1 /*
2 * FreeModbus Libary: A portable Modbus implementation for Modbus ASCII/RTU.
3 * Copyright (c) 2006 Christian Walter <[email protected]>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 *
28 * File: $Id: mbtcp.c,v 1.3 2006/12/07 22:10:34 wolti Exp $
29 */
30
31 /* ----------------------- System includes ----------------------------------*/
32 #include "stdlib.h"
33 #include "string.h"
34
35 /* ----------------------- Platform includes --------------------------------*/
36 #include "port.h"
37
38 /* ----------------------- Modbus includes ----------------------------------*/
39 #include "mb.h"
40 #include "mbconfig.h"
41 #include "mbtcp.h"
42 #include "mbframe.h"
43 #include "mbport.h"
44
45 #if MB_SLAVE_TCP_ENABLED > 0
46
47 /* ----------------------- Defines ------------------------------------------*/
48
49 /* ----------------------- MBAP Header --------------------------------------*/
50 /*
51 *
52 * <------------------------ MODBUS TCP/IP ADU(1) ------------------------->
53 * <----------- MODBUS PDU (1') ---------------->
54 * +-----------+---------------+------------------------------------------+
55 * | TID | PID | Length | UID |Code | Data |
56 * +-----------+---------------+------------------------------------------+
57 * | | | | |
58 * (2) (3) (4) (5) (6)
59 *
60 * (2) ... MB_TCP_TID = 0 (Transaction Identifier - 2 Byte)
61 * (3) ... MB_TCP_PID = 2 (Protocol Identifier - 2 Byte)
62 * (4) ... MB_TCP_LEN = 4 (Number of bytes - 2 Byte)
63 * (5) ... MB_TCP_UID = 6 (Unit Identifier - 1 Byte)
64 * (6) ... MB_TCP_FUNC = 7 (Modbus Function Code)
65 *
66 * (1) ... Modbus TCP/IP Application Data Unit
67 * (1') ... Modbus Protocol Data Unit
68 */
69
70 #define MB_TCP_TID 0
71 #define MB_TCP_PID 2
72 #define MB_TCP_LEN 4
73 #define MB_TCP_UID 6
74 #define MB_TCP_FUNC 7
75
76 #define MB_TCP_PROTOCOL_ID 0 /* 0 = Modbus Protocol */
77
78
79 /* ----------------------- Start implementation -----------------------------*/
80 eMBErrorCode
eMBTCPDoInit(USHORT ucTCPPort)81 eMBTCPDoInit( USHORT ucTCPPort )
82 {
83 eMBErrorCode eStatus = MB_ENOERR;
84
85 if( xMBTCPPortInit( ucTCPPort ) == FALSE )
86 {
87 eStatus = MB_EPORTERR;
88 }
89 return eStatus;
90 }
91
92 void
eMBTCPStart(void)93 eMBTCPStart( void )
94 {
95 }
96
97 void
eMBTCPStop(void)98 eMBTCPStop( void )
99 {
100 /* Make sure that no more clients are connected. */
101 vMBTCPPortDisable( );
102 }
103
104 eMBErrorCode
eMBTCPReceive(UCHAR * pucRcvAddress,UCHAR ** ppucFrame,USHORT * pusLength)105 eMBTCPReceive( UCHAR * pucRcvAddress, UCHAR ** ppucFrame, USHORT * pusLength )
106 {
107 eMBErrorCode eStatus = MB_EIO;
108 UCHAR *pucMBTCPFrame;
109 USHORT usLength;
110 USHORT usPID;
111
112 if( xMBTCPPortGetRequest( &pucMBTCPFrame, &usLength ) != FALSE )
113 {
114 usPID = pucMBTCPFrame[MB_TCP_PID] << 8U;
115 usPID |= pucMBTCPFrame[MB_TCP_PID + 1];
116
117 if( usPID == MB_TCP_PROTOCOL_ID )
118 {
119 *ppucFrame = &pucMBTCPFrame[MB_TCP_FUNC];
120 *pusLength = usLength - MB_TCP_FUNC;
121 eStatus = MB_ENOERR;
122
123 /* Modbus TCP does not use any addresses. Fake the source address such
124 * that the processing part deals with this frame.
125 */
126 *pucRcvAddress = MB_TCP_PSEUDO_ADDRESS;
127 }
128 }
129 else
130 {
131 eStatus = MB_EIO;
132 }
133 return eStatus;
134 }
135
136 eMBErrorCode
eMBTCPSend(UCHAR _unused,const UCHAR * pucFrame,USHORT usLength)137 eMBTCPSend( UCHAR _unused, const UCHAR * pucFrame, USHORT usLength )
138 {
139 eMBErrorCode eStatus = MB_ENOERR;
140 UCHAR *pucMBTCPFrame = ( UCHAR * ) pucFrame - MB_TCP_FUNC;
141 USHORT usTCPLength = usLength + MB_TCP_FUNC;
142
143 /* The MBAP header is already initialized because the caller calls this
144 * function with the buffer returned by the previous call. Therefore we
145 * only have to update the length in the header. Note that the length
146 * header includes the size of the Modbus PDU and the UID Byte. Therefore
147 * the length is usLength plus one.
148 */
149 pucMBTCPFrame[MB_TCP_LEN] = ( usLength + 1 ) >> 8U;
150 pucMBTCPFrame[MB_TCP_LEN + 1] = ( usLength + 1 ) & 0xFF;
151 if( xMBTCPPortSendResponse( pucMBTCPFrame, usTCPLength ) == FALSE )
152 {
153 eStatus = MB_EIO;
154 }
155 return eStatus;
156 }
157
158 #endif
159