Diff: mbfuncdisc.cpp

Revision:

0:0453a0a7e500

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mbfuncdisc.cpp	Thu Apr 15 12:10:34 2010 +0000
@@ -0,0 +1,125 @@
+ /*
+  * FreeRTOS Modbus Libary: A Modbus serial implementation for FreeRTOS
+  * 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
+  */
+
+
+
+/* ----------------------- System includes ----------------------------------*/
+#include "stdlib.h"
+#include "string.h"
+
+/* ----------------------- Platform includes --------------------------------*/
+#include "port.h"
+
+/* ----------------------- Modbus includes ----------------------------------*/
+#include "mb.h"
+#include "mbframe.h"
+#include "mbproto.h"
+#include "mbconfig.h"
+
+/* ----------------------- Defines ------------------------------------------*/
+#define MB_PDU_FUNC_READ_ADDR_OFF           ( MB_PDU_DATA_OFF )
+#define MB_PDU_FUNC_READ_DISCCNT_OFF        ( MB_PDU_DATA_OFF + 2 )
+#define MB_PDU_FUNC_READ_SIZE               ( 4 )
+#define MB_PDU_FUNC_READ_DISCCNT_MAX        ( 0x07D0 )
+
+/* ----------------------- Static functions ---------------------------------*/
+eMBException    prveMBError2Exception( eMBErrorCode eErrorCode );
+
+/* ----------------------- Start implementation -----------------------------*/
+
+#if MB_FUNC_READ_COILS_ENABLED > 0
+
+eMBException
+eMBFuncReadDiscreteInputs( UCHAR * pucFrame, USHORT * usLen )
+{
+    USHORT          usRegAddress;
+    USHORT          usDiscreteCnt;
+    UCHAR           ucNBytes;
+    UCHAR          *pucFrameCur;
+
+    eMBException    eStatus = MB_EX_NONE;
+    eMBErrorCode    eRegStatus;
+
+    if( *usLen == ( MB_PDU_FUNC_READ_SIZE + MB_PDU_SIZE_MIN ) )
+    {
+        usRegAddress = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF] << 8 );
+        usRegAddress |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_ADDR_OFF + 1] );
+        usRegAddress++;
+
+        usDiscreteCnt = ( USHORT )( pucFrame[MB_PDU_FUNC_READ_DISCCNT_OFF] << 8 );
+        usDiscreteCnt |= ( USHORT )( pucFrame[MB_PDU_FUNC_READ_DISCCNT_OFF + 1] );
+
+        /* Check if the number of registers to read is valid. If not
+         * return Modbus illegal data value exception. 
+         */
+        if( ( usDiscreteCnt >= 1 ) &&
+            ( usDiscreteCnt < MB_PDU_FUNC_READ_DISCCNT_MAX ) )
+        {
+            /* Set the current PDU data pointer to the beginning. */
+            pucFrameCur = &pucFrame[MB_PDU_FUNC_OFF];
+            *usLen = MB_PDU_FUNC_OFF;
+
+            /* First byte contains the function code. */
+            *pucFrameCur++ = MB_FUNC_READ_DISCRETE_INPUTS;
+            *usLen += 1;
+
+            /* Test if the quantity of coils is a multiple of 8. If not last
+             * byte is only partially field with unused coils set to zero. */
+            if( ( usDiscreteCnt & 0x0007 ) != 0 )
+            {
+                ucNBytes = ( UCHAR ) ( usDiscreteCnt / 8 + 1 );
+            }
+            else
+            {
+                ucNBytes = ( UCHAR ) ( usDiscreteCnt / 8 );
+            }
+            *pucFrameCur++ = ucNBytes;
+            *usLen += 1;
+
+            eRegStatus =
+                eMBRegDiscreteCB( pucFrameCur, usRegAddress, usDiscreteCnt );
+
+            /* If an error occured convert it into a Modbus exception. */
+            if( eRegStatus != MB_ENOERR )
+            {
+                eStatus = prveMBError2Exception( eRegStatus );
+            }
+            else
+            {
+                /* The response contains the function code, the starting address
+                 * and the quantity of registers. We reuse the old values in the 
+                 * buffer because they are still valid. */
+                *usLen += ucNBytes;;
+            }
+        }
+        else
+        {
+            eStatus = MB_EX_ILLEGAL_DATA_VALUE;
+        }
+    }
+    else
+    {
+        /* Can't be a valid read coil register request because the length
+         * is incorrect. */
+        eStatus = MB_EX_ILLEGAL_DATA_VALUE;
+    }
+    return eStatus;
+}
+
+#endif