Callback

Callbacks

Register read/write callback

Use one callback function for multiple registers

Incoming request callback (applicable to server/slave)

Modbus TCP/TLS Incoming connection callback

Modbus TCP/TLS Transaction result

Callback API

bool onSetCoil(uint16_t address, cbModbus cb = nullptr, uint16_t numregs = 1);
bool onSetHreg(uint16_t address, cbModbus cb = nullptr, uint16_t numregs = 1);
bool onSetIsts(uint16_t address, cbModbus cb = nullptr, uint16_t numregs = 1);
bool onSetIreg(uint16_t address, cbModbus cb = nullptr, uint16_t numregs = 1);

• address Address of register assign callback on
• cb Callback function
• numregs Count of sequental segisters assign this callback to

Assign callback function on register modify event. Multiple sequental registers can be affected by specifing numregs parameter.

bool onGetCoil(uint16_t address, cbModbus cb = nullptr, uint16_t numregs = 1);
bool onGetHreg(uint16_t address, cbModbus cb = nullptr, uint16_t numregs = 1);
bool onGetIsts(uint16_t address, cbModbus cb = nullptr, uint16_t numregs = 1);
bool onGetIreg(uint16_t address, cbModbus cb = nullptr, uint16_t numregs = 1);

• address Address of register assign callback on
• cb Callback function
• numregs Count of sequental segisters assign this callback to

Assign callback function on register query event. Multiple sequental registers can be affected by specifing numregs parameter.

bool removeOnGetCoil(uint16_t offset, cbModbus cb = nullptr, uint16_t numregs = 1);
bool removeOnSetCoil(uint16_t offset, cbModbus cb = nullptr, uint16_t numregs = 1);
bool removeOnGetHreg(uint16_t offset, cbModbus cb = nullptr, uint16_t numregs = 1);
bool removeOnSetHreg(uint16_t offset, cbModbus cb = nullptr, uint16_t numregs = 1);
bool removeOnGetIsts(uint16_t offset, cbModbus cb = nullptr, uint16_t numregs = 1);
bool removeOnSetIsts(uint16_t offset, cbModbus cb = nullptr, uint16_t numregs = 1);
bool removeOnGetIreg(uint16_t offset, cbModbus cb = nullptr, uint16_t numregs = 1);
bool removeOnSetIreg(uint16_t offset, cbModbus cb = nullptr, uint16_t numregs = 1);

• address Address of register assign callback on
• cb Callback function or NULL to remove all the callbacks.
• numregs Count of sequental segisters remove this callback to.

Disconnect specific callback function or all callbacks of the type if cb=NULL.

typedef Modbus::ResultCode (*cbRequest)(Modbus::FunctionCode fc, const Modbus::RequestData data);
bool onRequest(cbRequest cb = _onRequestDefault);
bool onRequestSuccess(cbRequest cb = _onRequestDefault);

union Modbus::RequestData {
    struct {
        TAddress reg;
        uint16_t regCount;
    };
    struct {
        TAddress regRead;
        uint16_t regReadCount;
        TAddress regWrite;
        uint16_t regWriteCount;
    };
    struct {
        TAddress regMask;
        uint16_t andMask;
        uint16_t orMask;
    };
};

Callback function receives Modbus function code, structure Modbus::RequestData containing register type and offset (TAddress structure) and count of registers requested. The function should return [result code](#Result codes Modbus::ResultCode) Modbus::EX_SUCCESS to allow request processing or Modbus error code to block processing. This code will be returned to client/master.

void onConnect(cbModbusConnect cb);
void onDisonnect(cbModbusConnect cb);

Assign callback function on incoming connection event.

typedef bool (*cbModbusConnect)(IPAddress ip);

• ip Client's address of incomig connection source. INADDR_NONE for on disconnect callback.

Result codes Modbus::ResultCode

Value	Hex	Definition	Decription
Modbus::EX_SUCCESS	0x00	Custom	No error
Modbus::EX_ILLEGAL_FUNCTION	0x01	Modbus	Function Code not Supported
Modbus::EX_ILLEGAL_ADDRESS	0x02	Modbus	Output Address not exists
Modbus::EX_ILLEGAL_VALUE	0x03	Modbus	Output Value not in Range
Modbus::EX_SLAVE_FAILURE	0x04	Modbus	Slave or Master Device Fails to process request
Modbus::EX_ACKNOWLEDGE	0x05	Modbus	Not used
Modbus::EX_SLAVE_DEVICE_BUSY	0x06	Modbus	Not used
Modbus::EX_MEMORY_PARITY_ERROR	0x08	Modbus	Not used
Modbus::EX_PATH_UNAVAILABLE	0x0A	Modbus	Not used
Modbus::EX_DEVICE_FAILED_TO_RESPOND	0x0B	Modbus	Not used
Modbus::EX_GENERAL_FAILURE	0xE1	Custom	Unexpected master error
Modbus::EX_DATA_MISMACH	0xE2	Custom	Inpud data size mismach
Modbus::EX_UNEXPECTED_RESPONSE	0xE3	Custom	Returned result doesn't mach transaction
Modbus::EX_TIMEOUT	0xE4	Custom	Operation not finished within reasonable time
Modbus::EX_CONNECTION_LOST	0xE5	Custom	Connection with device lost
Modbus::EX_CANCEL	0xE6	Custom	Transaction/request canceled

Modbus Library for Arduino

ModbusRTU, ModbusTCP and ModbusTCP Security

(c)2020 Alexander Emelianov

The code in this repo is licensed under the BSD New License. See LICENSE.txt for more info.