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Add modbus library
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scripts/examples/32-modbus/modbus_rtu_slave.py
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12
scripts/examples/32-modbus/modbus_rtu_slave.py
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import time
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from pyb import UART
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from modbus import ModbusRTU
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uart = UART(3)
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modbus = ModbusRTU(uart)
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while(True):
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if modbus.any():
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modbus.handle()
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else:
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time.sleep(100)
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# image processing in there
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scripts/libraries/modbus.py
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scripts/libraries/modbus.py
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import struct
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class ModbusRTU():
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def __init__(self, uart, slave_id=0x01):
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self.SLAVE_ID = slave_id
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self.uart = uart
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self.uart.init(19200, bits=8, parity=0, stop=1, timeout=1, timeout_char=4)
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self.HOLDING_REGISTERS = [0]*30
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def any(self):
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return self.uart.any()
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def crc16(self, data):
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crc = 0xFFFF
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CRC16_TABLE = [
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0x0000,0xC0C1,0xC181,0x0140,0xC301,0x03C0,0x0280,0xC241,0xC601,
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0x06C0,0x0780,0xC741,0x0500,0xC5C1,0xC481,0x0440,0xCC01,0x0CC0,
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0x0D80,0xCD41,0x0F00,0xCFC1,0xCE81,0x0E40,0x0A00,0xCAC1,0xCB81,
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0x0B40,0xC901,0x09C0,0x0880,0xC841,0xD801,0x18C0,0x1980,0xD941,
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0x1B00,0xDBC1,0xDA81,0x1A40,0x1E00,0xDEC1,0xDF81,0x1F40,0xDD01,
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0x1DC0,0x1C80,0xDC41,0x1400,0xD4C1,0xD581,0x1540,0xD701,0x17C0,
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0x1680,0xD641,0xD201,0x12C0,0x1380,0xD341,0x1100,0xD1C1,0xD081,
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0x1040,0xF001,0x30C0,0x3180,0xF141,0x3300,0xF3C1,0xF281,0x3240,
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0x3600,0xF6C1,0xF781,0x3740,0xF501,0x35C0,0x3480,0xF441,0x3C00,
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0xFCC1,0xFD81,0x3D40,0xFF01,0x3FC0,0x3E80,0xFE41,0xFA01,0x3AC0,
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0x3B80,0xFB41,0x3900,0xF9C1,0xF881,0x3840,0x2800,0xE8C1,0xE981,
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0x2940,0xEB01,0x2BC0,0x2A80,0xEA41,0xEE01,0x2EC0,0x2F80,0xEF41,
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0x2D00,0xEDC1,0xEC81,0x2C40,0xE401,0x24C0,0x2580,0xE541,0x2700,
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0xE7C1,0xE681,0x2640,0x2200,0xE2C1,0xE381,0x2340,0xE101,0x21C0,
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0x2080,0xE041,0xA001,0x60C0,0x6180,0xA141,0x6300,0xA3C1,0xA281,
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0x6240,0x6600,0xA6C1,0xA781,0x6740,0xA501,0x65C0,0x6480,0xA441,
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0x6C00,0xACC1,0xAD81,0x6D40,0xAF01,0x6FC0,0x6E80,0xAE41,0xAA01,
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0x6AC0,0x6B80,0xAB41,0x6900,0xA9C1,0xA881,0x6840,0x7800,0xB8C1,
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0xB981,0x7940,0xBB01,0x7BC0,0x7A80,0xBA41,0xBE01,0x7EC0,0x7F80,
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0xBF41,0x7D00,0xBDC1,0xBC81,0x7C40,0xB401,0x74C0,0x7580,0xB541,
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0x7700,0xB7C1,0xB681,0x7640,0x7200,0xB2C1,0xB381,0x7340,0xB101,
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0x71C0,0x7080,0xB041,0x5000,0x90C1,0x9181,0x5140,0x9301,0x53C0,
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0x5280,0x9241,0x9601,0x56C0,0x5780,0x9741,0x5500,0x95C1,0x9481,
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0x5440,0x9C01,0x5CC0,0x5D80,0x9D41,0x5F00,0x9FC1,0x9E81,0x5E40,
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0x5A00,0x9AC1,0x9B81,0x5B40,0x9901,0x59C0,0x5880,0x9841,0x8801,
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0x48C0,0x4980,0x8941,0x4B00,0x8BC1,0x8A81,0x4A40,0x4E00,0x8EC1,
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0x8F81,0x4F40,0x8D01,0x4DC0,0x4C80,0x8C41,0x4400,0x84C1,0x8581,
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0x4540,0x8701,0x47C0,0x4680,0x8641,0x8201,0x42C0,0x4380,0x8341,
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0x4100,0x81C1,0x8081,0x4040
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]
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for char in data:
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crc = (crc >> 8) ^ CRC16_TABLE[((crc) ^ char) & 0xFF]
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return struct.pack('<H',crc)
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def handle(self):
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REQUEST = self.uart.read()
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additional_address = REQUEST[0]
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error_check = REQUEST[-2:]
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function_code = REQUEST[1]
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data = REQUEST[2:]
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RESPONSE = struct.pack('b', self.SLAVE_ID)
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if self.SLAVE_ID != additional_address:
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RESPONSE += struct.pack('b', function_code|0x80)
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RESPONSE += struct.pack('b', 0x04)#SLAVE_ID
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elif self.crc16(REQUEST[:-2]) != error_check:
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RESPONSE += struct.pack('b', function_code|0x80)
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RESPONSE += struct.pack('b', 0x04)#CRC error
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elif function_code == 0x03:
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starting_address = struct.unpack('>h', data[:2])[0]
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quantity_of_registers = struct.unpack('>h', data[2:4])[0]
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response_registers = self.HOLDING_REGISTERS[starting_address:starting_address+quantity_of_registers]
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RESPONSE += struct.pack('b', function_code)
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RESPONSE += struct.pack('b', 2*quantity_of_registers)
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for b in response_registers:
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RESPONSE += struct.pack('>h', b)
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elif function_code == 0x06:
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register_address = struct.unpack('>h', data[:2])[0]
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register_value = struct.unpack('>h', data[2:4])[0]
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self.HOLDING_REGISTERS[register_address] = register_value
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RESPONSE += struct.pack('b', function_code)
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RESPONSE += struct.pack('>h', register_address)
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RESPONSE += struct.pack('>h', self.HOLDING_REGISTERS[register_address])
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elif function_code == 0x10:
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starting_address = struct.unpack('>h', data[:2])[0]
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quantity_of_registers = struct.unpack('>h', data[2:4])[0]
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byte_of_registers = struct.unpack('b', data[4:5])[0]
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values = struct.unpack('>%dh'%quantity_of_registers, data[5:])
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self.HOLDING_REGISTERS[starting_address:starting_address+quantity_of_registers] = values
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if byte_of_registers == 2*quantity_of_registers:
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RESPONSE += struct.pack('b', function_code)
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RESPONSE += struct.pack('>h', starting_address)
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RESPONSE += struct.pack('>h', quantity_of_registers)
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else:
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RESPONSE += struct.pack('b', function_code|0x80)
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RESPONSE += struct.pack('b', 0x04)
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else:
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RESPONSE += struct.pack('b', function_code|0x80)
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RESPONSE += struct.pack('b', 0x01)#not support
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RESPONSE += self.crc16(RESPONSE)
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print(RESPONSE)
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self.uart.write(RESPONSE)
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