Change SLAVE_ID about arduinomodbusslave

[yaacov]

No, you can add a Modbus::setSlaveID function to update the unitID private var [1] [2].

[1] https://github.com/yaacov/ArduinoModbusSlave/blob/master/src/ModbusSlave.cpp#L43
[2] https://github.com/yaacov/ArduinoModbusSlave/blob/master/src/ModbusSlave.h#L93

[yaacov]

p.s
a pull request is welcome :-)

[g6pl]

Hello. You do not understand me ... :( I would like to change the value of SLAVE_ID during program operation

[g6pl]

This is not the fault of the library, but the lack of my knowledge of arduino ..

[g6pl]

I would like the program to read the SLAVE_ID from the EEPROM memory and then run the Modbus slave (SLAVE_ID, CTRL_PIN); How can I run Modbus slave (SLAVE_ID, CTRL_PIN) in Void Setup or Void Loop?

[yaacov]

No, the slave-id is set in the constructor [1]

Once it is set, it can not be changed. If you add a new method to the Modbus class [2] that update the private unitID var [3], you will be able to change the unit id (that was set by SLAVE_ID in the constructor) while program is running ( e.g. inside loop or setup)

[1] https://github.com/yaacov/ArduinoModbusSlave/blob/master/examples/simple/simple.ino#L38
[2] https://github.com/yaacov/ArduinoModbusSlave/blob/master/src/ModbusSlave.h#L73
[3] https://github.com/yaacov/ArduinoModbusSlave/blob/master/src/ModbusSlave.h#L93

an example of such a method:

/**
 * Set Unit ID of modbus object.
 *
 * @param unitID the modbus slave id.
 */
void Modbus::setUnitID(uint8_t _unitID)
{
    // set modbus slave unit id
    unitID = _unitID;
}

[yaacov]

Changing CTRL_PIN is more tricky :-) , the easiest way is to create a new modbus object with a new Serial stream [1] and a new ctrl pin.

Check carefully that you must get the ctrl_pin at runtime, it may get a little interesting if you have little experience with arduino.

[1] https://github.com/yaacov/ArduinoModbusSlave/blob/master/src/ModbusSlave.cpp#L39

[g6pl]

In ModbusSlave.h i change:
`class Modbus {
public:
Modbus(uint8_t unitID, int ctrlPin);
Modbus(Stream &serial, uint8_t unitID, int ctrlPin);
void begin(unsigned long boud);
int poll();
int readCoilFromBuffer(int offset);
uint16_t readRegisterFromBuffer(int offset);
void writeCoilToBuffer(int offset, int state);
void writeRegisterToBuffer(int offset, uint16_t value);
uint8_t writeStringToBuffer(int offset, uint8_t *str, uint8_t length);
CallBackFunc cbVector[CB_MAX];
void Modbus::setUnitID(uint8_t _unitID)
{
// set modbus slave unit id
unitID = _unitID;
}
private:
Stream &serial;
uint32_t timeout;
uint32_t last_receive_time;
uint16_t calcCRC(uint8_t *buf, int length);

int ctrlPin = -1;
uint8_t unitID;
uint8_t lengthIn;
uint8_t bufIn[MAX_BUFFER];
uint8_t bufOut[MAX_BUFFER];

};
#endif
`

This is ok?

[yaacov]

it's nicer to add the function in the xxx.c file, and only the header void setUnitID(uint8_t _unitID); in the xxx.h file

[g6pl]

`
#define CTRL_PIN 4
#define BAUDRATE 9600
#define SLAVE_ID 5

Modbus slave(SLAVE_ID, CTRL_PIN);

void setup()
{
SLAVE_ID = 12; //how i can change? This is no good.. :(
.
.
.
}
`

[g6pl]

any ideas?

[yaacov]

once you have the setUnitID method header defined in the .h and body defined in the .c file you can call it slave.setUnitID(12)

[g6pl]

Thank you very much.
Everything works :)
Happy New Year!

[yaacov]

Happy New Year!

Happy New Year 🎉 🎈