How to get numbers from a log message in logstash?

Thank you everybody who answers my question.. Especially, Ben Lim.

With your help, I got this result.

{
      "@version" => "1",
    "@timestamp" => "2014-02-20T11:07:28.125Z",
          "type" => "syslog",
          "host" => "ymkim-SD550",
          "path" => "/var/log/syslog",
            "ts" => "Feb 20 21:07:27",
          "user" => "ymkim",
          "func" => "REG",
          "8192" => 16,
          "8193" => 32,
          "8194" => 17,
          "8195" => 109
}

from $ logger REG,2000,4,10,20,11,6d

This is my config file.

input { 
  file { 
        path => "/var/log/syslog"
        type => "syslog"
  } 
}

filter {
  grok {
        match => ["message", "%{SYSLOGTIMESTAMP:ts} %{SYSLOGHOST:hostname} %{WORD:user}: %{WORD:func},%{WORD:address},%{NUMBER:regNumber},%{GREEDYDATA:regValue}"]
  }

  if [func] == "REG" {  
      modbus_csv {
          start_address => "address"
          num_register => "regNumber"
          source => "regValue"
          remove_field => ["regValue", "hostname", "message", 
                "address", "regNumber"]
      }
  }

}

output {
    stdout { debug => true }
  elasticsearch { }
}

and modified csv filter, named modbus_csv.rb.

# encoding: utf-8
require "logstash/filters/base"
require "logstash/namespace"

require "csv"

# CSV filter. Takes an event field containing CSV data, parses it,
# and stores it as individual fields (can optionally specify the names).
class LogStash::Filters::MODBUS_CSV < LogStash::Filters::Base
  config_name "modbus_csv"
  milestone 2

  # The CSV data in the value of the source field will be expanded into a
  # datastructure.
  config :source, :validate => :string, :default => "message"

  # Define a list of column names (in the order they appear in the CSV,
  # as if it were a header line). If this is not specified or there
  # are not enough columns specified, the default column name is "columnX"
  # (where X is the field number, starting from 1).
  config :columns, :validate => :array, :default => []
  config :start_address, :validate => :string, :default => "0"
  config :num_register, :validate => :string, :default => "0"

  # Define the column separator value. If this is not specified the default
  # is a comma ','.
  # Optional.
  config :separator, :validate => :string, :default => ","

  # Define the character used to quote CSV fields. If this is not specified
  # the default is a double quote '"'.
  # Optional.
  config :quote_char, :validate => :string, :default => '"'

  # Define target for placing the data.
  # Defaults to writing to the root of the event.
  config :target, :validate => :string

  public
  def register

    # Nothing to do here

  end # def register

  public
  def filter(event)
    return unless filter?(event)

    @logger.debug("Running modbus_csv filter", :event => event)

    matches = 0

    @logger.debug(event[@num_register].hex)
    for i in 0..(event[@num_register].hex)
        @columns[i] = event[@start_address].hex + i
    end
    if event[@source]
      if event[@source].is_a?(String)
        event[@source] = [event[@source]]
      end

      if event[@source].length > 1
        @logger.warn("modbus_csv filter only works on fields of length 1",
                     :source => @source, :value => event[@source],
                     :event => event)
        return
      end

      raw = event[@source].first
      begin
        values = CSV.parse_line(raw, :col_sep => @separator, :quote_char => @quote_char)

        if @target.nil?
          # Default is to write to the root of the event.
          dest = event
        else
          dest = event[@target] ||= {}
        end

        values.each_index do |i|
          field_name = @columns[i].to_s || "column#{i+1}"
          dest[field_name] = values[i].hex
        end

        filter_matched(event)
      rescue => e
        event.tag "_modbus_csvparsefailure"
        @logger.warn("Trouble parsing modbus_csv", :source => @source, :raw => raw,
                      :exception => e)
        return
      end # begin
    end # if event

    @logger.debug("Event after modbus_csv filter", :event => event)

  end # def filter

end # class LogStash::Filters::Csv

Finally, I got a chart what I want. (*func = REG (13) 4096 mean per 10m | (13 hits))