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SimpleModbusMaster.h

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+#ifndef SIMPLE_MODBUS_MASTER_H
+#define SIMPLE_MODBUS_MASTER_H
+
+// SimpleModbusMasterV10
+
+/* 
+	 SimpleModbusMaster allows you to communicate
+	 to any slave using the Modbus RTU protocol.
+	
+	 To communicate with a slave you need to create a packet that will contain 
+   all the information required to communicate to the slave.
+   Information counters are implemented for further diagnostic.
+   These are variables already implemented in a packet. 
+   You can set and clear these variables as needed.
+   
+   The following modbus information counters are implemented:    
+   
+   requests - contains the total requests to a slave
+   successful_requests - contains the total successful requests
+	 failed_requests - general frame errors, checksum failures and buffer failures 
+   retries - contains the number of retries
+   exception_errors - contains the specific modbus exception response count
+	 These are normally illegal function, illegal address, illegal data value
+	 or a miscellaneous error response.
+	
+   And finally there is a variable called "connection" that 
+   at any given moment contains the current connection 
+   status of the packet. If true then the connection is 
+   active. If false then communication will be stopped
+   on this packet until the programmer sets the connection
+   variable to true explicitly. The reason for this is 
+   because of the time out involved in modbus communication.
+   Each faulty slave that's not communicating will slow down
+   communication on the line with the time out value. E.g.
+   Using a time out of 1500ms, if you have 10 slaves and 9 of them
+   stops communicating the latency burden placed on communication
+   will be 1500ms * 9 = 13,5 seconds!  
+   Communication will automatically be stopped after the retry count expires
+   on each specific packet.
+	
+   All the error checking, updating and communication multitasking
+   takes place in the background.
+  
+   In general to communicate with to a slave using modbus
+   RTU you will request information using the specific
+   slave id, the function request, the starting address
+   and lastly the data to request.
+   Function 1, 2, 3, 4, 15 & 16 are supported. In addition to
+   this broadcasting (id = 0) is supported for function 15 & 16.
+	 
+   Constants are provided for:
+	 Function 1  - READ_COIL_STATUS
+	 Function 2  - READ_INPUT_STATUS
+   Function 3  - READ_HOLDING_REGISTERS 
+	 Function 4  - READ_INPUT_REGISTERS
+	 Function 15 - FORCE_MULTIPLE_COILS
+   Function 16 - PRESET_MULTIPLE_REGISTERS 
+	 
+	 Note:  
+   The Arduino serial ring buffer is 128 bytes or 64 registers.
+   Most of the time you will connect the Arduino using a MAX485 or similar.
+ 
+   In a function 3 or 4 request the master will attempt to read from a
+   slave and since 5 bytes is already used for ID, FUNCTION, NO OF BYTES
+   and two BYTES CRC the master can only request 122 bytes or 61 registers.
+ 
+   In a function 16 request the master will attempt to write to a 
+   slave and since 9 bytes is already used for ID, FUNCTION, ADDRESS, 
+   NO OF REGISTERS, NO OF BYTES and two BYTES CRC the master can only write
+   118 bytes or 59 registers.
+    
+   Note:
+   Using a USB to Serial converter the maximum bytes you can send is 
+   limited to its internal buffer which differs between manufactures. 
+ 
+   Since it is assumed that you will mostly use the Arduino to connect without
+   using a USB to Serial converter the internal buffer is set the same as the
+   Arduino Serial ring buffer which is 128 bytes.
+*/
+
+#include "Arduino.h"
+
+#define READ_COIL_STATUS 1 // Reads the ON/OFF status of discrete outputs (0X references, coils) in the slave.
+#define READ_INPUT_STATUS 2 // Reads the ON/OFF status of discrete inputs (1X references) in the slave.
+#define READ_HOLDING_REGISTERS 3 // Reads the binary contents of holding registers (4X references) in the slave.
+#define READ_INPUT_REGISTERS 4 // Reads the binary contents of input registers (3X references) in the slave. Not writable.
+#define FORCE_MULTIPLE_COILS 15 // Forces each coil (0X reference) in a sequence of coils to either ON or OFF.
+#define PRESET_MULTIPLE_REGISTERS 16 // Presets values into a sequence of holding registers (4X references).
+
+typedef struct
+{
+  // specific packet info
+  unsigned char id;
+  unsigned char function;
+  unsigned int address;
+	// For functions 1 & 2 data is the number of points
+  // For functions 3, 4 & 16 data is the number of registers
+  // For function 15 data is the number of coils
+  unsigned int data; 
+  unsigned int* register_array;
+  
+  // modbus information counters
+  unsigned int requests;
+  unsigned int successful_requests;
+	unsigned int failed_requests;
+	unsigned int exception_errors;
+  unsigned int retries;
+  	
+  // connection status of packet
+  unsigned char connection; 
+  
+  bool *connectionValid;
+  bool *valueValid;
+  
+}Packet;
+
+typedef Packet* packetPointer;
+
+// function definitions
+void modbus_update();
+
+void modbus_construct(Packet *_packet, 
+											unsigned char id, 
+											unsigned char function, 
+											unsigned int address, 
+											unsigned int data, 
+											unsigned int* register_array);
+											
+void modbus_configure(HardwareSerial* SerialPort,
+											long baud, 
+											unsigned char byteFormat,
+											unsigned int _timeout, 
+											unsigned int _polling, 
+											unsigned char _retry_count, 
+											unsigned char _TxEnablePin,
+											Packet* _packets, 
+											unsigned int _total_no_of_packets);
+
+#endif