#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