forked from espressif/esp-modbus
106 lines
4.1 KiB
C
106 lines
4.1 KiB
C
/*
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* FreeRTOS Modbus Libary: A Modbus serial implementation for FreeRTOS
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* Copyright (c) 2016, 2017 Nucleron R&D LLC <main@nucleron.ru>
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* Copyright (C) 2006 Christian Walter <wolti@sil.at>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#include <mb_common.h>
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#include <mb_proto.h>
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#include "mb_slave.h"
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/* ----------------------- Defines ------------------------------------------*/
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#define MB_PDU_FUNC_READ_ADDR_OFF (MB_PDU_DATA_OFF)
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#define MB_PDU_FUNC_READ_DISCCNT_OFF (MB_PDU_DATA_OFF + 2)
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#define MB_PDU_FUNC_READ_SIZE (4)
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#define MB_PDU_FUNC_READ_DISCCNT_MAX (0x07D0)
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/* ----------------------- Static functions ---------------------------------*/
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mb_exception_t mb_error_to_exception(mb_err_enum_t error_code);
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/* ----------------------- Start implementation -----------------------------*/
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#if MB_FUNC_READ_COILS_ENABLED > 0
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mb_exception_t
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mbs_fn_read_discrete_inp(mb_base_t *inst, uint8_t *frame_ptr, uint16_t *len_buf)
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{
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uint16_t reg_addr;
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uint16_t discrete_cnt;
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uint8_t byte_num;
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uint8_t *frame_cur;
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mb_exception_t status = MB_EX_NONE;
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mb_err_enum_t reg_status = MB_EILLFUNC;
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(void)inst;
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if (*len_buf == (MB_PDU_FUNC_READ_SIZE + MB_PDU_SIZE_MIN)) {
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reg_addr = (uint16_t)(frame_ptr[MB_PDU_FUNC_READ_ADDR_OFF] << 8);
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reg_addr |= (uint16_t)(frame_ptr[MB_PDU_FUNC_READ_ADDR_OFF + 1]);
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reg_addr++;
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discrete_cnt = (uint16_t)(frame_ptr[MB_PDU_FUNC_READ_DISCCNT_OFF] << 8);
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discrete_cnt |= (uint16_t)(frame_ptr[MB_PDU_FUNC_READ_DISCCNT_OFF + 1]);
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/* Check if the number of registers to read is valid. If not
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* return Modbus illegal data value exception.
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*/
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if ((discrete_cnt >= 1) &&
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(discrete_cnt < MB_PDU_FUNC_READ_DISCCNT_MAX)) {
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/* Set the current PDU data pointer to the beginning. */
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frame_cur = &frame_ptr[MB_PDU_FUNC_OFF];
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*len_buf = MB_PDU_FUNC_OFF;
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/* First byte contains the function code. */
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*frame_cur++ = MB_FUNC_READ_DISCRETE_INPUTS;
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*len_buf += 1;
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/* Test if the quantity of coils is a multiple of 8. If not last
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* byte is only partially field with unused coils set to zero. */
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if ((discrete_cnt & 0x0007) != 0) {
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byte_num = (uint8_t) (discrete_cnt / 8 + 1);
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} else {
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byte_num = (uint8_t) (discrete_cnt / 8);
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}
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*frame_cur++ = byte_num;
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*len_buf += 1;
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/* Call r/w function if defined*/
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if (inst->rw_cbs.reg_discrete_cb) {
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reg_status = inst->rw_cbs.reg_discrete_cb(inst, frame_cur, reg_addr, discrete_cnt);
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}
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/* If an error occured convert it into a Modbus exception. */
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if (reg_status != MB_ENOERR) {
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status = mb_error_to_exception(reg_status);
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} else {
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/* The response contains the function code, the starting address
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* and the quantity of registers. We reuse the old values in the
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* buffer because they are still valid. */
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*len_buf += byte_num;;
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}
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} else {
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status = MB_EX_ILLEGAL_DATA_VALUE;
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}
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} else {
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/* Can't be a valid read coil register request because the length
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* is incorrect. */
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status = MB_EX_ILLEGAL_DATA_VALUE;
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}
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return status;
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}
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#endif
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