Module: ModBus::RTU

Included in:

RTUClient, RTUServer, RTUSlave, RTUViaTCPClient, RTUViaTCPServer, RTUViaTCPSlave

Defined in:

lib/rmodbus/rtu.rb

Constant Summary

CHUNK_SIZE =

1500

CrcHiTable =

[
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81,
0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01,
0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81,
0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01,
0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81,
0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01,
0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81,
0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0,
0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01,
0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81, 0x40, 0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41,
0x00, 0xC1, 0x81, 0x40, 0x01, 0xC0, 0x80, 0x41, 0x01, 0xC0, 0x80, 0x41, 0x00, 0xC1, 0x81,
0x40]

CrcLoTable =

[
0x00, 0xC0, 0xC1, 0x01, 0xC3, 0x03, 0x02, 0xC2, 0xC6, 0x06, 0x07, 0xC7, 0x05, 0xC5, 0xC4,
0x04, 0xCC, 0x0C, 0x0D, 0xCD, 0x0F, 0xCF, 0xCE, 0x0E, 0x0A, 0xCA, 0xCB, 0x0B, 0xC9, 0x09,
0x08, 0xC8, 0xD8, 0x18, 0x19, 0xD9, 0x1B, 0xDB, 0xDA, 0x1A, 0x1E, 0xDE, 0xDF, 0x1F, 0xDD,
0x1D, 0x1C, 0xDC, 0x14, 0xD4, 0xD5, 0x15, 0xD7, 0x17, 0x16, 0xD6, 0xD2, 0x12, 0x13, 0xD3,
0x11, 0xD1, 0xD0, 0x10, 0xF0, 0x30, 0x31, 0xF1, 0x33, 0xF3, 0xF2, 0x32, 0x36, 0xF6, 0xF7,
0x37, 0xF5, 0x35, 0x34, 0xF4, 0x3C, 0xFC, 0xFD, 0x3D, 0xFF, 0x3F, 0x3E, 0xFE, 0xFA, 0x3A,
0x3B, 0xFB, 0x39, 0xF9, 0xF8, 0x38, 0x28, 0xE8, 0xE9, 0x29, 0xEB, 0x2B, 0x2A, 0xEA, 0xEE,
0x2E, 0x2F, 0xEF, 0x2D, 0xED, 0xEC, 0x2C, 0xE4, 0x24, 0x25, 0xE5, 0x27, 0xE7, 0xE6, 0x26,
0x22, 0xE2, 0xE3, 0x23, 0xE1, 0x21, 0x20, 0xE0, 0xA0, 0x60, 0x61, 0xA1, 0x63, 0xA3, 0xA2,
0x62, 0x66, 0xA6, 0xA7, 0x67, 0xA5, 0x65, 0x64, 0xA4, 0x6C, 0xAC, 0xAD, 0x6D, 0xAF, 0x6F,
0x6E, 0xAE, 0xAA, 0x6A, 0x6B, 0xAB, 0x69, 0xA9, 0xA8, 0x68, 0x78, 0xB8, 0xB9, 0x79, 0xBB,
0x7B, 0x7A, 0xBA, 0xBE, 0x7E, 0x7F, 0xBF, 0x7D, 0xBD, 0xBC, 0x7C, 0xB4, 0x74, 0x75, 0xB5,
0x77, 0xB7, 0xB6, 0x76, 0x72, 0xB2, 0xB3, 0x73, 0xB1, 0x71, 0x70, 0xB0, 0x50, 0x90, 0x91,
0x51, 0x93, 0x53, 0x52, 0x92, 0x96, 0x56, 0x57, 0x97, 0x55, 0x95, 0x94, 0x54, 0x9C, 0x5C,
0x5D, 0x9D, 0x5F, 0x9F, 0x9E, 0x5E, 0x5A, 0x9A, 0x9B, 0x5B, 0x99, 0x59, 0x58, 0x98, 0x88,
0x48, 0x49, 0x89, 0x4B, 0x8B, 0x8A, 0x4A, 0x4E, 0x8E, 0x8F, 0x4F, 0x8D, 0x4D, 0x4C, 0x8C,
0x44, 0x84, 0x85, 0x45, 0x87, 0x47, 0x46, 0x86, 0x82, 0x42, 0x43, 0x83, 0x41, 0x81, 0x80,
0x40]

Instance Method Summary (collapse)

• - (Object) clean_input_buff private
• - (Object) crc16(msg) private

  Calc CRC16 for massage.

• - (Object) read_rtu_pdu private
• - (Object) read_rtu_request(io) private
• - (Object) read_rtu_response(io) private

  We have to read specific amounts of numbers of bytes from the network depending on the function code and content.

• - (Object) send_rtu_pdu(pdu) private
• - (Object) serv_rtu_requests(io, &blk) private

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# File 'lib/rmodbus/rtu.rb', line 49

def clean_input_buff
  win_platform = RUBY_PLATFORM.include? "mingw"
  begin
    # Read up to CHUNK_SIZE bytes of trash.
    if win_platform
      # non-blocking reads are not supported by Windows
      @io.readpartial(CHUNK_SIZE)
    else
      @io.read_nonblock(CHUNK_SIZE)
    end
  rescue Errno::EAGAIN
    # Ignore the fact we couldn't read.
  rescue Exception => e
    raise e unless win_platform && e.is_a?(EOFError) # EOFError means we are done
  end
end

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# File 'lib/rmodbus/rtu.rb', line 136

def crc16(msg)
  crc_lo = 0xff
  crc_hi = 0xff

  msg.unpack('c*').each do |byte|
    i = crc_hi ^ byte
    crc_hi = crc_lo ^ CrcHiTable[i]
    crc_lo = CrcLoTable[i]
  end

  return ((crc_hi << 8) + crc_lo)
end

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# File 'lib/rmodbus/rtu.rb', line 76

def read_rtu_pdu
  msg = read_rtu_response(@io)

  log "Rx (#{msg.size} bytes): " + logging_bytes(msg)

  if msg.getbyte(0) == @uid
    return msg[1..-3] if msg[-2,2].unpack('n')[0] == crc16(msg[0..-3])
    log "Ignore package: don't match CRC"
  else
    log "Ignore package: don't match uid ID"
  end
  loop do
    #waite timeout
    sleep(0.1)
  end
end

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# File 'lib/rmodbus/rtu.rb', line 93

def read_rtu_request(io)
	# Read the slave_id and function code
	msg = io.read(2)

	# If msg is nil, then our client never sent us anything and it's time to disconnect
	return if msg.nil?

	function_code = msg.getbyte(1)
	if [1, 2, 3, 4, 5, 6].include?(function_code)
		# read 6 more bytes and return the message total message
		msg += io.read(6)
	elsif [15, 16].include?(function_code)
		# Read in first register, register count, and data bytes
		msg += io.read(5)
		# Read in however much data we need to + 2 CRC bytes
		msg += io.read(msg.getbyte(6) + 2)
	else
		raise ModBus::Errors::IllegalFunction, "Illegal function: #{function_code}"
	end

	log "Server RX (#{msg.size} bytes): #{logging_bytes(msg)}"

	msg
end

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# File 'lib/rmodbus/rtu.rb', line 23

def read_rtu_response(io)
 # Read the slave_id and function code
  msg = nil
  while msg.nil?
   msg = io.read(2)
  end

  function_code = msg.getbyte(1)
  case function_code
    when 1,2,3,4 then
      # read the third byte to find out how much more
      # we need to read + CRC
      msg += io.read(1)
      msg += io.read(msg.getbyte(2)+2)
    when 5,6,15,16 then
      # We just read in an additional 6 bytes
      msg += io.read(6)
    when 22 then
      msg += io.read(8)
    when 0x80..0xff then
      msg += io.read(3)
    else
      raise ModBus::Errors::IllegalFunction, "Illegal function: #{function_code}"
  end
end

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# File 'lib/rmodbus/rtu.rb', line 66

def send_rtu_pdu(pdu)
  msg = @uid.chr + pdu
  msg << crc16(msg).to_word
  
  clean_input_buff  
  @io.write msg

  log "Tx (#{msg.size} bytes): " + logging_bytes(msg)
end

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# File 'lib/rmodbus/rtu.rb', line 118

def serv_rtu_requests(io, &blk)
  loop do
    # read the RTU message
    msg = read_rtu_request(io)
    # If there is no RTU message, we're done serving this client
    break if msg.nil?

    if msg.getbyte(0) == @uid and msg[-2,2].unpack('n')[0] == crc16(msg[0..-3])
      pdu = yield msg
      resp = @uid.chr + pdu
      resp << crc16(resp).to_word
      log "Server TX (#{resp.size} bytes): #{logging_bytes(resp)}"
      io.write resp
  end
 end
end