JP2008252882A - Serial communication apparatus for sensor and serial communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, in a conventional serial communication apparatus for a position detector, it is necessary for a sensor such as a position detector to have an ID number and when utilizing serial communication as a means for providing sensor information to a servo control unit in a multi-axis machine, much time and effort may be required for setting or managing the ID number. <P>SOLUTION: A plurality of servo control units and a plurality of sensors such as position detectors are connected by a communication master which includes a plurality of serial ports and is connected with the plurality of servo control units by serial transmission lines, and a communication slave which includes a plurality of serial ports, is connected with the plurality of sensors by serial transmission lines and is capable of being cascaded, thereby accomplishing a serial communication apparatus in which the sensors correspond to time slots of serial communication. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a sensor serial communication device and a serial communication method for serial transmission between a plurality of sensors attached to a plurality of motors and a plurality of servo control units of a controller.

The number of serial transmission paths provided between the controller and the position detector attached to the motor needs to be equal to the number of position detectors when the position detectors are individually connected. Therefore, wiring saving is achieved by multidrop connection.
For example, in Patent Document 1, the number of serial transmission paths connected to the controller is suppressed by providing a branching section in the serial transmission path.
In Patent Document 2 and Patent Document 3, the number of wires is reduced by performing multidrop connection on the serial transmission path between the position detector and the controller.

FIG. 27 shows a conventional serial communication device for position detector.
A controller 1 that processes position data of a plurality of motors 61 to 62 or a change amount per unit time, and provided for each motor, detects the position data of the motor or a change amount per unit time, and detects the position data or Position detectors 50 to 51 each having a data transmission unit that transmits a change amount per unit time to the controller, and serial transmission paths S5 to S8 that connect the position detector and the controller, and the serial transmission path A branch unit 30 is provided, connected to each position detector, and the position data of the position detector or the amount of change per unit time received from the controller is transmitted to the controller as a serial signal from the data transmitter. It is configured to do.
Then, the position detector selected by the address from the branch unit transmits its own address and position data.

FIG. 28 shows a conventional serial communication device for a position detector having another configuration.
Position detectors 51 to 53 for detecting respective rotational positions are provided for a plurality of motors 61 to 63 that drive a plurality of operating axes such as arms. This position detector outputs position detector information as serial data. The controller 1 and the plurality of position detectors are connected by a single serial transmission line S5, and the request signal is transmitted from the controller to the position detector, so that the position detector is positioned according to the contents of the request signal. The detector information is transmitted to the controller.
For example, in the individual mode, the driving device transmits a position detector ID number together with a request signal, and a position detector that matches the position detector ID number transmits data.
In the continuous mode, a request signal is transmitted and an ID number designating all position detectors is transmitted. The position detector transmits data in a preset order (ID number order). The ID number is set from the outside of the position detector and is stored in the EEPROM.

FIG. 29 shows a conventional serial communication device for a position detector having another configuration.
From the parallel / serial conversion means 501 for converting the parallel signal from the detection 505 into a serial signal to the position detector 51 side, the transmission means 503 for transmitting the serial signal converted by the parallel / serial conversion means, and from the controller 1 side Receiving means 504 for receiving the control signal, transmission / reception control means 502 for controlling transmission / reception on the position detector side, transmission means 103 for transmitting the control signal to the position detector side on the controller side, and from the position detector side Receiving means 104 for receiving a signal; serial / parallel converting means 101 for converting a serial signal from the receiving means into a parallel signal; transmission / reception control means 102 for controlling transmission / reception on the controller side; the position detector side; A pair of serial transmission lines S5 for signal transmission between the controller side and a plurality of position detection It is intended to be constructed from.
When the position detector data is required, the control device transmits a data request signal including information on the position detector number. Each position detector performs a series of data transmission / reception operations when the position detector number given in advance matches the position detector number included in the data request signal.

Patent 2873262 (FIG. 1) JP 2006-260581 (FIG. 1) Patent 2611124 (FIG. 5)

As described above, in the case of the conventional serial communication device for position detector, in any example, it is essential that the position detector has an ID number.
However, it is easy for human error to enter a position detector in which an ID number is set in advance so that the correspondence with the servo control unit is not mistaken. In addition, it is difficult to set the ID number after the motor has been incorporated into the device with a position detector that has not been previously set with an ID number. This is because it is difficult to identify and communicate with a position detector connected to a serial transmission path and having no ID number set.
As a result, it is difficult to use serial communication for the construction of an actual multi-axis machine, and although there is a great expectation for wiring saving, it is not so popular.

  The present invention has been made in view of such problems, and makes it easy to associate a plurality of servo control units with a plurality of sensors attached to a plurality of motors even if the sensor does not have an ID number. An object of the present invention is to provide a sensor serial communication device that can be easily restored even when a disconnection occurs in a serial transmission path.

In order to solve the above problem, the present invention is configured as follows.
According to the first aspect of the present invention, one or more servo control units and one or more sensors attached to one or more motors driven by the servo control unit are connected to one communication master and one or more communication units. In the serial communication device for sensors connected by the serial transmission path including the slave,
The communication master includes one or more servo serial ports for connecting one or more servo control units, and a cascade connection serial port for connecting the communication slaves,
The communication slave includes a cascade connection serial port for cascading with the communication master or another communication slave, and one or more sensor serial ports for connecting one or more sensors in a 1: 1 ratio. It is characterized by comprising.

  According to a second aspect of the present invention, in the first aspect, the communication master corresponds to the sensor information received from the communication slave, the order in which the sensor information is received and the servo serial port number in ascending or descending order. And means for transmitting to the servo serial port at the same time.

  According to a third aspect of the present invention, the communication master according to the first aspect is configured such that the communication master simultaneously matches the sensor information received from the communication slave with the order of reception and the servo serial port number according to the correspondence table. A means for transmitting to the servo serial port is provided.

  According to a fourth aspect of the present invention, in the third aspect, the correspondence table is downloaded from the outside to the communication master at the time of initialization.

  According to a fifth aspect of the present invention, in the first aspect, the communication slave includes means for transmitting the sensor information from the subsequent stage to the previous stage from the self, and then transmitting the sensor information of the self to the previous stage. It is characterized by that.

According to a sixth aspect of the present invention, one or more servo control units and one or more sensors attached to one or more motors driven by the one or more servo control units are connected to one communication master and one In the communication method of the serial communication device for sensors connected by the serial transmission path including the above communication slaves,
Step M1 in which the communication master transmits a sensor information request command to the communication slave via a serial port for cascade connection; Step M2 in which sensor information for the sensor information request command is received from the communication slave; and the sensor information A step M3 for transmitting the servo from the servo serial port to the corresponding servo control unit,
The communication slave receives the sensor information request command and forwards it to the communication slave in the subsequent stage, and simultaneously transmits the sensor information request command to its own sensor and receives the sensor information from the sensor. Step S2, Step S3 for transferring the sensor information from the subsequent stage to the communication slave or the communication master in the previous stage, and Step S4 for transmitting the sensor information of its own to the communication master or the communication slave in the previous stage. It is characterized by that.

  According to a seventh aspect of the present invention, in the sixth aspect, the Step M3 associates the sensor information received from the communication slave with the order of reception and the number of the servo serial port in ascending or descending order. At the same time, the data is transmitted to the servo serial port.

  According to an eighth aspect of the present invention, in the sixth aspect, the step M3 is configured such that the sensor information received from the communication slave is associated with the order of reception and the servo serial port number according to the correspondence table. Are simultaneously transmitted to the servo serial port.

  The invention according to claim 9 is the invention according to claim 8, wherein the correspondence table is downloaded from the outside to the communication master at the time of initialization.

  According to a tenth aspect of the present invention, in the sixth aspect, the step S4 transmits the sensor information from the rear stage to the front stage from the self, and thereafter connected to the sensor serial port of the self. The sensor information from the sensor is transmitted to the communication master or the previous communication slave in descending or ascending order of the sensor serial port number.

According to an eleventh aspect of the present invention, one or more servo control units and one or more sensors attached to one or more motors driven by the servo control unit are connected to one communication master and one or more communication units. In the serial communication device for sensors connected by the serial transmission path including the slave,
The communication master includes one or more servo serial ports for connecting one or more servo control units, and a cascade connection serial port for connecting two communication slaves,
The communication slave includes a cascade connection serial port for cascading with the communication master or another communication slave, and one or more sensor serial ports for connecting one or more sensors in a 1: 1 ratio. It is characterized by comprising.

The invention according to a twelfth aspect of the present invention is the communication master according to the eleventh aspect, wherein the communication master normally uses only one of the cascade connection serial ports for connecting the two communication slaves.
When an abnormality occurs in the serial transmission path connecting the communication master and the communication slave, the system further comprises means for performing an operation using another system of the serial port for cascade connection that was not normally used. It is a thing.

The invention according to claim 13 is the communication master according to claim 11, wherein the communication master normally uses only one of the cascade connection serial ports for connecting the two communication slaves.
When an abnormality occurs in the serial transmission path connecting the communication slaves, in addition to the serial port for cascade connection that was normally used, another system of the serial port for cascade connection that was not normally used is used. And a means for performing the operation.

  According to a thirteenth aspect of the present invention, in the eleventh aspect, the communication slave determines that the serial port for cascade connection to which the communication master is connected at the time of initialization is the upper side, and thereafter initializes again. It is characterized by comprising means for maintaining the state until it is performed.

  According to the inventions according to claims 1, 2 and 5, and according to the inventions according to claims 6, 7 and 10, an ID number is assigned to a sensor such as a position detector. Even if it is not set, a plurality of servo control units that servo-control a plurality of motors incorporated in a multi-axis machine can obtain information from sensors such as position detectors corresponding to the servo control unit by serial communication. it can. Therefore, there is no need to set the ID number when incorporating the sensor into the multi-axis machine or to take over the ID number when replacing the sensor. Serial communication can be easily used as a means for providing information.

  According to the third and fourth aspects of the invention or the eighth and ninth aspects of the invention, in addition to the above effects, the correspondence between the servo control unit and the sensor can be logically changed. Therefore, convenience in using the serial communication device for the sensor is increased.

  According to the invention described in claim 11, claim 12, claim 13, and claim 14, in addition to the above effect, when a disconnection point is detected in the serial transmission line, it is easily recovered simply by reconnecting the cable. Therefore, the convenience in using the serial communication device for the sensor is increased.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a system configuration diagram of a sensor serial communication apparatus according to a first embodiment of the present invention.
1 is a controller, 11 to 14 are servo control units provided in the controller 1, and 19 is a common clock for the controller 1 and the communication master 2 to operate in synchronization.
2 is a communication master connected to the servo control units 11 to 14 via the serial transmission paths S1 to S4, 3 is a communication slave connected to the communication master 2 via the serial transmission path S5, and 4 is a communication slave 3 connected to the serial transmission path S6. The connected communication slave, 5 is a terminator, 61 to 64 are motors, 51 to 54 are sensors such as position detectors attached to the motors 61 to 64, and the communication slaves 3 to 3 are connected by serial transmission paths S7 to S10. 4 is connected.

  Note that the communication slaves can be cascade-connected in the required number of stages, but here, for simplicity, an example in which only two stages are cascade-connected is shown. In addition, although an arbitrary number of sensor ports can be provided for each communication slave, an example in which the number of sensor ports is 2 is shown for simplicity. In addition, the power lines for the servo control units 11 to 14 to supply power to the motors 61 to 64 and the cables for supplying the control power to the sensors 51 to 54 are not shown for simplicity.

  The communication master 2 has a plurality of serial ports for connecting the servo control unit. Hereinafter, the serial ports are referred to as servo ports. A number for identifying each servo port is called a servo port number. The servo port number is determined in advance and is expressed as, for example, sp1, sp2, sp3, sp4.

  The communication slave 3 and the communication slave 4 have a serial port for connecting a sensor through a serial transmission path. Hereinafter, the serial port is referred to as a sensor port. A number for identifying the sensor port is referred to as a sensor port number. The sensor port number is determined in advance and is expressed as, for example, p1 and p2.

Further, hereinafter, the effective sensor port refers to a sensor port to which a sensor is actually connected.
The number of effective sensor ports in the subsequent stage refers to the total number of effective sensor ports in the communication slaves subsequent to the own communication slave.
A time slot is a unit of time division when a serial transmission path is used in time division when each communication slave transmits sensor information received via an effective sensor port to the communication master. .

  In the configuration of FIG. 1, the motion control unit (not shown) of the controller 1 interprets a work program (not shown) downloaded from the outside in order to control the multi-axis machine, 14 is generated. The servo control units 11 to 14 servo-control the motors 61 to 64 based on the command, but the sensor information from the sensors 51 to 54 necessary for the servo control is transmitted to the communication slave 3, the communication slave 4, and the communication master. 2 can be obtained.

  In FIG. 6, the communication master 2 transmits a sensor information request to the communication slave 3, the communication slave 3 transmits a sensor information request to the sensor 51, the sensor 51 transmits the sensor information 331 to the communication slave 3, and the communication slave 3. Shows how the sensor information 331 is transmitted to the communication master 2 using the time slot t4. However, in FIG. 6, the sensor information transmitted to the communication master 2 using the time slots t1 to t3 is omitted from being transmitted to the communication slaves 3 to 4 via the serial transmission paths S8 to S10, respectively. ing. Further, the transmission speed of the serial transmission path S5 is described as an example in the case of twice that of the serial transmission path S7.

First, the communication master 2 transmits the sensor information request 310 to the serial transmission path S5, and the communication slave 3 receives the sensor information request 310 and transfers it to the sensor 51 via the serial transmission path S7. In response to the sensor information request 310, the sensor 51 transmits the sensor information 331 to the communication slave 3 via the serial transmission path S7.
The communication slave 3 first transfers the sensor information 333 to 334 from the subsequent stage to the previous stage, and then can set the sensor information 331 to 332 received from its own valid detector port in descending order (in ascending order) of the sensor port number. Is transmitted to the previous stage.

Communication on the serial transmission line is time-division multiplexed, and the time slot numbers are assigned in order starting from the one corresponding to the sensor port number of the communication slave at a later stage, and within the same communication slave, the descending order of the sensor port number ( (Ascending order is also possible), and allocation is made as t1, t2, t3, t4 so that there is no space.
The length of the time slot is the sum of the transmission time of the sensor information and the transmission time for the number of bits increased based on encoding and the gap time to absorb the delay time depending on the transmission path length and transmission circuit. The total number of time slots is the total number of valid sensor ports to which sensors are actually connected.
The number of time slots is counted every time the time slot length is set in a timer (not shown) provided in the transmission / reception processing unit of the communication master or each communication slave, and the time is up. .
The reference point for counting the time slot in the communication master 2 is the time when the transmission of the sensor information request 310 is completed to each communication slave, and the reference point for counting the time slot in the communication slave 3 is the communication slave 3. Is the time when the reception of the sensor information request 310 from the communication master is completed.

  In order to realize communication using time slots as shown in FIG. 6, each communication slave 3 to 4 grasps the number of its own effective sensor ports and subsequent effective sensor ports at the initialization stage. I have to leave. The communication master 2 must keep track of the number of all effective sensor ports.

The initialization procedure will be described below.
First, the communication slaves 3 and 4 set the cascade switches SW1 and SW2 for turning on / off the serial transmission path to OFF by a power-on reset (not shown). Further, the sensor port number of its own effective sensor port is detected and stored in the effective position detection port number column (FIGS. 3A and 3B) of the slave sensor port tables 32 and 42.
When the cascade switches SW1 and SW2 are OFF, the communication slave connected to the communication master 2 is only the communication slave 3 closest to the communication master 2. In this state, the communication master 2 sets the communication slave numbers of the communication slaves 3 and 4 and grasps the number of valid sensor ports according to the flowchart shown in FIG.

The communication master 2 transmits to the communication slave 3 a communication slave number setting command including the communication slave number # 1 and a request for the number of valid sensor ports.
The communication slave 3 that has received the communication slave number setting command responds according to the flowchart shown in FIG. That is, when the cascade switch SW1 is OFF, the communication slave number # 1 is stored in the communication slave number column (FIG. 3A) of the slave sensor port table 32, and the communication slave 3 stored in the slave sensor port table 32 is stored. Is returned to the communication master 2, and then the cascade switch SW1 is turned ON.
The communication master 2 stores the returned number of sensor ports of the communication slave 3 in the effective sensor port number column (FIG. 2) of the communication master effective sensor port table 22.

The communication master 2 repeats the same initialization procedure as described above until the number of sensor ports from the last communication slave 4 is received while incrementing the communication slave number. The number of sensor ports from the last communication slave 4 indicates that the previous reply was from the last communication slave 4 when the timer timed out after sending a valid sensor port request command. In this way, it can be judged.
This time-up occurs when a timer value set in a serial communication monitoring timer (not shown) provided in the transmission / reception processing unit of the communication master 2 has timed out.

Next, the communication master 2 transmits the number of subsequent effective sensor ports to each of the communication slaves 3 and 4 according to the flowchart shown in FIG. First, a command for setting the number of post-stage effective sensor ports as shown in FIG. In this case, “1” is set as the communication slave number, and “2” is set as the effective sensor port number of the communication slave 4 that is the subsequent stage of the communication slave 3 as the subsequent stage effective port number.
Upon receiving this command, the communication slave 3 performs processing according to the flowchart shown in FIG. 10 and stores the number of subsequent sensor ports in the subsequent sensor port number column (FIG. 3A) of the communication slave sensor port table 32. Thereafter, the response is returned to the communication master 2.

Next, the communication master 2 performs the procedure for setting the number of subsequent effective sensor ports in the same manner for the communication slave 4. However, since the communication slave 4 is the last stage, the number of effective sensor ports “0” is set. Send a command. If the number of communication slaves is arbitrary, the setting procedure for the number of subsequent effective sensor ports is repeated by the number of communication slaves stored from the communication master sensor port table 22.
When the initialization procedure as described above is completed, the communication master 2 stores information as shown in FIG. 2 in the communication master valid sensor port table 22, and the communication slaves 3 and 4 have communication slave valid sensor port tables 32 and 42. 3-a and 3-b are stored in FIG. 3, and the cascade switches SW1 and SW2 are all turned on.

Next, communication between the communication master 2 and the communication slaves 3 and 4 during servo control will be described with reference to FIGS.
First, the communication master 2 communicates a sensor information request command as shown in FIG. 5D in synchronization with a sensor information request from any of the servo control units 11 to 14 of the controller 1 or in synchronization with the clock 19. Transmit to slaves 3 and 4.
The communication slaves 3 and 4 that have received the sensor information request command transmit the sensor information request command to the sensors 51 to 54 via the valid sensor ports p1 and p2 and the serial transmission paths S7 to S10, respectively. The sensors 51 to 54 transmit the sensor information to the communication slaves 3 and 4 via the serial transmission paths S7 to 10 and the effective sensor ports p1 and p2.

The communication slave 4 has no effective sensor port on the rear stage, so that the sensor information from the sensors 53 and 54 can be arranged in descending order (in ascending order) of the sensor port number without waiting for transmission of sensor information from the rear stage. To the communication slave 3.
The communication slave 3 transmits the sensor information from the sensors 51 and 52 to the communication master 2 in the descending order of the sensor port numbers (it can also be in ascending order) after the time slot has elapsed for the number of subsequent effective sensor ports.
Since the communication master 2 has received sensor information from all valid sensor ports after the time slot has elapsed for all sensor ports, the communication master 2 receives the sensor information in the order in which the sensor information is received, that is, the time slot numbers t1 to t4. The sensor information is transmitted to the servo ports sp1 to sp4 by associating the order with the ascending order of the servo port numbers sp1 to sp4 (it is also possible to set the descending order).

  FIG. 13 is a timing diagram of communication between the communication master 2 and the communication slaves 3 and 4 at the time of servo control, and shows sensor information requests and sensor information flowing on the serial transmission paths S1 to S4, S5, S6, and S7 to S10. ing. This timing diagram describes that the communication speeds of the serial transmission lines S5 and S6 are twice the communication speeds of the serial transmission lines S1 to S4 and S7 to S10.

After initialization is completed and servo control is started, sensor information request commands 311 to 314 from the servo control units 11 to 14 are transmitted to the serial transmission lines S1 to S4 at the same timing. This is because the servo control units 11 to 14 operate in synchronization with the common clock 19.
The communication master 2 transmits an arbitrary one sensor information request command to the communication slaves 3 and 4. In FIG. 13, the sensor information request command 311 from the servo control unit 11 is sent to the communication slaves 3 and 4 through the serial communication path S5. , S6 is transmitted.
The communication slave 3 that has received the sensor information request command 311 transmits the sensor information request command 311 to the sensors 51 to 52 via the serial transmission paths S7 to S8 in order to obtain sensor information of the sensors 51 to 52. The sensors 51 to 52 simultaneously receive the sensor information request command 311 and transmit sensor information 331 to 332 as responses thereto to the communication slave 3 via the serial transmission paths S7 to S8.

Similarly, the communication slave 4 that has received the sensor information request command 311 transmits the sensor information request command 311 to the sensors 53 to 54 via the serial transmission paths S9 to S10 in order to obtain sensor information of the sensors 53 to 54. To do. The sensors 53 to 54 simultaneously receive the sensor information request command 311 and transmit sensor information 333 to 334 as responses to the command to the communication slave 4 via the serial transmission paths S9 to S10.
Since the number of effective sensor ports in the rear stage is set to 0, the communication slave 4 does not receive sensor information from the rear stage, and the sensor information of its own can be in descending order (in ascending order) of the sensor port number. Send to the previous stage. That is, first, the sensor information 334 is transmitted to the communication slave 3 via the serial transmission path S6, and then the sensor information 333 is transmitted to the communication slave 3 via the serial transmission path S6.

  Since the number of effective sensor ports in the subsequent stage is set to 2, the communication slave 3 counts the sensor information from the subsequent stage for the number of time slots “2” via the serial transmission path S6, and sets the serial transmission path S5. Via the communication master 2. Thereafter, its own sensor information 332 is transmitted to the communication master 2 via the serial transmission path S5, and then the sensor information 331 is transmitted to the communication master 2 via the serial transmission path S5.

  The communication master 2 can also arrange the sensor information 331 to 334 in the reverse order of the order of reception, that is, the descending order of the time slot numbers t1 to t4 in ascending order (ascending order) of the servo port numbers sp1 to sp4. ), Servo ports sp1 to sp4 are output. Since the sensor information received in each time slot is known from the sensor attached to which motor, the sensor information output to this servo port is from the sensor attached to which motor. I know what it is. Therefore, if the servo ports sp1 to sp4 and the servo control units 11 to 14 are connected by the serial transmission paths S1 to S4 based on the information, each servo control unit 11 to 14 can acquire the sensor information required by itself. Can be received.

When the servo control units 11 to 14 and the servo ports sp1 to sp4 can be connected by the individual serial transmission paths S1 to S4, it is easy to appropriately correspond the servo control units 11 to 14 and the servo ports sp1 to sp4.
However, when the servo control units 11 to 14 and the servo ports sp1 to sp4 are connected by a ribbon cable or printed wiring, the correspondence between the servo control units 11 to 14 and the servo ports sp1 to sp4 is fixed. There is a possibility that a state in which sensor information from a sensor attached to a motor controlled by the servo control unit cannot be received may occur.
In such a case, the communication master 2 has a time slot / servo port correspondence table 23, that is, a correspondence table of time slot numbers and servo port numbers as shown in FIG. 4, and a servo port corresponding to the time slot number. The sensor information received at the time slot number is transmitted.
The time slot / servo port correspondence table 23 can be easily set to the communication master 2 from an external engineering tool or the like via the serial port (not shown) of the controller 1, the servo control unit 11, and the serial transmission path S1. Can be downloaded.

Next, parameter writing to the sensor will be described with reference to FIG. The individual writing to the sensor is performed by the time slot method in the same manner as the reading of the sensor information by enabling only the writing to the sensor port to which the sensor is connected. For this purpose, a sensor port mask request 341 as shown in FIG. 5C is transmitted to each communication slave, and only writing to the sensor port is enabled and writing to other sensor ports is disabled.
Thereafter, the communication master 2 sends a sensor write request 352 for writing data such as parameters. In FIG. 14, a sensor write request 352 is transmitted to the sensor 52. Note that the method for transmitting the response from the sensor 52 to the communication master 2 is the same as that for transmitting the sensor information, and a description thereof will be omitted.

Next, the operation of the sensor serial communication apparatus according to the third embodiment of the present invention will be described with reference to FIG. FIG. 15 is a system configuration diagram of the sensor serial communication apparatus according to the third embodiment of the present invention. In FIG. 15, the description of the same components as those in FIG. 1 is omitted. Reference numeral 24 is a communication master transmission / reception processing unit, 25 is a communication master valid sensor port table, and 26 is a time slot / servo port correspondence table. The communication master transmission / reception processing unit 21, communication master valid sensor port table 22, time slot / servo port, respectively. The same operation as in the correspondence table 23 is performed. Reference numeral 27 denotes a servo port correspondence circuit, which associates the time slot number with the servo port number according to the servo port / time slot correspondence tables 23 and 26, and transmits the sensor information to the servo ports sp1 to sp4.
33 and 43 are high-order port storage circuits, which determine and store that the port that received the communication slave number setting command transmitted from the communication master 2 at the time of initialization is the high-order side and store the port selection signals 34 and 44. Output, and the operation of the port switching circuits 35 and 45 is switched.

The operation of the port switching circuits 35 and 45 will be described with reference to FIG. FIG. 16 is a block diagram of the communication slave 3 according to the third embodiment of the present invention.
When a communication slave number setting command is received from the serial transmission path S5 at the time of initialization, the higher-order port storage circuit 33 stores that the serial transmission path S5 side is the higher-order side, and sends a port selection signal 34 to the port switching circuit 35. "0" is output to. Further, the cascade switch SW1 is turned on.
As a result, the port switching circuit 35 can output the sensor information request command from the serial transmission path S5 to the communication slave transmission / reception processing unit 31, and can output it to the communication slave connected to the serial transmission path S6. Further, sensor information from the serial transmission path S6 can be output to the serial transmission path S5 (FIG. 30-a).

When a communication slave number setting command is received from the serial transmission path S6 at the time of initialization, the higher-order port storage circuit 33 stores that the serial transmission path S6 side is the higher-order side, and the port switching circuit 35 “1” is output to the port selection signal 34. Further, the cascade switch SW1 is turned on.
As a result, the port switching circuit 35 can output the sensor information request command from the serial transmission path S6 to the communication slave transmission / reception processing unit 31, and can output it to the communication slave connected to the serial transmission path S5. Further, the sensor information from the serial transmission path S5 can be output to the serial transmission path S6 (FIG. 30-b).

  When the upper port storage circuit 33 stores the upper port at the time of initialization, the upper port storage circuit 33 holds the state until the initialization is performed again. As a result, the communication master 2 can be connected to either of the serial transmission paths S5 and S6.

In the configuration of FIG. 15, the communication master 2 and the communication slaves 3 and 4 are connected via serial transmission paths S5 to S6. The operation is equivalent to that of the first embodiment of the present invention.
However, when a disconnection occurs in the serial transmission path S5 or the serial transmission path S6, data cannot be normally transmitted / received thereafter.

Hereinafter, as a first mode of the third embodiment of the present invention, a recovery procedure when the disconnection D1 occurs in the serial transmission line S5 will be described with reference to FIG.
First, the terminator 5 is removed, and the power is turned on while the communication master 2 and the communication slave 4 are connected by the serial transmission path S11. The communication slaves 3 and 4 set the cascade switches SW1 and SW2 for turning on / off the serial transmission path to OFF by a power-on reset (not shown). Further, the sensor port number of its own valid sensor port is detected and stored in the valid sensor port number column (FIGS. 3-a and 3-b) of the slave valid sensor port tables 32 and.
The communication master 2 sets the communication slave numbers of the communication slaves 3 and 4 and grasps the number of valid sensor ports according to the flowchart shown in FIG.

  The communication master 2 transmits a communication slave number setting command composed of the communication slave number # 1 and the number of valid sensor ports from the communication master transmission / reception processing unit 21. However, since the disconnection D1 occurs in the serial transmission path S5 and the communication slave 3 cannot receive the communication slave number setting command, the serial communication monitoring timer (provided in the transmission / reception processing unit of the communication master 2) When the timer value set in (not shown) expires, it can be determined that no communication slave is connected to the serial transmission path S5. Therefore, the communication master 2 stores “0” in the effective sensor port number column (FIG. 18A) of the communication master effective sensor port table 22.

Next, the communication master 2 transmits a communication slave number setting command including the communication slave number # 1 and the number of valid sensor ports from the communication master transmission / reception processing unit 24. The communication slave 4 that has received the communication slave number setting command responds according to the flowchart shown in FIG. That is, when the cascade switch SW2 is OFF, the port that has received the communication slave number setting command is determined to be the upper side, and is stored in the upper side port storage circuit 44. Next, the communication slave number # 1 is stored in the communication slave number column (FIG. 19B) of the slave sensor port table 42, and the number of effective sensor ports of the communication slave 4 stored in the slave sensor port table 42 is set as the communication master. 2 and then turn on the cascade switch SW2.
The communication master 2 stores the returned sensor port number of the communication slave 4 in the effective sensor port number column (FIG. 18B) of the communication master effective sensor port table 25.

The communication master 2 repeats the same initialization procedure as described above from the communication master transmission / reception processing unit 24 until the number of sensor ports from the last communication slave 3 is received while incrementing the communication slave number. The number of sensor ports from the last communication slave 3 indicates that the last reply was from the last communication slave 3 when the timer timed out after sending a valid sensor port request command In this way, it can be judged.
This time-up occurs when a timer value set in a serial communication monitoring timer (not shown) provided in the transmission / reception processing unit of the communication master 2 has timed out.

Next, the communication master 2 transmits the number of subsequent effective sensor ports to each of the communication slaves 3 and 4 according to the flowchart shown in FIG. First, a command for setting the number of post-stage effective sensor ports as shown in FIG. In this case, “1” is set as the communication slave number, and “2” is set as the effective sensor port number of the communication slave 3 subsequent to the communication slave 4 as the number of subsequent effective ports.
Upon receiving this command, the communication slave 4 performs processing according to the flowchart shown in FIG. 10, and stores the number of subsequent sensor ports in the number of subsequent sensor ports in the communication slave sensor port table 42 (FIG. 19B). Thereafter, the response is returned to the communication master 2.

Next, the communication master 2 performs the procedure for setting the number of subsequent effective sensor ports in the same manner for the communication slave 3, but since the communication slave 3 is the last stage, the number of effective sensor ports “0” is set. Send a command. If the number of communication slaves is arbitrary, the setting procedure for the number of subsequent effective sensor ports is repeated by the number of communication slaves stored from the communication master sensor port table 22.
When the initialization procedure as described above is completed, the communication master 2 stores information as shown in FIGS. 18A and 18B in the communication master valid sensor port tables 22 and 25, and the communication slaves 3 and 4 communicate with each other. Information as shown in FIGS. 19A and 19B is stored in the slave effective sensor port tables 32 and 42, and the cascade switches SW1 and SW2 are all ON.

  FIG. 25 is a timing chart of communication between the communication master 2 and the communication slaves 3 and 4 during the servo control when the disconnection D1 occurs in the serial transmission path S5. The sensor information flowing on the serial transmission paths S9 and S11 is shown in FIG. Shows request and sensor information. In this timing diagram, the communication speeds of the serial transmission paths S6 and S11 are described as being twice the communication speed of the serial transmission paths S1 to S4 and S7 to S10.

After initialization is completed and servo control is started, sensor information request commands 311 to 314 from the servo control units 11 to 14 are transmitted to the serial transmission lines S1 to S4 at the same timing. This is because the servo control units 11 to 14 operate in synchronization with the common clock 19.
The communication master transmission / reception processing unit 24 of the communication master 2 transmits any one sensor information request command to the communication slaves 3 and 4, but in FIG. 25, the sensor information request command 311 from the servo control unit 11 is transmitted to the communication slave 3. 4 via serial communication paths S11 and S6.
The communication slave 4 that has received the sensor information request command 311 transmits the sensor information request command 311 to the sensors 53 to 54 via the serial transmission paths S9 to S10 in order to obtain sensor information of the sensors 53 to 54. The sensors 53 to 54 simultaneously receive the sensor information request command 311 and transmit sensor information 333 to 334 as responses to the command to the communication slave 4 via the serial transmission paths S9 to S10.

Similarly, the communication slave 3 that has received the sensor information request command 311 transmits the sensor information request command 311 to the sensors 51 to 52 via the serial transmission paths S7 to S8 in order to obtain sensor information of the sensors 51 to 52. To do. The sensors 51 to 52 simultaneously receive the sensor information request command 311 and transmit sensor information 331 to 332 as responses thereto to the communication slave 3 via the serial transmission paths S7 to S8.
Since the communication slave 3 has the number of effective sensor ports in the subsequent stage set to 0, it is possible to set its own sensor information in descending order (in ascending order) of the sensor port number without receiving sensor information from the subsequent stage. Send to the previous stage. That is, first, the sensor information 332 is transmitted to the communication slave 4 via the serial transmission path S6, and then the sensor information 331 is transmitted to the communication slave 4 via the serial transmission path S6.

  Since the number of effective sensor ports in the rear stage is set to 2, the communication slave 4 counts the sensor information from the rear stage by the number of time slots “2” via the serial transmission path S6 and sets the serial transmission path S11. Via the communication master 2. Thereafter, the sensor information 334 is transmitted to the communication master 2 through the serial transmission path S11, and then the sensor information 333 is transmitted to the communication master 2 through the serial transmission path S11.

  The communication master 2 associates the sensor information 331 to 334 with the order in which the sensor information is received according to the time slot / servo port correspondence table 26, that is, the time slot numbers t21 to t24 and the servo port numbers sp1 to sp4. The sensor information is transmitted to the servo ports sp1 to sp4.

Next, as a second mode of the third embodiment of the present invention, the recovery procedure when the disconnection D2 occurs in the serial transmission line S6 will be described with reference to FIG.
First, the terminator 5 is removed, and the power is turned on with the communication master 2 and the communication slave 4 connected by the serial transmission line 11. The communication slaves 3 and 4 set the cascade switches SW1 and SW2 for turning on / off the serial transmission path to OFF by a power-on reset (not shown). Further, the sensor port number of its own valid sensor port is detected and stored in the valid sensor port number column (FIGS. 3A and 3B) of the slave sensor port tables 32 and 42.
The communication master 2 sets the communication slave numbers of the communication slaves 3 and 4 and grasps the number of valid sensor ports according to the flowchart shown in FIG.

The communication master 2 transmits a communication slave number setting command including the communication slave number # 1 and a request for the number of valid sensor ports from the communication master transmission / reception processing unit 21. The communication slave 3 that has received the communication slave number setting command responds according to the flowchart shown in FIG. That is, when the cascade switch SW1 is OFF, the port that has received the communication slave number setting command is determined to be the upper side, and is stored in the upper side port storage circuit 34. Next, the communication slave number # 1 is stored in the communication slave number column (FIG. 22A) of the slave sensor port table 32, and the number of effective sensor ports of the communication slave 3 stored in the slave sensor port table 32 is set as the communication master. 2 and then turn on the cascade switch SW2.
The communication master 2 stores the returned number of sensor ports of the communication slave 3 in the effective sensor port number column (FIG. 21-a) of the communication master effective sensor port table 22.

  The communication master 2 repeats the same initialization procedure as described above from the communication master transmission / reception processing unit 21 while incrementing the communication slave number. However, since the disconnection D2 occurs in the serial transmission path S6, the timer value set in the serial communication monitoring timer (not shown) provided in the transmission / reception processing unit of the communication master 2 times out. It can be determined that no more communication slaves are connected.

Next, the communication master 2 transmits a communication slave number setting command including the communication slave number # 2 and the request for the number of valid sensor ports from the communication master transmission / reception processing unit 24. The communication slave 4 that has received the communication slave number setting command responds according to the flowchart shown in FIG. That is, when the cascade switch SW2 is OFF, the port that has received the communication slave number setting command is determined to be the upper side, and is stored in the upper side port storage circuit 44. Next, the communication slave number # 2 is stored in the communication slave number column (FIG. 22B) of the slave sensor port table 42, and the number of effective sensor ports of the communication slave 4 stored in the slave sensor port table 42 is set as the communication master. 2 and then turn on the cascade switch SW2.
The communication master 2 stores the returned sensor port number of the communication slave 4 in the effective sensor port number column (FIG. 21B) of the communication master effective sensor port table 25.

  The communication master 2 repeats the same initialization procedure as described above from the communication master transmission / reception processing unit 24 while incrementing the communication slave number. However, since the disconnection D2 occurs in the serial transmission path S6, the timer value set in the serial communication monitoring timer (not shown) provided in the transmission / reception processing unit of the communication master 2 times out. It can be determined that no more communication slaves are connected.

Next, the communication master transmission / reception processing unit 21 of the communication master 2 transmits the number of subsequent-stage effective sensor ports to the communication slave 3 according to the flowchart shown in FIG. First, a command for setting the number of post-stage effective sensor ports as shown in FIG. In this case, “1” is set as the communication slave number, and the number of effective sensor ports “0” is set as the number of effective sensor ports because the communication slave 3 is the last stage because the disconnection D2 occurs in the serial transmission path S6. Send a command to If the number of communication slaves is arbitrary, the setting procedure for the number of subsequent effective sensor ports is repeated by the number of communication slaves stored from the communication master sensor port table 22.
Upon receiving this command, the communication slave 3 performs processing according to the flowchart shown in FIG. 10 and stores the number of subsequent sensor ports in the subsequent sensor port number column (FIG. 22A) of the communication slave sensor port table 32. Thereafter, the response is returned to the communication master 2.

Similarly, the communication master transmission / reception processing unit 24 of the communication master 2 transmits the number of subsequent effective sensor ports to the communication slave 4 according to the flowchart shown in FIG. First, a command for setting the number of post-stage effective sensor ports as shown in FIG. In this case, “2” is set as the communication slave number, and the number of valid sensor ports is set to “0” as the number of effective sensor ports is set to the last stage because the communication slave 4 is the last stage because the disconnection D2 occurs in the serial transmission path S6. Send a command to If the number of communication slaves is arbitrary, the setting procedure for the number of subsequent effective sensor ports is repeated by the number of communication slaves stored from the communication master sensor port table 22.
Upon receiving this command, the communication slave 4 performs processing according to the flowchart shown in FIG. 10 and stores the number of subsequent sensor ports in the subsequent sensor port number column (FIG. 22B) of the communication slave sensor port table 42. Thereafter, the response is returned to the communication master 2.
When the initialization procedure as described above is completed, the communication master 2 stores information as shown in FIGS. 21-a and 21-b in the communication master valid sensor port tables 22 and 25, and the communication slaves 3 and 4 communicate with each other. Information as shown in FIGS. 22A and 22B is stored in the slave effective sensor port tables 32 and 42, and the cascade switches SW1 and SW2 are all turned ON.

  FIG. 26 is a timing diagram of communication between the communication master 2 and the communication slaves 3 and 4 during the servo control when the disconnection D2 occurs in the serial transmission path S6. On the serial transmission paths S5, S7, S9, and S11 The sensor information request and the sensor information flowing through are shown. This timing diagram describes that the communication speeds of the serial transmission lines S5 and S11 are twice the communication speed of the serial transmission lines S1 to S4 and S7 to S10.

After initialization is completed and servo control is started, sensor information request commands 311 to 314 from the servo control units 11 to 14 are transmitted to the serial transmission lines S1 to S4 at the same timing. This is because the servo control units 11 to 14 operate in synchronization with the common clock 19.
The communication master transmission / reception processing units 21 and 24 of the communication master 2 transmit arbitrary one sensor information request command to the communication slaves 3 and 4, respectively, but in FIG. 26, the sensor information request command 311 from the servo control unit 11 is communicated. The data is transmitted to the slaves 3 and 4 via serial communication paths S6 and S11, respectively.
The communication slave 3 that has received the sensor information request command 311 transmits the sensor information request command 311 to the sensors 51 to 52 via the serial transmission paths S7 to S8 in order to obtain sensor information of the sensors 51 to 52. The sensors 51 to 52 simultaneously receive the sensor information request command 311 and transmit sensor information 331 to 332 as responses thereto to the communication slave 3 via the serial transmission paths S7 to S8.
Similarly, the communication slave 4 that has received the sensor information request command 311 transmits the sensor information request command 311 to the sensors 53 to 54 via the serial transmission paths S9 to S10 in order to obtain sensor information of the sensors 53 to 54. To do. The sensors 53 to 54 simultaneously receive the sensor information request command 311 and transmit sensor information 333 to 334 as responses to the command to the communication slave 4 via the serial transmission paths S9 to S10.

  Since the communication slave 3 has the number of effective sensor ports in the subsequent stage set to 0, it is possible to set its own sensor information in descending order (in ascending order) of the sensor port number without receiving sensor information from the subsequent stage. Send to the previous stage. That is, first, the sensor information 332 is transmitted to the communication master 2 via the serial transmission path S5, and then the sensor information 331 is transmitted to the communication master 2 via the serial transmission path S5.

  Similarly, since the number of effective sensor ports in the subsequent stage is set to 0, the communication slave 4 can also set its own sensor information in descending order (in ascending order) of the sensor port number without receiving sensor information from the subsequent stage. Is transmitted to the previous stage. That is, first, the sensor information 334 is transmitted to the communication master 2 via the serial transmission path S11, and then the sensor information 333 is transmitted to the communication master 2 via the serial transmission path S11.

  The communication master 2 receives the sensor information 331 to 334 in the order of receiving the sensor information according to the time slot / servo port correspondence tables 23 and 26, that is, the time slot numbers t1 to t2, t21 to t22, and the servo port number sp1. The sensor information is transmitted to the servo ports sp1 to sp4 in correspondence with .about.sp4.

  The description so far has described an example in which a sensor such as a position detector attached to the motor is connected to the servo control unit, a serial transmission path, a communication slave, and a communication master in a 1: 1 ratio. However, the configuration of connecting a plurality of sensors to one servo control unit according to the application can be easily realized by changing the connection between the servo control unit and the servo port.

As described above, according to the present invention, although the sensor attached to the motor and the servo control unit are connected by the serial transmission path, it is not necessary to set the sensor ID number. The load can be greatly reduced.
Further, even when any of the serial transmission paths between the communication master and the communication slave or between the communication slave and the communication slave is disconnected, the serial communication can be easily restored.
Thus, the present invention is suitable for construction of a multi-axis machine incorporating a plurality of servo controlled motors.

The system block diagram of the serial communication apparatus for sensors which shows 1st Example of this invention Communication master effective sensor port table showing the first embodiment of the present invention Communication slave effective sensor port table showing the first embodiment of the present invention Time slot / servo port correspondence table showing the second embodiment of the present invention Communication data format according to the first embodiment of the present invention Timing diagram of communication using time slots, showing the first embodiment of the present invention Communication master effective sensor port grasp processing showing the first embodiment of the present invention Communication sensor valid sensor port grasp processing of the first embodiment of the present invention Communication master effective sensor port number transmission processing showing the first embodiment of the present invention Communication slave effective port number reception processing showing the first embodiment of the present invention Communication processing during communication master operation showing the first embodiment of the present invention Communication processing during communication slave operation, showing the first embodiment of the present invention Timing chart of communication during operation, showing the first embodiment of the present invention Sensor writing process according to the first embodiment of the present invention The system block diagram of the serial communication apparatus for sensors which shows 3rd Example of this invention Communication slave block diagram showing the third embodiment of the present invention The system block diagram of the serial communication apparatus for sensors which shows the 1st form of 3rd Example of this invention Communication master effective sensor port table showing the first form of the third embodiment of the present invention Communication slave effective sensor port table showing the first form of the third embodiment of the present invention The system block diagram of the serial communication apparatus for sensors which shows the 2nd form of 3rd Example of this invention Communication master effective sensor port table showing the second mode of the third embodiment of the present invention Communication slave effective sensor port table showing the second mode of the third embodiment of the present invention Communication master effective sensor port grasping process showing the third embodiment of the present invention Communication sensor valid sensor port grasping process showing the third embodiment of the present invention Timing diagram of communication using time slot, showing the first mode of the third embodiment of the present invention Timing diagram of communication using time slots, showing the second mode of the third embodiment of the present invention System configuration diagram of the sensor serial communication device of the conventional example System configuration diagram of the sensor serial communication device of the conventional example System configuration diagram of the sensor serial communication device of the conventional example The figure which shows the flow of the information in the communication slave block of 3rd Example of this invention.

Explanation of symbols

1 Controller 11-14 Servo control unit 19 Clock 2 Communication master 21, 24 Communication master transmission / reception processing unit 22, 25 Communication master valid sensor port table 23, 26 Time slot / servo port correspondence table 3, 4 Communication slave 31, 41 Communication slave Transmission / reception processor 32, 42 Communication slave valid sensor port table 33, 43 Upper port storage circuit 34, 44 Port selection signal 35, 45 Port switching circuit 311 to 314 Sensor information request command 321 to 324 Sensor information request command 331 to 334 Sensor Information 341 Sensor port mask request 351, 353, 354 Empty request 352 Sensor write request 5 Terminator 51-54 Sensor 61-64 Motor S1-S11 Serial transmission path sp1-sp4 Servo port p1-p2 Sensor Port 101 Serial / parallel conversion unit 102 Transmission / reception control unit 103 Transmission unit 104 Reception unit 105 Position detector selector 501 Serial / parallel conversion unit 502 Transmission / reception control unit 503 Transmission unit 504 Reception unit 505 Detector 70 Branch unit

Claims (14)

One or more servo controllers and one or more sensors attached to one or more motors driven by the servo controllers are connected by a serial transmission line including one communication master and one or more communication slaves. In the serial communication device for sensors,
The communication master includes one or more servo serial ports for connecting one or more servo control units, and a cascade connection serial port for connecting the communication slaves,
The communication slave includes a cascade connection serial port for cascading with the communication master or another communication slave, and one or more sensor serial ports for connecting one or more sensors in a 1: 1 ratio. A serial communication device for sensors, comprising:   2. The communication master according to claim 1, wherein the communication master associates the sensor information received from the communication slave with the order in which the sensor information is received and the number of the servo serial port in ascending or descending order, and simultaneously with the servo serial. A serial communication device for a sensor comprising means for transmitting to a port.   2. The means according to claim 1, wherein the communication master transmits the sensor information received from the communication slave to the servo serial port simultaneously after associating the received order with the servo serial port number according to the correspondence table. A serial communication device for sensors, comprising:   4. The sensor serial communication device according to claim 3, wherein the correspondence table is downloaded from the outside to the communication master at the time of initialization.   2. The serial communication for sensors according to claim 1, wherein the communication slave includes means for transmitting the sensor information from the subsequent stage to the previous stage from itself, and thereafter transmitting the sensor information of the own apparatus to the previous stage. apparatus. Serial transmission path including one or more servo control units and one or more sensors attached to one or more motors driven by one or more servo control units, one communication master and one or more communication slaves In the communication method of the sensor serial communication device connected in
Step M1 in which the communication master transmits a sensor information request command to the communication slave via a serial port for cascade connection; Step M2 in which sensor information for the sensor information request command is received from the communication slave; and the sensor information A step M3 for transmitting the servo from the servo serial port to the corresponding servo control unit,
The communication slave receives the sensor information request command and forwards it to the communication slave in the subsequent stage, and simultaneously transmits the sensor information request command to its own sensor and receives the sensor information from the sensor. Step S2, Step S3 for transferring the sensor information from the subsequent stage to the communication slave or the communication master in the previous stage, and Step S4 for transmitting the sensor information of its own to the communication master or the communication slave in the previous stage. A communication method of a serial communication device for sensors.   7. The step M3 according to claim 6, wherein the sensor information received from the communication slave is associated with the receiving order and the servo serial port number in ascending or descending order and simultaneously to the servo serial port. A communication method for a serial communication device for a sensor, characterized in that the transmission is performed.   7. The step M3 of claim 6, wherein the step M3 transmits the sensor information received from the communication slave to the servo serial port at the same time after associating the received order with the servo serial port number according to the correspondence table. A communication method of a serial communication device for a sensor, characterized in that:   9. The communication method for a sensor serial communication device according to claim 8, wherein the correspondence table is downloaded from the outside to the communication master at the time of initialization.   7. The step S4 according to claim 6, wherein the step S4 transmits the sensor information from the subsequent stage to the front stage, and then the sensor information from the sensor connected to the serial port for the sensor is transmitted to the sensor. A communication method for a serial communication device for a sensor, comprising: transmitting to the communication master or the previous communication slave in descending or ascending order of serial port numbers. One or more servo controllers and one or more sensors attached to one or more motors driven by the servo controllers are connected by a serial transmission line including one communication master and one or more communication slaves. In the serial communication device for sensors,
The communication master includes one or more servo serial ports for connecting one or more servo control units, and a cascade connection serial port for connecting two communication slaves,
The communication slave includes a cascade connection serial port for cascading with the communication master or another communication slave, and one or more sensor serial ports for connecting one or more sensors in a 1: 1 ratio. A serial communication device for sensors, comprising: In Claim 11, the said communication master uses only one system among the serial ports for cascade connection for connecting the said communication slave of 2 systems normally,
A unit for performing an operation using another system of the serial port for cascade connection that is not normally used when an abnormality occurs in the serial transmission path connecting the communication master and the communication slave; A unique sensor serial device. In Claim 11, the said communication master uses only one system among the serial ports for cascade connection for connecting the said communication slave of 2 systems normally,
When an abnormality occurs in the serial transmission path connecting the communication slaves, in addition to the cascade connection serial port that is normally used, another system of the cascade connection serial port that is not normally used A sensor serial device comprising means for performing an operation using a sensor.   12. The communication slave according to claim 11, wherein the communication slave determines that the cascade connection serial port to which the communication master is connected at the time of initialization is on the upper side, and thereafter holds the state until initialization is performed again. A sensor serial device characterized by comprising:

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