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/*
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* Copyright (c) 2002,2016 Mario de Sousa (msousa@fe.up.pt)
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*
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* This file is part of the Modbus library for Beremiz and matiec.
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*
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* This Modbus library is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser
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* 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 License
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* along with this Modbus library. If not, see <http://www.gnu.org/licenses/>.
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*
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* This code is made available on the understanding that it will not be
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* used in safety-critical situations without a full and competent review.
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*/
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/* write a modbus frame */
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/* WARNING: when calling this function, the *frame_data buffer
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* must be allocated with an extra *extra_bytes
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* beyond those required for the frame_length.
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* This is because the extra bytes will be used
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* to store the crc before sending the frame.
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*
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* The *extra_bytes value will be returned by the
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* modbus_init() function call.
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*/
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/* NOTE: calling this function will flush the input stream,
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* which means any frames that may have arrived
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* but have not yet been read using modbus_read()
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* will be permanently lost...
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*/
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int modbus_write(int nd,
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u8 *frame_data,
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size_t frame_length,
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u16 transaction_id,
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const struct timespec *transmit_timeout
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);
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/* read a modbus frame */
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/*
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* The frame is read from:
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* - the node descriptor nd, if nd >= 0
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* - any valid and initialised node descriptor, if nd = -1
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* In this case, the node where the data is eventually read from
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* is returned in *nd.
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* NOTE: (only avaliable if using TCP)
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*/
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/* NOTE: calling modbus_write() will flush the input stream,
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* which means any frames that may have arrived
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* but have not yet been read using modbus_read()
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* will be permanently lost...
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*
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* NOTE: Ususal select semantics for (a: recv_timeout == NULL) and
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* (b: *recv_timeout == 0) also apply.
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* (a) Indefinite timeout
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* (b) Try once, and and quit if no data available.
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*/
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/* NOTE: send_data and send_length is used to pass to the modbus_read() function
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* the frame that was previously sent over the same connection (node).
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* This data is then allows the modbus_read() function to ignore any
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* data that is read but identical to the previously sent data. This
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* is used when using serial ports that echoes back all the data that is
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* sent out over the same serial port. When using some RS232 to RS485
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* converters, this functionality is essential as not all these converters
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* are capable of not echoing back the sent data.
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* These parameters are ignored when using TCP!
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*/
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/* RETURNS: number of bytes read
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* -1 on read from file/node error
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* -2 on timeout
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*/
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int modbus_read(int *nd, /* node descriptor */
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u8 **recv_data_ptr,
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u16 *transaction_id,
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const u8 *send_data,
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int send_length,
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const struct timespec *recv_timeout);
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/* init the library */
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int modbus_init(int nd_count, /* maximum number of nodes... */
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optimization_t opt,
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int *extra_bytes);
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/* shutdown the library...*/
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int modbus_done(void);
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/* Open a node for master / slave operation.
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* Returns the node descriptor, or -1 on error.
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*/
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int modbus_connect(node_addr_t node_addr);
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int modbus_listen(node_addr_t node_addr);
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/* Close a node, needs a node descriptor as argument... */
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int modbus_close(int nd);
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/* Tell the library that the user will probably not be communicating
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* for some time...
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* This will allow the library to release any resources it will not
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* be needing during the silence.
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* NOTE: This is onlyused by the TCP version to close down tcp connections
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* when the silence will going to be longer than second.
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*/
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int modbus_silence_init(void);
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/* determine the minmum acceptable timeout... */
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/* NOTE: timeout values passed to modbus_read() lower than the value returned
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* by this function may result in frames being aborted midway, since they
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* take at least modbus_get_min_timeout() seconds to transmit.
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*/
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double modbus_get_min_timeout(int baud,
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int parity,
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int data_bits,
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int stop_bits);
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