JPH11234364A - Communication control method and communication module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid making a device configuration complicated and to improve the reliability of communication. SOLUTION: A master module receives a 1st password that is sent from a slave module (102) in parallel with transmitting of a command and decides whether or not the received 1st password coincides with a 1st password that is previously set up (104). It decides that a communication error occurs in the case of noncoincidence here, it resends a command (102) after the transmission time for one command elapses. Subsequently, the master module receives a status whose leading bit is set to zero as command response (108), and when the leading bit of the received status is not zero, it decides that a communication error occurs and receives status again (108). Thus, a communication error is accurately and also fast detected by relatively simple processing and error measures is quickly taken.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control method and a communication module. A function of receiving a command from another communication module and transmitting a status to the other communication module, and a function of counting a clock for synchronizing transmission and reception operations with an octal counter. The present invention relates to a communication control method for controlling communication between communication modules and the communication module.

[0002]

2. Description of the Related Art Conventionally, when an optional device is driven in a device such as a printer, information such as various commands and status relating to a driving operation is exchanged while repeating bidirectional serial communication between various driving circuits in the device. Was.

At this time, a circuit for transmitting a command and requesting processing (hereinafter, referred to as a master module) transmits a command to a circuit for receiving and executing the command (hereinafter, referred to as a slave module). Sends a status to the master module in response to the command. FIG. 9 shows the state of the transmission and reception. In the time chart of FIG. 9, data transmitted from the master module is represented by TxD, and data transmitted from the slave module is represented by RxD (the same applies to the following time charts). (CLK).

As shown in FIG. 9, the master module receives dummy data having no special meaning from the slave module in parallel with the command transmission, and the slave module transmits the dummy data in parallel with the status transmission. Receive from.

As a method of detecting a communication error in the above-described bidirectional serial communication, a parity bit is added to a command transmitted from the master module or a status returned from the slave module.
A method of detecting a communication error by checking the parity bit when each module receives the signal has been proposed.

[0006] Normally, the standby time is longer than the communication time, so that the influence of noise or the like is often affected during the standby time.
For example, as shown in FIG. 10, when noise occurs during standby before issuing a command and mixes with the clock, the portion recognized as a command by the slave module deviates from the original command, and the command cannot be transmitted / received normally.

In the case where the above-described communication error detection method using the parity bit is adopted, the slave module can recognize as an error if a parity error has occurred. However, at this point, the master module cannot recognize that an error has occurred, and recognizes the occurrence of the error only after receiving the status. Further, depending on the state of the error, there is a case where it cannot be recognized as a parity error.

On the other hand, as a method for detecting a communication error,
Japanese Patent Application Laid-Open No. 8-32647 discloses that a 1-byte communication time for normal communication is defined in advance, a 1-byte communication time is measured at the time of communication, and the measured value is set to a predetermined communication time. A method of determining a communication error when different from each other has been proposed.

However, measurement of 1-byte communication time cannot be realized with an inexpensive CPU and requires special external hardware and the like, which increases the cost of the equipment and complicates the device configuration. There was such an inconvenience.

[0010]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned problems, and a communication control method capable of improving communication reliability while avoiding complication of a device configuration. It is an object to provide a method and a communication module.

[0011]

In order to achieve the above object, a communication control method according to the present invention has a function of transmitting a command to another communication module and receiving a status from the other communication module. Control communication between a plurality of communication modules having a function of receiving a command from a communication module and transmitting the status to the other communication module, and a function of counting a clock for synchronizing transmission / reception operations with an octal counter. A receiving communication module that receives a command, transmits a preset password to the transmitting communication module that transmits the command in parallel with the reception of the command, and transmits the password only for a transmission time of one command. After the elapse, it is determined whether or not the count value of the octal counter is 0, and if the count value is not 0, Resetting the octal counter and re-receiving the command, the transmitting communication module receives the password in parallel with the transmission of the command, and determines whether the received password matches a preset password; If the received password does not match a preset password, the command is retransmitted after a transmission time of one command has elapsed.

According to a second aspect of the present invention, there is provided a communication control method for transmitting a command to another communication module, receiving a status from the other communication module, and receiving a command from the other communication module to perform the other communication. A function for transmitting a status in which the first bit is set to a predetermined value to the module, and a clock for synchronizing the transmission / reception operation with 8
A communication control method for controlling communication between a plurality of communication modules having a function of counting with a hexadecimal counter, wherein a transmitting side communication module for transmitting a command transmits a preset password in parallel with reception of the status. The command is transmitted to the receiving communication module that receives the command, and after elapse of the transmission time of one command, it is determined whether or not the first bit of the received status matches the predetermined value. If the first bit does not match the predetermined value, the status is received again, and the receiving communication module receives the password in parallel with the transmission of the status, and the received password matches the preset password. It is determined whether or not the received password does not match a preset password. After a lapse transmission time only retransmits the status is reset to the octal counter, characterized in that.

Further, the communication module according to claim 3 is
A function of transmitting a command to another communication module and receiving a status from the other communication module, a function of receiving a command from the other communication module and transmitting the status to the other communication module, and synchronizing transmission / reception operations Communication module having a function of counting the clock for the octal counter, when transmitting a command,
Receiving means for receiving a password transmitted from another communication module, determining means for determining whether or not the received password matches a preset password; and Command resending control means for controlling the command to be resent if the password does not match.

Further, the communication module according to claim 4 is
A function of transmitting a command to another communication module and receiving a status from the other communication module, a function of receiving a command from the other communication module and transmitting the status to the other communication module, and synchronizing transmission / reception operations Communication module having a function of counting the clock for the octal counter, when receiving a command,
Transmitting means for transmitting a preset password to another communication module; count value determining means for determining whether or not the count value of the octal counter is 0; Command re-receiving control means for resetting the binary counter and controlling to re-receive the command.

[0015] The communication module according to a fifth aspect of the present invention includes:
A function of transmitting a command to another communication module and receiving a status from the other communication module, receiving a command from the other communication module, and transmitting a status in which a leading bit is set to a predetermined value to the other communication module. A communication module having a function and a function of counting a clock for synchronizing a transmission / reception operation with an octal counter, and a password transmission means for transmitting a preset password to another communication module when receiving a status. A first bit determining means for determining whether a first bit of a received status matches the predetermined value, and a status re-receiving when the first bit of the received status does not match the predetermined value. Control means for controlling the status re-reception.

Further, the communication module according to claim 6 is
A function of transmitting a command to another communication module and receiving a status from the other communication module, receiving a command from the other communication module, and transmitting a status in which a leading bit is set to a predetermined value to the other communication module. A communication module having a function and a function of counting a clock for synchronizing transmission / reception operations with an octal counter, and a password receiving means for receiving a password transmitted from another communication module when transmitting a status. A password determining means for determining whether a received password matches a preset password, and resetting the octal counter if the received password does not match the preset password, Status retransmission control means for controlling retransmission of Characterized in that it has.

The communication control method according to the first aspect of the present invention has a function of transmitting a command to another communication module and receiving a status from the other communication module, and a function of receiving a command from another communication module and transmitting the command to the other communication module. A communication control method for controlling communication between a plurality of communication modules having a function of transmitting a status and a function of counting a clock for synchronizing transmission and reception operations with an octal counter.

When a transmitting-side communication module (hereinafter, abbreviated as a transmitting side) that transmits a command transmits a command to a receiving-side communication module (hereinafter, abbreviated as a receiving side) that receives a command, the receiving side transmits the command. A password set in advance is transmitted to the transmitting side in parallel with the reception. Then, after the transmission time of one command has elapsed, the receiving side
It is determined whether or not the count value of the octal counter is 0.

Generally, a command is 1 byte (8 bits)
Since transmission / reception is performed in units, if the transmission / reception of the command is normal, the octal counter counts a clock of a multiple of 8, and the count value becomes 0.

Therefore, when the count value of the octal counter is not 0 as described above, it can be determined that an error has occurred during transmission / reception of the command, and the receiving side resets the octal counter and receives the command again.

Thus, the receiving side can accurately and promptly detect the occurrence of an error when transmitting / receiving a command, and prepare for re-receiving the command.

One transmitting side receives the password sent from the receiving side in parallel with the transmission of the command, and determines whether or not the received password matches a preset password.

If the transmission and reception of the command are normal, the received password matches the password set in advance. Therefore, if the received password does not match the preset password, it can be determined that an error has occurred during transmission / reception of the command. Resend to At this time, the receiving side prepares for re-reception of the command as described above, so that the re-transmitted command is received by the receiving side.

Thus, the transmitting side can accurately and promptly detect the occurrence of an error when transmitting and receiving a command, and retransmit the command.

As described above, according to the communication control method of the first aspect, the receiving side accurately and promptly detects the occurrence of an error when transmitting / receiving a command based on the fact that the count value of the clock by the octal counter is not 0. Error recovery can be performed quickly, and the transmitting side can accurately and quickly detect the occurrence of an error during command transmission / reception by checking that the received password does not match the preset password, and quickly recover the error. It can be performed.

As described above, since relatively simple processing such as checking the count value of the octal counter and checking the received password is performed, an expensive circuit for performing complicated processing while avoiding a complicated device configuration is installed. And the reliability of communication can be improved.

Next, in the communication control method according to the second aspect,
After receiving the command normally, the receiving side transmits a status as a response to the command to the transmitting side. The first bit of this status is set to a predetermined value ("0" or "1").

The transmitting side transmits a preset password to the receiving side in parallel with the reception of the status, and after the transmission time of one command has elapsed, the first bit of the received status matches the predetermined value. It is determined whether or not to perform.

If the status transmission / reception is normal, the first bit of the received status matches a predetermined value. Therefore, when the first bit of the status received as described above does not match the predetermined value, it can be determined that an error has occurred during transmission and reception of the status, and the transmitting side receives the status again.

Thus, the transmitting side can accurately and promptly detect the occurrence of an error when transmitting and receiving the status, and prepare for the re-reception of the status.

One receiving side receives the password transmitted from the transmitting side in parallel with the transmission of the status, and determines whether or not the received password matches a preset password.

If the status transmission / reception is normal, the password matches the password set in advance. Therefore, if the received password does not match the preset password, it can be determined that an error has occurred during the transmission and reception of the status, and the receiving side resets the octal counter after the transmission time of one command has elapsed. Reset and resend status. At this time, the transmitting side prepares for the status re-reception as described above, and thus the retransmitted status is received by the transmitting side.

As a result, the receiving side can accurately and promptly detect the occurrence of an error when transmitting and receiving the status, and retransmit the status.

As described above, according to the communication control method of the second aspect, the transmitting side can accurately and promptly determine the occurrence of an error at the time of transmitting / receiving a status by not finding that the first bit of the received status does not match the predetermined value. In addition, the receiving side can detect the occurrence of an error at the time of transmitting / receiving the status accurately and promptly by noting that the received password does not match the preset password, and promptly recovering the error. Error recovery can be performed.

Since relatively simple processing such as checking of the first bit of the received status and checking of the received password is performed as described above, an expensive circuit for performing complicated processing while avoiding the complexity of the device configuration can be avoided. The reliability of communication can be improved while avoiding installation.

[0036] The communication module according to claim 3 can be adopted as a transmission-side communication module capable of executing communication based on the communication control method according to claim 1 described above, and as a reception-side communication module. Communication module can be adopted.

That is, at the time of transmitting / receiving a command, in the communication module according to the fourth aspect, as a receiving side, the transmitting means transmits a preset password to the transmitting side in parallel with the reception of the command. Then, after the transmission time of one command has elapsed, the count value determining means determines whether or not the count value of the octal counter is 0.

In this determination, the count value of the octal counter is 0.
Otherwise, it can be determined that an error has occurred during transmission / reception of the command, so the command re-reception control means resets the octal counter and controls to re-receive the command.

As described above, according to the communication module of the fourth aspect, a simple process of checking the count value of the octal counter can be performed as a receiving side at the time of transmitting and receiving a command.
The occurrence of an error can be detected accurately and promptly to prepare for re-reception of a command.

On the other hand, at the time of transmitting / receiving a command, in the communication module according to the third aspect, the receiving means as the transmitting side includes:
Upon receiving the transmitted password, the determination unit determines whether the received password matches a preset password.

In this determination, if the received password does not match the preset password, it can be determined that an error has occurred during the transmission and reception of the command. Therefore, after the transmission time of one command has elapsed, the command retransmission control means Retransmits the command to the receiver.

As described above, according to the communication module of the third aspect, the transmission side at the time of command transmission / reception detects the occurrence of an error accurately and promptly by a simple process of checking the received password, and transmits the command. Can be resent.

Next, the communication module according to the fifth aspect can be adopted as a transmission-side communication module capable of executing communication based on the communication control method according to the second aspect. The communication module according to item 6 can be employed.

That is, at the time of transmitting and receiving the status,
In the communication module described above, as a transmitting side, a password transmitting unit transmits a preset password to the receiving side in parallel with the reception of the status, and after elapse of a transmission time of one command, the head bit determining unit It is determined whether the first bit of the received status matches a predetermined value.

If the first bit of the received status does not match the predetermined value in this determination, it can be determined that an error has occurred during the transmission / reception of the status, and the status re-reception control means performs control to re-receive the status. I do.

As described above, according to the communication module of the fifth aspect, the transmission side at the time of command transmission / reception detects the occurrence of an error accurately and promptly by a simple process of checking the first bit of the received status. , Can be prepared for a status re-receipt.

On the other hand, at the time of status transmission / reception,
In the communication module described above, as a receiving side, a password receiving unit receives a password sent from the transmitting side, and a password determining unit determines whether the received password matches a preset password. I do.

In this determination, if the received password does not match the password set in advance, it can be determined that an error has occurred during transmission and reception of the status. The means controls to reset the octal counter and retransmit the status.

As described above, according to the communication module of the sixth aspect, as a receiving side at the time of transmitting and receiving a command, the occurrence of an error is accurately and promptly detected by a simple process of checking the received password, and the status is determined. Can be resent.

[0050]

Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 2, a communication module built in a general built-in microcomputer for performing serial communication includes a CPU 22, a serial data register 28 for storing received data and data to be transmitted, and
A clock generator 26 for generating a clock for setting the timing of data transmission / reception, an octal counter 24 for counting a clock transmitted from the data transmission side at the time of data reception, and a command reception waiting state described later. A password storage unit 32 storing predetermined values of a password (hereinafter, referred to as a first password) and a password for acquiring a status (hereinafter, referred to as a second password). And
The serial data register 28 is connected to a data processing unit and a data output unit (not shown) via a data bus 30.

A microcomputer includes a plurality of communication modules as described above. Hereinafter, a communication control method in a case where a command is transmitted from one communication module to another communication module will be described.

In this embodiment, as shown in FIG. 1, a communication module for transmitting a command is a master module 1
0, the communication module that receives the command is the slave module 20, the data transmitted from the master module 10 is TxD, and the data transmitted from the slave module 20 is RxD. The exchange of data between the master module 10 and the slave module 20 is executed in synchronization with a clock (CLK) output from the master module 10.

In parallel with the transmission of the command from the master module 10 in the time period T1 shown in FIG. 3, the slave module 20 transmits the first password indicating that the slave module 20 is in the command reception waiting state to the master module. Send to module 10. Thereafter, the master module 10 transmits the second password for acquiring the status to the slave module 20 in parallel with the status transmission from the slave module 20 in the time zone T2 shown in FIG.

Further, the slave module 20 sends the status as a response to the command to the master module 1.
Before returning to 0, the status bit 0 must be set to "0" as shown in FIG. That is, bit 0 of the transmitted status is always set to “0”.

Next, the communication control method according to the present embodiment will be specifically described with reference to FIGS. In the present embodiment, the control routine of FIG. 7 is executed by the CPU of the master module 10 and the control routine of FIG.

First, in a time zone T1 shown in FIG. 3, a command is transmitted from the master module 10 to the slave module 20.
The first password is transmitted from the slave module 20 to the master module 10 at the same time.

That is, the master module 10 transmits a command and receives a first password (step 102 in FIG. 7), and determines whether the received first password matches the regular first password. Is determined (step 104). If no communication error occurs before and during the transmission of the command, the received first password matches the formal first password, and the process proceeds to step 108 described later.

On the other hand, in the slave module 20, the octal counter 24 is reset (step 202 in FIG. 8).
Thereafter, transmission of the first password and reception of the command are performed (step 204). Then, it is determined whether or not the count value of the octal counter 24 after receiving the command is 0.
If no communication error occurs before and during the reception of the command, the count value of the octal counter 24 counted during reception of the command in byte units becomes 0, and the process proceeds to step 210 described later.

However, if noise enters the clock before or during the transmission of the command, as shown in FIG. 5, the part recognized as the first password by the master module 10 is shifted from the original first password. So
In step 104 of FIG. 7, it is determined that the received first password does not match the regular first password, and the master module 10 recognizes that a communication error has occurred. Then, it waits for the transmission time of one command (step 1).
06) Then, the process returns to step 102 to resend the command.
In this way, the master module 10 can accurately and quickly detect a communication error that has occurred before or during the transmission of a command, and can quickly respond to the error.

On the other hand, in the slave module 20, the part recognized as a command is shifted from the original command as shown in FIG. 5, so that the count value of the octal counter 24 counted during reception of the command is other than 0. Value. Therefore, in step 206 of FIG. 8, it is determined that the count value of the octal counter 24 is not 0, and the slave module 20 recognizes that a communication error has occurred. And
Waited for one command transmission time (step 208)
Thereafter, the flow returns to step 202 to reset the octal counter 24 and prepare for receiving the retransmitted command. In this way, the slave module 20 can accurately and promptly detect a communication error that has occurred before or during the reception of a command, and can quickly respond to the error.

The reason for waiting for the transmission time of one command in step 106 of FIG. 7 and step 208 of FIG. 8 is that the octal counter 24 may count up to 7 bits at the maximum. .

Next, in the time zone T2 shown in FIG.
To 0, a second password is transmitted from the master module 10 to the slave module 20 in parallel.

That is, in the master module 10, the second
The password is transmitted and the status is received (see FIG. 7).
Step 108), it is determined whether or not the first bit of the received status is 0 (Step 110). If no communication error occurs before and during the reception of the status, the first bit of the received status is 0, so that an affirmative determination is made in step 110, and the processing in FIG. 7 ends.

On the other hand, the octal counter 24 is reset in the slave module 20 (step 210 in FIG. 8).
Thereafter, transmission of the status and reception of the second password are performed (step 212). Then, it is determined whether or not the received second password matches the legitimate second password (step 214). If no communication error occurs before and during transmission of the status, the received second password matches the formal second password, so an affirmative determination is made in step 214, and the processing in FIG. 8 ends. .

However, if noise enters the clock before or during status transmission, as shown in FIG.
Since the part recognized as the status by the master module 10 deviates from the original status, the first bit of the received status is 0 in step 110 of FIG.
Is not determined, the master module 10 recognizes that a communication error has occurred. Then, after waiting for a predetermined time (for example, transmission time of one command) (step 112), the process returns to step 108 to prepare for reception of the retransmitted status. Thus, the master module 10
It is possible to accurately and quickly detect a communication error occurring before or during reception of a status, and to quickly deal with the error.

On the other hand, in the slave module 20 as well, the portion recognized as the second password is shifted from the original second password as shown in FIG. Is determined not to match the regular second password, and the master module 10 recognizes that a communication error has occurred. And
After waiting for a predetermined time (eg, transmission time of one command) (step 216), the process returns to step 210, resets the octal counter 24, and retransmits the status. In this manner, the slave module 20 can accurately and promptly detect a communication error that occurred before or during the transmission of the status, and can quickly respond to the error.

According to the communication control method of the present embodiment described above, the relatively simple processing of checking the count value of the octal counter, checking the received password, and checking the first bit of the received status,
The occurrence of a communication error can be accurately and promptly detected, and the error can be quickly recovered. In other words, communication reliability can be improved without using an expensive circuit for performing complicated processing while avoiding a complicated device configuration.

It is to be noted that not only the status but also the format of the command is set so that the first bit is always 0 as shown in FIG. 4, and the slave module 20 checks the octal counter 24 in step 206 in FIG. Alternatively, it may be determined whether or not the first bit of the received command is 0. In this case, even a communication module that cannot read the octal counter can detect the occurrence of a communication error before or during command reception as a slave module.

[0070]

As described above, according to the first aspect of the present invention, it is possible to check the count value of the octal counter,
A relatively simple process such as checking a received password detects an error at the time of command transmission / reception accurately and quickly, and performs error recovery. Therefore, an expensive circuit that avoids complicated device configuration and performs complicated processing. The communication reliability can be improved while avoiding the installation of the communication.

According to the second aspect of the present invention, the relatively simple processing of checking the first bit of the received status and checking the received password makes it possible to accurately and accurately generate an error when transmitting and receiving the status. Since detection is performed quickly and error recovery is performed, the reliability of communication can be improved while avoiding the complexity of the device configuration and the installation of expensive circuits for performing complicated processing.

According to the third aspect of the present invention, the transmission side at the time of command transmission / reception detects the occurrence of an error accurately and quickly by a simple process of checking the received password, and retransmits the command. Therefore, it is possible to improve the reliability of communication while avoiding the complicated configuration of the device and the installation of an expensive circuit for performing complicated processing.

According to the fourth aspect of the present invention, as a receiving side at the time of command transmission / reception, the occurrence of an error is accurately and promptly detected by a simple process of checking the count value of an octal counter, and the command Since preparations are made for re-reception, the reliability of communication can be improved while avoiding the complexity of the device configuration and the installation of expensive circuits for performing complicated processing.

According to the fifth aspect of the present invention, as a transmitting side at the time of command transmission / reception, an error occurrence is accurately and promptly detected by a simple process of checking the first bit of the received status, and the status is checked. Therefore, the reliability of communication can be improved while avoiding the complexity of the device configuration and the installation of expensive circuits for performing complicated processing.

According to the sixth aspect of the present invention, as a receiving side at the time of transmitting / receiving a command, the occurrence of an error is accurately and promptly detected by a simple process of checking the received password, and the status is retransmitted. Therefore, it is possible to improve the reliability of communication while avoiding the complicated configuration of the device and the installation of an expensive circuit for performing complicated processing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a master module and a slave module according to an embodiment of the present invention.

FIG. 2 is a block diagram illustrating a schematic configuration of a communication module.

FIG. 3 is a timing chart showing normal data transmission / reception in the embodiment of the present invention.

FIG. 4 is a diagram showing a data format of a status.

FIG. 5 is a timing chart showing data transmission / reception when a clock contains noise before command transmission.

FIG. 6 is a timing chart showing data transmission and reception when a clock contains noise before status reception.

FIG. 7 is a flowchart showing a control routine executed by the master module.

FIG. 8 is a flowchart showing a control routine executed by a slave module.

FIG. 9 is a timing chart showing conventional data transmission / reception under normal conditions.

FIG. 10 is a timing chart showing data transmission / reception in the related art when a clock contains noise before command transmission.

[Explanation of symbols]

 Reference Signs List 10 master module 20 slave module 22 CPU 24 octal counter 28 serial data register 32 password storage unit

Claims (6)

[Claims] A function of transmitting a command to another communication module and receiving a status from the other communication module;
Communication between a plurality of communication modules having a function of receiving a command from another communication module and transmitting the status to the other communication module, and a function of counting a clock for synchronizing transmission and reception operations by an octal counter A receiving communication module that receives a command, transmits a preset password to the transmitting communication module that sends the command in parallel with the reception of the command, and transmits one command. After a lapse of time, it is determined whether or not the count value of the octal counter is 0. If the count value is not 0, the octal counter is reset and a command is received again. The module receives the password in parallel with the transmission of the command, and the received password is set in advance. Determining whether or not the received password matches the received password; and if the received password does not match a preset password, retransmitting the command after a lapse of one command transmission time. 2. A function of transmitting a command to another communication module and receiving a status from the other communication module, receiving a command from the other communication module, and setting the first bit in the other communication module to a predetermined value. A communication control method for controlling communication between a plurality of communication modules having a function of transmitting a status and a function of counting a clock for synchronizing a transmission / reception operation with an octal counter, comprising: The side communication module transmits a password set in advance to the receiving side communication module that receives the command in parallel with the reception of the status. After a transmission time of one command has elapsed, the first bit of the received status is It is determined whether or not the received status matches the predetermined value, and the first bit of the received status is the predetermined bit. If the received password does not match the status, the receiving side communication module receives the password in parallel with the transmission of the status, and determines whether the received password matches a preset password. A communication control method for resetting the octal counter and retransmitting the status after a lapse of one command transmission time if the received password does not match a preset password. A function of transmitting a command to another communication module and receiving a status from the other communication module;
A communication module having a function of receiving a command from another communication module and transmitting the status to the other communication module, and a function of counting a clock for synchronizing transmission / reception operations with an octal counter, comprising: Receiving means for receiving a password transmitted from another communication module during transmission; determining means for determining whether or not the received password matches a preset password; and And a command retransmission control means for controlling retransmission of the command when the password does not match the set password. 4. A function of transmitting a command to another communication module and receiving a status from the other communication module.
A communication module having a function of receiving a command from another communication module and transmitting the status to the other communication module, and a function of counting a clock for synchronizing transmission / reception operations with an octal counter, comprising: Transmitting means for transmitting a preset password to another communication module at the time of receiving; count value determining means for determining whether or not the count value of the octal counter is 0; and when the count value is not 0 And a command re-receiving control means for resetting the octal counter and controlling to re-receive the command. 5. A function of transmitting a command to another communication module and receiving a status from the other communication module, receiving a command from the other communication module, and setting the first bit in the other communication module to a predetermined value. A communication module having a function of transmitting a set status and a function of counting a clock for synchronizing a transmission / reception operation with an octal counter, and transmitting a preset password to another communication module when receiving the status. A password transmitting unit for performing the operation, a first bit determining unit for determining whether a first bit of the received status matches the predetermined value, and a status when the first bit of the received status does not match the predetermined value. Status re-reception control means for controlling re-reception of communication module . 6. A function of transmitting a command to another communication module and receiving a status from the other communication module, receiving a command from the other communication module, and setting the first bit in the other communication module to a predetermined value. A communication module having a function of transmitting a status, and a function of counting a clock for synchronizing transmission / reception operations with an octal counter, and receives a password transmitted from another communication module when transmitting the status. Password receiving means, password determining means for determining whether or not a received password matches a preset password, and when the received password does not match a preset password, the octal counter Status resend to control reset and resend status And a communication control unit.