mbtcp.cpp

00001 /* 
00002  * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
00003  * Copyright (c) 2006 Christian Walter <wolti@sil.at>
00004  * All rights reserved.
00005  *
00006  * Redistribution and use in source and binary forms, with or without
00007  * modification, are permitted provided that the following conditions
00008  * are met:
00009  * 1. Redistributions of source code must retain the above copyright
00010  *    notice, this list of conditions and the following disclaimer.
00011  * 2. Redistributions in binary form must reproduce the above copyright
00012  *    notice, this list of conditions and the following disclaimer in the
00013  *    documentation and/or other materials provided with the distribution.
00014  * 3. The name of the author may not be used to endorse or promote products
00015  *    derived from this software without specific prior written permission.
00016  *
00017  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
00018  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
00019  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
00020  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
00021  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
00022  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
00023  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
00024  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
00025  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
00026  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
00027  *
00028  * File: $Id: mbtcp.c,v 1.3 2006/12/07 22:10:34 wolti Exp $
00029  */
00030 
00031 /* ----------------------- System includes ----------------------------------*/
00032 #include "stdlib.h"
00033 #include "string.h"
00034 
00035 /* ----------------------- Platform includes --------------------------------*/
00036 #include "port.h"
00037 
00038 /* ----------------------- Modbus includes ----------------------------------*/
00039 #include "mb.h"
00040 #include "mbconfig.h"
00041 #include "mbtcp.h"
00042 #include "mbframe.h"
00043 #include "mbport.h"
00044 
00045 #if MB_TCP_ENABLED > 0
00046 
00047 /* ----------------------- Defines ------------------------------------------*/
00048 
00049 /* ----------------------- MBAP Header --------------------------------------*/
00050 /*
00051  *
00052  * <------------------------ MODBUS TCP/IP ADU(1) ------------------------->
00053  *              <----------- MODBUS PDU (1') ---------------->
00054  *  +-----------+---------------+------------------------------------------+
00055  *  | TID | PID | Length | UID  |Code | Data                               |
00056  *  +-----------+---------------+------------------------------------------+
00057  *  |     |     |        |      |                                           
00058  * (2)   (3)   (4)      (5)    (6)                                          
00059  *
00060  * (2)  ... MB_TCP_TID          = 0 (Transaction Identifier - 2 Byte) 
00061  * (3)  ... MB_TCP_PID          = 2 (Protocol Identifier - 2 Byte)
00062  * (4)  ... MB_TCP_LEN          = 4 (Number of bytes - 2 Byte)
00063  * (5)  ... MB_TCP_UID          = 6 (Unit Identifier - 1 Byte)
00064  * (6)  ... MB_TCP_FUNC         = 7 (Modbus Function Code)
00065  *
00066  * (1)  ... Modbus TCP/IP Application Data Unit
00067  * (1') ... Modbus Protocol Data Unit
00068  */
00069 
00070 #define MB_TCP_TID          0
00071 #define MB_TCP_PID          2
00072 #define MB_TCP_LEN          4
00073 #define MB_TCP_UID          6
00074 #define MB_TCP_FUNC         7
00075 
00076 #define MB_TCP_PROTOCOL_ID  0   /* 0 = Modbus Protocol */
00077 
00078 
00079 /* ----------------------- Start implementation -----------------------------*/
00080 eMBErrorCode
00081 eMBTCPDoInit( USHORT ucTCPPort )
00082 {
00083     eMBErrorCode    eStatus = MB_ENOERR ;
00084 
00085     if( xMBTCPPortInit( ucTCPPort ) == FALSE )
00086     {
00087         eStatus = MB_EPORTERR ;
00088     }
00089     return eStatus;
00090 }
00091 
00092 void
00093 eMBTCPStart( void )
00094 {
00095 }
00096 
00097 void
00098 eMBTCPStop( void )
00099 {
00100     /* Make sure that no more clients are connected. */
00101     vMBTCPPortDisable( );
00102 }
00103 
00104 eMBErrorCode
00105 eMBTCPReceive( UCHAR * pucRcvAddress, UCHAR ** ppucFrame, USHORT * pusLength )
00106 {
00107     eMBErrorCode    eStatus = MB_EIO ;
00108     UCHAR          *pucMBTCPFrame;
00109     USHORT          usLength;
00110     USHORT          usPID;
00111 
00112     if( xMBTCPPortGetRequest( &pucMBTCPFrame, &usLength ) != FALSE )
00113     {
00114         usPID = pucMBTCPFrame[MB_TCP_PID] << 8U;
00115         usPID |= pucMBTCPFrame[MB_TCP_PID + 1];
00116 
00117         if( usPID == MB_TCP_PROTOCOL_ID )
00118         {
00119             *ppucFrame = &pucMBTCPFrame[MB_TCP_FUNC];
00120             *pusLength = usLength - MB_TCP_FUNC;
00121             eStatus = MB_ENOERR ;
00122 
00123             /* Modbus TCP does not use any addresses. Fake the source address such
00124              * that the processing part deals with this frame.
00125              */
00126             *pucRcvAddress = MB_TCP_PSEUDO_ADDRESS;
00127         }
00128     }
00129     else
00130     {
00131         eStatus = MB_EIO ;
00132     }
00133     return eStatus;
00134 }
00135 
00136 eMBErrorCode
00137 eMBTCPSend( UCHAR _unused, const UCHAR * pucFrame, USHORT usLength )
00138 {
00139     eMBErrorCode    eStatus = MB_ENOERR ;
00140     UCHAR          *pucMBTCPFrame = ( UCHAR * ) pucFrame - MB_TCP_FUNC;
00141     USHORT          usTCPLength = usLength + MB_TCP_FUNC;
00142 
00143     /* The MBAP header is already initialized because the caller calls this
00144      * function with the buffer returned by the previous call. Therefore we 
00145      * only have to update the length in the header. Note that the length 
00146      * header includes the size of the Modbus PDU and the UID Byte. Therefore 
00147      * the length is usLength plus one.
00148      */
00149     pucMBTCPFrame[MB_TCP_LEN] = ( usLength + 1 ) >> 8U;
00150     pucMBTCPFrame[MB_TCP_LEN + 1] = ( usLength + 1 ) & 0xFF;
00151     if( xMBTCPPortSendResponse( pucMBTCPFrame, usTCPLength ) == FALSE )
00152     {
00153         eStatus = MB_EIO ;
00154     }
00155     return eStatus;
00156 }
00157 
00158 #endif
00159