Encoder and control system

Abstract

Tax system that includes: - an encoder (1) and - a control device (2, 20, 200) configured to control a target object using information sent via serial communication from the encoder (1), - where the encoder (1) comprises: - a position information generation unit (11) configured to generate position information consisting of a predefined data set and containing absolute position data of an object to be detected, - a configuration information generation unit (12) configured to generate configuration information specifying a proportion of the absolute position data in the data set during serial communication, and - a transmitter unit (13) configured to send the position information and the configuration information as serial data to the control unit, and - wherein the control device comprises (2, 20, 200): - a receiving unit (21) configured to receive the position and configuration information sent by the encoder (1), - a storage unit (23) configured to store the configuration information received by the receiving unit (21), and - a reporting unit (24) which is configured to carry out a configuration discrepancy notification when the configuration information stored in the storage unit (23) does not match the configuration information received by the receiving unit (21) on the next occasion.

Description

Background of the invention 1. Field of the invention

[0001] The present invention relates to an encoder and a control system. 2. Description of the related prior art

[0002] In a control system that includes an encoder performing serial communication, the encoder receives a signal requesting position information from a control unit and communicates the position information generated at a specific time via serial data. The amount of position information held by the encoder varies; that is, it includes multi-rotation data for the object being detected and position data within a single rotation. This varies depending on the encoder. In particular, with a battery-free encoder that stores the multi-rotation data (indicating the number of rotations of the object being detected) exclusively within the encoder itself, the amount of multi-rotation data can vary depending on the battery-free method and the size of the encoder.

[0003] Therefore, a serial interface method is reported in which the data transmission format type of the encoder used can be automatically determined and processed by a CNC (Computer Numerical Control) device (e.g. JP H05 - 113 809 A).

[0004] However, in a case where the configuration of the amount of position data sent by the encoder is misread due to noise, a component failure, or the like, or in a case where the encoder changes the configuration of the amount of position data as a result of replacing the encoder, the weighting of the position data changes, which poses a problem affecting operation. Summary of the invention

[0005] One objective of the present invention is to provide an encoder and a control system, whereby an impact on operation can be avoided even if a configuration of a set of position data sent by the encoder changes.

[0006] The problem is solved by a control system with the features of claim 1 and by an encoder with the features of claim 6.

[0007] A control system according to an example of the present disclosure comprises an encoder and a control unit configured to control a target object using information transmitted by the encoder via serial communication. The encoder comprises a position information generation unit configured to generate position information consisting of a predefined data set and containing absolute position data of an object to be detected, a configuration information generation unit configured to generate configuration information specifying a portion of the absolute position data in the data set during serial communication, and a transmission unit configured to send the position information and the configuration information as serial data to the control unit.The control unit comprises a receiving unit configured to receive the position and configuration information sent by the encoder, a storage unit configured to store the configuration information received by the receiving unit, and a reporting unit configured to issue a configuration discrepancy message if the configuration information stored in the storage unit does not match the configuration information received by the receiving unit the next time.

[0008] According to the encoder and the control system as described in the present disclosure, even in a case where the configuration of the amount of position data sent by the encoder changes, the impact on the operation can be avoided. Brief description of the drawings Fig. Figure 1 is a configuration representation of a control system according to Example 1. Fig. Figure 2A is a representation showing a configuration of position information of an encoder in the control system according to Example 1. Fig. Figure 2B is a representation showing an example of position information for an encoder in the control system according to Example 1. Fig. Figure 2C is a representation that shows another example of position information of an encoder in the control system according to Example 1. Fig. 2D is a representation that shows another example of position information of an encoder in the control system according to Example 1. Fig. Figure 3 is a representation that shows an example of position information for different encoder types when a configuration of position information is set in a specific format. Fig. Figure 4 is a time diagram of a position information request signal sent by a control device and a response signal sent by an encoder in the control system according to Example 1. Fig. Figure 5 is a configuration representation of a control system according to Example 2. Fig. Figure 6 is a time diagram of a position information request signal or configuration information request signal sent by a control device and a response signal sent by an encoder to the control system according to Example 2. Fig. 7 is a configuration representation of a control system according to Example 3. Fig. Figure 8 is a representation showing an example where configuration information sent by an encoder changes in the control system according to Example 1. Fig. 9A is a representation showing a state in which, in the control system according to Example 3, a control device stores configuration information initially sent by an encoder. Fig. Figure 9B is a representation showing an example where, in the control system according to Example 3, after saving the configuration information initially sent by an encoder, the configuration information sent the next time has changed. Detailed description

[0009] Below, with reference to the drawings, an encoder and a control system according to the present invention are described. However, the technical scope of the invention is not limited to these embodiments and includes the invention described in the claims and their equivalent elements.

[0010] First, a control system according to Example 1 is described. A configuration representation of the control system according to Example 1 is shown in Fig. 1 shown. A control system 101 according to Example 1 comprises an encoder 1 and a control device 2, which controls a target object using information sent by the encoder 1 via serial communication.

[0011] The encoder 1 included in the control system 101 according to Example 1 comprises a position information generation unit 11, a configuration information generation unit 12, a transmitter unit 13, a sensor unit 14, and an analog-to-digital (A / D) converter 15. The encoder 1 is located near a motor 10, which represents an object to be detected, and detects the position and speed of movement of a rotating shaft (not shown) of the motor 10.

[0012] The sensor unit 14 detects the movement of the rotating shaft of the motor 10, which represents the object to be detected, and outputs an analog signal corresponding to the distance traveled by the rotating shaft. The A / D converter 15 performs an A / D conversion on the analog signal output by the sensor unit 14 and outputs a digital signal.

[0013] The encoder 1 receives a position information request signal from the control unit 2, which requests the position information of the object to be detected.

[0014] The position information generation unit 11 generates position information consisting of a predefined data set and containing absolute position data of the object to be detected (e.g., the motor 10). If the encoder 1 is a linear encoder, the position information is formed by the absolute position data. If, however, the encoder 1 is a rotary encoder, the position information is formed by multi-rotation data and the absolute position data (position data within a single rotation). Here, the term "data set" refers to the total number of bits representing the multi-rotation data and the total number of bits representing the absolute position data. The data set is defined as the format of the serial communication between the encoder 1 and the control unit 2.

[0015] Fig. Figure 2A shows a configuration of the encoder's position information for the control system according to Example 1. Fig. Figure 2A shows an example where the specified amount of position information is 28 bits. The position information is formed by the multi-rotation data of X bits and the absolute position data of Y bits. In the example in Fig. In example 2A, the sum of X and Y is 28.

[0016] The configuration information generation unit 12 generates configuration information that specifies the proportion of absolute position data within the data set during serial communication. This proportion is represented by the distribution of the multi-rotation data and the absolute position data, or by the position of a boundary between the different data types, and so on. The configuration information contains details about the amount of absolute position data. In the case of the Fig. In the example shown in Figure 2A, the configuration information can be represented by the set of multirotation data (X bits), the set of absolute position data (Y bits), or both data sets within the given data set (28 bits). For example, the configuration information can be specified by (X = m), (Y = n), or (X = m, Y = n) (where m and n are positive integers). In this case, the sum of m and n is the data set (m + n) of position information. Since the data set (m + n) is known, if the set (X = m) of multirotation data is received as configuration information, it is possible to calculate the set of absolute position data (Y = m + n - X = n), and if the set (Y = n) of absolute position data is received, it is possible to calculate the set of multirotation data (X = m + n - Y = m).

[0017] Thus, the position information generation unit 11 generates the position information, which contains the absolute position data and the multi-rotation data of the object to be detected, and the configuration information generation unit 12 generates the configuration information, which specifies the distribution of the absolute position data and the multi-rotation data in the data set during serial communication.

[0018] The transmitter unit 13 of the encoder 1 sends the position information corresponding to the configuration information together with the configuration information to the control unit 2. The position information generation unit 11 and the configuration information generation unit 12 of the encoder 1 can be implemented by hardware, such as a circuit executing their functions, or by a computing device, such as a CPU (central processing unit), which uses software executing their functions.

[0019] The control unit 2 comprises a receiver unit 21 and a control unit 22.

[0020] The receiver unit 21 receives the position and configuration information sent by the encoder 1. In the case of the Fig. In the example shown, the receiving unit 21 of the control device 2 receives the position information and configuration information sent by the transmitting unit 13 of the encoder 1.

[0021] The control unit 22 processes the position information received by the receiver unit 21 based on the configuration information received by the receiver unit 21.

[0022] This shows Fig. 3. To illustrate a specific example of configuration information, an example of position information for various encoders is given when the configuration of the position information is defined in a specific format. As in Fig. Figure 3 shows an example of serial communication in a format where the position information of the specified data set (28 bits) specifies the amount of multi-rotation data with 12 bits and the amount of absolute position data with 16 bits.

[0023] If each data set is specified in the communication format, the encoder must meet the bit count described above. With a battery-free encoder or similar device, the amount of multi-rotation data that can be output varies depending on the battery-free method and the encoder size, and it is possible that the bit count in the format cannot be met.

[0024] As with a Fig. In the case of encoder A shown in Figure 3, the format described above cannot be fulfilled with a battery-free encoder where the amount of multirotation data is only 11 bits, resulting in missing bits. If this is not addressed, a problem arises when the encoder rotates by 12 bits (4096) or more. Therefore, processing is required on the receiving end of the position information to mask the most significant bit of the multirotation data. However, if the amount of multirotation data held by the encoder cannot be determined automatically, some parameter settings must be configured manually.

[0025] In contrast, with encoder 1 according to Example 1, the configuration information, which defines the amounts of multi-rotation and absolute position data held by encoder 1, is sent from the encoder to the control unit 2 via serial communication, along with the position information in serial communication format. This makes it possible to perform control using a format that is optimal for encoder 1.

[0026] In other words, according to the encoder in Example 1, in the case of encoder A, by sending the information to the control unit that of the 28 bits of position information the amount of multi-rotation data is 11 bits or the amount of absolute position data is 17 bits, or by sending both pieces of information, the control unit can determine the configuration of the position information sent by the encoder and optimal control can be achieved without performing manual parameter settings. Fig. Figure 2B shows an example of the encoder's position information in the control system from Example 1. According to the encoder in Example 1, the configuration information generation unit 12 generates the configuration information (X = 11, Y = 17), where the set of multirotation data from encoder A is 11 bits and the set of absolute position data is 17 bits. In this case, the least significant bit d0 of the absolute position data is missing, and thus, for example, a value of 0 can be assigned. Since d0 is the least significant bit, it does not significantly affect the accuracy of the data.

[0027] Furthermore, as with an encoder B in Fig. 3. There is a case where, to improve resolution, more absolute position data is output than multirotation data. However, in a case where the amount of absolute position data is limited to 16 bits by the serial communication format, 5 bits of the lower-level absolute position data cannot be sent, creating a problem in which the superiority of the high-resolution encoder is lost.

[0028] Fig. Figure 2C shows another example of configuring the encoder's position information in the control system according to Example 1. As in Fig. As shown in Figure 2C, with the encoder according to Example 1, in the case of encoder B, it is possible to use the high resolution of encoder B, since the configuration information (X = 7, Y = 21), where of the 28 bits of the data set the amount of multirotation data is 7 bits and the amount of absolute data is 21 bits, can be specified on the encoder side.

[0029] Furthermore, as with an encoder C in Fig. 3. In the case of an encoder (especially a linear encoder) that does not require multi-rotation data, the multi-rotation data is not available, and therefore all data must be sent as absolute position data. However, a problem arises in that optimal data cannot be sent if the configuration of the position information in serial communication format specifies the presence of multi-rotation data.

[0030] Fig. Figure 2D shows another example of configuring the encoder's position information for the control system according to Example 1. As in Fig. As shown in 2D, with the encoder according to Example 1, in the case of encoder C, the transmission of the optimal data can be carried out, since the configuration information (X = 0, Y = 28), in which of the 28 bits of the data set the amount of multi-rotation data is 0 bits and the amount of absolute position data is 28 bits, can be specified on the encoder side.

[0031] The description above provides an example of configuration information showing the data distribution where, of the specified data set (28 bits), 12 bits are for multi-rotation data and 16 bits are for absolute position data (e.g., X = 12, Y = 16). However, configuration information is not limited to this example and can include information specifying a boundary between absolute position data and multi-rotation data during serial communication.In particular, the configuration information contains information specifying the position of the least significant bit (LSB) of the multirotation data or the absolute position data, the position of the most significant bit (MSB) of the multirotation data or the absolute position data, or both the position of the least significant bit (LSB) and the position of the most significant bit (MSB), where the positions are adjacent to the boundary between the multirotation data and the absolute position data in the position information. For encoder A from... Fig. 2B, for example, could be information indicating that the boundary between the multirotation data and the absolute position data lies between an 11th bit, which is the least significant bit of the multirotation data, and a 12th bit, which is the most significant bit of the absolute position data, as shown by an arrow.

[0032] The serial communication between encoder 1 and control unit 2 is now described. Control unit 2 sends the signal to request position information (the position information request signal) to encoder 1 at a predefined interval. Encoder 1 sends the position information and configuration information as serial data to control unit 2 whenever it receives the request signal from control unit 2. The configuration information preferably includes information about the amount of absolute position data or multi-rotation data. Fig. Figure 4 is a time diagram of the position information request signal sent by the control device and a response signal sent by the encoder in the control system according to Example 1. For example, a time at which encoder 1 receives the position information request signal is referred to as time r1, r2 and r3 of a falling edge of a pulse of the position information request signal.

[0033] The position information generation unit 11 generates the position information after a predefined time period following the receipt of the position information request signal. In the case of the Fig. In the example shown, the position information generation unit 11 generates the position information of the object to be detected based on the digital signal output by the A / D converter 15. The position information includes the multi-rotation data with the X bits and the absolute position data with the Y bits.

[0034] The configuration information generation unit 12 generates the configuration information (X = m, Y = n) that specifies the set of multirotation data (X = m), the set of absolute position data (Y = n), or both. The configuration information preferably contains the information about the set of absolute position data. However, if the data set (m + n) is already known, the set (Y = n) of absolute position data can be calculated from the set (X = m) of multirotation data.

[0035] The transmitter unit 13 sends the position information and the configuration information as a series of serial data to the control unit 2. Fig. For example, when encoder 1 receives a first position information request signal at time r1, transmitter unit 13 sends the position information and configuration information as a series of serial data to control unit 2 at time t1 after the specified time interval. Similarly, when encoder 1 receives a second position information request signal at time r2, transmitter unit 13 sends the position information and configuration information as a series of serial data to control unit 2 at time t2 after the specified time interval. Likewise, when encoder 1 receives a third position information request signal at time r3, transmitter unit 13 sends the position information and configuration information as a series of serial data to control unit 2 at time t3 after the specified time interval.

[0036] As described above, encoder 1 can transmit the correct position information whenever the position information request signal is received by sending both the position information and the configuration information, even if the configuration information changes. Examples of cases where the configuration information changes include a case where the position information configuration changes according to the size of the position information, a case where the encoder is changed, and the like.

[0037] According to the control system of Example 1, communication of the position data in a format optimal for the encoder is possible by sending the configuration information, which specifies the division of the amount of multi-rotation data and the amount of absolute position data in the position data of the serial data from the encoder, to the control device.

[0038] Now, a tax system based on Example 2 will be described. Fig. Figure 5 shows a configuration diagram of the control system according to Example 2. A control system 102 according to Example 2 differs from the control system 101 according to Example 1 in that the transmitting unit 13 sends the position information and the configuration information as a series of serial data or as separate serial data to a control unit 20, that the control system 2 further includes a storage unit 23 that stores the configuration information received by the receiving unit 21, and that the control unit 22 processes the position information received by the receiving unit 21 based on the configuration information stored in the storage unit 23. Since the rest of the configuration of the control system 102 according to Example 2 is similar to that of the control system 101 according to Example 1, a detailed description of it is omitted.

[0039] The transmitter unit 13 of the encoder 1 sends the position information corresponding to the configuration information to the control unit 20. The configuration information preferably contains information about the amount of absolute position data.

[0040] The position information generation unit 11 generates the position information, which includes the absolute position data and the multi-rotation data of the object to be detected. The configuration information generation unit 12 generates the configuration information, which specifies the distribution of the absolute position data and the multi-rotation data within the data set during serial communication. The configuration information preferably includes information about the amount of absolute position data or multi-rotation data.

[0041] The transmitter unit 13 sends the position information corresponding to the configuration information to the control unit 20.

[0042] The receiver unit 21 of the control device 20 receives the position and configuration information sent by the encoder. The memory unit 23 of the control device 20 stores the configuration information received by the receiver unit 21. The control unit 22 of the control device 20 processes the position information received by the receiver unit 21 based on the configuration information stored in the memory unit 23. By storing the configuration information sent by the encoder 1 in the memory unit 23 on the control device 20, the encoder 1 does not need to constantly send the configuration information along with the position information.

[0043] The position and configuration information sent and received by the control system according to Example 2 will now be described. Fig. Figure 6 shows a timing diagram of the position information request signal or configuration information request signal sent by the control device and the response signal sent by the encoder in the control system according to Example 2.

[0044] For example, the time at which the control unit 20 sends the position information request signal is referred to as time r1, r2 and r3 of the falling edge of the pulse of the position information request signal.

[0045] The position information generation unit 11 generates the position information after a predetermined time period following the receipt of the position information request signal. In the case of the Fig. In the example shown in Figure 5, the position information generation unit 11 generates the position information of the object to be detected based on the digital signal output by the A / D converter 15. The position information includes the multi-rotation data with the X bits and the absolute position data with the Y bits.

[0046] The configuration information generation unit 12 generates the configuration information (X = m, Y = n) that specifies the set of multirotation data (X = m bits), the set of absolute position data (Y = n bits), or both. The configuration information preferably contains the information about the set of absolute position data. However, if the data set (m + n) is already known, the set (Y = n) of absolute position data can be calculated from the set (X = m) of multirotation data.

[0047] The configuration information can include information specifying the boundary between absolute position data and multirotation data during serial communication. Specifically, the configuration information includes information specifying the position of the least significant bit (LSB) of the multirotation data or the absolute position data, the position of the most significant bit (MSB) of the multirotation data or the absolute position data, or both the position of the least significant bit (LSB) and the position of the most significant bit (MSB), with the positions being adjacent to the boundary between the multirotation data and the absolute position data in the position information.

[0048] The control unit 20 sends an initial request signal of position information or configuration information to the encoder 1 when serial communication is initiated. Here, the "initial request signal" is a signal to request the position information or configuration information that the control unit 20 sends to the encoder 1 when serial communication is initiated. Fig. 6 For example, encoder 1 receives the first request signal to request the position information or the configuration information at time r1, which represents the start of serial communication.

[0049] When encoder 1 receives the first request signal from control unit 20, encoder 1 sends the configuration information together with the position information as a series of serial data to control unit 20, or sends the configuration information as separate serial data to control unit 20. Fig. At time t1, the transmitting unit 13 sends the configuration information along with the position information as a series of serial data to the control unit 20 using serial communication. Alternatively, the configuration information can be sent to the control unit as separate serial data.

[0050] The memory unit 23 of the control device 20 stores the configuration information received from the encoder 1. Consequently, the configuration of the multi-rotation data and the absolute position data in the position information received from the second time onwards can be determined based on the configuration information stored in the memory unit 23.

[0051] Encoder 1 can send encoder specification information, along with configuration information, to control unit 20 when it receives the first request signal from control unit 20. The encoder specification information preferably includes details such as a drawing number, model, serial number, and / or similar information. Sending this encoder specification information allows control unit 20 to verify whether the encoder has been modified.

[0052] The control unit sends a second request signal containing position information to the encoder in a predefined cycle after sending the first request signal. The "second request signal" is a signal for requesting position information, which is sent by the control unit 20 to the encoder 1 in the predefined cycle after the first request signal has been sent. As described in Fig. As shown in Figure 6, encoder 1 receives the second request signal of the position information at time r2 as the request signal sent for the second time.

[0053] Encoder 1 sends the position information as separate serial data to control unit 20 whenever (t = t2, t3, ...) encoder 1 receives the second request signal from control unit 20. As in Fig. As shown in Figure 6, at time t2 the transmitter unit 13 sends the position information as separate serial data to the control unit 20. Thereafter, the encoder 1 similarly sends the position information as separate serial data to the control unit 20 whenever it receives the second request signal from the control unit 20 after time t3, which is then the third request signal.

[0054] Thus, in the control system according to Example 2, when the encoder receives the first position information request signal, the configuration information is sent to the control unit only once, and the configuration information received by the control unit is stored. With such a configuration, the encoder can send the configuration information only once; from the second time onward, it only sends the position information, thereby providing some flexibility in the serial data transmitted by the encoder.

[0055] The above description gives an example where the encoder sends the configuration information only once after receiving the position information request signal; however, the present invention is not limited to such an example. For instance, periodically sending the configuration information makes it possible to confirm that there has been no change to the position information configuration. Furthermore, if the encoder's position information configuration changes, the configuration information can be sent whenever the position information changes. An example of a case where the configuration information changes includes a case where the position information configuration changes according to the size of the position information or a case where the encoder itself is changed.

[0056] Now, a tax system based on Example 3 will be described. Fig. Figure 7 shows a configuration representation of a control system according to Example 3. A control system 103 according to Example 3 is equipped with the encoder 1 and a control unit 200, which controls a target object using information sent from the encoder 1 via serial communication.

[0057] The encoder 1 of control system 103 according to example 3 has the same configuration as the encoder 1 in control system 101 according to example 1.

[0058] The position information generation unit 11 of the encoder 1 generates the position information, which includes the absolute position data and the multi-rotation data of the object to be detected. The configuration information generation unit 12 of the encoder 1 generates the configuration information, which specifies the distribution of the absolute position data and the multi-rotation data within the data set during serial communication. The transmitter unit 13 sends the position information corresponding to the configuration information to the control unit 200.

[0059] The control unit 200 in the control system 103 according to example 3 comprises the receiving unit 21, the storage unit 23 and a signaling unit 24.

[0060] The receiving unit 21 receives the position and configuration information sent by the encoder 1. The storage unit 23 stores the configuration information received by the receiving unit 21 from the encoder 1. The reporting unit 24 reports a configuration discrepancy if the configuration information stored in the storage unit 23 does not match the configuration information received by the receiving unit 21 the next time.

[0061] Now, a process in the control system according to Example 3 is described, in which a warning or similar is issued when the control unit 200 receives configuration information that differs from the configuration information stored in the memory unit. First, a case is described in which the configuration information sent by encoder 1 changes to configuration information that differs from the configuration information previously received by the control unit 200. Fig. Figure 8 shows an example where, in control system 101, the configuration information sent by the encoder changes according to Example 1. Fig. 8. It is assumed that the normal configuration information d1 sent by encoder 1 is information indicating that the multirotation data is 12 bits and the absolute position data is 16 bits. At this time, the configuration information may be abnormal due to noise, a component failure, and the like, or the configuration information may change as a result of replacing the encoder. As in Fig. As shown in Figure 8, for example, it is assumed that the configuration information d1 in the serial communication circuit has changed to the configuration information d2, which indicates that the multi-rotation data is 11 bits and the absolute position data is 17 bits.

[0062] In the control system according to Example 1, the control unit 2 is not equipped with the storage unit and therefore cannot detect changes to the configuration information. The configuration information d2, which has changed from the normal configuration information, is used as is. As a result, because the weighting of the position data (the distribution of the multi-rotation data and the absolute position data) changes, the control is executed based on the faulty position information.

[0063] In contrast, in the control system 103 according to Example 3, the storage unit 23 initially stores the normal configuration information received from the encoder 1. Fig. Figure 9A shows a state in which, in the control system according to Example 3, the control unit 200 stores the normal configuration information initially sent by the encoder. It is assumed that the normal configuration information d1 in the response signal sent by encoder 1 is the information indicating that the multi-rotation data is 12 bits and the absolute position data is 16 bits. The memory unit 23 stores this normal configuration information d1.

[0064] Fig.Figure 9B shows an example where, in the control system from Example 3, after the initial configuration information sent by the encoder was saved, the subsequent configuration information has changed. In the serial communication loop, for example, it is assumed that the normal configuration information d1 has changed to configuration information d2, which specifies that the multi-rotation data is 11 bits and the absolute position data is 17 bits. Examples of cases where the configuration information is sent multiple times include situations where the encoder has been changed, the control system has been reactivated, the configuration information has been sent multiple times to confirm that it has not changed, etc.

[0065] The reporting unit 24 sends a configuration discrepancy message if the normal configuration information stored in the storage unit 23 (X = 12, Y = 16) does not match the configuration information (X = 11, Y = 17) received next by the receiving unit 21. The control unit 200 can stop controlling the target object (e.g., motor 10) when the reporting unit 24 sends a configuration discrepancy message.

[0066] Thus, according to the control system shown in Example 3, by storing the configuration information of encoder 1 (the position data configuration) in the control unit 200, a comparison can be made with the retransmitted configuration information. If a change is detected, an operational anomaly can be prevented by generating warning information or by stopping the processing of the position information in conjunction with generating the warning information. Furthermore, in the event that the configuration information is read incorrectly, an operational anomaly can also be prevented by generating warning information or by stopping the processing of the position information in conjunction with generating the warning information. Additionally, it is possible to use the fact that the configuration information has changed to check whether the encoder has been replaced.

[0067] The control unit 200 can further include a display unit 25 that shows the configuration discrepancy as visual information. In a case where the signaling unit 24 generates warning information or a command to stop the processing of the position information, the signaling unit 24 can display on the display unit 25 the possibility that the encoder has been replaced by another encoder. By performing such a display, a user can easily recognize the possibility that the encoder has been replaced.

[0068] Furthermore, the transmitter unit 13 of the encoder 1 can send the encoder specification information along with the configuration information. The encoder specification information preferably includes information relating to the drawing number, model, serial number of the encoder, and / or the like. Additionally, the transmitter unit 13 can send the encoder specification information when the control unit 200 sends a signal requesting this information. Sending the encoder specification information allows the control unit to verify whether the encoder has been replaced.

[0069] The control unit 200 can further include an update processing unit 26, which overwrites the configuration information stored in the storage unit 23 with the configuration information received next by the receiving unit 21. With such a configuration, after the encoder has been replaced by a new encoder, the position information can be processed using the configuration information of the new encoder.

[0070] The control unit 22, the signaling unit 24 and the update processing unit 26, which are provided in the control device 200, can be implemented by hardware, such as a circuit executing their functions, or by a computing device, such as a CPU (central processing unit), which uses software executing their functions accordingly.

Claims

[1] Tax system that includes: - an encoder (1) and - a control device (2, 20, 200) which is arranged to control a target object using information sent from the encoder (1) via serial communication, - wherein the encoder (1) comprises: - a position information generation unit (11) configured to generate position information consisting of a predetermined amount of data and containing absolute position data of an object to be detected, - a configuration information generation unit (12) configured to generate configuration information indicating a proportion of the absolute position data in the data set during serial communication, and - a transmitting unit (13) configured to transmit the position information and the configuration information as serial data to the control device, and - wherein the control device (2, 20, 200) comprises: - a receiving unit (21) configured to receive the position information and configuration information sent by the encoder (1), - a storage unit (23) configured to store the configuration information received by the receiving unit (21), and - a reporting unit (24) configured to report a configuration discrepancy when the configuration information stored in the storage unit (23) does not match the configuration information received by the receiving unit (21) the next time. [2] The control system according to claim 1, wherein the control device (2, 20, 200) stops the control of the target object when the notification unit (24) performs the notification of the configuration discrepancy. [3] A control system according to claim 1 or 2, further comprising a display device (25) arranged to display the configuration discrepancy as visual information. [4] A control system according to any one of claims 1 to 3, wherein the control device (2, 20, 200) further comprises an update processing unit (26) configured to overwrite the configuration information stored in the storage unit (23) with the configuration information received by the receiving unit (21) next time. [5] Control system according to one of claims 1 to 4, wherein - the position information generating unit (11) generates the position information containing the absolute position data and multi-rotation data of the object to be detected, and - the configuration information generation unit (12) generates the configuration information indicating a division of the absolute position data and the multi-rotation data in the data set during the serial communication. [6] An encoder (1) provided in the control system according to any one of claims 1 to 5, wherein the transmitting unit (13) is configured to transmit the position information corresponding to the configuration information to the control device (2, 20, 200).

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