Class: RS232

Inherits:
Object
  • Object
show all
Defined in:
lib/rs232.rb

Defined Under Namespace

Modules: Win32 Classes: CommTimeouts, DCB

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(address, params = {}) ⇒ RS232

serial port object constructor also sets the parameters and timeout properties through an hash argument

hash arguments options:
  :mode
  :file
  :attr
  :dcblength
  :baudrate
  :bytesize
  :stopbits
  :parity
  :delimiter
  :read_interval_timeout
  :read_total_timeout_multiplier
  :read_total_timeout_constant
  :write_total_timeout_multiplier
  :write_total_timeout_constant



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# File 'lib/rs232.rb', line 27

def initialize address, params = {} 
  mode  = params[:mode]  || Win32::GENERIC_READ | Win32::GENERIC_WRITE
  share = params[:share] || 0 #Win32::FILE_SHARE_DELETE
  type  = params[:file]  || Win32::OPEN_EXISTING
  attr  = params[:attr]  || Win32::FILE_ATTRIBUTE_NORMAL

  @serial = Win32::CreateFileA( address, mode, share, nil, type, attr, nil) 
  @error  = Win32.error_check

  puts "RS232 >> got file handle 0x%.8x for com port %s" % [@serial, address]   

  # com port connection configuration with C struct
  DCB.new.tap do |p|  # check below for DCB struct definition
    p[:dcblength] = DCB::Sizeof  
    Win32::GetCommState @serial, p
    p[:baudrate] = params[:baudrate] || 9600
    p[:bytesize] = params[:bytesize] || 8
    p[:stopbits] = params[:stopbits] || DCB::ONESTOPBIT
    p[:parity]   = params[:parity]   || DCB::NOPARITY
    Win32::SetCommState @serial, p
    @error = Win32.error_check
  end        

  # com port connection timeouts configuration with C struct
  CommTimeouts.new.tap do |timeouts|
    timeouts[:read_interval_timeout]          = params[:read_interval_timeout]          ||  50 
    timeouts[:read_total_timeout_multiplier]  = params[:read_total_timeout_multiplier]  ||  50
    timeouts[:read_total_timeout_constant]    = params[:read_total_timeout_constant]    ||  10
    timeouts[:write_total_timeout_multiplier] = params[:write_total_timeout_multiplier] ||  50
    timeouts[:write_total_timeout_constant]   = params[:write_total_timeout_constant]   ||  10     
    Win32::SetCommTimeouts @serial, timeouts
    @error = Win32.error_check
  end    

  grow_buffer 128
  @count = FFI::MemoryPointer.new :uint, 1
  @report = false
  @delimiter = params[:delimiter] || "\r\n"
end

Instance Attribute Details

#count ⇒ Object (readonly)

number of last read/write bits



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# File 'lib/rs232.rb', line 7

def count
  @count
end

#delimiter ⇒ Object

flag set by client, if true reports read/write bits



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# File 'lib/rs232.rb', line 5

def delimiter
  @delimiter
end

#error ⇒ Object (readonly)

number of last read/write bits



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# File 'lib/rs232.rb', line 7

def error
  @error
end

#report ⇒ Object

flag set by client, if true reports read/write bits



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# File 'lib/rs232.rb', line 5

def report
  @report
end

Instance Method Details

#grow_buffer(size) ⇒ Object

increases the buffer size for reading and writing



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# File 'lib/rs232.rb', line 100

def grow_buffer size
  if @buffer.nil? || @buflen < size
    @buffer = FFI::MemoryPointer.new :char, @buflen = size
  end
end

#query(string) ⇒ Object

write + read helper method for queries



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# File 'lib/rs232.rb', line 88

def query string
  write string
  read
end

#read ⇒ Object

reads a string from the Serial port



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# File 'lib/rs232.rb', line 80

def read
  Win32::ReadFile @serial, @buffer, @buflen, @count, nil
  @error = Win32.error_check
  puts "read count %i" % @count.read_uint32 if @report
  @buffer.read_string.chomp
end

#stop ⇒ Object

closes the Com port TODO: sets this as object finilizer



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# File 'lib/rs232.rb', line 94

def stop
  Win32::CloseHandle @serial
  @error = Win32.error_check
end

#write(string) ⇒ Object

writes a string to the Serial port automatically appends the delimiter characters stored in @delimiter



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# File 'lib/rs232.rb', line 69

def write string
  command = "%s%s" % [string.chomp, @delimiter]
  grow_buffer command.length
  @buffer.write_string  command
  Win32::WriteFile @serial, @buffer, command.length, @count, nil
  @error = Win32.error_check
  @buffer.write_string "\0" #empty string buffer
  puts "write count %i" % @count.read_uint32 if @report
end