JP2022102238A - Communication device, elevator communication device, and communication method - Google Patents

Abstract

To detect a sign of a communication failure due to a delay in a communication path in a CAN communication system.SOLUTION: A communication device 1 for transmitting and receiving data to/from another communication device via a communication line based on a CAN communication protocol includes: a control unit 3 that controls the transmission and reception of the data; a delay time calculation unit 6 that inputs therein the transmission data output from the control unit 3 and the reception data output from the other communication device as a response to the transmission data, and calculates a delay time of a communication path from ACK signals included in the transmission data and the reception data; and a delay determination unit 7 that compares the delay time with a threshold value and outputs delay determination information.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to communication equipment.

There is a CAN (Controller Area Network) communication method as one of the network protocols that are widely used in in-vehicle networks. This communication method is also widely used in industrial equipment, agricultural machinery, medical equipment, railways, elevators, etc.

In the CAN communication method, a binary digital signal having a logical value of "0" and "1" is converted into a differential signal, and a two-wire communication bus line (CAN_H line (hereinafter, H line) and CAN_L line (hereinafter, hereafter,). It is transmitted via the L line)). The differential signals transmitted on the H line and the L line each represent two states, dominant and recessive, depending on the voltage level. In the protocol standardized by ISO11898, if the voltage of the signal of the H line is high level, the voltage of the signal of the L line is low level, and the potential difference between the H line and the L line exceeds a predetermined value, the logical value "0" is used as a dominant. If the voltage of the H line signal is low level, the voltage of the L line signal is high level, and the potential difference between the H line and L line is less than or equal to a predetermined value (including the same potential), it is a logical value as recessive. Represents "1".

If communication is stopped for some reason during the operation of the CAN communication system, safety may be affected in the above-mentioned applications such as in-vehicle devices. Therefore, a method of detecting a sign of a communication failure has been proposed so that the communication system does not stop unintentionally during operation.

In the method proposed conventionally, signals transmitted and received by the CAN transceiver of the communication device are input to a monitoring circuit provided on the communication line to detect an abnormality. For the high level and low level voltage values of the H line and L line signals input to the monitoring circuit, set the voltage judgment value to judge the presence or absence of abnormality, and set the voltage value and the power judgment value. Abnormality (a sign leading to element destruction) is detected by comparison (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-108952

In the above-mentioned prior art, the presence or absence of abnormality in the CAN transceiver is determined by comparing the voltage values of the H line and the L line with the voltage determination value for determining the presence or absence of abnormality, and a sign leading to element destruction is detected. However, in the CAN communication system, a communication failure may occur due to a delay in the communication path. Although the prior art detects the deterioration of the CAN transceiver, it does not have a mechanism for detecting the delay of the communication path.

The cause of the delay of the communication path is, for example, in addition to the temperature change of the environment where the communication line is installed, when the communication line is combined with other wiring such as the power line into the communication cable, the other wiring becomes a load condition. The heat may be generated accordingly, and the temperature of the communication line may rise. When the temperature of the communication line rises, the impedance increases and a delay occurs. Further, when the CAN communication method is applied to a device having a long service life such as an elevator, the communication line deteriorates over time due to long-term use, the impedance increases, and a delay occurs.

An object of the present disclosure is to detect a sign of a communication failure due to a delay in a communication path in a CAN communication system.

In order to solve the above-mentioned problems and achieve the object, the communication device according to the present disclosure is a communication device that transmits / receives data to / from another communication device via a communication line based on the CAN communication protocol. The control unit that controls transmission / reception, the transmission data output from the control unit, and the reception data output from other communication devices as a response to the transmission data are input, and the transmission data and the ACK signal included in the reception data are used as inputs. It includes a delay time calculation unit that calculates the delay time of the communication path, and a delay determination unit that compares the delay time with the threshold value and outputs delay determination information.

According to the present disclosure, in a CAN communication system, it is possible to detect a sign of a communication failure due to a delay in a communication path.

The figure which shows the structural example of the communication system which concerns on Embodiment 1 The figure which shows the structural example of the CAN transceiver which concerns on Embodiment 1 The figure which shows an example of the data frame structure used in the CAN communication system which concerns on Embodiment 1. Truth table of logical operations executed by the delay time calculation unit according to the first embodiment. The figure which shows typically the logical operation result of the delay time calculation part which concerns on Embodiment 1. The figure which shows the configuration example of the delay time calculation part and the delay determination part which concerns on Embodiment 1 The figure which shows the relationship between the time width of the delay time pulse and the threshold value which concerns on Embodiment 1. The figure which shows the modification of the structure of the communication system which concerns on Embodiment 1 The figure which shows the modification of the structure of the communication system which concerns on Embodiment 1 A flowchart illustrating the operation of the first communication device according to the first embodiment. A flowchart illustrating the operation of the first communication device according to the second embodiment. The figure which shows the structural example of the communication system which concerns on Embodiment 3 The figure which shows typically the relationship between the delay time and the use time which concerns on Embodiment 3. A flowchart illustrating the operation of the first communication device according to the third embodiment. The hardware diagram of the first communication apparatus which concerns on Embodiments 1 to 3.

Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. In each figure, the same or corresponding parts are designated by the same reference numerals. Duplicate descriptions will be simplified or omitted as appropriate. The present disclosure is not limited to the embodiments described below.

Embodiment 1.
FIG. 1 is a diagram showing a configuration example of a communication system according to an embodiment of the present disclosure. The first communication device 1 is connected to the second communication device 11 via the communication line 8. The first communication device 1 has a communication control board 2, and the communication control board 2 has a control unit 3, a CAN controller 4, and a CAN transceiver 5. The communication control board 2 further includes a delay time calculation unit 6 and a delay determination unit 7 for detecting a sign of a communication failure due to a delay in the communication path.

The second communication device 11 also has a communication control board 12, and the communication control board 12 has a control unit 13, a CAN controller 14, and a CAN transceiver 15. Note that FIG. 1 discloses a configuration in which the first communication device 1 and the second communication device 11 are connected for the sake of simplicity, but the first communication device 1 is the second communication device 11. It may be connected to a plurality of other communication devices other than the above. Further, the configuration of each part of the first communication device 1 and the second communication device 11 is the same except that the delay time calculation unit 6 and the delay determination unit 7 are provided on the first communication device 1 side. Further, when the first communication device 1 is used as a master and it is connected to a plurality of other communication devices (that is, when it is one-to-many communication), the communication device specified by the first communication device 1 is used. It is also possible to use the listen-only function that responds to the first communication device 1. The same applies to the subsequent embodiments in the case of one-to-many communication. The listen-only function will be described later.

The communication line 8 is a two-wire communication bus line (H line 81, L line 82), and a twisted pair cable is generally used. The communication line 8 may be installed as a communication cable together with other wiring such as a power line.

The control unit 3 includes a CAN controller 4. The CAN controller 4 controls the transmission and reception of data to and from the second communication device 11 via the CAN transceiver 5. Further, the control unit 3 detects the delay of the communication path based on the delay determination information output from the delay determination unit 7.

The control unit 3 is a microcomputer and includes a processor 31 and a memory 32. The processor 31 is, for example, a CPU (Central Processing Unit), a microprocessor, and a DSP (Digital Signal Processor). The memory 32 is, for example, a RAM (Random Access Memory) or a ROM (Read Only Memory), and stores software programs, log data, and the like. When the processor 31 executes the software program stored in the memory 32, the function of at least one circuit of the first communication device 1 is realized. The memory 32 is not limited to the mode built in the control unit 3 as shown in the figure. It may be an external storage device capable of inputting / outputting data to / from the first communication device 1.

FIG. 2 is a diagram showing a configuration example of the CAN transceiver 5. The CAN transceiver 5 has a transmit buffer 51, a receive buffer 52, transistors 53, 54, input / output ports 55 (for H line), and 56 (for L line). The transmission buffer 51 converts the transmission data (TxD), which is binary digital data received from the CAN controller 4, into a differential signal and outputs the transmission data to the transistors 53 and 54. The transistors 53 and 54 adjust the voltage of the differential signals transmitted through the H line 81 and the L line 82 so that they have a predetermined potential, respectively. The voltage-adjusted differential signal is output from the input / output ports 55 and 56 and transmitted to the CAN transceiver 15 of the second communication device 11 via the communication line 8. Further, the input / output ports 55 and 56 receive the differential signal transmitted from the second communication device 11. The reception buffer 52 converts the differential signal into received data (RxD), which is binary digital data, and outputs the differential signal to the CAN controller 4.

Next, an ACK (Acknowledge) function for confirming that the data transmitted from the CAN controller 4 of the first communication device 1 can be normally received by the CAN controller 14 of the second communication device 11 will be described. FIG. 3 is a diagram showing an example of a data frame structure used in the CAN communication method. In the present disclosure, the "data frame" is a format for transmitting and receiving data between communication devices, and means a group of transmitted signals. The frame structure is an example, and the present disclosure can be applied as long as it is a CAN communication method in which a signal corresponding to an ACK signal is transmitted and received.

Data frames include SOF (Start Of Frame), ID (Identifier), RTR (Remote Transmission Request), control field, data field, CRC (Cyclic Redundancy Check) sequence, CRC delimiter, ACK (Acknowledge) slot, ACK delimiter, EOF (End Of Frame) is included. The numbers shown in the figure indicate the bit lengths that can be used in each part. Note that ITM (Intermission) is not included in the data frame. After ITM, the bus will be idle.

The CAN controller 4 performs a CRC operation from the data of the SOF, ID, control field, and data field, stores the operation result in the CRC sequence, and transmits the CRC operation. The ACK slot contains a 1-bit length ACK signal (hereinafter referred to as ACK bit). The CAN controller 4 sets the ACK bit to recessive (“1”) and transmits.

The CAN controller 14 of the second communication device 11 responds to the CAN controller 4 at the timing when the CAN controller 4 transmits the ACK bit of the ACK slot of the data frame. The CAN controller 14 similarly performs a CRC operation on the contents of the received data frame. When the calculation result matches the result calculated by the CAN controller 4 stored in the CRC sequence, the CAN controller 14 sets the ACK bit to dominant (“0”) and responds to the CAN controller 4 asynchronously.

In the CAN protocol, the signal on the communication line 8 has a higher priority than the recessive, so even if the CAN controller 4 sets the ACK bit to recessive, the CAN controller 14 sets this to the dominant. , The ACK bit in the data frame monitored by the CAN controller 4 is also dominant. Therefore, the CAN controller 4 recognizes that the second communication device 11 has normally received the data by confirming that the ACK bit in the data frame is dominant.

Next, a method of detecting the delay of the communication path will be described.

The transmission data transmitted from the CAN controller 4 by the branch 2a between the CAN controller 4 and the CAN transceiver 5 is input to the delay time calculation unit 6. Further, the data received from the second communication device 11 is input to the CAN controller 4 via the CAN transceiver 5, and is also input to the delay time calculation unit 6 as received data by the branch 2b. Since the received data is the data transmitted by the CAN controller 4 except for the ACK bit, the bits before the ACK slot are the same as the data transmitted by the CAN controller 4 unless there is an abnormality in the communication path. ..

The delay time calculation unit 6 makes a logical operation using the transmission data and the reception data as inputs. FIG. 4 is a truth table of logical operations executed by the delay time calculation unit 6. The delay time calculation unit 6 executes a logical operation for the binary signal bit as shown in the truth table of FIG. 4, with the high voltage state as recessive (“H”) and the low voltage state as dominant (“L”). The calculation result Q is output to the delay determination unit 7. As shown in the following logical formula, the operation result Q is output by taking the logical product of the transmitted data and the received data whose logic is inverted.

図５は、遅延時間算出部６の論理演算を模式的に示す図である。縦軸を電圧、横軸を時間として、（ａ）送信データ、（ｂ）受信データ、（ｃ）論理演算結果が示される。前述の通り、第２の通信装置１１が正常にデータを受信してＡＣＫビットをドミナントに設定して応答した場合、遅延時間算出部６に入力される送信データと受信データのＡＣＫスロットの前までのビットは同じであるから、図４に示す真理値表に従う論理演算の結果、これらのビットの電圧レベルはドミナント（“Ｌ”）となる。

FIG. 5 is a diagram schematically showing a logical operation of the delay time calculation unit 6. The vertical axis is voltage and the horizontal axis is time, and (a) transmission data, (b) reception data, and (c) logical operation results are shown. As described above, when the second communication device 11 normally receives the data, sets the ACK bit to dominant, and responds, the transmission data input to the delay time calculation unit 6 and the front of the ACK slot of the reception data are reached. Since the bits of are the same, the voltage level of these bits becomes dominant (“L”) as a result of the logical operation according to the truth table shown in FIG.

On the other hand, regarding the ACK bit, the ACK bit of the transmission data transmitted by the first communication device 1 is recessive (“H”), whereas the response from the second communication device 11 is dominant (“L”). ). Since this response is asynchronously replied from the second communication device 11 at the timing when the first communication device 1 is transmitting the ACK bit, it is partially recessive (“H”) to the ACK bit of the received data. There will be a period of "). As shown in FIG. 5C, a signal having a recessive (“H”) period is extracted as the logical operation result Q of the ACK bits of the transmission data and the reception data. In the following description, this extracted signal is referred to as a delay time pulse.

FIG. 6 is a diagram showing a configuration example of the delay time calculation unit 6 and the delay determination unit 7. The delay time calculation unit 6 performs the above-mentioned logical operation by the logical operation unit 61, and outputs the extracted delay time pulse to the counter unit 62. The counter unit 62 accurately measures the time width by sampling the delay time pulse using a clock (for example, about 100 times the communication speed) that is faster than the bit time of the communication speed. The fast clock here means a clock that can measure the time width of the delay time pulse with a certain degree of accuracy in order to calculate the delay time of the communication path, and is appropriately selected. be able to. The delay time pulse indicates that the delay increases as the time width decreases. The delay time calculation unit 6 calculates the delay time from the time width of the delay time pulse and outputs it to the delay determination unit 7. Since the delay time of the communication path is obtained by subtracting the time width of the delay time pulse from the time width of the ACK bit, the time width of the delay time pulse itself can be treated in the same manner as the delay time. Therefore, the delay time calculation unit 6 may output the time width of the delay time pulse itself as the calculated delay time to the delay determination unit 7. Alternatively, the delay time or the variation in the time width of the delay time pulse starting from the state of the communication path after the communication path is opened or maintained may be output as the calculated delay time.

The delay time depends on the length of time from the transmission of the recessive ACK bit by the CAN controller 4 to the reception of the dominant ACK bit set by the CAN controller 14. The delay determination unit 7 or the control unit 3 continuously monitors the signs of communication failure due to the delay of the communication path from the fluctuation of the delay time. The delay determination unit 7 reads the threshold value held in the memory 32, compares the delay time with the threshold value in the comparison unit 71, and outputs the delay determination information.

In order to detect a sign of a communication failure, the threshold value is set based on a delay time shorter than the limit value of the delay time at which the communication failure occurs. The short delay time here is set with a certain margin from the limit value in consideration of the stable operation of the communication system. FIG. 7 is obtained by extracting the ACK bit portion of the ACK slot from the data string of FIG. 5, and schematically shows the relationship between the time width of the delay time pulse and the threshold value. The sections AB, AC, and AD indicated by the arrows correspond to the delay times, respectively. Sections AB correspond to the delay time when the communication path is opened, or when the parts are replaced due to maintenance and the state is similar to that at the time of opening. The sections AD indicate the limit value of the delay time, and if the delay time is longer than this, a communication failure occurs. The sections A and C correspond to the above-mentioned threshold values, and are set as allowable values in a stable communicable range with a delay time shorter than the limit value. Therefore, stable communication continuation is guaranteed even when the delay time reaches the threshold value.

The delay determination unit 7 is a delay time calculated by the delay time calculation unit 6 (delay time pulse time width, delay time or delay time pulse time starting from the state of the communication path after the communication path is opened or maintained. (Including width fluctuation) and the threshold are compared, and the delay judgment information is output. The delay determination information shows the result of comparing the delay time and the threshold value, and includes information that the delay time is less than the threshold value or the delay time is longer than the threshold value. When the delay determination unit 7 determines that the delay time is equal to or longer than the threshold value, the control unit 3 detects a sign of a communication failure due to a delay in the communication path based on the output delay determination information. It should be noted that the condition is that the delay time is equal to or greater than the threshold value, but since the condition that the delay time is equal to or greater than the threshold value includes the condition that the delay time exceeds the threshold value, the delay time exceeds the threshold value. It may be replaced with, and there is no substantial difference between them. Similarly, in the following description, the condition is that the delay time is equal to or greater than the threshold value, but the delay time may be "exceeded" from the threshold value.

As an additional configuration, a listen-only function that can be used when the first communication device 1 is used as a master and is connected to a plurality of other communication devices (that is, when one-to-many communication is performed) will be described. .. This function identifies another communication device that responds to the ACK bit by transmitting a listen-only request from the first communication device 1 in order to measure the delay time of the communication path. In the modification of the communication system shown in FIG. 8, it is assumed that the communication devices 101, 102, and 103 corresponding to the above-mentioned second communication device are connected to the first communication device 1. When the first communication device 1 issues a listen-only request to the communication devices 101 and 102, the communication devices 101 and 102 shift from the normal communication mode to the listen-only mode. In this mode, the communication devices 101 and 102 do not respond to the ACK bit even if they receive the data transmitted from the first communication device 1. Since the communication device 103 is in the normal communication mode, when the data transmitted from the first communication device 1 is received, the ACK bit is changed from the recessive state to the dominant state and responds as described above. That is, by using this function for a plurality of communication devices connected to the first communication device 1 in one-to-many communication, the first communication device 1 extracts an ACK bit from the designated communication device. can do. Since the listen-only function partially restricts communication other than the specified communication device, it is more desirable to use it in situations where communication is not affected, such as during test operation and maintenance.

As an additional configuration, as shown in FIG. 9, the first communication device 1 may be provided with a notification unit 9 that executes a process of turning on the fail lamp and displaying a warning on the display of the control panel. FIG. 9 is a diagram showing a modified example of the communication system. When the delay determination unit 7 determines that the delay time is equal to or longer than the threshold value, the control unit 3 outputs a command to the notification unit 9, and the notification unit 9 notifies the outside of a sign of a communication failure due to a delay in the communication path. Alternatively, the delay determination unit 7 may directly issue a command to the notification unit 9. This enables predictive maintenance in which communication is systematically stopped and parts that cause delays in the communication path are replaced.

Further, as an additional configuration, in the comparison between the delay time and the threshold value, the delay determination unit 7 repeats the comparison a plurality of times, and outputs the delay determination information by the determination based on the comparison result of the plurality of times. Delay time There is a possibility that erroneous judgment may occur due to fluctuations in the time width of the pulse and measurement error of the counter unit 62, and by making a judgment based on multiple comparisons, a sign of failure due to a delay in the communication path is detected. The accuracy of the pulse can be improved.

Further, as an additional configuration, the difference between the delay time predicted from the installation information of the communication path and the delay time calculated by the delay time calculation unit 6 may be compared with the threshold value. For example, the delay determination unit 7 predicts the delay time with the difference between the delay time prediction value calculated from the installation information of the communication path and the delay time calculated by the delay time calculation unit 6 being less than 20% as a threshold. When it is determined that the difference between the value and the calculated delay time is equal to or greater than the threshold value, it is detected that there is a sign of a communication failure due to the delay in the communication path even if the communication can be continued. As a result, it is possible to detect a sign of a communication failure before the delay time cumulatively increases until the delay time reaches the threshold value due to a characteristic deterioration cause such as aged deterioration. For example, it leads to early detection of initial defects after the communication path is opened or after maintenance is performed.

The information included in the communication path installation information corresponds to, for example, basic information of the communication system such as the length of the communication line 8 and the communication speed, the installation environment of the communication cable in which the communication line 8 is integrated, and the load status. Examples thereof include a table in which the expected temperature fluctuation range of the communication cable, basic information, temperature fluctuation and usage time, and the delay time predicted from these are associated with each other. Then, the delay time is predicted based on the actual communication cable length, communication speed, temperature measurement value, communication cable usage time information, and installation information. Parameters related to the delay time other than the above may be included. Regarding the above table, for example, the relationship between the installation information and the delay time predicted from the installation information is determined in advance based on theoretical prediction or statistical analysis of actual data obtained from the communication system. It can be calculated and stored in the memory 32. In addition, a trained model that estimates the predicted value of the delay time from the installation information of the communication path by extracting the feature amount from the actual data obtained from the communication system and performing machine learning is generated in advance and held in the memory 32. You may stay.

Next, the operation of the first communication device 1 will be described with reference to the flowchart of FIG. The transmission data output by the first communication device 1 toward the second communication device 11 and the received data as a response from the second communication device 11 are input (S101). A delay time pulse is extracted from the transmission data and the ACK bit of the reception data (S102), and the time width of the delay time pulse is measured (S103).

The delay time calculated based on the time width of the measured delay time pulse is compared with the threshold value, and it is determined whether the delay time is equal to or longer than the threshold value (S104). If it is determined that the delay time is less than the threshold value, the processes of steps S101 to S103 are repeated. If it is determined that the delay time is equal to or greater than the threshold value, communication problems may occur if the delay time continues to increase and communication problems occur. A sign of failure is detected (S105).

Although the delay time calculation unit 6, the delay determination unit 7, and the control unit 3 have different configurations in FIGS. 1 and 9, the control unit 3 includes the delay time calculation unit 6 and the delay determination unit 7. May be. The delay determination unit 7 may not read the threshold value from the memory 32, but may have its own storage means to hold the threshold value.

As described above, the first communication device 1 according to the first embodiment is a communication device that transmits / receives data to / from another communication device via the communication line 8 based on the CAN communication protocol, and transmits / receives data. The control unit 3 to be controlled, the transmission data output from the control unit 3, and the reception data output from another communication device as a response to the transmission data are input, and the transmission data and the ACK signal included in the reception data are used as inputs. It has a delay time calculation unit 6 that calculates a delay time of a communication path, and a delay determination unit 7 that compares the delay time with a threshold value and outputs delay determination information. With such a configuration, it is possible to detect a sign of a defect caused by a delay in the communication path.

In particular, in elevators, the communication cable is longer than the other uses mentioned above, and some of them have a service life of several hundred meters, so the effects of delays in the communication path due to temperature fluctuations and aging deterioration are affected. Easy to receive. Therefore, the present disclosure for detecting a sign of a malfunction caused by a delay in a communication path is suitable for an elevator communication device that communicates between an elevator control panel and an operating device of a car or a landing. Similarly, in the embodiment described below, the disclosed communication device can be applied to the elevator control to be an elevator communication device.

Embodiment 2.
The first communication device 1 according to the second embodiment will be described. The first communication device 1 according to the present disclosure compares the delay time calculated by the delay time calculation unit 6 with the first threshold value and the second threshold value.

In the present embodiment, the first threshold value and the second threshold value are set based on the delay time shorter than the limit value of the delay time. The second threshold value corresponds to the threshold value described in the first embodiment and is set based on a delay time longer than the first threshold value. That is, the second threshold value is set with respect to the allowable value of the delay time, and the first threshold value preliminarily indicates a sign of communication failure due to the delay of the communication path before the delay time reaches the second threshold value. Set to detect. It should be noted that the setting is not limited to two threshold values, and it is also possible to set three or more threshold values.

The delay determination unit 7 compares the delay time calculated by the delay time calculation unit 6 with the first threshold value, and when it is determined that the delay time is equal to or greater than the first threshold value, the control unit 3 is informed of the first delay determination information. Is output. Then, the delay determination unit 7 compares the delay time calculated by the delay time calculation unit 6 with the second threshold value, and when it is determined that the delay time is equal to or greater than the second threshold value, the control unit 3 receives the second delay. Output the judgment information. When the delay time is equal to or longer than the first threshold value, the control unit 3 executes the control process set according to the first threshold value. The control unit 3 executes different control processes depending on whether the delay time is equal to or greater than the first threshold value and the delay time is equal to or greater than the second threshold value.

As an example of the control process set according to the first threshold value, the control unit 3 changes the log data collection condition in order to utilize it for maintenance when the delay time reaches the second threshold value. After the delay time reaches the first threshold value, the control unit 3 starts recording logs such as the delay time or the time width of the delay time pulse, the ambient temperature of the communication line 8, and the load status of the communication cable. Alternatively, if the log is acquired before the delay time reaches the first threshold value, the control unit 3 shortens the cycle for acquiring the log. By reducing the data collection in a situation where there is a low possibility that a problem will occur while obtaining the log data to be used for maintenance, the storage resource of the memory 32 for recording the log data can be efficiently used. In particular, when the first communication device 1 manages communication with a plurality of other communication devices as a master, the amount of log data collected from these communication devices becomes large, so such a setting is effective. Is. The log data may be stored in the memory 32 of the first communication device 1 or an external storage device (not shown).

Further, the notification unit 9 may notify the maintenance staff that the delay time has reached the first threshold value or more. In a state where the delay time is less than the second threshold value but is greater than or equal to the first threshold value, by preliminarily detecting a sign of a communication failure due to a delay in the communication path, it is possible to predict when maintenance is required. It enhances the nature and makes it possible to prepare for more planned maintenance. If the period from the previous maintenance to reaching the first threshold is short, there is a possibility that something is wrong with the communication path, and maintenance is performed before the delay time reaches the second threshold. It is possible to detect defective parts at an early stage.

Next, the operation of the first communication device 1 will be described with reference to the flowchart of FIG. The steps common to FIG. 10 of the first embodiment are designated by the same step numbers, and duplicate description will be omitted.

After the time width of the delay time pulse is measured (S103), it is determined whether the delay time is equal to or greater than the first threshold value (S201). If it is determined that the delay time is less than the first threshold value, the process returns to before step S101, and the monitoring of the delay time is continued. When it is determined that the delay time is equal to or greater than the first threshold value, the output control process is executed according to the first threshold value exemplified above (S202).

Next, it is determined whether the delay time is equal to or greater than the second threshold value (S203). If it is determined that the delay time is less than the second threshold value, the process returns to the previous step S101, and the monitoring of the delay time is continued. If it is determined that the delay time is equal to or greater than the second threshold value, communication problems may occur if the delay time continues to increase as it is. Therefore, the output second delay determination information causes a delay in the communication path. A sign of a communication failure caused by the above is detected (S105). In addition, step S203 may be executed after step S201, or the determination of step S201 and step S203 may be executed in parallel, and then steps S202 and S105 may be executed.

As described above, in the communication device 1 according to the second embodiment, the delay determination unit 7 compares the delay time calculated by the delay time calculation unit 6 with at least the first threshold value and the second threshold value, and is a control unit. Reference numeral 3 is configured to execute different control processes depending on whether the delay time is equal to or greater than the first threshold value and the delay time is equal to or greater than the second threshold value. With such a configuration, it is possible to preliminarily detect a sign of a malfunction caused by a delay in the communication path and prepare for maintenance or maintenance.

Embodiment 3.
The first communication device 1 according to the third embodiment will be described. In the present embodiment, as shown in FIG. 12, the first communication device 1 includes a delay cause estimation unit 10. The delay cause estimation unit 10 estimates the delay cause when the delay time exceeds the threshold value.

If the cause of the delay is aged deterioration, the delay time increases according to the usage time after installation. On the other hand, if the cause of the delay is due to temperature fluctuations of the communication cable, irregular noise, or the like, the delay time may temporarily fluctuate accordingly. For example, when the communication cable is temporarily overloaded and the temperature of the communication line 8 bundled with the communication cable rises, the delay time increases due to the increase in the impedance of the communication line 8. However, when the overload is eliminated, the temperature of the communication cable drops and the delay time decreases.

The delay cause estimation unit 10 estimates the cause of the delay time exceeding the threshold value, and estimates whether the delay cause is temporary characteristic deterioration such as temperature fluctuation. If it is presumed that the characteristics are temporarily deteriorated, the control unit 3 adjusts the communication speed within a range that does not affect the communication of the system. Specifically, the master first communication device 1 transmits the baud rate setting change information to the local second communication device 11, and both the master and the local use the processors 31 and 131 of the control units 3 and 13. By self-resetting, the communication speed is reduced to increase the margin for delay and continue communication.

An example of the cause estimation method of the delay cause estimation unit 10 will be described with reference to FIG. The delay cause estimation unit 10 refers to the relationship between the delay time and the usage time from the log data. In FIG. 13, the horizontal axis is the usage time of the communication path after the communication path is opened or after maintenance, and the vertical axis is the delay time, and the delay time of the communication path at each usage time is plotted. Temporary deterioration of characteristics such as temperature fluctuations and non-temporary deterioration of characteristics due to aging are mixed as causes of delay in the communication path. Therefore, as shown in FIG. 13, the delay time at each use time varies due to the influence of temporary deterioration of characteristics. The delay cause estimation unit 10 extracts usage time data that is less affected by delay due to temporary deterioration of characteristics from the temperature of the communication cable, load status, measured values of environmental noise, etc., and approximates them with a straight line or a curve. By doing so, the tendency of the delay time excluding the influence of temporary characteristic deterioration is predicted. The extracted data as shown in FIG. 13 may be approximated by a band having a certain width instead of being approximated by a curve. Prediction of the tendency of the delay time excluding the influence of such temporary characteristic deterioration may be performed with reference to the delay time predicted from the above-mentioned communication path installation information.

When the delay time excluding the influence of temporary characteristic deterioration is predicted to reach the threshold value at the usage time t2, and the threshold value is reached at the usage time t1 before the usage time t2, the delay cause estimation unit. Reference numeral 10 refers to data such as the temperature and load status of the communication cable at that time, and estimates whether the cause of the delay time exceeding the threshold value is due to temporary deterioration of characteristics. For example, when the threshold value is reached, if there is a temporary temperature rise such as the communication cable being overloaded, it is presumed that the characteristics are temporarily deteriorated.

The operation of the first communication device 1 will be described with reference to the flowchart of FIG. The steps common to FIG. 9 of the first embodiment are designated by the same step numbers, and duplicate description will be omitted.

If the delay time is determined to be equal to or greater than the threshold value in step S104, the cause of the delay is presumed (S301). Next, based on the estimation result, it is determined whether or not the cause of the delay is due to the temporary deterioration of the characteristics (S302). If the cause of the delay is due to a temporary deterioration of characteristics, the communication speed is adjusted (S303). After the communication speed is adjusted, the process returns to the front of step S101, and the monitoring of the delay time is continued. On the other hand, if the cause of the delay is not due to temporary deterioration of characteristics, it is presumed that the cause of the delay is mainly due to deterioration over time. Therefore, the output delay determination information detects a sign of a communication failure due to a delay in the communication path (S105).

As described above, the communication device 1 according to the third embodiment includes a delay cause estimation unit 10 for estimating the cause of the delay time exceeding the threshold value, and the estimated delay cause is a temporary deterioration of characteristics. In addition, the control unit 3 is configured to adjust the communication speed. With such a configuration, stable communication can be continued by increasing the margin for delay.

In the first embodiment, it has been described that the processor 31 of the control unit 3 may read the software program stored in the memory 32 to realize the functions of each part of the first communication device 1, but the embodiment has been described. The same applies to 2 and 3. Further, as shown in FIG. 15, each functional unit of the first communication device 1 including the control unit 3 is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, and an ASIC (Application Specific Integrated Circuit). ), FPGA (Field-Programmable Gate Array), or a processing circuit 33 combining these. Further, a part of the functions of the first communication device 1 may be realized by a software program, and the remaining functions may be realized by a dedicated processing circuit 33.

Although the embodiments of the present disclosure have been described above, the configuration of the first communication device of the present disclosure is not limited to the embodiments described in the first to third embodiments. It is also possible to combine the first communication device 1 of the present disclosure with another known technique, and to the extent that it does not deviate from the gist of the present disclosure, it is possible to omit or change a part of the configuration, such as combining as appropriate. Is also possible.

1 1st communication device, 2 communication control board, 3 control unit, 31 processor, 32 memory, 4 CAN controller, 5 CAN transceiver, 6 delay time calculation unit, 7 delay determination unit, 8 communication line, 9 notification unit, 10 Delay cause estimation unit, 11 Second communication device

Claims (11)

A communication device that sends and receives data to and from other communication devices via a communication line based on the CAN communication protocol.
A control unit that controls the transmission and reception of data,
The transmission data output from the control unit and the reception data output from the other communication device as a response to the transmission data are input, and the transmission data and the ACK signal included in the reception data delay the communication path. A delay time calculation unit that calculates the time, and a delay time calculation unit
A communication device including a delay determination unit that compares the delay time with a threshold value and outputs delay determination information. The communication device according to claim 1, wherein the threshold value is set based on a delay time shorter than a limit value of the delay time at which a communication failure occurs. The delay time calculation unit includes a logic operation unit, and extracts a delay time pulse for calculating the delay time from the ACK signal by taking a logical product of the transmission data and the reception data whose logic is inverted. The communication device according to claim 1 or 2, wherein the communication device is characterized by the above. The method according to any one of claims 1 to 3, wherein the delay time calculation unit includes a counter unit and measures the time width of the delay time pulse with a clock that is faster than the bit time of the communication speed. Communication device. When the communication device is connected to a plurality of the other communication devices, the communication device sends a listen-only request to identify the other communication device that responds to the ACK signal in order to measure the delay time of the communication path. The communication device according to any one of claims 1 to 4, wherein the communication device is to be used. 6. The communication device described. The delay determination unit is characterized in that the difference between the delay time predicted from the installation information of the communication path and the delay time calculated by the delay time calculation unit is compared with the threshold value. The communication device according to any one of the following items. The delay determination unit compares the first threshold value and the second threshold value set based on the delay time longer than the first threshold value with the delay time calculated by the delay time calculation unit.
From claim 1, the control unit executes different control processes depending on whether the delay time is equal to or greater than the first threshold value and the delay time is equal to or greater than the second threshold value. The communication device according to any one of 7. A delay cause estimation unit for estimating a delay cause in which the delay time exceeds the threshold value is provided.
The communication device according to any one of claims 1 to 8, wherein when the cause of the delay is due to a temporary deterioration of characteristics, the control unit adjusts the communication speed. An elevator communication device to which the communication device according to any one of claims 1 to 9 is applied to elevator control. A communication method for transmitting and receiving data to and from other communication devices via a communication line based on the CAN communication protocol.
A step of calculating the delay time of the communication path from the transmission data and the ACK signal included in the reception data by inputting the transmission data and the reception data output from the other communication device as a response to the transmission data.
The step of comparing the delay time with the threshold value,
A communication method including a step of outputting delay determination information based on a comparison between the delay time and the threshold value.

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