control unit 4 are sequentially returned to the upper control apparatus
6 in response to this command (ST 53). Thus, the upper control apparatus 6 can collect
the error data stored in the write/read control unit 4.
[0055] If the command indicates none of the writing/reading operations for the ID unit 2
and the error data monitor, ST 56 follows to see if the command represents to clear
the error data or not. If the command indicates that the error data is cleared, the
error data stored until now in the RAM 20 in the control unit 4 are all cleared (ST
57). Then, the processing routine is returned to ST 2.
[0056] Next, in the case of monitoring the error data by the monitor unit 7, the mode setting
device 12 is set to the MONITOR mode. Thus, the answer in ST 2 is YES and ST 12 follows
to see if the key input data exists or not. The discrimination regarding the presence
or absence of the key input data is performed by the interrupting process shown in
Fig. 7. The kind of key operated is decided by the data fetched by the interrupting
process (ST 13). If the operated key is not the error (ERR) key 33, the answer in
ST 54 is NO. Then, a check is made to see if the operated key is the clear (CLR) key
43 or not (ST 56). However, if the operated key is not the clear key 43, the answer
in ST 56 is NO. In this case, the writing/reading operation of data into/from the
ID unit 2, test mode process or the like is executed as mentioned in the above embodiment.
Thereafter, the processing routine is returned to ST 2. The error data generated in
the writing/reading operation are also stored into the RAM 20.
[0057] As the result of the analysis of the key input data, if the operated key is the error
key 33, the answer in ST 54 is YES. Thus, the error data stored in the RAM 20 in the
write/read control unit 4 are successively read out and sequentially displayed on
the LCD 11 of the monitor unit 7. Thus, the operator can know which kind of error
data occurred in the write/read control unit 4 in the past. In the case where the
error data are monitored for a certain period of time and the error data obtained
so far are cleared, the operator needs to press the clear key 43, Therefore, the answer
in ST 56 is YES and the error data stored so far in the RAM 20 in the control unit
4 are cleared (ST 57).
[0058] An explanation will now be made with respect to an example of the display in the
case of monitoring the error data in the monitor unit 7.
[0059] When the operator presses the error (ERR) key 33 in the MONITOR mode, "ERRORl-4"
is displayed on the LCD 11.
[0060] This display content indicates that the selection of the contents from error status
1 to 4 should be made. If the numeral 1 is designated by a numeral key of the keys
13, the newest error data (among thirty errors) is designated. When the numeral 2
is designated, the statistic error data is designated. When the numeral 3 is designated,
the newest error data is cleared. When the numeral 4 is designated, the statistic
error data is cleared. When the RESET key 32 is operated, the stop of the display
of the error data is indicated. When the operator inputs the numeral key 1 subsequent
to the ERR key 33, that is, when the operator designates to monitor the newest error
data, "N01RD110" is displayed on the LCD 11. N01 indicates the error generating order
No. The number of generating order of the newest error data assumes "01" and that
of the oldest error data assumes "30". On the other hand, RD represents an error generation
command and "1" indicates the transmission path No. and "10" represents the error
code No. The error code display and the error message display can be alternately switched
by the key 44 or 45. The error message "H.PARITY" is displayed by operating the key
44 or 45 for the example of error mentioned above. By again operating the key 44 or
45, the original display content "N01RD110" can be displayed. Further, by operating
the INC key 47 to display the error data of the next order, for instance, "N02RD170"
is displayed. To again display the original data, by pressing the DEC key 46, "N01RD110"
is displayed. By operating the INC key 47 or DEC key 46, the error data can be arbitrarily
shifted forward or backward.
[0061] In the case of the statistic error data, "87-09-30" is displayed. In this case, the
year, month and day of the date to start to obtain the statistic error data are displayed.
When the INC key 47 is pressed, the next content is displayed and, e.g., "SZZ9 110"
is displayed. ZZ9 indicates the number of occurrence times of the errors. "1" in the
third digit indicates the transmission path No. and "10" represents the error code.
By pressing the key 44 or 45, the error message corresponding to the eror code displayed
at present is displayed. On the other hand, by pressing the INC key 47, the next statistic
errors are sequentially displayed in accordance with the order of the error codes.
Similarly, by pressing the DEC key 46, the statisitic errors can be sequentially reversely
displayed. After all of the statistic errors were displayed, the display is further
advanced and the MCBF by the calculation of the following equations is displayed.

[0062] Next, in the case of clearing the newest error data, "CLEAR N?" is displayed and
the execution of the clearing operation is confirmed. In this case, by pressing the
SET key 48, the clearing operation is performed. At this time, by pressing the RESET
key 32, the clearing operation can be also stopped. In the case of clearing the statisitc
error date, "CLEAR S?" is displayed to confirm the execution of the clearing operation.
When the operator operates the SET key 48, the clearing operation is executed.