JP2005242486A - Servo controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a volatile storage area necessary for storage of servo software in a servo arithmetic part, and to prevent reduction of an arithmetic speed in the servo arithmetic part. <P>SOLUTION: In this servo controller, a plurality of pieces of servo software are prepared in each of various functions such as a characteristic of a servo shaft, or execution of a servomotor for various kinds of movement operation or machining operation. An upper control part stores the servo software, loads only the servo software optimum to each the servo arithmetic part. The servo arithmetic part executes prescribed operation by the loaded servo software. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a servo control device that controls a servo motor with servo software.

  Examples of machines that are driven and controlled by the numerical control device include various machines such as machine tools such as NC lathes and NC milling machines, electric injection molding machines, and industrial robots. In the conventional numerical control apparatus, software is generated for each machine in order to drive and control each machine. These softwares are configured by themselves and can be used alone, and are stored in a nonvolatile storage area such as a ROM or a hard disk in the numerical controller.

  Each of the machines is also provided with a plurality of drive mechanisms, and performs a predetermined operation as a whole by performing the same or different operations. In order to drive a plurality of drive mechanisms as described above, it is necessary to cause the servo motors included in these drive mechanisms to execute predetermined functions. The servo motor is driven by a servo calculation unit. The servo calculation unit controls the servo motor by interpreting the command received from the host control unit with servo software and controlling the servo motor.

Therefore, a servo control device that controls a plurality of servo motors needs to have servo software for causing each servo motor to execute an individual function.
Conventionally, all servo software required by the servo motor to be controlled by the servo control device is stored in the non-volatile storage area of the upper control unit of the servo control device, and each servo arithmetic device that is controlled by the servo control device On the other hand, all the servo software stored in the host controller is loaded.

FIG. 10 is a schematic diagram for explaining loading of conventional servo software into a servo arithmetic device.
In FIG. 10, the servo control device 11 includes a host control unit 12 and a servo calculation unit 13. The servo control device 11 stores all servo software (servo software A, servo software B, servo software C) in the non-volatile storage area 12b, and all servo software for the servo calculation units 13-1 and 13-2. Loading.
The servo calculation units 13-1 and 13-2 use the servo software necessary for executing a predetermined function from among all the servo software loaded from the host control unit 12, respectively. 2 is controlled.

The servo software that controls the servo axis requires various functions depending on the characteristics of the servo axis. For example, servo axis characteristics include motor type, detector type, linear axis, rotary axis, horizontal axis, gravity axis, high-precision axis, etc. Need to use servo software. Therefore, enormous program capacity is required to handle all of them.
Therefore, in order to store a large amount of servo software in the host control unit or servo calculation unit, there is a problem that the non-volatile storage area of the host control unit and the volatile storage area of the servo calculation unit also require a large capacity. .

In addition, since the servo calculation unit also executes unnecessary program portions, the time for executing the servo software increases, which impedes real-time processing.
Further, as the servo software program capacity increases, the number of development steps for developing this program also increases, resulting in a problem that development time and development cost increase.
Accordingly, an object of the present invention is to reduce a volatile storage area required for storing servo software in a servo calculation unit. It is another object of the present invention to prevent a decrease in calculation speed in the servo calculation unit.

  In the servo control device, a plurality of servo software is prepared for each of various functions such as the characteristics of the servo axis and the execution of the servo motor for various movement operations and machining operations. The host control unit stores these servo software, and loads only the servo software most suitable for each servo calculation unit. The servo calculation unit executes a predetermined operation by the loaded servo software.

  Alternatively, in the present invention, the servo software is prepared by dividing it into basic software and software for each function. The host controller prepares a correspondence relationship between the servo axis characteristics and the combination of servo software modules suitable for the servo axis characteristics in the form of a table or the like. The host control unit selects the optimum servo software module from the correspondence relationship for the servo axis to be used, and loads the selected servo software module on the servo calculation unit. The servo calculation unit executes a predetermined operation by the loaded servo software module.

The servo control device of the present invention includes a host control unit and a servo calculation unit that performs arithmetic processing on a movement command input from the host control unit with servo software, and drives and controls the servo motor based on the calculation result of the servo calculation unit. Servo control device.
The host control unit includes a storage unit that stores a plurality of servo software, a corresponding unit that associates the servo software with the servo motor, and a transfer unit that transfers the servo software stored in the storage unit to the servo calculation unit.

The transfer means transfers at least one of the servo software designated from the plurality of servo software to the servo calculation unit based on the designation by the designation means. The servo calculation unit drives and controls the servo motor associated with the corresponding unit based on the transferred servo software.
According to the present invention, since the servo calculation unit only needs to load the servo software designated by the designation means from among the servo software stored in the host control unit, the storage capacity for storing the servo software can be reduced. Can do.
Also, the correspondence relationship between the servo software and the servo motor is determined by the corresponding means, and the servo calculation unit loads the servo software from the upper control unit and also obtains information on the servo motor that executes the servo software from the upper control unit. The servo motor is driven and controlled by obtaining.

The servo software used in the servo control device of the present invention can be in two forms.
The first form of the servo software is a program that executes a predetermined function independently. The host control unit stores a program for executing a function used in each servo calculation unit in a storage area, and loads only a program used in each servo calculation unit from these programs. Each servo calculation unit performs drive control of the servo motor using the loaded program.

  Further, the second form of the servo software has a module structure including a common program part and a function-specific program part. The upper control unit stores a program part common to each servo calculation part and a function-specific program part for executing a function used in each servo calculation part in a storage area, and from these program parts, The common program part and the program part of the function used in each servo calculation part are loaded. Each servo calculation unit constitutes servo software that realizes a predetermined function by a combination of the loaded common program part and the function-specific program part, and performs drive control of the servo motor.

  The designation means for designating the servo software can be either a parameter, a setting pin, or an external signal. The parameters, setting pins, and external signals are one form for specifying the servo software, and other forms may be used. The designation means can be provided at any part of the servo control device or outside. When provided in the servo control device, for example, it can be specified by a parameter stored in a storage unit provided in the servo calculation unit or a setting pin provided in the servo calculation unit.

If the servo software has a module structure, the correspondence between the parameters, setting pins, external signals, etc. and the combination of servo software modules is stored in advance in a correspondence table, and the combination of modules corresponding to the designation Is read from the correspondence table, and the servo software module is read.
In addition, the servo calculation unit may control driving of a plurality of servo motors, and in order to execute a predetermined function by the servo calculation unit, which servo motor should be controlled by the loaded servo software. Need to be identified.
Therefore, a correspondence relationship between the servo software and a servo motor that is driven and controlled by the servo software is determined in advance, and a servo motor to be executed by the servo software is specified based on the correspondence relationship.

The host control unit of the present invention stores the correspondence between the servo software and the servo motor, specifies the servo motor with respect to the servo software, and transfers the servo motor to the servo calculation unit. Corresponding means for determining the correspondence between the servo software and the servo motor can be in the form of parameters, setting pins, or external signals. By changing the setting of these parameters, the servo software and the servo motor The correspondence can also be changed. The parameters, setting pins, and external signals are one form for specifying the correspondence between the servo software and the servo motor, and other forms may be used.
The servo control device of the present invention further includes a decoding program. The decryption program uses a plurality of encrypted servo software after decryption by the decryption program.

The host control unit stores encrypted servo software, and the servo calculation unit stores a decryption program. The servo calculation unit decrypts the encrypted servo software sent from the host control unit by the decryption program.
The servo calculation unit can be configured by a DSP. The decryption program can be stored in the mask ROM of the DSP.

According to the present invention, since only the necessary servo software is loaded into the servo operation unit, the volatile storage area required for storing the servo software can be reduced.
In addition, since the servo software that is not used is not stored in the volatile storage area of the servo calculation unit, it is possible to prevent unnecessary servo software from being executed and to prevent a reduction in calculation speed in the servo calculation unit.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
In the first embodiment of the present invention, a plurality of servo software is prepared for each function at the upper level of the servo control device, and only the most suitable servo software for executing each function is selected from the servo control device. The servo motor is driven and controlled using the loaded servo software.

  FIG. 1 is a schematic diagram for explaining the first embodiment. In FIG. 1, the servo control device includes servo software A, B, C,... For executing different functions on the servo axes. Each servo software is composed of a basic part and a functional part unique to each function. For example, the servo software A that executes the function a is composed of software for a basic part and a function a part, and the servo software B that executes the function b is composed of software for a basic part and a function b part. The basic part is software for causing the servo axis to perform basic operations, and the servo axis can be caused to execute basic operations only by this basic part.

The upper part of the servo control device prepares these servo software A, B, C,..., And when executing a predetermined function for each servo axis, these servo software A, B, C,. Select the optimum servo software for each servo axis.
For example, when the function a is performed, the servo software A used for the function a is selected from the servo software A, B, C,..., And when the function b is performed, the servo software A, B, C,. Servo software B to be used for execution of function b is selected. Further, when executing the function a and the function b, the servo software A used for executing the function a and the servo software B used for executing the function b are selected from the servo software A, B, C,.

In the second embodiment of the present invention, servo software is prepared by dividing it into basic software and software for each function. Also, a correspondence relationship between the servo axis characteristics and the combination of servo software modules suitable for the servo axis characteristics is prepared.
The upper control unit of the servo controller selects the optimal combination of servo software modules based on the corresponding relationship with the servo axis to be used, loads it to the lower level of the servo controller, and uses the loaded servo software module. The servo motor is driven and controlled.

FIG. 2 is a schematic diagram for explaining the second embodiment. 2, the servo control device includes a basic module M and modules am, bm, cm,... For each function.
Each servo software is composed of a combination of a basic module M and module portions am, bm, cm,. For example, the servo software for function a is composed of a combination of a basic module M and a function module am for function a, and the servo software for function b is composed of a combination of the basic module M and a function module bm for function b. . The servo software for the functions a and b is composed of a combination of the basic module M, the function module am for the function a, and the function module bm for the function b.
Next, a configuration example of the servo control device according to the first embodiment of the present invention will be described with reference to a schematic block diagram for explaining a first configuration example of the servo control device of the present invention shown in FIG.

In FIG. 3, the servo control device 1 of the first configuration example includes a host control unit 2 configured by a CNC device and the like, and a servo calculation unit 3 that drives and controls each servo axis.
The host control unit 2 transfers the servo software and various non-volatile storage areas 2b and 2c, the designation means 2d for designating the servo, and the servo software stored in the volatile storage area to the servo calculation unit 3. Transfer means 2a for loading.

  Here, the nonvolatile storage area 2b stores a plurality of servo software (servo software A, B, C,...). In order to transfer servo software from the host control unit 2 to the servo calculation unit 3, it is necessary to specify the servo software to be transferred from among a plurality of servo software stored in the nonvolatile storage area 2b. The servo software is specified by parameters, setting pins, or external signals.

The host controller 2 identifies servo software by parameters, setting pins, or external signals, reads the identified servo software from the nonvolatile storage area 2b, and transfers it to the servo calculator 3 by the transfer means 2a.
In the present invention, in order to specify servo software by a parameter, a setting pin, or an external signal, a correspondence relationship between the parameter, a setting pin, or an external signal and the servo software is prepared. Get the servo software for the selected parameter, setting pin, or external signal.
Therefore, the upper control unit 2 reads the specific servo software from the plurality of servo software stored in the non-volatile storage area 2b, and the correspondence relationship between the servo software parameters (or setting pins or external signals) and the servo software Includes a non-volatile storage area 2c.

  The servo calculation unit 3 may include a plurality of servo axes and servo motors that are driven and controlled. In such a case, the servo calculation unit 3 needs to specify which servo motor is to be driven and controlled by the servo software transferred from the transfer means 2a. Therefore, the host control unit 2 includes a designation unit that designates a servo motor in order to identify which servo motor is driven and controlled by the servo software. The designation means for designating the servo motor can be a parameter, a setting pin, or an external signal. The parameter can be stored in a nonvolatile storage area.

  On the other hand, the servo control device 1 can include a plurality of servo calculation units 3 (3-1, 3-2,...). The plurality of servo calculation units 3 perform predetermined functions using servo software loaded from the host control unit 2. FIG. 3 shows an example in which the function a is performed by the servo calculation unit 3-1, and an example in which the function b is performed by the servo calculation unit 3-2.

Hereinafter, the functional servo calculation unit 3-1 will be described as an example.
The servo calculation unit 3-1 includes a servo motor 4-1 that drives the servo shaft. Although FIG. 3 shows an example in which the servo motors 4-1a and 4-1b are provided, the number of servo motors to be installed is set according to the function to be performed. A plurality of servo motors may be provided for each servo axis.
The servo calculation unit 3-1 includes a volatile storage area 3-1 a and stores servo software loaded from the transfer unit 2 a of the host control unit 2. Since the servo software is stored in the volatile storage area, by storing the servo software in the volatile storage area every time the function to be executed is changed, a plurality of types of functions can be executed by one servo operation unit.
In addition, the servo calculation unit 3-1 performs drive control using servo software for the servo motor specified by the specifying unit of the host control unit 2.

FIG. 4 is a diagram illustrating an operation example by the servo control device 1 of the first configuration example. The numbers shown in parentheses below correspond to the numbers in FIG. Also, the numbers with the symbol S correspond to the numbers in FIGS.
The host control unit 2 receives the designation of the servo software used in the servo computation unit (S1), notifies the designated servo software to the nonvolatile storage area 2b (S2), and transfers the read servo software to the servo computation unit 3 (S3).

  The designation of the servo software is performed by, for example, the parameter (1) stored in the storage means of the servo calculation unit 3 or the setting pin (2) provided in the servo calculation unit 3, or input to the servo calculation unit 3 from the outside. You can also. When the servo software is specified by an external signal, the external signal is input from the servo calculation unit 3 to the high-order control unit 2 or directly input to the high-order control unit 2 from a device other than the servo calculation unit 3 or input means. (3).

The non-volatile memory area 2c stores the correspondence between parameters (or setting pins and external signals) and servo software, and uses this correspondence to correspond to the input parameters (or setting pins and external signals). For example, information such as servo software name (5) and function name is read (S2).
The nonvolatile storage area 2b reads the servo software (6) based on information such as the servo software name, for example, and the transfer means 2a transfers the read servo software to the servo calculation unit 3. 3 and 4 show an example in which the servo software A and B are read and transferred (S3).

The servo calculation unit 3-1 stores the transferred servo software (9) in the volatile storage area 3-1a, and the servo calculation unit 3-2 stores the transferred servo software (10) in the volatile storage area 3-1b. To store.
On the other hand, designation information for designating a servo motor is set in the designation means 2d (for example, a non-volatile storage area) of the upper control unit 2 by, for example, correspondence with servo software or the like (S4). The servo calculation unit 3 receives the servo motor designation (8) from the designation means (S5).
The servo calculation unit 3-1 receives the servo software A (9) and the servo motor designation (8), and drives and controls the designated servo motors 4-1a and 4-1b. The servo calculation unit 3-2 receives the servo software B (10) and the servo motor designation (8), and passes the calculation result (11) to the designated servo motors 4-2a and 4-2b for driving. Control is performed (12).

FIG. 5 is a diagram for explaining loading of servo software between the upper control unit and the servo calculation units 1 to 3 in the first embodiment.
The upper control unit prepares a plurality of servo software A, B,... For each function (function a, function b,...). The upper control unit loads only the servo software most suitable for executing each function from the above into the servo calculation unit, and the servo calculation unit controls the drive of the servo motor using the loaded servo software and performs a predetermined function. To implement.

Here, each servo software includes a basic part and a functional part. The basic part can perform basic operations only by this part, and the functional part can perform each function by combining with the basic part.
In this loading, the servo controller is informed of which servo software is to be loaded by a designation means such as a parameter, a setting pin, or an external signal in accordance with the characteristics of the servo axis.
For example, by setting the parameter “A” for the servo calculation units 1 and 3 and specifying the servo software A, the servo software A is loaded into the servo calculation units 1 and 3. Further, by setting the parameter “B” for the servo calculation unit 2 and designating the servo software B, the servo software B is loaded into the servo calculation unit 2.

  Further, when the corresponding servo software n does not exist in the setting of the parameter “N”, for example, it is determined that the arbitrarily set servo software is loaded into the servo calculation unit. As a result, at least the basic part is loaded on the servo calculation unit, the basic operation can be performed, and the situation where the apparatus does not start up can be prevented. At the same time, a warning that the corresponding servo software does not exist can be issued to alert the user.

Next, a configuration example of the servo control device according to the second embodiment of the present invention will be described with reference to a schematic block diagram for explaining a second configuration example of the servo control device of the present invention shown in FIG.
In the second embodiment of the present invention, servo software is divided into basic software and software for each function, and is prepared as a module. Also, an optimum servo software module according to the characteristics of the servo axis is prepared. In this embodiment, the servomotor is driven and controlled by loading the combination into the servo calculation unit.

In FIG. 6, the servo control device 1 of the second configuration example includes a host control unit 2 configured by a CNC device or the like, and a servo calculation unit 3 that drives and controls each servo axis, as in the first configuration example. .
The configuration of the second configuration example and the configuration of the first configuration example are different from each other in the configuration of the host control unit, and other configurations can be made common. Therefore, only the different configurations will be described below and shared. The description of the configuration to be omitted is omitted.

  The host controller 2 includes a nonvolatile storage area 2b that stores modularized servo software, a nonvolatile storage area 2e that stores the correspondence between the combination of the servo operation section and the module, and a designation unit 2d that designates the servo. And transfer means 2a for transferring the servo software stored in the volatile storage area to the servo calculation unit 3 for loading.

  Here, the nonvolatile storage area 2b stores servo software having a plurality of functions in the form of a basic module M and functional modules am, bm, cm,. Each function a, b, c can be implemented by a combination of the basic module M and the function modules am, bm, cm,. For example, the servo software for function a can be configured by a combination of the basic module M and the function module am, and the servo software for function b can be configured by a combination of the basic module M and the function module bm. The servo software for executing the functions a and b can be constituted by a combination of the basic module M, the function module am, and the function module bm.

  In order for the servo calculation unit to perform a predetermined function, it is necessary to determine what combination of function modules constitute the servo software. In the present invention, this combination of functional modules can be provided in the form of a correspondence table.

FIG. 7 is a diagram for explaining loading of servo software between the upper control unit and the servo calculation units 1 to 3 in the second embodiment.
The higher-level control unit modularizes software for executing the functions (function a, function b,...), And the basic module M, the function module am for the function a, the function module bm for the function b, and the function c. A functional module is prepared for each function such as the functional modules cm,. The host control unit loads the most suitable combination of modules for executing each function from these into the servo calculation unit, and the servo calculation unit combines the loaded modules to configure the servo software to drive the servo motor. Control and implement a predetermined function.

  In this loading, the correspondence table defines the correspondence of which combination of modules is transferred to each servo calculation unit. For example, in FIG. 7, a type representing a combination of modules is determined, and by setting this type in each servo calculation unit, a combination of modules of each servo calculation unit is determined, and in FIG. 8, a combination of modules for each type is determined. ing.

For example, type 1 is a combination of modules that implement function a and function d, and consists of a basic module, function module am, and function module bm. Type 2 is a combination of modules that implement function b and function c. The basic module, the functional module bm, and the functional module cm.
In FIG. 7, when type 1 is set in the servo calculation unit 1, a combination of a basic module, a functional module am, and a functional module dm is set in type 1 according to the correspondence table. It is loaded into the calculation unit 1.

Similarly, when type 2 is set in the servo calculation unit 2, the combination of the basic module, the function module bm, and the function module cm is set in the type 2 according to the correspondence table. It is loaded into the servo calculation unit 2.
In the second mode, the basic part of the servo software and the module for each function are stored in the non-volatile storage area on the host controller, and a correspondence table for determining which function module is to be combined for each type is prepared. Therefore, it is possible to easily select and set the modules used in each servo calculation unit, and it is also possible to easily change the combination of modules.
Note that the combination of functional modules is not limited to the configuration provided in the form of a table, but may be configured to prepare parameters to be selected for each functional module.

Furthermore, the present invention can increase the security of servo software by encrypting the servo software.
FIG. 9 is a diagram for explaining a configuration of encryption and decryption of servo software. In FIG. 9, the host control unit 2 takes in the encrypted servo software, stores it in the nonvolatile storage area 2 b, and transfers it to the servo calculation unit 3.
On the other hand, the servo calculation unit 3 stores the decryption program in the non-volatile storage area, and decrypts and executes the encrypted servo software transferred from the upper control unit 2.

In creating the servo software, the completed servo software A, B,... Is encrypted by a predetermined processing means such as a personal computer to create encrypted servo software A ′, B ′,. The encrypted servo software A ′, B ′,... Are stored in the nonvolatile storage area of the upper control unit. In storing the encrypted servo software A ′, B ′,..., The first and second embodiments of the present invention described above can be applied. When the first embodiment is applied, encrypted servo software A ′, B ′,... Is created for each function, and the encrypted servo software A ′, B ′,. Keep it. When the second mode is applied, the servo software has a module configuration, and an encrypted module encrypted in units of modules is created and stored in the upper control unit.
When the servo control device 1 is turned on, the encrypted servo software or the encrypted module is written in the nonvolatile storage area of the servo calculation unit 3 in the same manner as described above. Since the servo calculation unit 3 cannot operate with the encrypted servo software, the decryption program stored in the internal non-volatile storage area is executed to decrypt the encrypted servo software or the encryption module. After returning to the original state, the amplifier 5 is driven to control the servo motor 4.

  If the servo calculation unit stores the data in an external storage means such as an external ROM, the encryption may be decrypted. As a countermeasure against such a case, it is possible to prevent the decoding program from being taken out by forming the servo operation section by a digital signal processor (DSP) and storing it in the mask ROM area inside the DSP.

According to the embodiment of the present invention, by creating servo software for each function, the program capacity is reduced and the development man-hour is reduced. Further, since the volatile storage area of the servo arithmetic unit can be small, it is advantageous in terms of cost.
Further, since the program capacity is small in the servo calculation unit, the processing time can be shortened. It is also possible to easily select and set a function that matches the characteristics of the servo axis. By using the correspondence table, servo software having various types of functions can be easily created by combining modules.

  The technology of the present invention can be applied to various machines such as NC lathes and NC milling machines, electric injection molding machines, industrial robots, and the like.

It is the schematic for demonstrating a 1st form. It is the schematic for demonstrating a 2nd form. It is a schematic block diagram for demonstrating the 1st structural example of the servo control apparatus of this invention. It is a figure which shows the operation example by the servo control apparatus 1 of a 1st structural example. In a 1st form, it is a figure for demonstrating loading of the servo software between a high-order control part and the servo calculating parts 1-3. It is a schematic block diagram for demonstrating the 2nd structural example of the servo control apparatus of this invention. In a 2nd form, it is a figure for demonstrating loading of the servo software between a high-order control part and the servo calculating parts 1-3. It is a figure for demonstrating a correspondence table. It is a figure for demonstrating the structure of the encryption of a servo software, and a decoding. It is the schematic for demonstrating loading to the servo arithmetic unit of the conventional servo software.

Explanation of symbols

1,11 Servo control device 2,12 Upper level control unit 2a, 12a Transfer means 2b, 2c, 2e, 12b Non-volatile storage area 2d Designating means 2e Corresponding table 3,3-1, 3-2, 13-1, 13-2 Servo calculation unit 3-1a, 3-2a Volatile storage area 4, 4-1a, 4-1b, 4-2a, 4-2b, 14-1a, 14-1b, 14-2a, 14-2b Servo motor 5 Amplifier

Claims (9)

In a servo control device that includes a host control unit and a servo calculation unit that performs arithmetic processing on a movement command input from the host control unit using servo software, and drives and controls a servo motor based on a calculation result of the servo calculation unit.
The upper control unit includes storage means for storing a plurality of servo software,
Corresponding means for associating the servo software with the servo motor;
Transfer means for transferring servo software stored in the storage means to the servo calculation unit;
The transfer means transfers at least any one servo software designated from the plurality of servo software to the servo operation unit based on designation by the designation means,
The servo control device, wherein the servo calculation unit drives and controls a servo motor associated with the correspondence unit based on the transferred servo software.   2. The servo control apparatus according to claim 1, wherein each servo software of the plurality of servo software is a program for executing a predetermined function independently.   2. The servo control device according to claim 1, wherein each servo software of the plurality of servo software is configured in a module structure including a common program part and a function-specific program part.   4. The servo control device according to claim 1, wherein the designation means for designating the servo software is a parameter, a setting pin, or an external signal.   4. The correspondence means for associating the servo software with the servo motor is any one of a parameter, a setting pin, or an external signal set in the host control unit. Servo control device.   4. The servo control apparatus according to claim 3, wherein the combination of the servo software having the module structure is stored in advance in a correspondence table.   The servo control device according to claim 1, further comprising a decryption program, wherein the plurality of encrypted servo software are decrypted by the decryption program. The upper control unit stores encrypted servo software,
The servo calculation unit stores the decoding program,
8. The servo control apparatus according to claim 7, wherein the servo calculation unit decrypts the encrypted servo software sent from the host control unit by the decryption program. 9. The servo control apparatus according to claim 8, wherein the servo calculation unit is configured by a DSP, and the decoding program is stored in a mask ROM of the DSP.

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