/*
  * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
  * Copyright (C) 2006 Christian Walter <wolti@sil.at>
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 of the License, or (at your option) any later version.
  *
  * This library 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser General Public
  * License along with this library; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  *
  * File: $Id: mbframe.h,v 1.8 2006/06/25 00:12:28 wolti Exp $
  */

#ifndef _MB_FRAME_H
#define _MB_FRAME_H

#ifdef __cplusplus
PR_BEGIN_EXTERN_C
#endif

/*!
 * Constants which defines the format of a modbus frame. The example is
 * shown for a Modbus RTU/ASCII frame. Note that the Modbus PDU is not
 * dependent on the underlying transport.
 *
 * <code>
 * <------------------------ MODBUS SERIAL LINE PDU (1) ------------------->
 *              <----------- MODBUS PDU (1') ---------------->
 *  +-----------+---------------+----------------------------+-------------+
 *  | Address   | Function Code | Data                       | CRC/LRC     |
 *  +-----------+---------------+----------------------------+-------------+
 *  |           |               |                                   |
 * (2)        (3/2')           (3')                                (4)
 *
 * (1)  ... MB_SER_PDU_SIZE_MAX = 256
 * (2)  ... MB_SER_PDU_ADDR_OFF = 0
 * (3)  ... MB_SER_PDU_PDU_OFF  = 1
 * (4)  ... MB_SER_PDU_SIZE_CRC = 2
 *
 * (1') ... MB_PDU_SIZE_MAX     = 253
 * (2') ... MB_PDU_FUNC_OFF     = 0
 * (3') ... MB_PDU_DATA_OFF     = 1
 * </code>
 */

/* ----------------------- Defines ------------------------------------------*/
#define MB_PDU_SIZE_MAX     253 /*!< Maximum size of a PDU. */
#define MB_PDU_SIZE_MIN     1   /*!< Function Code */
#define MB_PDU_FUNC_OFF     0   /*!< Offset of function code in PDU. */
#define MB_PDU_DATA_OFF     1   /*!< Offset for response data in PDU. */

/* ----------------------- Prototypes  0-------------------------------------*/
typedef void    ( *pvMBFrameStart ) ( void );

typedef void    ( *pvMBFrameStop ) ( void );

typedef eMBErrorCode( *peMBFrameReceive ) ( UCHAR * pucRcvAddress,
                                            UCHAR ** pucFrame,
                                            USHORT * pusLength );

typedef eMBErrorCode( *peMBFrameSend ) ( UCHAR slaveAddress,
                                         const UCHAR * pucFrame,
                                         USHORT usLength );

typedef void( *pvMBFrameClose ) ( void );

#ifdef __cplusplus
PR_END_EXTERN_C
#endif
#endif