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firmware/Modbus-Serial/src/ModbusSerial.h

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+/*
+    ModbusSerial.h - Header for ModbusSerial Library
+    Copyright (C) 2023 Pascal JEAN aka epsilonrt
+    Copyright (C) 2014 André Sarmento Barbosa
+*/
+#include <Arduino.h>
+#include <Modbus.h>
+
+#pragma once
+
+/**
+ * @enum MB_PARITY
+ * @brief Parity
+ *
+ * See paragraph [2.5.1 RTU Transmission Mode] from
+ * MODBUS over serial line specification and implementation guide V1.02
+ * http://www.modbus.org/docs/Modbus_over_serial_line_V1_02.pdf
+ *
+ * The format (11 bits) for each byte in RTU mode is :
+ * Coding System:
+ *
+ * * 8–bit binary
+ *
+ * Bits per Byte:
+ *
+ *  * 1 start bit
+ *  * 8 data bits, least significant bit sent first
+ *  * 1 bit for parity completion
+ *  * 1 stop bit
+ *  .
+ *
+ * Even parity is required, other modes ( odd parity, no parity )
+ * may also be used. In order to ensure a maximum compatibility with
+ * other products, it is recommended to support also No parity mode.
+ * The default parity mode must be even parity.
+ * Remark : the use of no parity requires 2 stop bits.
+ */
+enum MB_PARITY {
+  MB_PARITY_NONE = SERIAL_8N2, ///< No parity
+  MB_PARITY_EVEN = SERIAL_8E1, ///< Even parity
+  MB_PARITY_ODD  = SERIAL_8O1  ///< Odd parity
+};
+
+/**
+ * @class ModbusSerial
+ * @brief Modbus over serial line Class
+ */
+class ModbusSerial : public Modbus {
+
+  public:
+    /**
+     * @brief Constructor
+     * @param port serial port to use
+     * @param txenPin if an RS485 circuit is used, this corresponds to the
+     * pin number connected to the transmit enable (DE) and receive disable (/RE) pin.
+     * -1 if not used.
+     */
+    ModbusSerial (Stream & port, byte slaveId, int txenPin = -1);
+
+    /**
+     * @brief Configure ModbusSerial object
+     * 
+     * configures txenPin on output if necessary and calculates the times of the RTU frame.
+     * 
+     * @warning the \c begin() function of the serial port passed to the constructor 
+     * must be called **BEFORE** calling this function.
+     * 
+     * @param baud baudrate in accordance with that used by the serial port
+     */
+    void config (unsigned long baud);
+
+    /**
+     * @brief Task that performs all operations on MODBUS
+     *
+     * Call once inside loop(), all magic here !
+     */
+    void task();
+
+    /**
+     * @brief Change the value of slave identifier
+     * @param slaveId identifier 1-247
+     */
+    void setSlaveId (byte slaveId);
+
+    /**
+     * @brief Return slave identifier
+     */
+    byte getSlaveId();
+
+    /**
+     * @brief Broadcast address
+     */
+    static const byte BroadcastAddress = 0;
+    
+  protected:
+    bool receive (byte * frame);
+    bool sendPDU (byte * pduframe);
+    bool send (byte * frame);
+    void reportServerId();
+
+  private:
+    Stream * m_stream;
+    int   m_txenPin;
+    byte  m_slaveId;
+
+    unsigned int m_t15; // inter character time out (us)
+    unsigned int m_t35; // frame delay  (us)
+
+  private:
+    word calcCrc (byte address, byte * pduframe, byte pdulen);
+};