JP5442575B2 - Communication equipment - Google Patents

Description

  The present invention relates to a communication device connected to a network that performs communication using a token.

  In a network system that performs communication using tokens, the hardware configuration of each communication device connected to the network needs to be set according to the communication method and communication speed.

  On the other hand, a communication device that can cope with a plurality of output forms has been proposed (for example, Patent Document 1). Whether or not the communication device described in Patent Document 1 detects a token within a predetermined period of time between a communication unit corresponding to the communication form of the two-wire field device and a communication unit that performs fieldbus communication. Depending on the, it is made to function selectively. Thereby, the communication device can easily and safely cope with a plurality of output forms.

JP 2010-134752 A (released on June 17, 2010)

  However, even in a network system of the same communication form, the baud rate is set to various values depending on the network (for example, 9.6 Kbps, 19.2 Kbps, 187.5 Kbps, 500 Kbps, 1.5 Mbps, 3 Mbps, 6 Mbps, 12 Mbps). Therefore, when a new device is connected to an existing network, it is necessary to pay attention so that the baud rate of the newly connected device matches the baud rate of the network.

  If the setting baud rate of a newly connected device is different from the baud rate of the network due to a user's setting error, the device does not receive a frame with the same baud rate as its own setting baud rate. There is a risk of not knowing. In this case, a newly connected device transmits a token itself to the network and interferes with network communication.

  For example, as shown in FIG. 6, the case where the programmable display 101a is newly connected to the Profibus network 100 will be described. In the Profibus network 100, communication is performed at a baud rate of 12 Mbps, and each of the programmable display device 101, the programmable logic controller (PLC) 102, and the personal computer (PC) 103 connected to the Profibus network 100. The baud rate is set to 12 Mbps. On the other hand, the baud rate of the newly connected programmable display 101a is set to 187.5 Kbps.

  In this case, since the newly connected programmable display 101a recognizes only data of 187.5 Kbps, it cannot recognize that communication at a different baud rate is being performed in the Profibus network 100. Therefore, the programmable display 101a determines that no device is connected on the Profibus network 100, and transmits an 187.5 Kbps token to the Profibus network 100. As a result, in the Profibus network 100, communication is interrupted, and device control by the existing programmable display 101 and PLC 102, data transfer between the PC 103 and the programmable display 101 / PLC 102, and the like may stop.

  The present invention has been made to solve the above problems, and an object of the present invention is to realize a communication device that can be connected to a network more safely.

  In order to solve the above problems, a communication device according to the present invention is a communication device connected to a network that performs communication using a token, and includes a receiving unit that receives a signal from the network, and A baud rate for comparing a transmission baud rate that is detected by the baud rate detection unit, a baud rate detection unit that detects a baud rate of the signal received by the reception unit, and a set baud rate set in the communication device. Comparing means, wherein the transmitting means does not transmit a token when the detected baud rate and the set baud rate are different.

  According to the above configuration, when the detected baud rate of the network detected by the baud rate detection means does not match the set baud rate set in the communication device, a token is not transmitted from the communication device to the network. For this reason, even if the baud rate setting is mistakenly connected to the network, it is possible to automatically prevent the network from being interrupted by the transmission of the token. A communication device that can be connected to a network more safely can be realized.

  In the communication device according to the present invention, when the reception unit does not receive a signal within a predetermined period after the communication device is connected to the network, the transmission unit preferably transmits a token.

  According to the above configuration, when the receiving unit does not receive a signal within a predetermined period after the communication device is connected to the network, that is, when no device is connected to the network, a token is transmitted from the communication device. Is done. Thereby, the network can be operated as a token ring.

  The communication device according to the present invention may be a programmable display or a programmable logic controller.

  The program according to the present invention causes a computer to operate as each means of any of the above communication devices.

  As described above, the communication device according to the present invention produces an effect that even if the baud rate setting is mistakenly connected to the network, the token is not transmitted, so that it is possible to connect to the network more safely.

It is a block diagram which shows the structure of the programmable display which concerns on embodiment of this invention. It is a figure which shows the timer value of the transmission data of a programmable display, reception data, and the monitoring timer part when the baud rate of a Profibus network and the setting baud rate of a programmable display do not correspond. It is a figure which shows the timer value of the transmission data of a programmable display, reception data, and the monitoring timer part when the baud rate of a profibus network and the setting baud rate of a programmable display correspond. It is a figure which shows the timer value of the transmission data of a programmable display, reception data, and a monitoring timer part when a programmable display does not receive a frame from a Profibus network. It is a flowchart in the case of connecting a programmable display to a Profibus network. It is a figure which shows the case where the programmable display from which a baud rate differs is newly connected to a Profibus network.

  An embodiment of the present invention will be described below with reference to FIGS. This embodiment demonstrates the case where a programmable display is newly connected to the Profibus network which comprises a token ring.

(Configuration of programmable display)
FIG. 1 is a block diagram illustrating a configuration of a programmable display 1 according to the present embodiment. The programmable display 1 is a communication device connected to the Profibus network 2 and includes a bus monitor circuit unit 3 and a CPU 4. The bus monitor circuit unit 3 is a circuit that controls communication between the programmable display device 1 and the Profibus network 2, and compares the baud rate of the Profibus network 2 with the set baud rate of the programmable display device 1 according to the comparison result. It has a bus monitor function that controls the transmission of tokens.

  As shown in FIG. 1, the bus monitor circuit unit 3 includes a communication reception unit (reception unit) 31, a reception baud rate detection unit (baud rate detection unit) 32, a baud rate setting unit 33, a baud rate comparison unit (baud rate comparison unit) 34, a connection An error detection unit 35, a token ring participation sequence unit 36, a monitoring timer unit 37, and a communication transmission unit (transmission means) 38 are provided.

  The communication receiving unit 31 is a block that receives a signal addressed to the address of its own device from the Profibus network 2.

  The reception baud rate detection unit 32 is a block that detects the baud rate of the data received by the communication reception unit 31. In the present embodiment, the reception baud rate detector 32 can monitor the baud rate of signals in the range of 9.6 Kbps to 12 Mbps.

  The baud rate setting unit 33 is a block that stores the value of the set baud rate of the programmable display device 1. The set baud rate of the programmable display 1 is set by a user operation, and data indicating the set baud rate is input from the CPU 4 to the baud rate setting unit 33.

  The baud rate comparison unit 34 is a block that compares the value of the reception baud rate detected by the reception baud rate detection unit 32 with the value of the set baud rate stored in the baud rate setting unit 33. The comparison result in the baud rate comparison unit 34 is output to the connection error detection unit 35, the token ring participation sequence unit 36, and the monitoring timer unit 37.

  The connection error detection unit 35 is a block that detects a connection error when the comparison results do not match. In this embodiment, in this case, the connection error detection unit 35 transmits a connection error notification to the CPU 4, and the CPU 4 notifies the user of the connection error by, for example, lighting a warning lamp (not shown).

  When the comparison result in the baud rate comparison unit 34 matches, the token ring participation sequence unit 36 analyzes the frame from the Profibus network 2 and causes the programmable display 1 to participate in the Profibus network 2 constituting the token ring. This is a block that performs a sequence.

  The monitoring timer unit 37 is composed of a down counter. The initial value of the timer value of the monitoring timer unit 37 is set to N (N is an integer), and the monitoring timer unit 37 connects the programmable display 1 to the Profibus network 2 and turns on the power of the programmable display 1. The count operation is performed from the time of turning on until the timer value becomes zero. The timer value of the monitoring timer unit 37 returns to the initial value N when the connection error detection unit 35 detects a connection error and when the connection of the programmable display 1 to the Profibus network 2 is completed. Is set to

  The communication transmitter 38 is a block that generates a signal to be transmitted from the programmable display device 1 to the Profibus network 2.

  Specifically, when the value of the reception baud rate matches the value of the set baud rate, the communication transmission unit 38 responds to an instruction from the token ring participation sequence unit 36 and receives FDL (Field bus Data) from the Profibus network 2. Link) A FDL response is generated and output in response to the request.

  Further, when the timer value of the monitoring timer unit 37 becomes 0, that is, when the communication receiving unit 31 does not receive a frame (signal) for a predetermined time after the programmable display 1 is connected to the Profibus network 2, The transmission unit 38 transmits the token to the Profibus network 2.

  On the other hand, if the value of the reception baud rate does not match the value of the set baud rate and a connection error is detected, the communication transmission unit 38 does not transmit a token. That is, even when the programmable display 1 having different baud rate settings is connected to the Profibus network 2, no token is transmitted from the programmable display 1. As a result, it is possible to automatically avoid network interference caused by a token being erroneously transmitted to the Profibus network 2 having a different baud rate.

(Transmission / reception data and timer value)
Next, data transmitted and received from the programmable display 1 to the Profibus network 2 and the timer value of the monitoring timer unit 37 will be described with reference to FIGS.

  FIG. 2 is a diagram illustrating transmission data and reception data of the programmable display 1 and a timer value of the monitoring timer unit 37 when the baud rate of the Profibus network 2 and the set baud rate of the programmable display 1 do not match.

  In the initial state, the timer value of the monitoring timer unit 37 is N. When the connection of the programmable display 1 to the Profibus network 2 is started, the monitoring timer unit 37 starts a down count. Here, when a signal with a baud rate different from the set baud rate (for example, an FDL request) is received from the Profibus network 2, a connection error is detected, and the timer value of the monitoring timer unit 37 is returned to the initial value N. A signal from the Profibus network 2 includes a token, data, etc. in addition to the FDL request. After that, every time an FDL request having a baud rate different from the set baud rate is received, the timer value of the monitoring timer unit 37 is returned to the initial value N, so that the timer value does not become zero. Therefore, no token is transmitted from the communication transmitter 38.

  FIG. 3 is a diagram illustrating the transmission data and reception data of the programmable display 1 and the timer value of the monitoring timer unit 37 when the baud rate of the Profibus network 2 matches the set baud rate of the programmable display 1.

  When the connection of the programmable display 1 to the Profibus network 2 is started, the monitoring timer unit 37 starts a down count. Here, when an FDL request having the same baud rate as the set baud rate is received from the Profibus network 2, the communication transmitter 38 outputs an FDL response to the FDL request. Thereby, the connection to the Profibus network 2 of the programmable display 1 is completed. When the programmable display device 1 receives a signal indicating the completion of connection, the timer value of the monitoring timer unit 37 is returned to the initial value N.

  FIG. 4 is a diagram illustrating transmission data and reception data of the programmable display 1 and a timer value of the monitoring timer unit 37 when the programmable display 1 does not receive a frame from the Profibus network 2.

  When the connection of the programmable display 1 to the Profibus network 2 is started, the monitoring timer unit 37 starts down-counting, but since no frame is received from the Profibus network 2, the monitoring timer unit 37 after a predetermined period has elapsed. The timer value of becomes 0. Therefore, the communication transmission unit 38 transmits the token to the Profibus network 2. Thereby, the Profibus network 2 can be operated as a token ring.

  The predetermined period is a period in which, in the standard of the Profibus network 2, when no frame is received, it can be considered that no device is connected on the network. In addition, since no device is connected on the Profibus network 2, even if a token is transmitted from the programmable display 1, there is no problem that communication is interrupted.

(Bus monitor procedure)
Then, the flowchart in the case of connecting the programmable display 1 to the Profibus network 2 is shown in FIG. When the connection of the programmable display 1 to the Profibus network 2 is started (step S1), the monitoring timer unit 37 starts down-counting (step S2) and bus monitoring is started (step S3).

  Here, the communication receiver 31 does not detect a frame (“NO” in step S5), and the timer value of the monitoring timer unit 37 becomes 0 after a predetermined period has elapsed (“YES” in step S4). The communication transmitter 38 transmits a token (step S6).

  On the other hand, when the communication receiving unit 31 detects a frame (“YES” in step S5) while the monitoring timer unit 37 is performing the down-counting operation (“NO” in step S4), the reception baud rate detecting unit 32 is The baud rate of the frame is detected, and the baud rate comparison unit 34 compares the detected baud rate with the set baud rate of the programmable display 1 (step S7).

  When the detected baud rate and the received baud rate match (“YES” in step S8), the token ring participation sequence unit 36 causes the programmable display 1 to output the predetermined signal such as the FDL response from the communication transmission unit 38. Normal participation is made in the token ring of the Profibus network 2 (step S9).

  If the detected baud rate and the received baud rate do not match (“NO” in step S8), the connection error detection unit 35 detects a connection error (step S10), and the monitoring timer unit 37 returns the timer value to the initial value N ( Step S11) and the process proceeds to step S2. Since frames from the Profibus network 2 are transmitted at predetermined intervals, the flow from Step S2 to Step S11 is repeated, and the timer value of the monitoring timer unit 37 does not become zero. Therefore, a token is not transmitted from the programmable display device 1, and it is possible to avoid interference with the network due to the erroneous transmission of the token.

  In this embodiment, since the detected baud rate and the received baud rate do not match, when the flow from step S2 to step S11 is repeated, the baud rate of the programmable display 1 is reset by the user's operation, and the detected baud rate and the received baud rate are received. Bus monitoring continues until the baud rate matches. In this case, the user may be notified of the connection error by turning on a warning lamp or displaying an error on the display screen.

(Implementation of the present invention by software)
Although the bus monitor circuit unit 3 of the programmable display device 1 according to the present embodiment is configured by hardware logic, at least a part of the functions of the bus monitor circuit unit 3 is performed by software using a CPU as follows. It may be realized.

  That is, the programmable display 1 includes a CPU (central processing unit) that executes instructions of a control program for realizing each function, a ROM (read only memory) that stores the program, and a RAM (random access memory) that expands the program. And a storage device (recording medium) such as a memory for storing the program and various data. An object of the present invention is to provide a recording medium in which a program code (execution format program, intermediate code program, source program) of a program of the programmable display 1 which is software that realizes the above-described functions is recorded so as to be readable by a computer. This can also be achieved by supplying the computer switch 1 and reading and executing the program code recorded on the recording medium by the computer (or CPU or MPU).

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape, a magnetic disk such as a floppy (registered trademark) disk / hard disk, and an optical disk such as a CD-ROM / MO / MD / BD / DVD / CD-R. A disk system including an IC card (including a memory card) / optical card or a semiconductor memory system such as a mask ROM / EPROM / EEPROM / flash ROM can be used.

  The programmable display 1 may be configured to be connectable to a communication network, and the program code may be supplied via the communication network. The communication network is not particularly limited. For example, the Internet, intranet, extranet, LAN, ISDN, VAN, CATV communication network, virtual private network, telephone line network, mobile communication network, satellite communication A net or the like is available. Further, the transmission medium constituting the communication network is not particularly limited. For example, even in the case of wired such as IEEE 1394, USB, power line carrier, cable TV line, telephone line, ADSL line, etc., infrared rays such as IrDA and remote control, Bluetooth ( (Registered trademark), 802.11 wireless, HDR, mobile phone network, satellite line, terrestrial digital network, and the like can also be used. The present invention can also be realized in the form of a computer data signal embedded in a carrier wave in which the program code is embodied by electronic transmission.

(Additional notes)
In said embodiment, although the programmable display was illustrated as a communication apparatus connected to a Profibus network, it is not limited to this. Examples of communication devices connected to the Profibus network include PLCs and PCs. Further, although the Profibus network is exemplified as the network for performing communication using the token, it is not limited to this.

  In addition, the programmable display device according to the above embodiment is a monitor that is an internal counter until the detected baud rate of the network does not match the set baud rate, and the baud rate is reset by the user until the detected baud rate matches the set baud rate. The timer unit continues the down count operation. On the other hand, if the detected baud rate of the network does not match the set baud rate, the set baud rate may automatically match the detected baud rate.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. That is, embodiments obtained by combining technical means appropriately modified within the scope of the claims are also included in the technical scope of the present invention.

  The present invention is suitable for a communication device connected to a network that performs communication using a token.

1 Programmable display 2 Profibus network (network)
3 Bus monitor circuit 4 CPU
31 Communication receiver (reception means)
32 Receive baud rate detector (baud rate detection means)
33 Baud rate setting unit 34 Baud rate comparison unit (baud rate comparison means)
35 Connection error detection unit 36 Token ring participation sequence unit 37 Monitoring timer unit 38 Communication transmission unit (transmission means)

Claims (1)

A communication device connected to a network that performs communication using a token,
Receiving means for receiving a signal from the network;
Transmitting means for transmitting a signal to the network;
Baud rate detecting means for detecting the baud rate of the signal received by the receiving means;
Baud rate comparison means for comparing the detected baud rate detected by the baud rate detection means with a set baud rate set in the communication device;
If the detected baud rate is different from the set baud rate, the transmitting means does not transmit a token, and if the receiving means does not receive a signal within a predetermined period after the communication device is connected to the network, A communication device characterized by transmitting a message.

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