Class: Simatic::Sessions::ReadSession

Inherits:
ExchangeSession show all
Defined in:
lib/simatic/sessions/read_session.rb

Overview

Read communication session

Instance Method Summary collapse

Methods inherited from Session

#packet_number

Constructor Details

#initialize ⇒ ReadSession 



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# File 'lib/simatic/sessions/read_session.rb', line 7

def initialize
  @read_memory = []
end

Instance Method Details

#make_request(memory_mappers) ⇒ Object

def add memory

@read_memory << memory if memory.instance_of? MemoryMapper

end



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# File 'lib/simatic/sessions/read_session.rb', line 15

def make_request memory_mappers
  @memory_mappers = memory_mappers
  param = [ FuncRead, # 8bit function

            @memory_mappers.count, # count of read-requests

          ].pack('C2')

  @memory_mappers.each do |memory_mapper|
    param += read_request memory_mapper
  end

  super param
end

#parse_response(raw_data) ⇒ Object 



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# File 'lib/simatic/sessions/read_session.rb', line 28

def parse_response raw_data
  super raw_data

  unless FuncRead == @function
    raise "unknown function 0x#{@function.to_s(16)} in #{self.class} response"
  end

  start_byte = 0
  data_block_number = 0
  while start_byte < @data.length

    unless @data[start_byte, 1].unpack('C').first == 0xff || @data[start_byte+=1, 1].unpack('C').first == 0xff  
      raise "one of data block is broken in #{self.class} response"
    end

    data_lenght_type = @data[start_byte+1,1].unpack('C').first # 4 - bits,

                                                               # 9 - bytes,

                                                               # 3 - bits + byte

    data_lenght_raw = @data[start_byte+2,2].unpack('n').first

    data_lenght = data_lenght_raw
    data_lenght = data_lenght_raw / 8 if data_lenght_type == 4

    @memory_mappers[data_block_number].raw_data = @data[start_byte + 4, data_lenght]

    start_byte += 4 + data_lenght
    data_block_number += 1
  end

  @memory_mappers = @memory_mappers.first if @memory_mappers.count == 1
  @memory_mappers
end