Inquiries about using SKU:SEN0492

I recently purchased the SKU:SEN0492 sensor, and I have some questions about this.

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I'm using a sensor and RS485 to usb module to test it before it's actually used.

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I wrote Python code that fetches distance data once a second, and there is a problem when I execute it.

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At first, I get the data well, but there is a problem that the value of the data is fixed from a certain point in time. When I move the laser, it is fixed to any value, so the value does not change.

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Below is an example distance value.

200mm, 10mm, 399mm ...... 12mm, 15mm, 15mm, 15mm, 15mm, 15mm, 15mm ......

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I don't know at what point or which of these problems arise. Is it a code problem? Or is it a hardware problem?

Can you tell me the cause of the problem? I attached my code together.

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Please give me any details or explanations on these matters.

import serial

import time

ser = serial.Serial('/dev/ttyLaser', baudrate=115200, bytesize=serial.EIGHTBITS,

                    parity=serial.PARITY_NONE, stopbits=serial.STOPBITS_ONE, timeout=1)

slave_address1 = 0x50

function_code1 = 0x03

register_address_high1 = 0x00

register_address_low1 = 0x34

read_length_high1 = 0x00

read_length_low1 = 0x01

crc_check_high1 = 0xC8

crc_check_low1 = 0x45

request_data1 = bytes([slave_address1, function_code1, register_address_high1, register_address_low1,

                      read_length_high1, read_length_low1, crc_check_high1, crc_check_low1])

response_length1 = 7 

response_data1 = None

def crc16(data):

        crc = 0xFFFF

        for b in data:

            crc ^= b

            for _ in range(8):

                if crc & 0x0001:

                    crc >>= 1

                    crc ^= 0xA001

                else:

                    crc >>= 1

        return crc.to_bytes(2, byteorder='little')

while True:

    ser.write(request_data1)

    data1 = ser.read(response_length1)

    if len(data1) == response_length1:

        crc_high1, crc_low1 = crc16(data1[:-2])

        if crc_high1 == data1[-2] and crc_low1 == data1[-1]:

            response_data1 = data1

            if response_data1:

                slave_address1, function_code1, data_length1, data_high1, data_low1, crc_high1, crc_low1 = response_data1

                data_value1 = (data_high1 << 8) + data_low1

                print(f"Response data1 (hex): {' '.join(f'{b:02X}' for b in response_data1)}")

                print(f"Slave address1: 0x{hex(slave_address1)[2:].zfill(2)}")

                print(f"Function code1: 0x{hex(function_code1)[2:].zfill(2)}")

                print(f"Data length1: 0x{hex(data_length1)[2:].zfill(2)}")

                print(f"Data value1: 0x{hex(data_value1)[2:].zfill(4)}")

                print(f"Data value1: {int(hex(data_value1), 16)}")

                print(f"CRC1: {' '.join(f'{b:02X}' for b in [crc_high1, crc_low1])}")

            else:

                print("Failed to receive sensor data.")

            time.sleep(1)

    else:

        print("Waiting for data...")

        continue