mirror of
https://github.com/3cky/mbusd.git
synced 2024-06-24 10:14:49 +02:00
5c064928ae
When multiple modbus frames were queued in the socket buffer conn_read() would read until it completely drained the kernel's socket buffer or filled the connection buffer. The first modbus frame in the buffer is then processed and sent to the tty, then the buffer is reused for the reponse after it is received from the tty possibly overwritting any subsequent modbus request frames already read. Avoid this by maintaining pre-connection length to read, so we only read a single modbus frame at a time.
90 lines
2.9 KiB
C
90 lines
2.9 KiB
C
/*
|
|
* OpenMODBUS/TCP to RS-232/485 MODBUS RTU gateway
|
|
*
|
|
* modbus.c - MODBUS protocol related procedures
|
|
*
|
|
* Copyright (c) 2002-2003, 2013, Victor Antonovich (v.antonovich@gmail.com)
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
*
|
|
* - Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions and the following disclaimer.
|
|
*
|
|
* - Redistributions in binary form must reproduce the above copyright
|
|
* notice, this list of conditions and the following disclaimer in the
|
|
* documentation and/or other materials provided with the distribution.
|
|
*
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
|
|
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR
|
|
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
|
|
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
|
|
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
|
|
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
|
|
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
|
|
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
|
|
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
|
|
*
|
|
* $Id: modbus.c,v 1.3 2015/02/25 10:33:58 kapyar Exp $
|
|
*/
|
|
|
|
#include "modbus.h"
|
|
#include "conn.h"
|
|
|
|
/*
|
|
* Check CRC of MODBUS frame
|
|
* Parameters: FRAME - address of the frame,
|
|
* LEN - frame length;
|
|
* Return: 0 if CRC failed,
|
|
* non-zero otherwise
|
|
*/
|
|
int
|
|
modbus_crc_correct(unsigned char *frame, unsigned int len)
|
|
{
|
|
return (!crc16(frame, len));
|
|
}
|
|
|
|
/*
|
|
* Write CRC to MODBUS frame
|
|
* Parameters: FRAME - address of the frame,
|
|
* LEN - frame length;
|
|
* Return: none
|
|
*/
|
|
void
|
|
modbus_crc_write(unsigned char *frame, unsigned int len)
|
|
{
|
|
WORD_WR_LE(frame + len, crc16(frame, len));
|
|
}
|
|
|
|
/*
|
|
* Write exception response to OpenMODBUS request
|
|
* Parameters: PACKET - address of the request packet,
|
|
* CODE - exception code;
|
|
* Return: none
|
|
*/
|
|
void
|
|
modbus_ex_write(unsigned char *packet, unsigned char code)
|
|
{
|
|
MB_FRAME(packet, MB_FCODE) |= 0x80;
|
|
MB_FRAME(packet, MB_DATA) = code;
|
|
WORD_WR_BE(packet + MB_LENGTH_H, MB_EX_LEN);
|
|
}
|
|
|
|
/*
|
|
* Check MODBUS packet header consistency
|
|
* Parameters: PACKET - address of the request packet,
|
|
* Return: RC_OK if (mostly) all is right, RC_ERR otherwise
|
|
*/
|
|
int
|
|
modbus_check_header(unsigned char *packet)
|
|
{
|
|
return (MB_FRAME(packet, MB_PROTO_ID_H) == 0 &&
|
|
MB_FRAME(packet, MB_PROTO_ID_L) == 0 &&
|
|
MB_FRAME(packet, MB_LENGTH_H) == 0 &&
|
|
MB_FRAME(packet, MB_LENGTH_L) > 0 &&
|
|
MB_FRAME(packet, MB_LENGTH_L) < BUFSIZE - CRCSIZE) ? RC_OK : RC_ERR;
|
|
}
|