JP5969412B2 - Displacement data transmitter - Google Patents

Description

  The present invention relates to a displacement data transmission device that transmits displacement data such as position and speed necessary for monitoring a safe state of a machine to a monitoring device or the like.

  In recent years, an increase in the scale of circuits mounted on control devices, speeding up of signal processing, miniaturization of integrated circuits, and the complexity of software embedded in control devices have increased the probability of accidental operation of control devices. There is a tendency. For this reason, in the unlikely event of a malfunction of the control device, a safety function for safely stopping the movable part of the machine to be controlled has been installed in the control device. Further, as a device for detecting a malfunction of the control device, a displacement data transmitting device for transmitting displacement data such as positions and velocities detected by a plurality of sensors installed in the movable part by serial communication, and based on the received displacement data A speed monitoring device that monitors whether the movable part has exceeded a safe speed is mounted on a control device having a safety function.

  FIG. 3 is a block diagram of an NC control system that controls a three-axis motor. FIG. 4 is a block diagram showing the inside of an encoder incorporating a conventional displacement data transmitting apparatus. FIG. 5 is a diagram showing a structure of a transmission frame of displacement data output from the encoder of FIG.

  FIG. 3 will be described. The NC device 20 transmits and receives control data to and from the motor control devices 21, 22, and 23 and the speed monitoring device 30 through a ring-shaped serial communication network indicated by signals SN0, SN1, SN2, SN3, and SN4. The motor control devices 21, 22, and 23 control the rotational position of each motor rotation shaft in accordance with a position command from the NC device 20. Specifically, the motor control devices 21, 22, and 23 are three-phase sensors that flow to the motors 24, 25, and 26 based on position data transmitted from the encoders 27, 28, and 29 through serial signals EN 1, EN 2, and EN 3, respectively. The currents P1, P2, and P3 are controlled.

  The position data transmitted from the encoders 27, 28, and 29 through the serial signals EN1, EN2, and EN3 are relayed and transmitted by the motor control devices 21, 22, and 23 through the serial signals SN1, SN2, and SN3. Received at. The speed monitoring device 30 detects the rotational speed by differential processing from the received position data of each motor, and compares it with a preset safety speed. In addition, when the signal GUAR indicating opening / closing of a mechanical door or the like is in a state indicating door opening, if any one of the motor rotation speeds exceeds the safe speed, the motor control device is generated by the signals SN4, SN0, SN1, and SN2. An emergency stop command is transmitted to 21, 22, and 23, and an emergency stop signal STOP is output to cut off a control power source such as a motor.

  Next, a conventional displacement data transmitting apparatus that is incorporated in the encoders 27, 28, and 29 and transmits position displacement data will be described with reference to the block diagram of FIG. In FIG. 4, a disc 2 on which magnetic information is recorded is fixed to the input shaft 1 of the encoder, and when the input shaft rotates, the recorded information is read by the magnetic sensors 3, 4 and 5, respectively. Signals A, B, and Z are converted into electrical signals. Signal A, signal B, and signal Z are respectively input to two independent position converters 6 and 7, and converted into binary position data PS1 and PS2 by different position conversion methods, respectively. In the example of FIG. 4, PS2 is more precise position data with higher resolution than PS1, and PS1 converts one rotation of the input shaft 1 into 16-bit data, whereas PS2 One rotation of axis 1 is converted into 20-bit data. In addition, if the position converters 6 and 7 have an abnormality in the amplitude or change pattern of the signals A, B, and Z, the signals ER1 and ER2 indicating the abnormality are output to the status register 10, respectively. The status register 10 indicates an abnormal state of the encoder with 8-bit status data STS, and the output value is fixed to 0 unless there is an abnormality. The two position data PS1 and PS2 are input to the microcomputer 13, and when the absolute value of the upper 16 bits difference between the two position data PS1 and PS2 exceeds a preset amount, a signal ER3 indicating an abnormality is output to the status register 10. Output to.

  The frame address register 8 stores a destination address of an 8-bit transmission frame and an 8-bit encoder-specific transmission source address as 16-bit address data DSA. The update counter circuit 9 counts up the 8-bit update count data CT every time a transmission start signal SDC is commanded. The cyclic code generator 11 performs a cyclic code calculation of 48-bit data of data DSA, data CT, data STS, and data PS1, and generates a 32-bit cyclic code CRC.

  The serial communication circuit 12 receives the position data request command transmitted from the motor control device and the transmitted position data as a serial signal RX, converts it into parallel data, and outputs it to the microcomputer 13 as a received data signal RXD. The microcomputer 13 outputs a transmission start signal SDC when the reception data signal RXD indicates a position data request command. When the transmission start signal SDC is input, the serial communication circuit 12 prefixes the code SD indicating the start of the frame with the data DSA, data STS, data CT, data PS1, and cyclic code CRC, as shown in FIG. The serial signal TX is sequentially transmitted as one position data communication frame. Further, the microcomputer 13 checks the position data PS1 in the transmitted position data communication frame from the received data signal RXD. If there is an abnormality, the microcomputer 13 stops the output of the transmission start signal SDC. Is not transmitted to notify the motor control device and the speed monitoring device of the abnormality.

  In the NC control system shown in FIG. 3, the position data frames transmitted by the encoders 27, 28, and 29 other than the code SD indicating the start of the frame are relayed and transmitted by the signals SN1, SN2, and SN3 as they are to monitor the speed. Received at device 30. The speed monitoring device 30 identifies the encoder from the transmission source address of the received position data frame, confirms that the status data STS is normal, checks whether the update count data CT is updated each time, and receives the received frame Check the cyclic code and received data contents.

By doing as described above, an encoder incorporating a conventional displacement data transmission device can reliably detect an abnormality and notify the outside of the failure even if any one of the internal circuits fails. ing. In addition, the update count data CT and a 32-bit strong cyclic code ensure that even if the content of the position data communication frame is garbled due to noise or failure of the relay device, etc., up to the speed monitoring device 30 It is possible to detect on the speed monitoring device 30 side. Further, in the speed monitoring device 30, it mounted normal two microcomputers, by cross-validation is performed above process the double so as to ensure high reliability.

In conventional displacement data transmission apparatus shown in FIG. 4, it is necessary to microcomputer 13 for diagnosing an abnormality in the apparatus in order to ensure the reliability of the apparatus, which is a factor of cost increase. Further, in one microcomputer, since the diagnosis of the microcomputer itself is not enough, the level of reliability were slightly lower.

Alternatively, by transmitting the two position data to the speed monitoring device, speed monitoring device diagnosis is a method of causing at two microcomputers mounted. However, in this method, it is possible to a microcomputer for diagnosing abnormal unnecessary, but the data size of the location data communication frame increases additional data content. Further, when the bit amount of communication data is increased, there is a problem that the number of bits of the cyclic code must be increased in order to reliably detect the error of the bit corruption.

  For this reason, a highly reliable displacement data transmitting apparatus that is low in cost and has a small amount of communication data has been desired.

  The present invention has been made under the circumstances as described above, and an object of the present invention is to provide a displacement data transmitting apparatus that is low in cost and has a small amount of communication data and high reliability.

  A displacement data transmitting apparatus according to the present invention is a displacement data transmitting means for transmitting displacement data detected from a sensor signal to the outside by serial communication, and is a displacement data converting means for converting the sensor signal into displacement data. First and second displacement data conversion means for converting a plurality of sensor signals into the same displacement data, and the second displacement data conversion means without the first displacement data converted by the first displacement data conversion means Comprises cyclic code generation means for generating a cyclic code having the number of bits of the second displacement data including the converted second displacement data, and output means for outputting the first displacement data and the cyclic code. It is characterized by that.

  In the displacement data transmitting apparatus according to the present invention, one of the first displacement data and the second displacement data is N-bit data (N is an integer equal to or greater than 1), and the other has a bit number greater than N. The displacement data conversion means converts data having a number of bits larger than N into N-bit data based on the value of the upper N bits of the first displacement data and the second displacement data. Is desirable.

  Further, in the displacement data transmitting apparatus according to the present invention, the displacement data converting means is configured such that when the value of the upper N bits of the first displacement data and the second displacement data is the same, more bits than the N bits. The number of data is converted into data of the upper N bits, and the upper N bits of the first displacement data and the second displacement data are different from each other, and the upper bits of the data having the number of bits larger than N When the data of the (N + 1) th bit is 1, the data having the number of bits larger than N is converted into data obtained by adding 1 to the data of the upper N bits, and the first displacement data and the second displacement data If the value of the upper N + 1 bits of the data having a higher number of bits than N is 0, the data having the number of bits higher than N is changed. It is desirable to convert the high-order N bits of the data 1 to the data obtained by subtracting.

  Further, in the displacement data transmitting apparatus according to the present invention, the cyclic code generation means further includes update check data whose data changes each time the output means outputs the first displacement data and the cyclic code. A cyclic code may be generated.

  In the displacement data transmitting apparatus according to the present invention, the cyclic code generating means may further generate a cyclic code including status data whose data changes when the displacement data transmitting apparatus is abnormal.

  In the present invention, of the two displacement data, the other displacement data is converted into a cyclic code and transmitted. Since it is possible to convert the cyclic code having the number of bits of the displacement data to the other displacement data, transmitting the displacement data and the cyclic code is almost equivalent to transmitting two displacement data. This makes it possible to transmit two pieces of displacement data without increasing the amount of communication compared to the conventional technique.

  In addition, when two pieces of displacement data are transmitted without a cyclic code, an abnormality cannot be detected simply by changing two bits of the same digit in the two pieces of displacement data at the same time. On the other hand, by converting the other displacement data into an appropriate cyclic code, even if one displacement data and the cyclic code are simultaneously garbled by 3 bits or more, an abnormality can be detected.

Further, in the speed monitoring device side, the two microcomputers, if each performed abnormality check by cyclic code of the received frame, the abnormality check of the two displacement data will be equivalent been to double. Therefore, on possible microcomputer for diagnosing abnormality of displacement data transmitting apparatus unnecessary, the abnormality diagnosis of the confidence level can also be improved by duplexing. As described above, it is possible to realize a displacement data transmitting apparatus that is low in cost, has a small amount of communication data, and has high reliability.

It is a block diagram of an encoder incorporating the displacement data transmitting apparatus of the present invention. It is a figure which shows another transmission frame structure of the displacement data which the displacement data transmitter of this invention outputs. It is a block diagram of NC control system which controls a 3 axis motor. It is a block diagram which shows the inside of the encoder incorporating the conventional displacement data transmitter. It is a figure which shows the structure of the transmission frame of the displacement data which the encoder of FIG. 3 outputs.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, components having the same functions as those in FIG. Further, as long as there is no abnormality, the present invention will be described on the assumption that the difference between the position data PS1 and the position data PS2 of the encoder in FIG. 1 is less than ± 0.25 bits in the unit system of the position data PS1.

  In FIG. 1, the displacement amount converter 14 has a least significant bit (LSB) corresponding to the lower 5 bits (the 16th bit from the higher order) of the 20-bit position data PS2 and the upper 16th bit of the 16-bit position data PS1. If the values are the same, the upper 16 bits of the position data PS2 are output as PS1 ′. If the lower 5th bit of PS2 is different from the least significant bit of PS1, and the lower 4th bit of PS2 is 1, a value obtained by adding 1 to the upper 16 bits of position data PS2 is output as PS1 '. Further, when the fifth bit of PS1 is different from the least significant bit of PS2, and the lower fourth bit of PS1 is 0, a value obtained by subtracting 1 from the upper 16 bits of position data PS2 is output as PS1 '. By the processing of these displacement amount converters 14, the position data PS1 ′ can be aligned with the value of the position data PS1 unless the difference between the position data PS1 and the position data PS2 exceeds ± 0.5 bits in the unit system of PS1. Is possible. Also, the lower 5 bits of PS2 and the least significant bit of PS1 are different, and the lower 4th bit and lower 3rd bit of PS2 are 1 and 1, or other than 0 and 0, the two position data are in the unit system of PS1. It is determined that a difference exceeding ± 0.25 bits has occurred, and a signal ER3 indicating abnormality is output to the status register 10.

  The cyclic code generator 11 performs a cyclic code operation on 48-bit data of data DSA, data CT, data STS, and data PS1 'to generate a 32-bit cyclic code CRC. The transmission command circuit 15 outputs a transmission start signal SDC when the reception data signal RXD is a position data request. When the transmission start signal SDC is input, the serial communication circuit 12 prefixes the code SD indicating the start of the frame with data DSA, data STS, data CT, data PS1, and cyclic code CRC, as in the conventional case of FIG. Are transmitted by serial signal TX as one position data communication frame. From the above, if an abnormality occurs in either the position data PS1 or the position data PS2 and a difference of ± 0.5 bits or more occurs in the PS1 unit system, the transmitted position data and the cyclic code CRC are Since they do not match, it is possible to detect an abnormality in the position data on the speed monitoring device side.

  In the embodiment of FIG. 1, PS1 ′ is input to the cyclic code generator 11 and PS1 is used as transmission data. However, PS1 may be input to the cyclic code generator 11 and PS1 ′ may be used as transmission data. . The size of the cyclic code generated by the cyclic code generator 11 is 32 bits. For example, a dedicated 16-bit cyclic code FC for transmission data is automatically added to the end of the communication frame on the serial communication circuit 12 side. When a bit cyclic code generation circuit is built in, the cyclic code generator 11 may be replaced with a 32-bit to 16-bit cyclic code generator to obtain a position data communication frame as shown in FIG. In this case, there is an advantage that the abnormality detection pattern of the cyclic code CRC and the cyclic code FC can easily identify whether the cause of the abnormality is due to communication or not. In addition, a magnetic sensor is shown as an example of a sensor that outputs a plurality of sensor signals. However, an electromagnetic sensor such as an optical sensor or a winding or other sensors can be realized. In the embodiment, the displacement data transmitting device that transmits position data has been described. However, the displacement data transmitting device that transmits other displacement data such as velocity, acceleration, temperature, pressure, and radiation dose can also be realized.

  In the above description, only the position data communication frame dedicated to speed monitoring has been described. However, in addition to the position data communication frame dedicated to speed monitoring, the actual encoder receives high-resolution position data PS2 in response to a command from the motor control device. The position data communication frame dedicated for motor control is also transmitted.

  1 input shaft, 2 disc, 3, 4, 5 magnetic sensor, 6, 7 position converter, 8 frame address register, 9 update counter circuit, 10 status register, 11 cyclic code generator, 12 serial communication circuit, 13 micro Computer, 14 Displacement converter, 15 Transmission command circuit, 20 NC control device, 21, 22, 23 Motor control device, 24, 25, 26 Motor, 27, 28, 29 Encoder, 30 Speed monitoring device.

Claims (5)

In a displacement data transmission device that transmits displacement data detected from a plurality of sensor signals to the outside by serial communication,
Displacement data conversion means for converting a plurality of sensor signals into displacement data, and first and second displacement data conversion means for converting the plurality of sensor signals into the same displacement data as long as there is no abnormality,
A cyclic code not including the first displacement data converted by the first displacement data conversion means and including the second displacement data converted by the second displacement data conversion means is generated with a bit number greater than or equal to the number of bits of the second displacement data. Cyclic code generation means;
Output means for outputting the first displacement data and the cyclic code;
Displacement data transmitting apparatus characterized by comprising: One of the first displacement data and the second displacement data is N-bit data (N is an integer of 1 or more), and the other is data having a bit number larger than N,
The displacement data conversion means converts data having a number of bits larger than N into N-bit data based on the value of the upper N bits of the first displacement data and the second displacement data.
The displacement data transmitting apparatus according to claim 1. The displacement data conversion means includes
If the value of the upper N bits of the first displacement data and the second displacement data is the same, the data having a number of bits larger than N is converted into the upper N bits of data,
If the value of the upper N bits of the first displacement data and the second displacement data is different and the data of the upper N + 1 bits of the data having a larger number of bits than N is 1, Is converted into data obtained by adding 1 to the data of the upper N bits,
If the value of the upper N bits of the first displacement data and the second displacement data are different, and the data of the upper N + 1 bits of the data having a larger number of bits than N is 0, the N Converting the data having a larger number of bits into data obtained by subtracting 1 from the data of the upper N bits,
The displacement data transmitting apparatus according to claim 2. The cyclic code generation means further generates a cyclic code including update check data whose data changes each time the output means outputs the first displacement data and the cyclic code.
The displacement data transmitting apparatus according to claim 1, wherein The cyclic code generation means further generates a cyclic code including status data whose data changes when the displacement data transmitting apparatus is abnormal.
5. The displacement data transmitting device according to claim 1, wherein

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