path: root/epan/dissectors/packet-cp2179.c

/* packet-cp2179.c
 * Routines for Communication Protocol 2179 (CP2179) Dissection
 * By Qiaoyin Yang (qiaoyin[DOT]yang[AT]gmail.com
 * Copyright 2014-2015,Schweitzer Engineering Laboratories
 *
 *
 ************************************************************************************************
 * Wireshark - Network traffic analyzer
 * By Gerald Combs <gerald@wireshark.org>
 * Copyright 1998 Gerald Combs
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 ************************************************************************************************
CP2179 protocol is a serial based protocol. The 2179 protocol is implemented with minor variations between vendors.
The RTAC implemented the 2179 client supporting a limited function codes and command codes. The RTAC doesn't support
multiple function codes in a single request and the dissector also doesn't support decoding these or corresponding responses.
 * Dissector Notes:
 A brief explanation of how a request and response messages are formulated in 2179 protocol.
 The CP2179 request messages will follow the pattern below:
AA AA BB CC DD DD XX XX .... XX EE EE

A = 16-bit address field. The Most significant 5 bit is the Client address, the 11 bits for RTU address.
B = 8-bit Function code
C = 8-bit Command code
D = 16-bit Number of characters in the data field.
X = data field
E = 16-bit CRC

AA AA BB CC DD EE EE XX XX ... XX FF FF

A = 16-bit address field. The Most significant 5 bit is the Client address, the 11 bits for RTU address.
B = 8-bit Function code
C = 8-bit Status
D = 8-bit Port Status
E = 16-bit Number of characters
X = data field
F = 16-bit CRC
 ************************************************************************************************/

#include "config.h"
#include <epan/packet.h>
#include <epan/conversation.h>
#include <epan/prefs.h>
#include <epan/proto_data.h>

void proto_reg_handoff_cp2179(void);
void proto_register_cp2179(void);

/* CP2179 function codes */
#define BASIC_SCAN                          0x00
#define SCAN_INCLUSIVE                      0x01
#define SCAN_FOR_SPECIAL_CALC               0x03
#define RETRIEVE_TIME_TAGGED_INFOR          0x04   /* not supported */
#define SCAN_BY_TABLE                       0x0A
#define SUPERVISORY_CONTROL                 0x10
#define RTU_CONFIG                          0x20
#define RETURN_RTU_CONFIG                   0x25
#define REPORT_EXCEPTION_DATA               0x0D

/* Function Code 0x00 (Basic Scan) Command codes */
#define SIMPLE_STATUS_DATA                 0x01
#define ALWAYS_RESERVED                    0x02
#define TWO_BIT_STATUS                     0x04
#define ANALOG_16_BIT                      0x08
#define ACCUMULATOR_16_BIT                 0x40

/* Function Code 0x03 (Special Calc) Command Codes */
#define SPECIAL_CALC_RANGE                 0x00
#define SPECIAL_CALC_ALL                   0x80

/* Function Code 0x10 (Supervisory Control) Command Codes */
#define SBO_SELECT_OPEN                    0x10
#define SBO_SELECT_CLOSE                   0x11
#define SBO_OPERATE                        0x20

/* Function Code 0x20 (RTU Control) Command Codes */
#define INIT_RTU_CONFIGURATION             0x00
#define RESET_ACCUMULATOR                  0x11

/* packet type */
#define BASIC_SCAN_QUERY_PACKET            1
#define BASIC_SCAN_RESPONSE_PACKET         2
#define SPECIAL_CALC_REQUEST_ALL           3
#define SPECIAL_CALC_RESPONSE_ALL          4
#define SPECIAL_CALC_REQUEST_RANGE         5
#define SPECIAL_CALC_RESPONSE_RANGE        6
#define SCAN_INCLUSIVE_16_ANALOG_REQUEST   7
#define SCAN_INCLUSIVE_16_ANALOG_RESPONSE  8
#define SBO_SELECT_REQUEST                 9
#define SBO_SELECT_RESPONSE                10
#define SBO_OPERATE_REQUEST                11
#define SBO_OPERATE_RESPONSE               12
#define INIT_RTU_REQUEST                   13
#define INIT_RTU_RESPONSE                  14
#define RESET_ACC_REQUEST                  15
#define RESET_ACC_RESPONSE                 16
#define SPECIAL_CALC_RESPONSE              17

/* packet length */
#define CP2179_MIN_LENGTH                  7
#define RESPONSE_HEADER_SIZE               7  /*includes addr, addr, function, status, port status, number of characters */
#define BASIC_SCAN_REQ_LEN                 8
#define SPECIAL_CALC_REQ_ALL_LEN           8
#define SBO_OPERATE_REQ_LEN                8
#define SPECIAL_CALC_REQ_RANGE_LEN         9
#define SBO_SELECT_REQ_LEN                 9
#define SBO_OPERATE_REPLY_LEN              9
#define SBO_SELECT_REPLY_LEN               10

static gboolean cp2179_telnet_clean = TRUE;


/* Packet type Lookup */
static const value_string cp2179_packettype_vals[] = {
{BASIC_SCAN_QUERY_PACKET,               "Basic Scan Request"},
{BASIC_SCAN_RESPONSE_PACKET,            "Basic Scan Response"},
{SPECIAL_CALC_REQUEST_ALL,              "Special Calc Request All"},
{SPECIAL_CALC_RESPONSE_ALL,             "Special Calc Response All"},
{SPECIAL_CALC_REQUEST_RANGE,            "Special Calc Request a Range"},
{SPECIAL_CALC_RESPONSE_RANGE,           "Special Calc Response a Range"},
{SPECIAL_CALC_RESPONSE,                 "Special Calc Response"},
{SCAN_INCLUSIVE_16_ANALOG_REQUEST,      "Scan Inclusive Request"},
{SCAN_INCLUSIVE_16_ANALOG_RESPONSE,     "Scan Inclusive Response"},
{SBO_SELECT_REQUEST,                    "SBO Select Request"},
{SBO_SELECT_RESPONSE,                   "SBO Select Response"},
{SBO_OPERATE_REQUEST,                   "SBO Operate Request"},
{SBO_OPERATE_RESPONSE,                  "SBO Operate Response"},
{INIT_RTU_REQUEST,                      "INIT RTU Request"},
{INIT_RTU_RESPONSE,                     "INIT RTU Response"},
{RESET_ACC_REQUEST,                     "RESET Accumulator Request"},
{RESET_ACC_RESPONSE,                    "RESET Accumulator Response"},
{-99,                                   "Unknown Function Code"},
{ 0,                                    NULL }

};

static value_string_ext cp2179_packettype_vals_ext = VALUE_STRING_EXT_INIT(cp2179_packettype_vals);

/* List contains request data  */
typedef struct {
    wmem_list_t *bs_request_frame_data;
} cp2179_conversation;


/* Function code Lookup */
static const value_string FunctionCodenames[] = {
{ BASIC_SCAN,                     "Basic Scan" },
{ SCAN_INCLUSIVE,                 "Scan Inclusive"},
{ SCAN_FOR_SPECIAL_CALC,          "Scan Floating Points" },
{ SCAN_BY_TABLE,                  "Scan by Table" },
{ SUPERVISORY_CONTROL,            "Supervisory Control" },
{ RTU_CONFIG,                     "RTU Internal Control" },
{ RETURN_RTU_CONFIG,              "Return RTU Config"},
{ REPORT_EXCEPTION_DATA,          "Report Exception data"},
{ 0,                              NULL }
};

/* Command code Lookup (FC00, FC03, FC10) */
static const value_string cp2179_CommandCodeNames [] = {
{ SIMPLE_STATUS_DATA,             "Simple Status" },
{ ALWAYS_RESERVED,                "Reserved" },
{ TWO_BIT_STATUS,                 "2 Bit Data Status" },
{ ANALOG_16_BIT,                  "16 Bit Analog" },
{ ACCUMULATOR_16_BIT,             "16 Bit Pulsed Accumulator" },
{ SBO_SELECT_OPEN,                "SBO Open" },
{ SBO_SELECT_CLOSE,               "SBO Close" },
{ SBO_OPERATE,                    "SBO Operate" },
{ SPECIAL_CALC_ALL,               "Request All Special Calc Data"},
{ SPECIAL_CALC_RANGE,             "Request a Range of Special Calc"},
{ 0,                              NULL }
};

static value_string_ext cp2179_CommandCodeNames_ext = VALUE_STRING_EXT_INIT(cp2179_CommandCodeNames);

/* Function Code 0x20 Command Code Lookup */
static const value_string cp2179_FC20_CommandCodeNames [] = {
{ INIT_RTU_CONFIGURATION,         "Initialize RTU Config" },
{ RESET_ACCUMULATOR,              "Accumulator Reset" },
{ 0,                              NULL }
};

/* Holds Request information required to later decode a response  */
typedef struct {
   guint32  fnum;  /* frame number */
   guint16  address_word;
   guint8   function_code;
   guint8   commmand_code;
   guint16  numberofcharacters;
   guint8   *requested_points;
} bs_request_frame;


static int proto_cp2179 = -1;

/* Initialize the subtree pointers */
static gint ett_cp2179 = -1;
static gint ett_cp2179_header = -1;
static gint ett_cp2179_addr = -1;
static gint ett_cp2179_fc = -1;
static gint ett_cp2179_data = -1;
static gint ett_cp2179_subdata = -1;

/* Initialize the protocol and registered fields */
static int hf_cp2179_request_frame = -1;
static int hf_cp2179_rtu_address = -1;
static int hf_cp2179_master_address = -1;
static int hf_cp2179_function_code = -1;
static int hf_cp2179_nop_flag = -1;
static int hf_cp2179_rst_flag = -1;
static int hf_cp2179_reserved = -1;
static int hf_cp2179_command_code = -1;
static int hf_cp2179_command_code_fc20 = -1;
static int hf_cp2179_sbo_request_point = -1;
static int hf_cp2179_resetacc_request_point = -1;
static int hf_cp2179_speccalc_request_point = -1;
static int hf_cp2179_scaninc_startreq_point = -1;
static int hf_cp2179_scaninc_stopreq_point = -1;
static int hf_cp2179_number_characters = -1;
static int hf_cp2179_analog_16bit = -1;
static int hf_cp2179_accumulator = -1;
static int hf_cp2179_crc = -1;
/* static int hf_cp2179_data_field = -1; */
static int hf_cp2179_status_byte = -1;
static int hf_cp2179_port_status_byte = -1;
static int hf_cp2179_simplestatusbit  = -1;
static int hf_cp2179_simplestatusbit0 = -1;
static int hf_cp2179_simplestatusbit1 = -1;
static int hf_cp2179_simplestatusbit2 = -1;
static int hf_cp2179_simplestatusbit3 = -1;
static int hf_cp2179_simplestatusbit4 = -1;
static int hf_cp2179_simplestatusbit5 = -1;
static int hf_cp2179_simplestatusbit6 = -1;
static int hf_cp2179_simplestatusbit7 = -1;
static int hf_cp2179_simplestatusbit8 = -1;
static int hf_cp2179_simplestatusbit9 = -1;
static int hf_cp2179_simplestatusbit10 = -1;
static int hf_cp2179_simplestatusbit11 = -1;
static int hf_cp2179_simplestatusbit12 = -1;
static int hf_cp2179_simplestatusbit13 = -1;
static int hf_cp2179_simplestatusbit14 = -1;
static int hf_cp2179_simplestatusbit15 = -1;
static int hf_cp2179_specialcalc       = -1;
static int hf_cp2179_2bitstatus        = -1;
static int hf_cp2179_2bitstatuschg0    = -1;
static int hf_cp2179_2bitstatuschg1    = -1;
static int hf_cp2179_2bitstatuschg2    = -1;
static int hf_cp2179_2bitstatuschg3    = -1;
static int hf_cp2179_2bitstatuschg4    = -1;
static int hf_cp2179_2bitstatuschg5    = -1;
static int hf_cp2179_2bitstatuschg6    = -1;
static int hf_cp2179_2bitstatuschg7    = -1;
static int hf_cp2179_2bitstatusstatus0 = -1;
static int hf_cp2179_2bitstatusstatus1 = -1;
static int hf_cp2179_2bitstatusstatus2 = -1;
static int hf_cp2179_2bitstatusstatus3 = -1;
static int hf_cp2179_2bitstatusstatus4 = -1;
static int hf_cp2179_2bitstatusstatus5 = -1;
static int hf_cp2179_2bitstatusstatus6 = -1;
static int hf_cp2179_2bitstatusstatus7 = -1;

static dissector_handle_t cp2179_handle;

static const int *cp2179_simplestatus_bits[] = {
  &hf_cp2179_simplestatusbit0,
  &hf_cp2179_simplestatusbit1,
  &hf_cp2179_simplestatusbit2,
  &hf_cp2179_simplestatusbit3,
  &hf_cp2179_simplestatusbit4,
  &hf_cp2179_simplestatusbit5,
  &hf_cp2179_simplestatusbit6,
  &hf_cp2179_simplestatusbit7,
  &hf_cp2179_simplestatusbit8,
  &hf_cp2179_simplestatusbit9,
  &hf_cp2179_simplestatusbit10,
  &hf_cp2179_simplestatusbit11,
  &hf_cp2179_simplestatusbit12,
  &hf_cp2179_simplestatusbit13,
  &hf_cp2179_simplestatusbit14,
  &hf_cp2179_simplestatusbit15,
  NULL
};

static const int *cp2179_2bitstatus_bits[] = {
  &hf_cp2179_2bitstatuschg0,
  &hf_cp2179_2bitstatuschg1,
  &hf_cp2179_2bitstatuschg2,
  &hf_cp2179_2bitstatuschg3,
  &hf_cp2179_2bitstatuschg4,
  &hf_cp2179_2bitstatuschg5,
  &hf_cp2179_2bitstatuschg6,
  &hf_cp2179_2bitstatuschg7,
  &hf_cp2179_2bitstatusstatus0,
  &hf_cp2179_2bitstatusstatus1,
  &hf_cp2179_2bitstatusstatus2,
  &hf_cp2179_2bitstatusstatus3,
  &hf_cp2179_2bitstatusstatus4,
  &hf_cp2179_2bitstatusstatus5,
  &hf_cp2179_2bitstatusstatus6,
  &hf_cp2179_2bitstatusstatus7,
  NULL
};


/**********************************************************************************************************/
/* Clean all instances of 0xFFFF from Telnet payload to compensate for IAC control code (replace w/ 0xFF) */
/* Function Duplicated from packet-telnet.c (unescape_and_tvbuffify_telnet_option)                        */
/**********************************************************************************************************/
static tvbuff_t *
clean_telnet_iac(packet_info *pinfo, tvbuff_t *tvb, int offset, int len)
{
  tvbuff_t     *telnet_tvb;
  guint8       *buf;
  const guint8 *spos;
  guint8       *dpos;
  int           skip_byte, len_remaining;

  spos=tvb_get_ptr(tvb, offset, len);
  buf = (guint8 *)wmem_alloc(pinfo->pool, len);
  dpos = buf;
  skip_byte = 0;
  len_remaining = len;
  while(len_remaining > 0){

    /* Only analyze two sequential bytes of source tvb if we have at least two bytes left */
    if (len_remaining > 1) {
        /* If two sequential 0xFF's exist, increment skip_byte counter, decrement  */
        /* len_remaining by 2 and copy a single 0xFF to dest tvb. */
        if((spos[0]==0xff) && (spos[1]==0xff)){
            skip_byte++;
            len_remaining -= 2;
            *(dpos++) = 0xff;
            spos += 2;
            continue;
        }
    }
    /* If we only have a single byte left, or there were no sequential 0xFF's, copy byte from src tvb to dest tvb */
    *(dpos++) = *(spos++);
    len_remaining--;
  }
  telnet_tvb = tvb_new_child_real_data(tvb, buf, len-skip_byte, len-skip_byte);
  add_new_data_source(pinfo, telnet_tvb, "Processed Telnet Data");

  return telnet_tvb;
}

/******************************************************************************************************/
/* Code to Dissect Request frames */
/******************************************************************************************************/
static int
dissect_request_frame(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, int offset, guint16 packet_type )
{
/* Set up structures needed to add the protocol subtree and manage it */
    proto_tree *cp2179_proto_tree = NULL;
    proto_tree *cp2179_addr_tree = NULL;
    proto_tree *cp2179_fc_tree = NULL;

    proto_item *cp2179_proto_item = NULL;

    guint8 req_command_code = 0;
    guint8 function_code = 0;

    guint16 address_word = -1;
    guint16 requestnumberofcharacters = 0;

    cp2179_proto_item = proto_tree_add_item(tree, proto_cp2179, tvb, 0, -1, ENC_NA);
    cp2179_proto_tree = proto_item_add_subtree(cp2179_proto_item, ett_cp2179_header);

    /* RTU & Master Address are encoded into a 16-bit word */
    address_word = tvb_get_letohs(tvb, offset);
    cp2179_addr_tree = proto_tree_add_subtree_format(cp2179_proto_tree, tvb, offset, 2, ett_cp2179_addr, NULL,
               "RTU Address: %d, Master Address: %d", (address_word & 0x7FF), ((address_word & 0xF800) >> 11) );

    proto_tree_add_item(cp2179_addr_tree, hf_cp2179_rtu_address, tvb, offset, 2, ENC_LITTLE_ENDIAN);
    proto_tree_add_item(cp2179_addr_tree, hf_cp2179_master_address, tvb, offset, 2, ENC_LITTLE_ENDIAN);
    offset += 2;

    /* Report the function code */
    function_code = tvb_get_guint8(tvb, offset) & 0x3f;
    cp2179_fc_tree = proto_tree_add_subtree_format(cp2179_proto_tree, tvb, offset, 1, ett_cp2179_fc, NULL,
               "Function Code: %s (0x%02x)", val_to_str_const(function_code, FunctionCodenames, "Unknown Function Code"), function_code);

    proto_tree_add_item(cp2179_fc_tree, hf_cp2179_function_code, tvb, offset, 1, ENC_LITTLE_ENDIAN);
    proto_tree_add_item(cp2179_fc_tree, hf_cp2179_reserved, tvb, offset, 1, ENC_LITTLE_ENDIAN);
    offset += 1;

    /* Because the function code basic scan for simple status and function code Internal Control for INIT RTU have the same
       command code. If the packet type is a INIT RTU request, interpret the command code as INIT RTU, or else report it as
       basic scan simple status command code.*/
    switch(packet_type)
    {
    case INIT_RTU_REQUEST:
    case RESET_ACC_REQUEST:
        proto_tree_add_item(cp2179_proto_tree,  hf_cp2179_command_code_fc20 , tvb, offset, 1, ENC_LITTLE_ENDIAN);
        break;

    case BASIC_SCAN_QUERY_PACKET:
    case SCAN_INCLUSIVE_16_ANALOG_REQUEST:
        req_command_code = tvb_get_guint8(tvb, offset);
        /* Update Info column with useful information of Command Code Type */
        col_append_fstr(pinfo->cinfo, COL_INFO, " [ %s ]", val_to_str_ext_const(req_command_code, &cp2179_CommandCodeNames_ext, "Unknown Command Code"));
        proto_tree_add_item(cp2179_proto_tree, hf_cp2179_command_code, tvb, offset, 1, ENC_LITTLE_ENDIAN);
        break;

    default:
        proto_tree_add_item(cp2179_proto_tree, hf_cp2179_command_code, tvb, offset, 1, ENC_LITTLE_ENDIAN);
        break;
    }
    offset += 1;

    requestnumberofcharacters = tvb_get_letohs(tvb, 4);
    proto_tree_add_item(cp2179_proto_tree, hf_cp2179_number_characters, tvb, offset, 2, ENC_LITTLE_ENDIAN);
    offset += 2;

    /*If request number is greater than 0, data field in the request is not empty, we need to report the data field*/
    if ( requestnumberofcharacters > 0 ){
        /*Depends on the packet type, the data field should be dissect differently*/
        switch (packet_type)
        {
            case SBO_SELECT_REQUEST:
                proto_tree_add_item(cp2179_proto_tree, hf_cp2179_sbo_request_point, tvb, offset, 1, ENC_LITTLE_ENDIAN);
                offset += 1;
                break;

            /*Reset Accumulator request data field will always only has 1 byte. The Sequence ID of the Accumulator that it wants to reset*/
            case RESET_ACC_REQUEST:
                proto_tree_add_item(cp2179_proto_tree, hf_cp2179_resetacc_request_point, tvb, offset, 1, ENC_LITTLE_ENDIAN);
                offset += 1;
                break;

            /* A special calculation that requests for a range of points will have a list of sequence ID of the Special Calculation points */
            case SPECIAL_CALC_REQUEST_RANGE:
                do{
                    proto_tree_add_item(cp2179_proto_tree, hf_cp2179_speccalc_request_point, tvb, offset, 1, ENC_LITTLE_ENDIAN);
                    offset += 1;
                }while(tvb_reported_length_remaining(tvb, offset) > 2);
                break;

            /*Scan Inclusive will have a starting sequence ID and a ending sequence ID in the data field.*/
            case SCAN_INCLUSIVE_16_ANALOG_REQUEST:
                do{
                    proto_tree_add_item(cp2179_proto_tree, hf_cp2179_scaninc_startreq_point, tvb, offset, 1, ENC_LITTLE_ENDIAN);
                    proto_tree_add_item(cp2179_proto_tree, hf_cp2179_scaninc_stopreq_point, tvb, offset+1, 1, ENC_LITTLE_ENDIAN);
                    offset += 2;
                }while(tvb_reported_length_remaining(tvb, offset) > 2);
                break;
        }
    }
        /*report the last two bytes as CRC in the request*/
    proto_tree_add_item(cp2179_proto_tree, hf_cp2179_crc, tvb, offset, 2, ENC_LITTLE_ENDIAN);

    return tvb_reported_length(tvb);
}


/******************************************************************************************************/
/* Code to dissect Response frames  */
/******************************************************************************************************/
static int
dissect_bs_response_frame(tvbuff_t *tvb, proto_tree *tree, packet_info *pinfo, int offset, guint16 packet_type)
{
    /* Set up structures needed to add the protocol subtree and manage it */
    proto_item *bs_response_item = NULL;
    proto_item *cp2179_proto_item = NULL;
    proto_item *cp2179_subdata_item = NULL;

    proto_tree *cp2179_proto_tree = NULL;
    proto_tree *cp2179_addr_tree = NULL;
    proto_tree *cp2179_fc_tree = NULL;
    proto_tree *cp2179_data_tree = NULL;

    cp2179_conversation  *conv;
    guint32 req_frame_num;
    guint16 req_address_word;
    guint8  req_command_code;
    gboolean request_found = FALSE;
    bs_request_frame *request_data;

    gint analogtestvalue = 0;
    gint analog16_num = 0;
    gint point_num = 0;

    guint function_code;
    guint simplestatusseq = 0x30;

    guint16 address_word = 0;
    guint16 numberofcharacters = -1;

    gfloat specialcalvalue = 0;

    cp2179_proto_item = proto_tree_add_item(tree, proto_cp2179, tvb, 0, -1, ENC_NA);
    cp2179_proto_tree = proto_item_add_subtree(cp2179_proto_item, ett_cp2179_header);

    /* RTU & Master Address are encoded into a 16-bit word */
    address_word = tvb_get_letohs(tvb, offset);

    cp2179_addr_tree = proto_tree_add_subtree_format(cp2179_proto_tree, tvb, offset, 2, ett_cp2179_addr, NULL,
                   "RTU Address: %d, Master Address: %d", (address_word & 0x7FF), ((address_word & 0xF800) >> 11) );

    proto_tree_add_item(cp2179_addr_tree, hf_cp2179_rtu_address, tvb, 0, 2, ENC_LITTLE_ENDIAN);
    proto_tree_add_item(cp2179_addr_tree, hf_cp2179_master_address, tvb, 0, 2, ENC_LITTLE_ENDIAN);
    offset += 2;

    /*The response always echos the function code in request, except when the RTU can't perform the required function.
    It may set the NOP or RST bit. Bit 0 to bit 5 is the field for function codes. Bit 6 is NOP bit. Bit 7 is RST bit. */
    function_code = tvb_get_guint8(tvb, offset) & 0x3f;

    cp2179_fc_tree = proto_tree_add_subtree_format(cp2179_proto_tree, tvb, offset, 1, ett_cp2179_fc, NULL,
               "Function Code: %s (0x%02x)", val_to_str_const(function_code, FunctionCodenames, "Unknown Function Code"), function_code);

    proto_tree_add_item(cp2179_fc_tree, hf_cp2179_function_code, tvb, offset, 1, ENC_LITTLE_ENDIAN);
    proto_tree_add_item(cp2179_fc_tree, hf_cp2179_nop_flag, tvb, offset, 1, ENC_LITTLE_ENDIAN);
    proto_tree_add_item(cp2179_fc_tree, hf_cp2179_rst_flag, tvb, offset, 1, ENC_LITTLE_ENDIAN);

    offset += 1;

    /* Status Byte & Port Status */
    proto_tree_add_item(cp2179_proto_tree, hf_cp2179_status_byte, tvb, offset, 1, ENC_LITTLE_ENDIAN);
    offset += 1;
    proto_tree_add_item(cp2179_proto_tree, hf_cp2179_port_status_byte, tvb, offset, 1, ENC_LITTLE_ENDIAN);
    offset += 1;

    /* Number of characters */
    numberofcharacters = tvb_get_letohs(tvb, 5);
    proto_tree_add_item(cp2179_proto_tree, hf_cp2179_number_characters, tvb, offset, 2, ENC_LITTLE_ENDIAN);
    offset += 2;

    /* get the converstation data */
    conv = (cp2179_conversation *)p_get_proto_data(wmem_file_scope(), pinfo, proto_cp2179, 0);

    if (conv) {
        wmem_list_frame_t *frame = wmem_list_head(conv->bs_request_frame_data);
        /* Cycle through all logged instances of request frames, looking for request frame number that occurred immediately
           prior to current frame number that has a matching address word */
        while (frame && !request_found) {
            request_data = (bs_request_frame *)wmem_list_frame_data(frame);
            req_frame_num = request_data->fnum;
            req_command_code = request_data->commmand_code;
            req_address_word = request_data->address_word;
                if ((pinfo->num > req_frame_num) && (req_address_word == address_word)) {
                    bs_response_item = proto_tree_add_uint(cp2179_proto_tree, hf_cp2179_request_frame, tvb, 0, 0, req_frame_num);
                    PROTO_ITEM_SET_GENERATED(bs_response_item);
                    request_found = TRUE;
                }
                frame = wmem_list_frame_next(frame);
        }

        if (request_found)
        {
            switch (packet_type)
            {
                case SBO_SELECT_RESPONSE:
                case SBO_OPERATE_RESPONSE:
                case RESET_ACC_RESPONSE:
                case INIT_RTU_RESPONSE:

                    if ( numberofcharacters > 0 ){
                        /*Based on the packet type, change the displayed messages*/
                        if ( packet_type == SBO_SELECT_RESPONSE ){
                            proto_tree_add_item(cp2179_proto_tree, hf_cp2179_sbo_request_point, tvb, offset, 1, ENC_LITTLE_ENDIAN);
                            offset += 1;
                        }
                        if ( packet_type == RESET_ACC_RESPONSE ){
                            proto_tree_add_item(cp2179_proto_tree, hf_cp2179_resetacc_request_point, tvb, offset, 1, ENC_LITTLE_ENDIAN);
                            offset += 1;
                        }
                    }
                    break;

                case SPECIAL_CALC_RESPONSE:
                    /* Based on the command code from the corresponding request, dissect the data field differently.
                       If required a range of Special calculation, display the requested sequence ID and corresponding
                       values. The requested sequence number is obtained from the previous request frame.  */
                    cp2179_data_tree = proto_tree_add_subtree(cp2179_proto_tree, tvb, offset, numberofcharacters, ett_cp2179_data, NULL, "CP2179 Data Field");

                    if (req_command_code == SPECIAL_CALC_ALL ){
                        do{
                            specialcalvalue = tvb_get_letohieee_float(tvb, offset );
                            proto_tree_add_float_format(cp2179_data_tree, hf_cp2179_specialcalc, tvb, offset, 4, specialcalvalue,
                                "Special Calculation %u : %f", point_num, specialcalvalue);
                            point_num += 1;
                            offset += 4;
                        }while(tvb_reported_length_remaining(tvb, offset) > 2);
                    }
                    /*If it request all the special calculation data, dissect all of them and associated a sequence ID with it.*/
                    else if (req_command_code == SPECIAL_CALC_RANGE ){
                        do{
                            specialcalvalue = tvb_get_letohieee_float(tvb, offset );
                            proto_tree_add_float_format(cp2179_data_tree, hf_cp2179_specialcalc, tvb, offset, 4, specialcalvalue,
                                "Special Calculation %u : %f",  request_data->requested_points[point_num], specialcalvalue);
                            point_num += 1;
                            offset += 4;
                        }while(tvb_reported_length_remaining(tvb, offset) > 2);
                    }
                    break;

                case SCAN_INCLUSIVE_16_ANALOG_RESPONSE:

                    cp2179_data_tree = proto_tree_add_subtree(cp2179_proto_tree, tvb, offset, numberofcharacters, ett_cp2179_data, NULL, "CP2179 Data Field");

                    /* Update Info column with useful information of Command Code Type */
                    col_append_fstr(pinfo->cinfo, COL_INFO, " [ %s ]", val_to_str_ext_const(req_command_code, &cp2179_CommandCodeNames_ext, "Unknown Command Code"));

                    /*Report the values of the requested SCAN inclusive data. To figure out which sequence ID the values in the response associated with,
                    we read the bs_request_frame information and show the corresponding sequence ID of the data in response frame.*/
                    do{
                        analogtestvalue = (gint16)tvb_get_letohs(tvb, offset);
                        proto_tree_add_uint_format(cp2179_data_tree, hf_cp2179_analog_16bit, tvb, offset, 2, request_data->requested_points[point_num],
                                                   "Analog (16 bit) %u : %i",  request_data->requested_points[point_num], analogtestvalue);
                        point_num += 1;
                        offset += 2;
                    }while(tvb_reported_length_remaining(tvb, offset) > 2);

                    break;

                case BASIC_SCAN_RESPONSE_PACKET:
                {
                    cp2179_data_tree = proto_tree_add_subtree(cp2179_proto_tree, tvb, offset, numberofcharacters, ett_cp2179_data, NULL, "CP2179 Data Field");

                    /* Update Info column with useful information of Command Code Type */
                    col_append_fstr(pinfo->cinfo, COL_INFO, " [ %s ]", val_to_str_ext_const(req_command_code, &cp2179_CommandCodeNames_ext, "Unknown Command Code"));

                    switch (req_command_code)
                    {
                        /* Based the command code from the request frame, we dissect the response data differently.
                           For example, if the request packet has command byte as ANALOG_16_BIT, the
                           the data field in the response should be dissected as 16-bit signed integer(s). */
                        case ACCUMULATOR_16_BIT:
                            do{
                                analogtestvalue = tvb_get_letohs(tvb, offset);
                                proto_tree_add_uint_format(cp2179_data_tree, hf_cp2179_accumulator, tvb, offset, 2, analog16_num,
                                                           "Accumulator %u : %u", analog16_num, analogtestvalue);
                                analog16_num += 1;
                                offset += 2;
                            }while(tvb_reported_length_remaining(tvb, offset) > 2);

                            break;

                        case ANALOG_16_BIT:
                            do{
                                analogtestvalue =(gint16)tvb_get_letohs(tvb, offset);
                                proto_tree_add_uint_format(cp2179_data_tree, hf_cp2179_analog_16bit, tvb, offset, 2, analog16_num,
                                                           "Analog (16 bit) %u : %i", analog16_num, analogtestvalue);
                                analog16_num += 1;
                                offset += 2;
                            }while(tvb_reported_length_remaining(tvb, offset) > 2);

                            break;

                        case SIMPLE_STATUS_DATA:
                            do{
                                cp2179_subdata_item = proto_tree_add_bitmask(cp2179_data_tree, tvb, offset, hf_cp2179_simplestatusbit,
                                                       ett_cp2179_subdata, cp2179_simplestatus_bits, ENC_LITTLE_ENDIAN);
                                proto_item_set_text(cp2179_subdata_item, "Simple Status Point 0x%x", simplestatusseq);

                                simplestatusseq += 1;
                                offset += 2;
                            }while(tvb_reported_length_remaining(tvb, offset) > 2);

                            break;

                        case TWO_BIT_STATUS:
                            do{
                                cp2179_subdata_item = proto_tree_add_bitmask(cp2179_data_tree, tvb, offset, hf_cp2179_2bitstatus,
                                                       ett_cp2179_subdata, cp2179_2bitstatus_bits, ENC_LITTLE_ENDIAN);
                                proto_item_set_text(cp2179_subdata_item, "2 Bit Status Point 0x%x", simplestatusseq);

                                simplestatusseq += 1;
                                offset += 2;
                            }while(tvb_reported_length_remaining(tvb, offset) > 2);

                            break;
                    } /* end of command code switch */

                } /* end of basic scan response switch */

                break;

            } /* end of packet type switch */

            proto_tree_add_item(cp2179_proto_tree, hf_cp2179_crc, tvb, offset, 2, ENC_LITTLE_ENDIAN);

        } /* request found */

    } /* conversation data found */

    if (!request_found) {
        proto_item_append_text(bs_response_item, ", No Request found");
        return 0;
    }

    return tvb_reported_length(tvb);
}

/******************************************************************************************************/
/* Load Request information into bs request struct */
/******************************************************************************************************/
static bs_request_frame* copy_bs_request_frame(tvbuff_t *tvb  )
{
 /* Set up structures needed to add the protocol request and use it for dissecting response packet */
    guint offset = 0;
    guint8 idx=0 ;
    bs_request_frame *frame;
    guint16 num_objects=0;

    /* get a new frame and initialize it */
    frame = wmem_new(wmem_file_scope(), bs_request_frame);

    /* update the data within the structure frame */
    frame->address_word = tvb_get_letohs(tvb, offset); offset +=2;
    frame->function_code = tvb_get_guint8(tvb, offset); offset +=1;
    frame->commmand_code = tvb_get_guint8(tvb, offset); offset +=1;
    frame->numberofcharacters = tvb_get_letohs(tvb, offset);offset +=2;

    /*Keep track of the request data field in a request.
      Such as SCAN INCLUSIVE request contains a Start Sequence Number and an Ending Sequence Number. */
    if (frame->function_code == SCAN_INCLUSIVE) {
        guint8 startpt, endpt;
        startpt = tvb_get_guint8(tvb, offset);
        endpt = tvb_get_guint8(tvb, offset+1);
        num_objects = (endpt - startpt) + 1;
        frame->requested_points = (guint8 *)wmem_alloc(wmem_file_scope(), num_objects * sizeof(guint8));

        /* We have a range of 'request' points */
        for (idx = 0; idx < num_objects; idx++) {
            frame->requested_points[idx] = startpt;
            startpt++;
        }
        /* offset += 2; */
    }
    /* Get Details for all Requested Points */
    else {
        num_objects = frame->numberofcharacters;
        frame->requested_points = (guint8 *)wmem_alloc(wmem_file_scope(), num_objects * sizeof(guint8));
        for (idx = 0; idx < num_objects; idx++) {
            frame->requested_points[idx] = tvb_get_guint8(tvb, offset);
            offset += 1;
        }

    }

    return frame;
}



/******************************************************************************************************/
/* Classify the different packet type  */
/******************************************************************************************************/
static int
classify_packet_type(tvbuff_t *tvb)
{
    int packet_type = -1;
    guint8 function_code;
    guint8 command_code;
    guint16 requestnumberofcharacters = 0;
    guint16 responsenumberofcharacters = 0;
    guint16 packet_length = 0;


    packet_length = tvb_reported_length(tvb);
    /*Get function code*/
    function_code = tvb_get_guint8(tvb, 2);
    /*Get command codes */
    command_code = tvb_get_guint8(tvb, 3);
    /* Get number of characters */
    requestnumberofcharacters = tvb_get_letohs(tvb, 4);
    responsenumberofcharacters = tvb_get_letohs(tvb, 5);

    /*The response always echos the function code in request, except when the RTU can't perform the required function.
    It may set the NOP or RST bit. Bit 0 to bit 5 is the field for function codes. Bit 6 is NOP bit. Bit 7 is RST bit. */

    /*Remove NOP and RST bit*/
    function_code = function_code & 0x3f ;

    /*2179 protocol frames doesn't have data tells you whether it is a request or a response. We will decide what packet type is based on
    multiple factors, function code, command code, the length of the packet*/
    switch (function_code ){
        case BASIC_SCAN:
            /*Basic scan request message, the number of characters is always 0 and length is fixed*/
            if ( (requestnumberofcharacters == 0) && (packet_length == BASIC_SCAN_REQ_LEN) ) {
                packet_type = BASIC_SCAN_QUERY_PACKET ; /* supported */
            }
            else if ( (responsenumberofcharacters > 0) && (packet_length > BASIC_SCAN_REQ_LEN) ) {
                packet_type = BASIC_SCAN_RESPONSE_PACKET; /* supported */
            }

            break;

        case SUPERVISORY_CONTROL:
            /*SBO select request messages always has number of characters equals to 1 and SBO length is fixed*/
            if ( (requestnumberofcharacters == 1) && (packet_length == SBO_SELECT_REQ_LEN) ) {
                packet_type = SBO_SELECT_REQUEST; /* supported */
            }
            /*SBO select response always has number of characters equals to 1 and SBO length is fixed. */
            else if ( (responsenumberofcharacters == 1) && (packet_length == SBO_SELECT_REPLY_LEN) ) {
                packet_type = SBO_SELECT_RESPONSE; /* supported */
            }
            /*SBO operate request always has number of characters as 0 */
            else if (requestnumberofcharacters == 0) {
                if ( (packet_length == SBO_OPERATE_REQ_LEN) && (command_code == SBO_OPERATE) ) {
                    packet_type = SBO_OPERATE_REQUEST; /* supported */
                }
            }
            /*SBO operate response always has number of characters as 0 */
            else if (responsenumberofcharacters == 0) {
                if (packet_length == SBO_OPERATE_REPLY_LEN) {
                    packet_type = SBO_OPERATE_RESPONSE; /* supported */
                }
            }

            break;

        case SCAN_FOR_SPECIAL_CALC:
            /*Scan for special cal has to command code associated with it, requests all special calculation data or a range of it */
            if ( (requestnumberofcharacters == 0) && (command_code == SPECIAL_CALC_ALL ) ) {
                packet_type = SPECIAL_CALC_REQUEST_ALL; /* supported */
            }
            else if ( (requestnumberofcharacters > 0) && (command_code == SPECIAL_CALC_RANGE ) ) {
                packet_type = SPECIAL_CALC_REQUEST_RANGE; /* supported */
            }
            /*If a packet has SCAN_FOR_SPECIAL_CAL as function code and it is not a request, then it is a response */
            else if ( (responsenumberofcharacters > 0) && (packet_length == (responsenumberofcharacters + 9) ) ) {
                packet_type = SPECIAL_CALC_RESPONSE; /* supported */
            }

            break;
        /*Scan Inclusive request always has request number of characters equals to 2 and a fixed command code */
        case SCAN_INCLUSIVE:
            /*If a packet has SCAN Inclusive function code and it is not a request, then it is a SCAN Inclusive response*/
            if ( (responsenumberofcharacters > 0) ) {
                packet_type = SCAN_INCLUSIVE_16_ANALOG_RESPONSE; /* supported */
            }

            if( (command_code == ANALOG_16_BIT) && (requestnumberofcharacters == 2) ) {
                packet_type = SCAN_INCLUSIVE_16_ANALOG_REQUEST; /* supported */
            }

            break;

        case RTU_CONFIG:
            if (responsenumberofcharacters == 0) {
                packet_type = INIT_RTU_RESPONSE;
            }
            if ( (requestnumberofcharacters == 0) && (command_code == INIT_RTU_CONFIGURATION) ) {
                packet_type = INIT_RTU_REQUEST;
            }

            if (responsenumberofcharacters == 1) {
                packet_type = RESET_ACC_RESPONSE;
            }
            if ( (requestnumberofcharacters == 1) && (command_code == RESET_ACCUMULATOR) ) {
                packet_type = RESET_ACC_REQUEST;
            }
            break;
        default :
            packet_type = -99;
            break;
    }

    return packet_type;
}



/******************************************************************************************************/
/* Code to dissect CP2179 protocol packets */
/******************************************************************************************************/
static int
dissect_cp2179_pdu(tvbuff_t *cp2179_tvb, packet_info *pinfo, proto_tree *tree, void* data _U_)
{
    int offset = 0;
    gint16 packet_type;
    col_set_str(pinfo->cinfo, COL_PROTOCOL, "CP2179");
    col_clear(pinfo->cinfo,COL_INFO);

    packet_type = classify_packet_type(cp2179_tvb);
    /* set information for Information column for CP2179 */
    col_add_fstr(pinfo->cinfo, COL_INFO, "%s", val_to_str_ext_const(packet_type, &cp2179_packettype_vals_ext, "Unknown Packet Type"));

    if (!pinfo->fd->flags.visited){
        conversation_t       *conversation = NULL;
        cp2179_conversation      *bs_conv_data = NULL;

        /* Find a conversation, create a new if no one exists */
        conversation = find_or_create_conversation(pinfo);
        bs_conv_data = (cp2179_conversation *)conversation_get_proto_data(conversation, proto_cp2179);

        if (bs_conv_data == NULL){
           bs_conv_data = wmem_new(wmem_file_scope(), cp2179_conversation);
           bs_conv_data->bs_request_frame_data = wmem_list_new(wmem_file_scope());
           conversation_add_proto_data(conversation, proto_cp2179, (void *)bs_conv_data);
        }

        p_add_proto_data(wmem_file_scope(), pinfo, proto_cp2179, 0, bs_conv_data);

        if ((packet_type == BASIC_SCAN_QUERY_PACKET) || (packet_type == SBO_SELECT_REQUEST)
           ||(packet_type == SPECIAL_CALC_REQUEST_ALL)||(packet_type == SBO_OPERATE_REQUEST)
           ||(packet_type == SPECIAL_CALC_REQUEST_RANGE)||(packet_type == INIT_RTU_REQUEST)
           ||(packet_type == RESET_ACC_REQUEST)||(packet_type == SCAN_INCLUSIVE_16_ANALOG_REQUEST)) {

            /*fill the bs request frame. It holds the request information.*/
            bs_request_frame    *frame_ptr = NULL;
            frame_ptr = copy_bs_request_frame(cp2179_tvb);

            /*also hold the current frame number*/
            frame_ptr->fnum = pinfo->num;
            wmem_list_prepend(bs_conv_data->bs_request_frame_data, frame_ptr);
        }
    } /* !visited */

    if (tvb_reported_length_remaining(cp2179_tvb, offset) > 0){
        switch (packet_type){
            case BASIC_SCAN_QUERY_PACKET:
            case SBO_SELECT_REQUEST:
            case SBO_OPERATE_REQUEST:
            case SPECIAL_CALC_REQUEST_ALL:
            case SPECIAL_CALC_REQUEST_RANGE:
            case SCAN_INCLUSIVE_16_ANALOG_REQUEST:
            case RESET_ACC_REQUEST:
            case INIT_RTU_REQUEST:
                dissect_request_frame(cp2179_tvb, tree, pinfo, offset, packet_type);
                break;

            case BASIC_SCAN_RESPONSE_PACKET:
            case SBO_SELECT_RESPONSE:
            case SBO_OPERATE_RESPONSE:
            case SPECIAL_CALC_RESPONSE:
            case SCAN_INCLUSIVE_16_ANALOG_RESPONSE:
            case INIT_RTU_RESPONSE:
            case RESET_ACC_RESPONSE:
                dissect_bs_response_frame(cp2179_tvb, tree, pinfo, offset, packet_type);
                break;
            default:
                break;
        } /* packet type */
    } /* length remaining */

    return tvb_reported_length(cp2179_tvb);
}


/******************************************************************************************************/
/* Dissect (and possibly Re-assemble) CP2179 protocol payload data */
/******************************************************************************************************/
static int
dissect_cp2179(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree, void *data)
{
    tvbuff_t *cp2179_tvb;
    gint length = tvb_reported_length(tvb);

   /* Check for the packet length, a 2179 Message is at least 7 byte long*/
    if(length < CP2179_MIN_LENGTH){
        return 0;
    }

    if((pinfo->srcport) && cp2179_telnet_clean){
        cp2179_tvb = clean_telnet_iac(pinfo, tvb, 0, length);
    }
    else{
        /* cp2179_tvb = tvb_new_subset_length_caplen( tvb, 0, length, length); */
        cp2179_tvb = tvb_new_subset_length( tvb, 0, length);
    }

    dissect_cp2179_pdu(cp2179_tvb, pinfo, tree, data);

    return length;
}

void
proto_register_cp2179(void)
{
    static hf_register_info hf[] =
    {
        { &hf_cp2179_request_frame,
            { "Request Frame", "cp2179.request_frame",
            FT_FRAMENUM, BASE_NONE,
            NULL, 0x0,
            NULL, HFILL }
        },

        { &hf_cp2179_rtu_address,
            { "RTU Address", "cp2179.RTUAddress",
            FT_UINT16, BASE_DEC,
            NULL, 0x7FF,
            NULL, HFILL }
        },

       { &hf_cp2179_master_address,
            { "Master Address", "cp2179.MasterAddress",
            FT_UINT16, BASE_DEC,
            NULL, 0xF800,
            NULL, HFILL }
        },
        { &hf_cp2179_function_code,
            { "Function Code", "cp2179.functioncode",
            FT_UINT8, BASE_HEX,
            VALS(FunctionCodenames), 0x3F,
            NULL, HFILL }
        },

        { &hf_cp2179_nop_flag,
            { "NOP Flag", "cp2179.nop_flag",
            FT_UINT8, BASE_DEC,
            NULL, 0x40,
            NULL, HFILL }
        },

        { &hf_cp2179_rst_flag,
            { "RST Flag", "cp2179.rst_flag",
            FT_UINT8, BASE_DEC,
            NULL, 0x80,
            NULL, HFILL }
        },

        { &hf_cp2179_reserved,
            { "Reserved Bits", "cp2179.Reserved",
            FT_UINT8, BASE_DEC,
            NULL, 0xC0,
            NULL, HFILL }
        },

        { &hf_cp2179_command_code,
            { "Command Code", "cp2179.commandcode",
            FT_UINT8, BASE_HEX,
            VALS(cp2179_CommandCodeNames), 0x0,
            NULL, HFILL }
        },

        { &hf_cp2179_command_code_fc20,
            { "Command Code (FC 0x20)", "cp2179.commandcodeinitrtu",
            FT_UINT8, BASE_HEX,
            VALS(cp2179_FC20_CommandCodeNames), 0x0,
            NULL, HFILL }
        },
       { &hf_cp2179_status_byte,
            { "RTU Status", "cp2179.rtustatus",
            FT_UINT8, BASE_DEC,
            0x0, 0x0,
            NULL, HFILL }
        },
       { &hf_cp2179_port_status_byte,
            { "Port Status", "cp2179.portstatus",
            FT_UINT8, BASE_DEC,
            0x0, 0x0,
            NULL, HFILL }
        },
       { &hf_cp2179_sbo_request_point,
            { "SBO Request Point", "cp2179.sbo_requestpoint",
            FT_UINT8, BASE_DEC,
            0x0, 0x0,
            NULL, HFILL }
        },
       { &hf_cp2179_resetacc_request_point,
            { "Reset Accumulator Request Point", "cp2179.resetacc_requestpoint",
            FT_UINT8, BASE_DEC,
            0x0, 0x0,
            NULL, HFILL }
        },
       { &hf_cp2179_speccalc_request_point,
            { "Special Calc Request Point", "cp2179.speccalc_requestpoint",
            FT_UINT8, BASE_DEC,
            0x0, 0x0,
            NULL, HFILL }
        },
       { &hf_cp2179_scaninc_startreq_point,
            { "Start Request Point", "cp2179.scaninc_startreq_point",
            FT_UINT8, BASE_DEC,
            0x0, 0x0,
            NULL, HFILL }
        },
       { &hf_cp2179_scaninc_stopreq_point,
            { "Stop Request Point", "cp2179.scaninc_stopreq_point",
            FT_UINT8, BASE_DEC,
            0x0, 0x0,
            NULL, HFILL }
        },
      { &hf_cp2179_number_characters,
            { "Number of Characters", "cp2179.numberofcharacters",
            FT_UINT16, BASE_DEC,
            0x0, 0x0,
            NULL, HFILL }
        },
      { &hf_cp2179_crc,
            { "CRC", "cp2179.crc",
            FT_UINT16, BASE_HEX,
            0x0, 0x0,
            NULL, HFILL }
        },
#if 0
      { &hf_cp2179_data_field,
            { "Data Field", "cp2179.datafield",
            FT_UINT8, BASE_DEC,
            0x0, 0x0,
            NULL, HFILL }
        },
#endif
      { &hf_cp2179_accumulator,
            { "Accumulator", "cp2179.accumulator",
            FT_UINT16, BASE_DEC,
            0x0, 0x0,
            NULL, HFILL }
        },

      { &hf_cp2179_specialcalc,
            { "Special Calc", "cp2179.specialcalc",
            FT_FLOAT, BASE_NONE,
            0x0, 0x0,
            NULL, HFILL }
        },

      { &hf_cp2179_analog_16bit,
         { "Analog 16-bit", "cp2179.analogdata",
         FT_UINT16, BASE_DEC,
         0x0, 0x0,
         NULL, HFILL }
        },
      { &hf_cp2179_simplestatusbit,
         { "Simple Status Bit", "cp2179.simplestatusbit",
         FT_UINT16, BASE_HEX,
         NULL, 0x0,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit0,
         { "Simple Status bit 0", "cp2179.simplestatusbit0",
         FT_BOOLEAN, 16,
         NULL, 0x0001,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit1,
         { "Simple Status bit 1", "cp2179.simplestatusbit1",
         FT_BOOLEAN, 16,
         NULL, 0x0002,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit2,
         { "Simple Status bit 2", "cp2179.simplestatusbit2",
         FT_BOOLEAN, 16,
         NULL, 0x0004,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit3,
         { "Simple Status bit 3", "cp2179.simplestatusbit3",
         FT_BOOLEAN, 16,
         NULL, 0x0008,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit4,
         { "Simple Status bit 4", "cp2179.simplestatusbit4",
         FT_BOOLEAN, 16,
         NULL, 0x0010,
         NULL, HFILL }
      },

      { &hf_cp2179_simplestatusbit5,
         { "Simple Status bit 5", "cp2179.simplestatusbit5",
         FT_BOOLEAN, 16,
         NULL, 0x0020,
         NULL, HFILL }
      },

      { &hf_cp2179_simplestatusbit6,
         { "Simple Status bit 6", "cp2179.simplestatusbit6",
         FT_BOOLEAN, 16,
         NULL, 0x0040,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit7,
         { "Simple Status bit 7", "cp2179.simplestatusbit7",
         FT_BOOLEAN, 16,
         NULL, 0x0080,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit8,
         { "Simple Status bit 8", "cp2179.simplestatusbit8",
         FT_BOOLEAN, 16,
         NULL, 0x0100,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit9,
         { "Simple Status bit 9", "cp2179.simplestatusbit9",
         FT_BOOLEAN, 16,
         NULL, 0x0200,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit10,
         { "Simple Status bit 10", "cp2179.simplestatusbit10",
         FT_BOOLEAN, 16,
         NULL, 0x0400,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit11,
         { "Simple Status bit 11", "cp2179.simplestatusbit11",
         FT_BOOLEAN, 16,
         NULL, 0x0800,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit12,
         { "Simple Status bit 12", "cp2179.simplestatusbit12",
         FT_BOOLEAN, 16,
         NULL, 0x1000,
         NULL, HFILL }
      },
      { &hf_cp2179_simplestatusbit13,
         { "Simple Status bit 13", "cp2179.simplestatusbit13",
         FT_BOOLEAN, 16,
         NULL, 0x2000,
         NULL, HFILL }
      },

      { &hf_cp2179_simplestatusbit14,
         { "Simple Status bit 14", "cp2179.simplestatusbit14",
         FT_BOOLEAN, 16,
         NULL, 0x4000,
         NULL, HFILL }
      },

      { &hf_cp2179_simplestatusbit15,
         { "Simple Status bit 15", "cp2179.simplestatusbit15",
         FT_BOOLEAN, 16,
         NULL, 0x8000,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatus,
         { "2 Bit Status", "cp2179.twobitstatus",
         FT_UINT16, BASE_HEX,
         NULL, 0x0,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatuschg0,
         { "2 Bit Status Change 0", "cp2179.twobitstatuschg0",
         FT_BOOLEAN, 16,
         NULL, 0x0001,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatuschg1,
         { "2 Bit Status Change 1", "cp2179.twobitstatuschg1",
         FT_BOOLEAN, 16,
         NULL, 0x0002,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatuschg2,
         { "2 Bit Status Change 2", "cp2179.twobitstatuschg2",
         FT_BOOLEAN, 16,
         NULL, 0x0004,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatuschg3,
         { "2 Bit Status Change 3", "cp2179.twobitstatuschg3",
         FT_BOOLEAN, 16,
         NULL, 0x0008,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatuschg4,
         { "2 Bit Status Change 4", "cp2179.twobitstatuschg4",
         FT_BOOLEAN, 16,
         NULL, 0x0010,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatuschg5,
         { "2 Bit Status Change 5", "cp2179.twobitstatuschg5",
         FT_BOOLEAN, 16,
         NULL, 0x0020,
         NULL, HFILL }
      },

      { &hf_cp2179_2bitstatuschg6,
         { "2 Bit Status Change 6", "cp2179.twobitstatuschg6",
         FT_BOOLEAN, 16,
         NULL, 0x0040,
         NULL, HFILL }
      },

      { &hf_cp2179_2bitstatuschg7,
         {  "2 Bit Status Change 7", "cp2179.twobitstatuschg7",
         FT_BOOLEAN, 16,
         NULL, 0x0080,
         NULL, HFILL }
      },

      { &hf_cp2179_2bitstatusstatus0,
         { "2 Bit Status bit 0", "cp2179.twobitstatusbit0",
         FT_BOOLEAN, 16,
         NULL, 0x0100,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatusstatus1,
         { "2 Bit Status bit 1", "cp2179.twobitstatusbit1",
         FT_BOOLEAN, 16,
         NULL, 0x0200,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatusstatus2,
         { "2 Bit Status bit 2", "cp2179.twobitstatusbit2",
         FT_BOOLEAN, 16,
         NULL, 0x0400,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatusstatus3,
         { "2 Bit Status bit 3", "cp2179.twobitstatusbit3",
         FT_BOOLEAN, 16,
         NULL, 0x0800,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatusstatus4,
         { "2 Bit Status bit 4", "cp2179.twobitstatusbit4",
         FT_BOOLEAN, 16,
         NULL, 0x1000,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatusstatus5,
         { "2 Bit Status bit 5", "cp2179.twobitstatusbit5",
         FT_BOOLEAN, 16,
         NULL, 0x2000,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatusstatus6,
         { "2 Bit Status bit 6", "cp2179.twobitstatusbit6",
         FT_BOOLEAN, 16,
         NULL, 0x4000,
         NULL, HFILL }
      },
      { &hf_cp2179_2bitstatusstatus7,
         { "2 Bit Status bit 7", "cp2179.twobitstatusbit7",
         FT_BOOLEAN, 16,
         NULL, 0x8000,
         NULL, HFILL }
}
    };

    /* Setup protocol subtree array */
    static gint *ett[] = {
      &ett_cp2179,
      &ett_cp2179_header,
      &ett_cp2179_addr,
      &ett_cp2179_fc,
      &ett_cp2179_data,
      &ett_cp2179_subdata

    };

    module_t *cp2179_module;

    proto_cp2179 = proto_register_protocol ("CP2179 Protocol", "CP2179", "cp2179");
    cp2179_handle = register_dissector("cp2179", dissect_cp2179, proto_cp2179);
    proto_register_field_array(proto_cp2179, hf, array_length(hf));
    proto_register_subtree_array(ett, array_length(ett));

    /* Register required preferences for CP2179 Encapsulated-over-TCP decoding */
    cp2179_module = prefs_register_protocol(proto_cp2179, NULL);

    /* Telnet protocol IAC (0xFF) processing; defaults to TRUE to allow Telnet Encapsulated Data */
    prefs_register_bool_preference(cp2179_module, "telnetclean",
                                  "Remove extra 0xFF (IAC) bytes from Telnet-encapsulated data",
                                  "Whether the SEL Protocol dissector should automatically pre-process Telnet data to remove IAC bytes",
                                  &cp2179_telnet_clean);


}


void
proto_reg_handoff_cp2179(void)
{
    dissector_add_for_decode_as_with_preference("tcp.port", cp2179_handle);
    dissector_add_for_decode_as("rtacser.data", cp2179_handle);
}

/*
 * Editor modelines  -  http://www.wireshark.org/tools/modelines.html
 *
 * Local variables:
 * c-basic-offset: 4
 * tab-width: 8
 * indent-tabs-mode: nil
 * End:
 *
 * vi: set shiftwidth=4 tabstop=8 expandtab:
 * :indentSize=4:tabSize=8:noTabs=true:
 */