Processing unit

Abstract

In a processing unit that communicates serially with an external sensor, the communication status is accurately analyzed and understood. [Solution] The processing device comprises an external sensor, a communication unit that performs serial communication of a predetermined signal at a predetermined first cycle via a predetermined serial communication line, an acquisition unit that acquires the predetermined signal as a branched signal via a branch line branched from the predetermined serial communication line at a predetermined second cycle shorter than the predetermined first cycle, synchronized with the serial communication of the predetermined signal between the communication unit and the sensor, and an analysis unit that performs an analysis of the communication state related to the predetermined signal based on the difference between the predetermined first cycle and the predetermined second cycle, and the branched signal.

Description

Technical Field

[0001] The present invention relates to a processing device.

Background Art

[0002] Generally, serial communication is performed between a motor and a sensor such as an encoder attached to the motor that detects the position or speed of a rotor, and drive control of the motor is performed using the detected data. Here, general-purpose physical layers such as RS485 and RS422 are often used for serial communication standards, but "communication protocols" including transmission codes, data formats, clock synchronization methods, and the like differ depending on encoder manufacturers. Therefore, based on model information of the motor and the like, a user needs to select a control device that conforms to the communication protocol of the encoder mounted on the motor. If the encoder mounted on the motor does not match the communication protocol of the control device that performs serial communication with the encoder, a communication error occurs and the motor cannot be driven.

[0003] Accordingly, a technique for identifying a protocol used in an encoder mounted on a motor to be driven is disclosed in, for example, Patent Document 1. In Patent Document 1, by providing a communication unit and a detection program corresponding to a plurality of types of communication protocols on the control device side, an appropriate communication state with the sensor to be used is formed. Further, as a technique for analyzing a protocol in communication between a control device and an externally located device such as a sensor, the technique disclosed in Patent Document 2 can be exemplified. In Patent Document 2, communication protocol analysis is performed using a waveform measured by an oscilloscope.

Prior Art Literature

Patent Documents

[0004]

Patent Document 1

Patent Document 2

[0005] When a processing unit is configured to perform desired processing by communicating serially with an external sensor and transmitting commands to the sensor or receiving detection signals from the sensor, the success or failure of the serial communication is crucial for achieving the desired processing. The desired processing may be related to the sensor itself, or it may be processing that controls an object using the detection signal from the sensor. In order to determine whether the serial communication is being performed properly, it may be necessary to analyze the communication state. Generally, in order to analyze the communication state of such serial communication, it is necessary to connect a dedicated device for analysis (e.g., a protocol analyzer) to the communication line (the line for serial communication between the sensor and the processing unit). However, even though it is a dedicated device, when such a device is connected to the communication line, it will have some effect on the electrical characteristics between the sensor and the processing unit, and the communication characteristics will change to some extent, so it is not easy to accurately grasp the communication state.

[0006] This invention has been made in view of the above problems, and aims to provide a technology for accurately analyzing and understanding the communication status in a processing device that performs serial communication with an external sensor. [Means for solving the problem]

[0007] A processing device relating to one aspect of the present disclosure comprises: an external sensor; a communication unit that performs serial communication of a predetermined signal at a predetermined first cycle via a predetermined serial communication line; an acquisition unit that, in synchronization with the serial communication of the predetermined signal between the communication unit and the sensor, acquires the predetermined signal as a branch signal via a branch line branched from the predetermined serial communication line at a predetermined second cycle shorter than the predetermined first cycle; and an analysis unit that performs an analysis of the communication state relating to the predetermined signal based on the difference between the predetermined first cycle and the predetermined second cycle, and the branch signal.

[0008] The processing unit performs serial communication with an external sensor regarding a predetermined signal via a predetermined serial communication line. In this serial communication, the predetermined signal may be either a detection signal from the sensor, i.e., serial communication of the predetermined signal from the sensor to the processing unit, or a command signal to the sensor, i.e., serial communication of the predetermined signal from the processing unit to the sensor. Alternatively, both serial communication of the predetermined signal from the sensor to the processing unit and serial communication of the predetermined signal from the processing unit to the sensor may be performed. In this case, the communication unit can be exemplified by having an input unit into which the detection signal from the sensor is input as the predetermined signal in the predetermined first cycle, and an output unit into which a command to the sensor is output as the predetermined signal in the predetermined first cycle.

[0009] The predetermined first period in the above serial communication may be a predetermined period that enables serial communication with an external sensor (for example, a period defined in a serial communication standard), or alternatively, any period or a variable period as long as serial communication with an external sensor is possible. Therefore, the processing device can grasp the predetermined first period as long as it is performing serial communication with an external sensor. Furthermore, it is preferable that the processing device is configured to perform a desired process through serial communication with an external sensor. The desired process is not limited to a specific process, and may, for example, be a process related to the sensor itself, or alternatively, a process that uses the detection signal from the sensor to control an object different from the sensor.

[0010] In the above-described processing device, the acquisition unit acquires branch signals in parallel with the serial communication of predetermined signals by the communication unit. Branch signals are formed when the predetermined signal is acquired by the acquisition unit via a branch line that is formed by branching off from a predetermined serial communication line. Therefore, although the predetermined signal and the branch signal each target substantially the same information, the acquisition of branch signals by the acquisition unit is performed in a predetermined second cycle that is shorter than the predetermined first cycle in serial communication. Consequently, the branch signal acquired by the acquisition unit means that the predetermined signal communicated on the predetermined serial communication line has been acquired with high resolution, and the branch signal reflects the difference caused by the difference between the predetermined first cycle and the predetermined second cycle.

[0011] Therefore, in the above-mentioned processing device, the analysis unit analyzes the communication state of a predetermined signal based on the difference between a predetermined first period and a predetermined second period, and the branch signal. As described above, the analysis unit utilizes the fact that the branch signal reflects the difference caused by the difference between the two periods. In a processing device configured in this way, since the acquisition unit and the analysis unit are included in the processing device, it is possible to avoid causing changes in electrical characteristics when analyzing the communication state of serial communication of a predetermined signal, and to accurately analyze and understand the communication state of the serial communication.

[0012] Here, the above-described processing device may further include a clock generation unit that generates a clock signal having a predetermined second period. In that case, the acquisition unit includes a first acquisition unit that branches the predetermined signal at the rising edge timing of the clock signal and acquires it as a first branch signal, and a second acquisition unit that branches the predetermined signal at the falling edge timing of the clock signal and acquires it as a second branch signal The system may include a second acquisition unit that acquires the signal as follows, and a branch signal generation unit that generates the branch signal by combining the first branch signal and the second branch signal.

[0013] The clock generation unit generates a clock signal having a predetermined second period based on a predetermined first period that it has identified. Then, the first acquisition unit acquires a first branch signal from the predetermined signal using the rising edge timing of the clock signal, and further, the second acquisition unit acquires a second branch signal from the predetermined signal using the falling edge timing of the clock signal. Finally, the branch signal generation unit combines the first and second branch signals to generate a branch signal. By utilizing the rising and falling edges of the clock signal in this way, it is possible to acquire the branch signal with higher resolution in effectively half the period of the predetermined second period, enabling a more suitable analysis of the communication state related to the predetermined signal.

[0014] Furthermore, in the processing apparatus described above, the analysis unit may analyze the communication state of the predetermined signal based on a predetermined number of consecutive bits of data determined based on the difference between a predetermined first period and a predetermined second period in the branch signal. As described above, the branch signal acquired by the acquisition unit means that the predetermined signal communicated on a predetermined serial communication line has been acquired with high resolution. Therefore, it is possible to analyze the communication state of the predetermined signal that is the target of serial communication based on the movement of a predetermined number of consecutive bits of data determined based on the difference between a predetermined first period and a predetermined second period. For example, if momentary noise is superimposed during serial communication, this can be reflected as data disturbance in the predetermined number of consecutive bits of data, and thus it becomes possible to analyze the communication state of the predetermined signal according to that disturbance.

[0015] Furthermore, in the above-described processing apparatus, the predetermined second period may be shortened in stages. In that case, the acquisition unit may acquire the branch signal at each of the progressively shortened predetermined second periods, and the analysis unit may analyze the communication state with the sensor based on the difference between the predetermined first period and each of the progressively shortened predetermined second periods, and the branch signal corresponding to each predetermined second period. By progressively shortening the predetermined second period, the branch signal based on the predetermined signal is acquired at progressively high resolution and analyzed at high resolution. With such a configuration, the analysis of the communication state of the predetermined signal can be suitably realized. However, if the predetermined second period is shortened too much, the capacity of the branch signal becomes too large, increasing the load required for the analysis of the communication state and taking more time. Therefore, for example, considering the time required for analysis, the range in which the predetermined second period is progressively shortened may be limited to a predetermined range.

[0016] Here, in the processing apparatus described above, as an example, the sensor may be an encoder associated with a motor, and the processing apparatus may be a motor driver that controls driving of the motor based on a detection signal from the encoder. Also, combinations of sensors and processing devices in other forms may be employed. [Advantageous Effects of Invention]

[0017] In a processing apparatus that performs serial communication with an external sensor, the communication state can be accurately analyzed and grasped. [Brief Description of Drawings]

[0018] [Figure 1] FIG. 1 is a first diagram showing a schematic configuration of a processing apparatus disclosed in the present application. [Figure 2] FIG. 2 is a flowchart showing a flow of analysis processing for analyzing a communication state with a sensor, which is executed by the processing apparatus shown in FIG. 1. [Figure 3] FIG. 3 is a diagram showing comparison between a branch signal and a detection signal in relation to the analysis processing shown in FIG. 2. [Figure 4] FIG. 4 is a second diagram showing a schematic configuration of a processing apparatus disclosed in the present application. [Figure 5] FIG. 5 is a diagram showing a schematic configuration of a servo system including a servo driver corresponding to the processing apparatus disclosed in the present application. [Figure 6] FIG. 6 is a diagram showing a control structure of a feedback system included in the servo driver shown in FIG. 5. [Figure 7] FIG. 7 is a flowchart showing a flow of analysis processing for analyzing a communication state with an encoder, which is executed by the servo driver shown in FIG. 5. [Mode for Carrying Out the Invention]

[0019] <First Embodiment> Embodiments of the present invention will be described in detail below with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and their descriptions will not be repeated in principle. Figure 1 shows a schematic configuration of a processing unit 50 that performs serial communication with an externally located sensor 80 via a cable 82. General-purpose physical layers such as RS485 and RS442 are used for serial communication standards. The processing unit 50 may be a processing unit used for various purposes as long as it is a device that performs serial communication with the sensor 80. One example is a servo driver incorporated into a servo system that servo-controls a motor.

[0020] First, the details of the processing unit 50 disclosed in this application will be described based on Figure 1. The sensor 80 is a detection device located outside the processing unit 50 and detects a predetermined parameter to be detected (for example, ambient temperature information) for a predetermined purpose, such as providing it for desired processing in the processing unit 50. The sensor 80 is connected to a cable 82, and a connector 81 attached to the end of the cable is coupled to a connector 52 on the processing unit 50 side, thereby establishing a communication line between the sensor 80 and the processing unit 50. The transmission and reception of signals between the sensor 80 and the processing unit 50 via the cable 82 is performed by serial communication. Specifically, the sensor 80 is configured to pass its detection data as a detection signal to the processing unit 50 side via the cable 82. In addition, commands related to the detection of the predetermined parameter by the sensor 80 (for example, trigger signals for starting and stopping detection) are passed from the processing unit 50 side to the sensor 80 side via the cable 82.

[0021] In the processing unit 50, a transceiver 51 is connected to the connector 52, and further connected to the communication unit 60. The communication unit 60 is composed of a custom LSI (ASIC: Application Specific IC), and the detection signal from the sensor 80 is transmitted to the communication unit 6 via the transceiver 51. The signal is sent to 0, and the command from the processing unit 50 is also delivered to the sensor 80 via the transceiver 51. The transceiver 51 converts the signals transmitted and received between the sensor 80 configuration (sensor 80, cable 82, connector 81) and the connector 52 on the processing unit 50 side, and the digital signals on the communication unit 60 side, which is composed of an ASIC. It is also configured to switch the direction of transmission and reception of signals between the processing unit 50 and the sensor 80, i.e., input and output, based on a switching signal from the switching unit 63 provided in the communication unit 60.

[0022] The communication unit 60 is composed of an ASIC and includes an input unit 61 to which detection signals from the sensor 80 are input via the transceiver 51, an output unit 62 to which commands are output from the processing unit 50 to the sensor 80, and a switching unit 63 to switch the direction of transmission and reception of the transceiver 51. A communication line 51a is provided between the transceiver 51 and the input unit 61, a communication line 51b is provided between the transceiver 51 and the output unit 62, and a communication line 51c is provided between the transceiver 51 and the switching unit 63. The communication unit 60 also has a serial / parallel conversion circuit inside, which converts the digital signal from the transceiver 51 to the parallel signal provided in the processing unit 50. Furthermore, the processing unit 50 is equipped with a processing unit 70 configured as a microcontroller (MCU), which processes signals input via the communication unit 60 and signals output to the communication unit 60. Specifically, the processing unit 70 is a CPU (Central Processing Unit) and memory This is a computing device that has a memory, and when a predetermined program stored in memory is executed, it processes signals input to the input unit 61 of the communication unit 60, or generates signals (commands) output from the output unit 62, or performs other desired processing. This desired processing is performed by the control unit 75 of the processing unit 70.

[0023] The processing unit 70 will now be described. The processing unit 70 has functional units including a switching detection unit 71, a clock generation unit 72, an acquisition unit 73, an analysis unit 74, and a control unit 75. These functional units are realized by the execution of a predetermined program in the MCU of the processing unit 70. The switching detection unit 71 is a functional unit that receives a switching signal output from the switching unit 63 via an input line 53 that is branched from the communication line 51c between the communication unit 60 and the transceiver 51, and detects the switching of the signal transmission and reception direction. By detecting the switching of the signal transmission and reception direction in this way, it becomes possible to synchronize the clock signal generated by the clock generation unit 72, which will be described later, with the serial communication between the communication unit 60 and the transceiver 51. The clock generation unit 72 then generates a clock signal that determines the timing for acquiring a predetermined signal by the acquisition unit 73, which will be described later, based on the detection result by the switching detection unit 71. The period of the clock signal generated by the clock generation unit 72 is set to be shorter than the communication period of the serial communication between the sensor 80 and the communication unit 60. For example, the period of the clock signal is set to 1 / 4 of the communication period of the serial communication.

[0024] The acquisition unit 73 is a functional unit that receives and acquires signals transmitted and received between the communication unit 60 and the transceiver 51 via an input line formed by branching off from the communication line between the communication unit 60 and the transceiver 51. Specifically, the acquisition unit 73 receives and acquires a detection signal transmitted from the transceiver 51 to the input unit 61 via the communication line 51a, via a branched line 54. Furthermore, the acquisition unit 73 receives and acquires a command transmitted from the output unit 62 to the transceiver 51 via the communication line 51b, via a branched line 55. The acquisition of each signal by the acquisition unit 73 is performed based on the period of the clock signal generated by the clock generation unit 72. The signals acquired by the acquisition unit 73 are referred to as branched signals in this application. Details of the acquisition process by the acquisition unit 73 will be described later.

[0025] The analysis unit 74 uses the branch signal acquired by the acquisition unit 73 to analyze the communication status of the serial communication between the processing unit 50 and the sensor 80. In this analysis process, the timing of the acquisition of the branch signal by the acquisition unit 73, that is, the difference between the communication period in the serial communication and the period of the clock signal related to the acquisition, is taken into consideration. Details of this analysis process will be described later. The control unit 75 is a functional unit that performs desired processing related to the detection signal input from the sensor 80 via the input unit 61 and commands output to the sensor 80 from the output unit 62. The processing by the control unit 75 may directly control the sensor 80, or alternatively, it may be a process that controls an object different from the sensor 80 using the detection signal from the sensor 80.

[0026] Here, the analysis process for analyzing the communication status with the sensor will be explained based on Figure 2. Figure 2 is a flowchart showing the flow of the analysis process. The analysis process is performed by the processing unit 70. First, in S101, the processing unit 50 sends a command to the sensor 80 to detect a predetermined parameter at the sensor 80 for a predetermined period of time and to send the detection signal to the processing unit 50. When this command is sent, the transmission and reception direction is adjusted by the switching unit 63 so that the transceiver 51 can transmit to the sensor 80. Then, when the transmission of the command is finished, the transmission and reception direction is switched by the switching unit 63 so that the detection signal from the sensor 80 is received by the transceiver 51. The switching signal at that time is detected by the switching detection unit 71 via the input line 53 (processing in S102).

[0027] In S102, when a switch in the transmission / reception direction is detected, in S103, the clock generation unit 72 The clock signal is generated by this process. By considering the detection of switching, the generated clock signal is synchronized with the serial communication of the detection signal (serial communication between the processing unit 50 and the sensor 80). The generated clock signal will be explained based on Figure 3. The clock signal is shown in the upper part of Figure 3, and its period is set to ΔT1. The period ΔT1 is set to 1 / 4 times the communication period ΔT0 of the serial communication of the detection signal. Therefore, four clock signals are included within the communication period ΔT0.

[0028] Then, in S104, the acquisition unit 73 performs the acquisition of the branch signal based on the clock signal generated in S102, specifically at the rising edge timing of the clock signal. The branch signal is the signal acquired at the acquisition timing described above in relation to the detection signal that has been branched via the branch line 54, etc., as described above. Considering that four clock signals are included in the communication period ΔT0, the acquisition unit 73 is able to acquire the signal with four times the resolution of the detection signal, as shown in the lower part of Figure 3. For example, in a specific period where the detection signal is "1", the branch signal will be acquired at four different timings (timings determined by the period ΔT1).

[0029] Therefore, for example, if the same value of "1" as the detection signal is obtained as the branch signal at four timing points, such as during period T10, it can be determined that no communication abnormality has occurred in the serial communication of the detection signal. On the other hand, if a value of "0" different from the detection signal is obtained as the branch signal at one of the four timing points, such as during period T20, it can be determined that a momentary communication abnormality (e.g., noise superposition) has occurred in the serial communication of the detection signal. This high-resolution signal acquisition of the detection signal is due to the difference between the communication period of the serial communication and the period of the clock signal that determines the acquisition timing. Therefore, in S105, as described above, the communication state of the serial communication of the detection signal is analyzed based on the data of four consecutive branch signals, which are based on the difference between the communication period of the serial communication and the period of the clock signal.

[0030] As shown in Figure 2, the analysis process enables the analysis of the communication status of the serial communication of the detection signal, depending on the configuration of each functional unit mounted on the processing unit 50. Since there is no need to connect external devices for analysis, the communication status can be analyzed more accurately. Furthermore, in analyzing the communication status, the information transmitted and received between the communication unit 60 and the transceiver 51 (the detection signal in the above case) is directly branched and the analysis processing is performed on the processing unit 70 side. Therefore, the analysis of the communication status can be performed without being affected by the structure of the communication unit 60.

[0031] Furthermore, while the analysis process shown in Figure 2 describes the analysis of the communication state when a detection signal is transmitted serially from the sensor 80 to the processing unit 50, the analysis of the communication state when a command is transmitted serially from the processing unit 50 to the sensor may be performed instead, or, as an alternative, the analysis of the communication state when both are performed may be performed.

[0032] <Variation> A modified example of the embodiment disclosed in this application will be described with reference to Figure 4. Figure 4 shows the schematic configuration of the modified processing apparatus 50. Of the configuration of the modified processing apparatus 50, those that are substantially the same as those of the processing apparatus 50 shown in Figure 1 are given the same reference numerals, and their detailed descriptions are omitted. The difference between the modified processing apparatus 50 and the processing apparatus 50 shown in Figure 1 concerns the configuration of the acquisition unit 73.

[0033] In this modified example, the acquisition unit 73 is composed of a first acquisition unit 731 and a second acquisition unit 732. The first acquisition unit 731 receives and acquires the detection signal transmitted from the transceiver 51 to the input unit 61 via the communication line 51a through the branched branch line 54. Furthermore, the first acquisition Unit 731 receives and acquires commands transmitted from output unit 62 to transceiver 51 via communication line 51b through a branched branch line 55. The acquisition of each signal by the first acquisition unit 731 is performed at the rising edge timing based on the period of the clock signal generated by clock generation unit 72, just as in the first embodiment described above. The signals acquired by the first acquisition unit 731 are referred to as first branch signals. Meanwhile, the second acquisition unit 732 receives and acquires detection signals via a second branch line 54a, which is further branched from branch line 54. Furthermore, the second acquisition unit 732 receives and acquires commands via a second branch line 55a, which is further branched from branch line 55. The acquisition of each signal by the second acquisition unit 732 is performed at the falling edge timing based on the period of the clock signal generated by clock generation unit 72. The signals acquired by the second acquisition unit 732 are referred to as second branch signals.

[0034] In this modified example, the acquisition unit 73 combines the first branch signal acquired by the first acquisition unit 731 and the second branch signal acquired by the second acquisition unit 732 to generate a branch signal, and then acquires it (corresponding to the process in S104 above). By adopting such a branch signal acquisition configuration, it becomes possible to acquire branch signals with even higher resolution compared to the first embodiment, thereby enabling a more suitable analysis of the communication state related to serial communication.

[0035] <Second Embodiment> The processing unit 50 according to the second embodiment of the present invention will be described with reference to Figure 5. The processing unit 50 according to this embodiment is a servo driver (hereinafter simply referred to as "driver") 4. The sensor that communicates serially with the processing unit driver 4 is an encoder 21 mounted on a motor 2 that is servo-controlled by the driver 4. In the following description, the driver 4 and encoder 21 will be referred to, but please note that these correspond to the processing unit 50 and sensor 80 according to the present invention, respectively. Furthermore, among the configurations of the driver 4 according to this embodiment, those that are substantially the same as those of the processing unit 50 shown in Figure 1 will be given the same reference numerals, and their detailed descriptions will be omitted.

[0036] Figure 5 is a schematic diagram of a control system including the driver 4 disclosed in this application. The control system comprises a network 1, a motor 2, a load device 3, a driver 4, and a PLC (Programmable Logic Controller) 5. In this control system, the PLC 5 receives the operation command signal. The signal is generated and delivered to the driver 4 via network 1. The driver 4 then servo-controls the motor 2, which is configured to drive the load device 3 to be controlled according to the operation command signal. Here, the load device 3 can be various types of mechanical devices (for example, the arm or conveying device of an industrial robot), and the motor 2 is attached to the load device 3 as an actuator to drive the load device 3. For example, the motor 2 is an AC servo motor.

[0037] An encoder 21 is attached to the motor 2, and the encoder 21 transmits a detection signal related to the operation of the motor 2, specifically the rotational operation of the rotor which is the movable element of the motor 2, to the communication unit 60 via serial communication. In Figure 5, for the sake of simplicity, the configuration corresponding to the transceiver 51 shown in Figure 1, etc., is omitted. The detection signal input to the communication unit 60 is passed to the processing unit 70, which is composed of an MCU, and is used for servo control (corresponding to the desired processing described above) by the control unit 75 of the processing unit 70. In Figure 5, for the sake of simplicity, the configuration corresponding to the switching detection unit 71, clock generation unit 72, acquisition unit 73, and analysis unit 74 shown in Figure 1, etc., is omitted.

[0038] Here, encoder 21 is an incremental encoder. The detection signal (hereinafter also referred to as the feedback signal) transmitted as feedback to the control unit 75 via the communication unit 60 is, for example, position information about the rotational position (angle) of the rotational shaft of motor 2, and its rotation This includes information such as the rotational speed of the shaft. The control unit 75 of the driver 4 performs servo control of the motor 2 based on the operation command signal from the PLC 5 and the feedback signal from the encoder 21, and supplies drive current to the motor 2 via the inverter 6. This supply current utilizes AC power sent from the AC power supply 7 to the inverter 6. In this embodiment, the inverter 6 is of the type that receives three-phase AC, but it may also be of the type that receives single-phase AC. The control unit 75 of the driver 4 is equipped with a feedback system that includes a position controller 41, a speed controller 42, and a current controller 43.

[0039] Based on Figure 6, the control structure of the feedback system of the control unit 75 of the driver 4 will be described. The feedback system of the control unit 75 includes a position controller 41, a speed controller 42, and a current controller 43. The position controller 41 performs, for example, proportional control (P control). Specifically, it calculates the speed command V_ref by multiplying the position deviation, which is the difference between the position command P_ref from the PLC 5 and the current position value P_act of the motor 2, by a predetermined position proportional gain. The current position value P_act is a parameter that represents the current position of the motor 2, obtained when the output of the encoder 21 is input to the position detector 45.

[0040] The speed controller 42 performs, for example, proportional-integral control (PI control). Specifically, it calculates the torque command τ_ref by multiplying the integral of the speed deviation, which is the difference between the speed command V_ref calculated by the position controller 41 and the current speed V_act of the motor 2, by a predetermined speed integral gain, and then multiplying the sum of this calculation result and the speed deviation by a predetermined speed proportional gain. Alternatively, the speed controller 42 may perform P control instead of PI control. The current speed V_act is a parameter that represents the current speed of the motor 2, obtained by inputting the output of the position detector 45 to the speed detector 46.

[0041] The current controller 43 generates a current command based on the torque command τ_ref calculated by the speed controller 42, the current position value P_act and current speed value V_act of the motor 2, and the drive current supplied to the motor 2 from the inverter 6. Based on this current command, it outputs voltage commands corresponding to each phase of the three-phase AC motor to the inverter 6. Upon receiving these voltage commands, the inverter 6 applies drive voltages to each phase (U phase, V phase, W phase) of the motor 2 to drive and control the motor 2. The drive current supplied to the motor 2 is detected by the current detector 44. In Figure 2, the configuration corresponding to each phase of the motor 2 is shown in a simplified manner, but in reality, the current detector 44 detects the current flowing through the windings of each phase of the motor 2 and returns the current values ​​of each phase to the current controller 43. The current controller 43 may include a filter (first-order low-pass filter) and one or more notch filters related to the torque command.

[0042] In the driver 4 configured in this way, the communication state analysis process for serial communication described with reference to Figures 1 to 4, that is, the communication state analysis process for serial communication of detection signals performed between the driver 4 and the encoder 21, can also be applied. Furthermore, a modified example of the communication state analysis process applicable to the driver 4 will be described with reference to Figure 7. Note that the analysis process shown in Figure 7 includes processes S101 to S105 and processes S201 to S207, but processes S101 to S105 have already been described, so their explanation will be omitted here. Note that the command to sensor 80 given in S101 should be read as a command to encoder 21.

[0043] Once processing in S105 is complete, the process proceeds to S201. In S201, the analysis results of the serial communication status analyzed in S105 determine whether the communication status is good or not. That is, as shown in Figure 3 during period T20, the period of the clock signal and the serial communication status are analyzed. If no irregularities are found in the bit sequence of four consecutive branch signals based on the difference with the period, the communication state can be determined to be good; otherwise, the communication state can be determined to be bad. If the determination in S201 is positive, the process proceeds to S202, and if the determination is negative... In the end, S206 determines if the communication status is faulty and terminates the analysis process.

[0044] In S202, it is determined whether or not a re-analysis of the communication status in S205, which will be described later, is possible. As will be explained in detail later, the period of the clock signal related to the acquisition of the branch signal is shortened for this re-analysis. This allows the branch signal to be acquired with higher resolution based on the detected signal, but increasing the resolution increases the data capacity of the branch signal, which increases the load on the analysis process and takes more time. Therefore, to prevent an unnecessary increase in the load on the analysis process, a limit is set on the shortening of the clock signal period for re-analysis. Then, in S202, it is determined whether or not re-analysis is possible, taking this limit into consideration. If the determination in S202 is positive, the process proceeds to S203. If the determination in S202 is negative, it means that further shortening of the clock signal period is not possible, which means that the communication status is sufficiently good, so the communication status is determined to be good in S207 and the analysis process is terminated.

[0045] In S203, the clock signal is regenerated. During this regeneration, the period of the clock signal is set to be even shorter than the period of the clock signal used when the branch signal was acquired immediately before. For example, if the period of the clock signal was set to 1 / 4 of the serial communication period ΔT0 when the branch signal was acquired immediately before, the period of the clock signal in the regeneration in S203 may be set to 1 / 8 of the serial communication period ΔT0. As a result, the branch signal can be acquired with twice the resolution. The period of the clock signal can be any other frequency as long as it is made even shorter. Once the processing in S203 is complete, the process proceeds to S204.

[0046] Then, in S204, the branch signal is acquired (processed by the acquisition unit 73) using the clock signal regenerated in S203, and based on the acquisition result, in S205, the communication status related to serial communication is analyzed (processed by the analysis unit 74). Once the processing in S205 is completed, the processing from S201 onwards is repeated.

[0047] According to the analysis process shown in Figure 7, a more detailed analysis of the serial communication status can be performed without placing an excessive load on the driver 4. Furthermore, this analysis process can also be applied to combinations of processing units and sensors other than the driver 4 and encoder 21.

[0048] <Note 1> An external sensor (80) and a communication unit (60) that performs serial communication of predetermined signals at a predetermined first cycle via predetermined serial communication lines (51a, 51b), An acquisition unit (73) acquires the predetermined signal as a branch signal via branch lines (54, 55) branched from the predetermined serial communication lines (51a, 51b) in a predetermined second cycle shorter than the predetermined first cycle, in synchronization with the serial communication (51a, 51b) of the predetermined signal between the communication unit (60) and the sensor (80), An analysis unit (74) performs an analysis of the communication state related to the predetermined signal based on the difference between the predetermined first period and the predetermined second period, and the branch signal. A processing device (50) comprising the above. <Note 2> The system further includes a clock generation unit (72) that generates a clock signal having the predetermined second period, The acquisition unit (73) is, A first acquisition unit (731) acquires the predetermined signal as a first branch signal by branching it at the rising edge timing of the clock signal, A second acquisition unit (732) acquires the predetermined signal as a second branch signal by branching it at the falling edge timing of the clock signal, A branch signal generation unit that generates the branch signal by combining the first branch signal and the second branch signal, Apparatus apparatus (50) as described in Appendix 1, having the following characteristics. <Note 3> The analysis unit (74) analyzes the communication state of the predetermined signal based on a predetermined number of consecutive bits of data in the branch signal, which is determined based on the difference between the predetermined first period and the predetermined second period. The processing apparatus (50) described in Appendix 1 or Appendix 2. <Note 4> The predetermined second period is shortened in stages. The acquisition unit (73) acquires the branch signal in each of the predetermined second cycles which are progressively shortened. The analysis unit (74) analyzes the communication status with the sensor based on the difference between the predetermined first period and each predetermined second period which is shortened in stages, and the branch signal corresponding to each predetermined second period. The processing apparatus (50) described in Appendix 3. <Note 5> The aforementioned communication unit (60) is An input unit (61) receives the detection signal from the sensor as the predetermined signal in the predetermined first cycle, An output unit (62) outputs a command to the sensor as the predetermined signal in the predetermined first cycle, A processing apparatus (50) having the following characteristics, as described in any one of the appendices 1 to 4. <Note 6> The sensor (80) is an encoder (21) associated with the motor (2), The processing unit (50) is a motor driver (4) that controls the drive of the motor (2) based on a detection signal from the encoder (21). The processing device (50) described in any one of the items from Appendix 1 to Appendix 5. [Explanation of symbols]

[0049] 2 motors 4. Driver (Servo Driver) 5 PLC 6 Inverters 21 encoders 60 Communications Department 70 Processing Unit 73 Acquisition Department 74 Analysis Department 80 sensors

Claims

1. An external sensor and a communication unit that performs serial communication of a predetermined signal at a predetermined first cycle via a predetermined serial communication line, An acquisition unit that, in synchronization with the serial communication of the predetermined signal between the communication unit and the sensor, acquires the predetermined signal as a branch signal via a branch line branched from the predetermined serial communication line in a predetermined second cycle shorter than the predetermined first cycle, An analysis unit that analyzes the communication state related to the predetermined signal based on the difference between the predetermined first period and the predetermined second period, and the branch signal, A processing device equipped with the following features.

2. The system further includes a clock generation unit that generates a clock signal having the predetermined second period, The acquisition unit is, A first acquisition unit that, at the timing of the rising edge of the clock signal, branches the predetermined signal and acquires it as a first branch signal, A second acquisition unit that, at the timing of the falling edge of the aforementioned clock signal, branches the predetermined signal and acquires it as a second branch signal, A branch signal generation unit that generates the branch signal by combining the first branch signal and the second branch signal, The apparatus according to claim 1, having

3. The analysis unit analyzes the communication state of the predetermined signal based on a predetermined number of consecutive bits of data determined based on the difference between the predetermined first period and the predetermined second period in the branch signal. The apparatus according to claim 1 or claim 2.

4. The predetermined second period is shortened in stages. The acquisition unit acquires the branch signal in each of the predetermined second cycles that are progressively shortened. The analysis unit analyzes the communication status with the sensor based on the difference between the predetermined first period and each predetermined second period which is shortened in stages, and the branch signal corresponding to each predetermined second period. The apparatus according to claim 3.

5. The aforementioned communications unit is An input unit into which the detection signal from the sensor, as the predetermined signal, is input during the predetermined first cycle, An output unit that outputs a command to the sensor as the predetermined signal in the predetermined first cycle, The apparatus according to claim 1 or claim 2, having the following features.

6. The sensor is an encoder associated with the motor, The processing device is a motor driver that controls the drive of the motor based on the detection signal from the encoder. The apparatus according to claim 1 or claim 2.

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