JP5287630B2 - Control system, control system communication method, communication unit, and communication unit communication method - Google Patents

Description

The present invention relates to a control system that performs communication between a programmable logic controller (PLC) and an external device, a communication method thereof, a PLC communication unit, and a communication method thereof.

A conventional programmable controller system includes a PLC, a general-purpose external device, and a protocol macro creation device that creates a protocol macro used for communication between the PLC and the external device (for example, Patent Document 1). The PLC includes a link unit that communicates with an external device and a CPU unit that controls the link unit.

The link unit stores a protocol macro created by the user using the protocol macro creation device. This protocol macro is created according to the protocol of the external device. On the other hand, the CPU unit stores a ladder program created separately by the user. This ladder program includes a dedicated command for commanding communication using a protocol macro stored in the link unit. When the CPU unit reads a dedicated command during execution of the ladder program, the communication unit communicates with an external device using a protocol macro.

Thus, since the user can realize the communication between the PLC and the external device by creating the ladder program using the dedicated command, the ladder program can be easily created.

JP 2002-189505 A (for example, paragraphs 0005 to 0007, FIG. 17)

However, the conventional programmable controller system has a problem that it takes time and effort to specify the cause when communication cannot be normally performed by the ladder program created as described above. In other words, the user checks whether there is a problem with the protocol macro using a dedicated device such as a line monitor during execution of the ladder program. If there is no problem with the protocol macro, then the problem occurs in each line of the ladder program. It was necessary to check whether there was.

A control system according to the present invention includes a PLC, an engineering tool connected to the PLC, and an external device connected to the PLC. The engineering tool communicates with the PLC. A communication test command means for performing a test command is provided. The PLC stores a control command program storage unit for storing a control command program, a communication data storage unit for storing first protocol data, and a second protocol data. A communication test / data storage unit to be stored, a protocol activation means for reading a protocol / data activation command in the control command program, and stored in the communication data storage unit based on the protocol / data activation command read by the protocol activation unit The external device according to the first protocol data And communication test means for communicating with the external device by the second protocol data stored in the communication test data storage section based on the communication test command received from the communication test command means. , Provided.

According to another aspect of the present invention, there is provided a control system communication method comprising: a control system comprising: a PLC; an engineering tool connected to the PLC; and an external device connected to the PLC. A protocol start step for reading the protocol / data start command, and a PLC stored in a communication data storage unit provided in the PLC based on the protocol / data start command read by the PLC in the protocol start step. A communication step for communicating with the external device using the protocol data; a communication test command step for the engineering tool to perform a communication test command to the PLC; and the communication test received by the PLC in the communication test command step Based on the command, provided in the PLC The second protocol data stored in the signal test data storage unit, characterized by comprising a communication test steps to communicate with the external device.

The communication unit according to the present invention includes a communication data storage unit for storing the first protocol data, a communication test data storage unit for storing the second protocol data, and a protocol data start command by the CPU unit. When the communication command determination unit determines whether or not the protocol / data activation command has been issued by the communication command determination unit and the communication command determination unit, the first communication protocol stored in the communication data storage unit is determined. Communication means that communicates with external devices based on data, communication test command determination means that determines whether or not a communication test command is issued by an engineering tool, and the communication test command determination means that the communication test command is determined If the second protocol data stored in the communication test data storage unit Characterized by comprising a communication test means to communicate with devices, the.

In addition, a communication unit communication method according to the present invention includes a communication unit having a communication data storage unit for storing first protocol data and a communication test data storage unit for storing second protocol data. When the communication command determination step determines whether or not the protocol / data activation command has been issued, and when the protocol / data activation command is determined in the communication command determination step, it is stored in the communication data storage unit. In the communication step of communicating with an external device using the first protocol data, the communication test command determining step for determining whether or not a communication test command has been issued by an engineering tool, and the communication test command determining step, the communication If it is determined that a test command has been issued, the communication test data And communicating the test step by said second protocol data stored in 憶部 to communicate with the external device, characterized by comprising a.

According to the present invention, it is possible to confirm whether or not the created protocol data can be normally communicated without creating a control command program after creating the protocol data with the engineering tool. Further, when debugging the control command program, the cause can be easily identified without using a dedicated device such as a line monitor.

FIG. 3 is a block diagram of a control system in the first embodiment. 1 is a perspective view of a PLC in a first embodiment. 3 is a block diagram illustrating a configuration of a storage area of a storage unit of a communication unit according to Embodiment 1. FIG. 3 is a block diagram of an engineering tool in Embodiment 1. FIG. 4 is a protocol / data setting screen according to the first embodiment. 3 is a packet setting screen according to the first embodiment. 3 is a diagram illustrating an example of three protocol data according to Embodiment 1. FIG. 4 is a flowchart showing a communication test process of the engineering tool 50 according to the first embodiment. 3 is a communication test execution screen in the first embodiment. 3 is a flowchart showing processing of a communication unit 30 in the first embodiment.

Embodiment 1 FIG.
A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 is a block diagram of a control system according to the first embodiment. FIG. 2 is a perspective view of the PLC according to the first embodiment. The control system 90 includes a PLC 1, an engineering tool 50, and an external device 60. The PLC 1 includes a power supply unit 10, a CPU unit 20, a communication unit 30, and a base unit 40. For convenience, the power supply unit 10 is omitted in FIG. The base unit 40 includes a bus 41 and an I / F unit 42 such as a plurality of slots. Each I / F unit 42 is connected to the bus 41. The power supply unit 10, the CPU unit 20, and the communication unit 30 are each connected to the I / F unit 42 of the base unit 40. In addition, any type of unit may be connected to the I / F unit 42 of the base unit 40, but in this embodiment, no other unit is connected.

The power supply unit 10 supplies power input from the external power supply to the CPU unit 20 and the communication unit 30 via the bus 41 of the base unit 40.

The CPU unit 20 stores a system program such as an operating system (OS), a control command program such as a ladder program or a C language program, or any data, and stores the data in the storage unit 22. Connected to the control unit 21 for executing the system program and the control command program, the I / F unit 23 connected to the external engineering tool 50 via the connection cable 70, and the bus 41 of the base unit 40. I / F unit 24. These are connected via a bus 25.

The I / F unit 23 is, for example, a universal serial bus (USB) interface 23a, a recommended standard 232 (RS-232) interface 23b shown in FIG. 2, or an Ethernet (registered) not shown. Trademark interface. As the connection cable 70, a USB cable corresponding to the I / F unit 23, an RS-232 cable, an Ethernet (registered trademark) cable, or the like is used.

The storage unit 22 includes a read-only memory (ROM), a random-access memory (RAM), or a flash memory. By using the flash memory, the capacity of the storage unit 22 can be increased. For example, the system program is stored in the ROM, the control command program is stored in the flash memory, and the data used when the control unit 21 executes the system program or the control command program is stored in the RAM or the flash memory. Can do.

The control unit 21 is a central processing unit (CPU) or a microcomputer.

The communication unit 30 is connected via a connection cable 80 to a storage unit 32 that stores a system program or any data, a control unit 31 that executes a system program stored in the storage unit 32, and an external device 60. And an I / F unit 34 connected to the bus 41 of the base unit 40. These are connected via a bus 35.

The I / F unit 33 is, for example, the Ethernet (registered trademark) interface 33a, the RS-232 interface 33b, or a USB interface (not shown) shown in FIG. As the connection cable 80, an Ethernet (registered trademark) cable, an RS-232 cable, a USB cable, or the like corresponding to the I / F unit 33 is used. The external device 60 is, for example, a temperature controller, a barcode reader, or a measurement device.

The storage unit 32 includes a ROM, a RAM, a flash memory, or the like. By using the flash memory, the capacity of the storage unit 32 can be increased. FIG. 3 is a block diagram illustrating a configuration of the storage area of the storage unit 32 of the communication unit 30 according to the first embodiment. The storage unit 32 includes a system program storage area 100 for storing system programs, a communication test command data storage area 101 for storing data for instructing a communication test, and communication test data for storing data used for the communication test. It has a storage area 102, a communication data storage area 103 for storing data used for normal communication, and a communication result data storage area 104 for storing data relating to the result of the communication test and normal communication.

For example, the system program storage area 100 is provided in the ROM, the communication test command data storage area 101 and the communication test data storage area 102 are provided in the RAM, and the communication data storage area 103 and the communication result data storage area 104 are provided in the flash memory. Can be provided.

The control unit 31 is a CPU or a microcomputer.

FIG. 4 is a block diagram of the engineering tool in the first embodiment. The engineering tool 50 includes a storage unit 52 that stores a program or any data, a control unit 51 that executes a program stored in the storage unit 52, and an I / F unit that is connected to the PLC 1 via a connection cable 70. 53, a display unit 54 such as a display screen, and an input unit 55 such as a keyboard and a mouse. These are connected via a bus 56.

The control unit 51 is, for example, a CPU. The I / F unit 53 is a USB interface, an RS-232 interface, or an Ethernet (registered trademark) interface corresponding to the connection cable 70. The storage unit 52 includes a ROM, a RAM, and the like. The storage unit 52 stores a system program and a program for creating protocol data and issuing a communication command to the PLC 1. In addition, the storage unit 52 may store a program for initial setting and setting change of the PLC 1 or a program for creating a control command program.

The data transmitted from the engineering tool 50 to the PLC 1 is first received by the I / F unit 23 of the CPU unit 20 through the connection cable 70. Thereafter, the control unit 21 of the CPU unit 20 determines whether or not the destination of the data received by the I / F unit 23 is the CPU unit 20. If the destination of the data is the CPU unit 20, the control unit 21 performs control. The unit 21 processes the data. On the other hand, when the destination of the received data is not the CPU unit 20, the control unit 21 transmits the data to the communication unit 30 via the base unit 40. Next, when the data is received by the I / F unit 34 of the communication unit 30, the control unit 31 of the communication unit 30 determines whether the destination of the data received by the I / F unit 34 is the communication unit 30. If the destination of the data is the communication unit 30, the control unit 31 processes the data. On the other hand, when the destination of the data is not the communication unit 30, the control unit 31 discards the data. As a result, the engineering tool 50 can instruct the CPU unit 20 and read / write data in the storage unit 32 of the communication unit 30.

The engineering tool 50 may be connected to the I / F unit 33 of the communication unit 30. Also in this case, the data transmitted from the engineering tool 50 to the PLC 1 is processed in the same manner as described above.

Next, the operation will be described. First, operations performed by the engineering tool 50 will be described with reference to FIGS. The operation performed by the engineering tool 50 is processed by the control unit 51 in accordance with each program stored in the storage unit 52. First, the engineering tool 50 creates protocol data to be used for communication between the communication unit 30 and the external device 60 based on the setting content by the user. Here, the user sets the contents of the protocol data by inputting necessary items through the input unit 55 on the screen displayed on the display unit 54. The protocol data is created according to the protocol of the external device 60. The protocol data setting screen in FIG. 5 and the packet setting screen in FIG. 6 are images of screens displayed on the display unit 54 when the user sets the contents of the protocol data.

In the protocol / data setting screen shown in FIG. 5, the user sets basic information of newly created protocol / data. For example, the manufacturer name of the external device 60 and the name of the external device 60 are input as information for specifying the external device 60, and the name and number of the protocol data are used as information for specifying this newly created protocol data. Enter. Further, “transmission”, “reception”, or “transmission and reception” is specified as the communication type of the protocol data. When the communication type is set to “transmission”, the protocol data is transmitted from the communication unit 30 to the external device 60. When the communication type is set to “reception”, the protocol data is received by the communication unit 30 from the external device 60. When the communication type is set to “transmission and reception”, the protocol data is transmitted from the communication unit 30 to the external device 60 and then returned from the external device 60 to the communication unit 30. In addition to this, it is possible to set various information regarding communication of protocol data, such as a reception waiting time for waiting for the communication unit 30 to receive the protocol data from the external device 60.

In the packet setting screen of FIG. 6, the user sets the contents of the newly created protocol data transmission packet or reception packet. For example, the name and number of protocol data to which the packet belongs are input as information for specifying the packet, and the transmission packet or the reception packet is specified as the packet type. Furthermore, the type, order, data length, etc. of each element constituting this packet are specified according to the protocol of the external device 60.

Next, the engineering tool 50 stores the protocol data created according to the contents set by the user on the protocol data setting screen of FIG. 5 or the packet setting screen of FIG. The storage unit 52 can store a plurality of similarly created protocol data.

FIG. 7 is a diagram showing an example of three protocol data. Each protocol data is composed of a transmission packet and a reception packet, and has different protocol data numbers “No. 1”, “No. 2”, and “No. 3”. These three protocol data are created in accordance with the protocol of the external device 60 which is “A company's temperature controller”.

The protocol data with the number “No. 1” is for the communication unit 30 to instruct the external device 60 to start. In the transmission packet, “STX” is a header, “02” is a station number of the external device 60, “00 01 00” is data indicating a command, “00 02 00” is data indicating activation, and “ETX” is a footer. is there. In the received packet, “Data 1” is a frame for storing data indicating that the external device 60 has received this protocol data, and “Data 2” is for storing data indicating that the external device 60 has been activated. It is a frame.

Similarly, the protocol data with the number “No. 2” is used by the communication unit 30 to instruct the external device 60 to read the temperature. “00 03 00” in the transmission packet is data indicating temperature reading, and “Data 2” in the reception packet is a frame for storing temperature value data read by the external device 60. The other constituent elements of the transmission packet and the reception packet are the same as the protocol data “No. 1”.

Similarly, the protocol data with the number “No. 3” is for the communication unit 30 to instruct the external device 60 to change the temperature. “00 04 00” in the transmission packet is data indicating a change in temperature, and “data 2” in the reception packet is a frame for storing data indicating that the external device 60 has changed the temperature. The other constituent elements of the transmission packet and the reception packet are the same as the protocol data “No. 1”.

Next, on the communication test execution screen shown in FIG. 9, the user selects the name and number of protocol data to be subjected to the communication test by a pull-down method. Thereby, one protocol data can be specified from the plurality of protocol data stored in the storage unit 52. Next, the user selects a “test execution” button on the communication test execution screen of FIG.

FIG. 8 is a flowchart showing a communication test process performed by the engineering tool 50 after the user selects the “execute test” button in FIG. The engineering tool 50 reads the protocol data specified in FIG. 9 by the user from the storage unit 52 (step S101), and then stores the read protocol data in the communication test data storage unit 32 of the communication unit 30. Write in the area 102 (step S102). If any data is already stored in the communication test data storage area 102, it is rewritten with this protocol data.

Next, the engineering tool 50 writes the communication test command data in the communication test command data storage area 101 of the storage unit 32 of the communication unit 30 (step S103). The communication test command data is data such as “1”, for example, and commands the communication unit 30 to perform a communication test. Here, when some data is already stored in the communication test command data storage area 101, it is rewritten to this communication test command data.

Next, the engineering tool 50 reads the communication test command data storage area 101 (step S104), and determines whether or not communication test completion data has been written (step S105). This communication test completion data is data different from the communication test command data such as “2”, for example, and is data indicating that the communication unit 30 has completed the communication test. As will be described later, when the communication unit 30 confirms that the communication test command data is written in the communication test command data storage area 101, the communication unit 30 performs a communication test, and then stored in the communication test command data storage area 101. Rewrite the communication test command data to the stored communication test completion data. If the communication test completion data is not written in S105, the process returns to S104.

If the communication test completion data has been written in S105, the engineering tool 50 next transmits the communication test result data related to this communication test from the communication result data storage area 104 of the storage unit 32 of the communication unit 30. Is read (step S106). This communication test result data is data representing whether or not the result of the communication test performed by the communication unit 30 is normal, and if abnormal, specifically indicates that the connection cable 80 is abnormal.

Next, the engineering tool 50 displays the communication test result information on the display unit 54 based on the communication test result data read in S106 (step S107). Thereafter, the communication test process is terminated.

If the result of the communication test is normal, this protocol data means that it can be used for normal communication between the communication unit 30 and the external device 60 without any problem. In order to use the protocol data for which the communication test has been completed for normal communication, the engineering tool 50 first transmits the protocol data to the communication data storage area of the storage unit 32 of the communication unit 30 according to the operation by the user. 103 is written. The communication data storage area 103 can store a plurality of protocol data for which the communication test has been completed.

Further, the user separately creates a control command program such as a ladder program including a start command for the protocol data by using an engineering tool or another device, and the created control command program is stored in the storage unit of the CPU unit 20. 22 is written. This control command program is executed by the CPU unit 20, and this protocol / data activation command instructs the communication unit 30 to communicate with the external device 60 using this protocol / data.

Next, when the execution of the control command program is instructed by the user, the engineering tool 50 instructs the CPU unit 20 to execute the control command program. Next, the CPU unit 20 starts execution of the control command program stored in the storage unit 22, and reads the protocol / data start command during the execution, and issues the protocol / data start command to the communication unit 30. .

Next, operations performed by the communication unit 30 will be described with reference to FIG. The operation performed by the communication unit 30 is processed by the control unit 31 according to the system program stored in the system program storage area 100. FIG. 10 is a flowchart showing processing of the communication unit 30 in the first embodiment. First, the communication unit 30 determines whether a protocol / data activation command has been issued by the CPU unit 20 (step S201). If a protocol / data activation command is issued in S201, the communication unit 30 then reads the protocol data for which this activation command has been issued from the communication data storage area 103 (step S202). Next, the data length and data content of the protocol data read in S202 are confirmed, and it is diagnosed whether or not this protocol data satisfies a predetermined condition for communicating with the external device 60 (step S203).

Next, the communication unit 30 determines whether or not this protocol data can be communicated with the external device 60 as a result of the diagnosis in S203 (step S204). If it is determined in S204 that the protocol data can be communicated, the communication is performed with the external device 60 using the protocol data (step S205). Next, the communication result data is written in the communication result data storage area 104 (step S206), and then the process returns to S201. The communication result data is data representing whether or not the result of the communication performed by the communication unit 30 is normal, and if abnormal, specifically indicates that the connection cable 80 is abnormal.

On the other hand, if it is determined in S204 that the protocol data cannot be communicated, then protocol abnormality data is written in the communication result data storage area 104 (step S206), and then the process returns to S201. This protocol abnormality data is data indicating that a predetermined condition is not satisfied because there is some abnormality in the protocol data.

On the other hand, if the protocol / data activation command is not issued in S201, the communication unit 30 next determines whether or not a communication test command is issued by the engineering tool 50 (step S208). That is, the communication test command data storage area 101 is read to determine whether or not communication test command data has been written. If the communication test command data is not written in S208, the process returns to step S201. Here, the case where the communication test command data is not written is, for example, a case where data different from the communication test command data such as communication test completion data is written, or no data is written. .

On the other hand, if the communication test command data has been written in S208, the communication unit 30 then reads the protocol data from the communication test data storage area 102 (step S209). Next, the data length and data content of the protocol data read in S209 are confirmed, and it is diagnosed whether or not the protocol data satisfies a predetermined condition for communicating with the external device 60 (step S210).

Then, the communication unit 30 determines whether or not this protocol data can be communicated with the external device 60 as a result of the diagnosis in S210 (step S211). If it is determined in S211 that the protocol data can be communicated, then the protocol data is communicated with the external device 60 (step S212). Next, the communication test result data is written in the communication result data storage area 104 (step S213). Next, the communication unit 30 writes the communication test completion data in the communication test command data storage area 101 (step S214), and then returns to S201.

On the other hand, if it is determined in S211 that the protocol data cannot be communicated, the communication unit 30 then writes the protocol abnormality data in the communication result data storage area 104 (step S215). Next, the process proceeds to S214, the communication test completion data is written in the communication test command data storage area 101, and then the process returns to S201.

In this embodiment, the engineering tool 50 writes the created protocol data in the communication test data storage area 102 in S102 of FIG. 8, but the protocol data stored in the communication data storage area 103 is written. Can be written in the communication test data storage area 102. This makes it possible to perform a protocol / data communication test when debugging the control command program.

In this embodiment, in S201 of FIG. 10, the communication unit 30 determines only whether the CPU / unit 20 has issued a protocol / data activation command. It may be determined whether or not a command has been issued, and thereafter, processing according to each command may be performed.

Further, the communication test command data storage area 101 of the communication unit 30 may be omitted. In this case, instead of determining whether or not the communication test command data is written in the communication test command data storage area 101 in S208 of FIG. 10, the communication unit 30 directly transmits the protocol to the communication test data storage area 102. -Determine whether data has been written. Further, the communication unit 30 deletes the protocol data in the communication test data storage area 102 instead of writing the communication test completion data in the communication test command data storage area 101 in S214 of FIG. On the other hand, the engineering tool 50 proceeds to S106 after S102 in FIG.

According to the present embodiment, it is possible to confirm whether or not the created protocol data can be normally communicated without creating a control command program after creating the protocol data with the engineering tool. . Further, when debugging the control command program, the cause can be easily identified without using a dedicated device such as a line monitor.

1 PLC
20 CPU unit 30 Communication unit 50 Engineering tool 60 External device 90 Control system 101 Communication test command data storage area 102 Communication test data storage area 103 Communication data storage area 104 Communication result data storage area

Claims (16)

PLC and
An engineering tool connected to the PLC;
In a control system comprising an external device connected to the PLC,
The engineering tool is
A communication test command means for issuing a communication test command to the PLC;
The PLC is
A control command program storage unit for storing the control command program;
A communication data storage unit for storing the first protocol data;
A communication test data storage unit for storing second protocol data;
Protocol starting means for reading a protocol / data starting command in the control command program;
Based on the protocol data activation command read by the protocol activation means, communication means for communicating with the external device by the first protocol data stored in the communication data storage unit;
Based on the communication test command received from the communication test command means, communication test means for communicating with the external device by the second protocol data stored in the communication test data storage unit;
A control system characterized by comprising: The engineering tool, writes the second protocol data to the communication test data storage unit,
The PLC includes a communication test command data storage unit,
The communication test command means writes the communication test command data in the communication test command data storage unit,
The communication test means is based on the second protocol data stored in the communication test data storage section based on the communication test command data written in the communication test command data storage section by the communication test instruction means. The control system according to claim 1, wherein the control system communicates with an external device. The PLC is control system according to claim 2, wherein the rewriting Turkey the communication test command data to be written to the communication test instruction data storage unit by the communication test command means in the communication test completion data. The communication test command means writes the second protocol data into the communication test data storage unit,
2. The control system according to claim 1, wherein the communication test means communicates with the external device by the second protocol data written in the communication test data storage unit by the communication test command means. The PLC is control system according to claim 4, wherein the benzalkonium delete the second protocol data to be written to the communication test data storage unit by the communication test command means. PLC and
An engineering tool connected to the PLC;
In a control system comprising an external device connected to the PLC,
A protocol starting step in which the PLC reads a protocol / data starting command in the control command program;
A communication step of communicating with the external device by the first protocol data stored in the communication data storage unit provided in the PLC based on the protocol data activation command read by the PLC in the protocol activation step; ,
A communication test command step in which the engineering tool issues a communication test command to the PLC;
A communication test in which the PLC communicates with the external device based on the second protocol data stored in the communication test data storage unit provided in the PLC based on the communication test command received in the communication test command step.・ Step and
A control system communication method characterized by comprising: A second protocol writing step in which the engineering tool writes the second protocol data to the communication test data storage unit;
In the communication test command step, after the second protocol writing step, the engineering tool writes communication test command data in a communication test command data storage unit provided in the PLC,
In the communication test step, the PLC communicates with the external device by the second protocol data based on the communication test command data written in the communication test command data storage unit in the communication test command step. The communication method of the control system according to claim 6. After the communication test step, a completion writing step in which the PLC rewrites the communication test command data written in the communication test command data storage unit in the communication test command step to communication test completion data;
8. The control system communication method according to claim 7, further comprising: In the communication test command step, the engineering tool writes the second protocol data in the communication test data storage unit,
7. The communication test step is characterized in that the PLC communicates with the external device by the second protocol data written in the communication test data storage unit in the communication test command step. Control system communication method. After the communication test step, the PLC deletes the second protocol data written in the communication test data storage unit in the communication test command step;
The communication method of the control system according to claim 9, further comprising: A communication data storage unit for storing the first protocol data;
A communication test data storage unit for storing second protocol data;
A communication command determining means for determining whether or not a protocol / data start command has been issued by the CPU unit;
If the communication command determining means determines that the protocol / data activation command has been issued, the communication means for communicating with an external device using the first protocol data stored in the communication data storage unit;
A communication test command determination means for determining whether a communication test command has been issued by the engineering tool;
When the communication test command determining means determines that the communication test command has been issued, communication test means for communicating with the external device by the second protocol data stored in the communication test data storage unit;
A communication unit comprising: A communication test command data storage unit is provided.
The communication test command determination means determines whether or not communication test command data is written in the communication test command data storage unit,
The communication test means, when the communication test command determination means determines that the communication test command data is written in the communication test command data storage unit, the communication test data storage unit stores the communication test command data. 12. The communication unit according to claim 11, wherein the communication unit communicates with the external device using second protocol data. The communication test command determination means determines whether or not the second protocol data is written in the communication test data storage unit,
When the communication test command determining unit determines that the second protocol data is written in the communication test data storage unit, the communication test unit determines the external device based on the second protocol data. The communication unit according to claim 11, wherein the communication unit communicates with the communication unit. In a communication unit having a communication data storage unit for storing first protocol data and a communication test data storage unit for storing second protocol data,
A communication command determination step for determining whether or not a protocol / data start command has been issued by the CPU unit;
If it is determined in the communication command determination step that the protocol data activation command has been issued, a communication step of communicating with an external device using the first protocol data stored in the communication data storage unit;
A communication test command determination step for determining whether a communication test command has been issued by the engineering tool;
A communication test step of communicating with the external device by the second protocol data stored in the communication test data storage unit when it is determined in the communication test command determining step that the communication test command has been made; ,
A communication unit communication method characterized by comprising: The communication unit further includes a communication test command data storage unit,
The communication test command determination step determines whether communication test command data is written in the communication test command data storage unit,
The communication test step is stored in the communication test data storage unit when it is determined in the communication test command determination step that the communication test command data is written in the communication test command data storage unit. 15. The communication unit communication method according to claim 14, wherein communication with the external device is performed by the second protocol data. The communication test command determination step determines whether or not the second protocol data is written in the communication test data storage unit,
In the communication test step, when it is determined in the communication test command determination step that the second protocol data is written in the communication test data storage unit, the external test data is determined by the second protocol data. 15. The communication method for a communication unit according to claim 14, wherein communication is performed with a device.

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