JP2001082983A - Encoder receiving circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the position detecting accuracy of a motor control device combined with an encoder for detecting the amount of movement or the absolute position of a motor and transmitting detected data to the motor control device by serial data transmission. SOLUTION: This encoder receiving circuit comprises: a serial-to-parallel converting part 1 for receiving serial data and converting it into parallel data; a data latching circuit 2 for latching count data; a presettable up-down counter 3 for simulating count data for the actual time of an encoder; a pulse oscillator 4 for generating up-down pulses; a frequency setting circuit 5 determining the frequencies and directions of the pulses; and a capturing circuit 6 for capturing data on the up-down counter.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an encoder receiving circuit of a motor control device for detecting a moving amount or an absolute position of a motor and combining the detected data with an encoder for transmitting the detected data to the motor control device by serial data transmission. .

[0002]

2. Description of the Related Art In an encoder that detects the amount of movement of a motor as the number of pulses, it is necessary to increase the number of pulses output from the encoder per unit length in order to increase the resolution of the amount of movement. However, on the other hand, the pulse frequency increases, and becomes close to the frequency of noise mixed into the data transmission path, so that the motor control device may not be able to count correctly.

As a solution to this, there is a method in which pulses are counted on the encoder side, and the counted data is transmitted to the motor control device at regular intervals using a serial communication technique. According to this method, the data modulation speed, that is, the pulse frequency is constant irrespective of the moving speed of the motor, and if the data modulation speed is sufficiently lower than the frequency of the noise, the motor control device can correctly count. Further, according to this method, data obtained by detecting the absolute position of the motor as a pulse code can be processed by the same method. Further, if an error correction code is added to transmission data, more accurate reception can be achieved.

However, in this method, the count data counted by the encoder is transmitted to the motor control device at regular intervals, so that the motor control device can reproduce only the count data at the time of reception. That is, the count data changing during the data transmission time is not known.

[0005]

The problem to be solved is that the encoder of the motor control device is combined with an encoder that detects the amount of movement or the absolute position of the motor and transmits the detected data to the motor control device by serial data transmission. The point that the receiving circuit cannot detect the real-time count data of the encoder during the data transmission time point.

[0006]

The invention according to claim 1 is characterized in that an up / down counter for simulating the count data of the encoder is built in the encoder receiving circuit, and the count data received from the encoder is stored in the up / down counter. The up / down counter is preset, and the count data of the up / down counter is changed at the frequency and direction calculated from the count data received this time and the change amount of the counter data received up to the previous time.

According to a second aspect of the present invention, in the first aspect of the present invention, there is provided a circuit for capturing count data of an up / down counter simulating count data of an encoder, and changes with time. The count data is captured at a timing synchronized with an external event.

According to the present invention, since the up / down counter for simulating the count data of the encoder is provided, it is possible to estimate and detect the real-time count data of the encoder during the data transmission time. Further, by capturing the count data with an external signal, the count data at the time of occurrence of an external event that is asynchronous with the data transmission cycle can be estimated and detected. Further, the data transmission cycle and the control cycle such as speed can be made asynchronous by the capture function.

According to a third aspect of the present invention, in the first and second aspects, the frequency setting circuit is replaced by software processing.

According to the present invention, the scale of a hardware circuit can be reduced. Furthermore, the degree of freedom of the frequency calculation method is increased, and an advanced calculation method that cannot be performed by a hardware circuit can be employed.

[0011]

An embodiment of the present invention will be described below.

FIG. 1 is a block diagram of an encoder receiving circuit according to one embodiment of the present invention. In FIG. 1, 1 is a serial / parallel converter, 2 is a data latch, 3 is an up / down counter, 4 is a pulse oscillator, 5 is a frequency setting circuit, and 6 is a capture circuit.

The operation of the encoder receiving circuit configured as described above will be described. From the encoder, count data of the encoder sampled at regular intervals and status data of the encoder are transmitted as serial data.

The serial / parallel converter 1 converts the serial data into parallel data. Parts other than the count data in the converted parallel data are processed by a circuit (not shown).

The count data converted into parallel data is latched by the data latch unit 2.

The latched count data is preset in the up / down counter 3 by the latch completion signal output from the data latch unit 2, and the frequency setting circuit 5 compares the count data up to the previous time with the data in the data latch unit 2. From the change in the count data, the amount of change until the next data transmission is predicted, and the frequency at which pulses corresponding to the amount of change are generated at equal intervals during the data transmission cycle and the direction of the change are determined.

According to the frequency and direction determined by the frequency setting circuit 5, the pulse generator 4 generates an up pulse or a down pulse designated by the direction at the frequency.

The pulses generated by the pulse oscillator 4 are counted by the up / down counter 3.

With the above operation, the estimated value of the real-time count data of the encoder during the data transmission time is obtained in the up-down counter 3. Since the up / down counter 3 is preset with the latest received data, the estimation error does not accumulate.

Next, the capture function will be described.
The capture circuit 6 captures count data of the up / down counter 3 using an external signal.

By the above operation, the capture circuit 6 obtains an estimated value of the real-time count data of the encoder when an external event occurs which is asynchronous with the data transmission cycle.
If the external event is used as a sampling cycle for speed control, the data transmission cycle and the speed control cycle can be made asynchronous.
If a plurality of capture circuits are provided, a plurality of external events can be handled.

[0022]

As described above, since the encoder receiving circuit of the present invention has an estimated value of the real-time count data of the encoder in the receiving circuit, the count data during the data transmission time can be estimated and detected. . Further, by capturing the estimated value of the count data by an external signal, it is possible to estimate and detect the real-time count data of the encoder when an external event occurs that is asynchronous with the data transmission cycle. Further, the data transmission cycle and the control cycle such as speed can be made asynchronous by the capture function.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of one embodiment of an encoder receiving circuit of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Serial-parallel conversion part 2 Data latch part 3 Up / down counter 4 Pulse oscillator 5 Frequency setting circuit 6 Capture circuit

Claims (3)

[Claims] 1. An encoder receiving circuit of a motor control device for detecting an amount of movement or an absolute position of a motor and transmitting the detected data to the motor control device by serial data transmission in an encoder receiving circuit of the motor control device. A serial-to-parallel conversion unit for receiving and parallel-converting the data, a data latch unit for latching count data from the serial-to-parallel conversion unit, a presettable up / down counter that simulates real-time count data of an encoder, and an up / down counter. An encoder receiving circuit including a pulse generator that generates a pulse and a frequency setting circuit that determines a pulse frequency and a direction. 2. The encoder according to claim 1, further comprising a capture circuit for capturing data of a presettable up / down counter simulating real-time count data of the encoder at a timing asynchronous with a data transmission timing from the encoder. Receiver circuit. 3. The encoder receiving circuit according to claim 1, wherein the data latch unit is readable from the CPU, the pulse oscillator is writable from the CPU, and the frequency setting circuit is replaced by software processing. 2. The encoder receiving circuit according to 2.