Thread: Modbus arduino library

Dear all ,
I am working with Modbus protocol library for arduino uno.the code written in c++. I have attached the library detail in PDF file.

Example code: The code works properly. The problem here if we want to add more slave 0-255 each time i need to configure manually set device id & very difficult to track which ID being used.

Code:

#include <ModbusRtu.h>
uint16_t au16data[16] = {
  3, 1415, 9265, 4, 2, 7182, 28182, 8, 0, 0, 0, 0, 0, 0, 1, -1 };
Modbus slave(1,0,0); // this is slave @1 and RS-232 or USB-FTDI


void setup() {
  slave.begin( 19200 ); // baud-rate at 19200
}


void loop() {
  slave.poll( au16data, 16 );
}

SO i decide to build 8:1 digital multiplexer & 16 pin with 8 out dip package. The output given to digital multiplexer.Depend on status of pin . The device ID being calculated. Even viewer can come to know which ID being set.

Code:

#include <ModbusRtu.h>
int SO_enable=5;
int S1_enable=4;
int S2_enable=3;
int Status_Out[8];
int Output_Read=2;
static int Device_ID;
unsigned long int curr_time;
Modbus *slave=0;




int array[8][3]={
  {    
    0,0,0      }
  ,
  {    
    0,0,1      }
  ,
  {    
    0,1,0      }
  ,  
  {    
    0,1,1      }
  ,
  {    
    1,0,0      }
  ,
  {    
    1,0,1      }
  ,
  {    
    1,1,0      }
  ,
  {    
    1,1,1      }




};


unsigned int ID_Check() {
  unsigned   int ID_value;
  for(int row=0;row<8;row++)
  {
    digitalWrite(SO_enable,array[row][0]);
    digitalWrite(S1_enable,array[row][1]);
    digitalWrite(S2_enable,array[row][2]);
    Status_Out[row]=digitalRead(Output_Read);


  }


  ID_value = 1 * Status_Out[0] + 2 * Status_Out[1] + 4 * Status_Out[2] + 8 * Status_Out[3] + 16 * Status_Out[4] + 32 * Status_Out[5] + 64 * Status_Out[6] + 128 * Status_Out[7];
  return(ID_value);
}




uint16_t au16data[16] = 
{
  3, 1415, 9265, 4, 2, 7182, 28182, 8, 0, 0, 0, 0, 0, 0, 1, -1
};






void setup() {
  //  Serial.begin(9600);
  pinMode(SO_enable, OUTPUT) ;// pin can enable/disable using digital IO 7 of arduino
  pinMode(S1_enable, OUTPUT) ;// pin can enable/disable using digital IO 6 of arduino
  pinMode(S2_enable, OUTPUT) ;// pin can enable/disable using digital IO 5 of arduino
  pinMode(Output_Read,INPUT);
  unsigned int Device_ID=ID_Check();
  slave=new Modbus(Device_ID,0,0);
  slave->begin(9600);


}


void loop() {
// Modbus_setup();
  delay(1000);
  for(int i = 0; i<8; i++)
  {
    au16data[i];
  }
}

I have already checked in serial monitor Device id changes as pin status changes.But when disable serial monitor & assign to device ID. slave fails to communicate. Please let me know how can resolve this.if ID_check() not used it work properly else it wont work.
I also tried with slave.setID(); & slave.getID(); is there way to make it work.


Modbus.pdf

Yes you are right When i change it to this code start working .

Code:

void loop() {
 slave->poll( au16data, 16 );
}

My application is string monitoring . I have used 3 analog mux Which shared by port Ao,A1,A2. A5 temprature,A3 High voltage. The code seems working fine when hard code the slave ID. when i assign using function i get errors..,



Now I based on this i implemented code , For below i didn't receive data, Here so,s1,s2 also used to read analog mux value

Code:

#include <avr/wdt.h>
#include"glob.h"
Modbus *slave=0;
int8_t state = 0;
unsigned long tempus;
// data array for modbus network sharing
uint16_t au16data[30];
int ID_Check() {
  int ID_value;
  for(int row=0;row<8;row++)
  {
    digitalWrite(SO_enable,array[row][0]);
    digitalWrite(S1_enable,array[row][1]);
    digitalWrite(S2_enable,array[row][2]);
    Status_Out[row]=digitalRead(Output_Read);


  }


  ID_value = 1 * Status_Out[0] + 2 * Status_Out[1] + 4 * Status_Out[2] + 8 * Status_Out[3] + 16 * Status_Out[4] + 32 * Status_Out[5] + 64 * Status_Out[6] + 128 * Status_Out[7];
  return(ID_value);
}


void setup()
{
  //  wdt_enable(WDTO_8S);


  Device_ID= ID_Check();
  slave=new Modbus(Device_ID,0,0);




  tempus = millis() + 1000;
  pinMode(3,OUTPUT);
  pinMode(SO_enable, OUTPUT) ;// pin can enable/disable using digital IO 7 of arduino
  pinMode(S1_enable, OUTPUT) ;// pin can enable/disable using digital IO 6 of arduino
  pinMode(S2_enable, OUTPUT) ;// pin can enable/disable using digital IO 5 of arduino
  //  pinMode(Enablepin, OUTPUT) ;// pin can enable/disable using digital IO 4 of arduino
  pinMode(A0, INPUT) ;
  pinMode(A5, INPUT) ;
  //spd & DC STATUS 
  pinMode(SPD_STATUS_PIN,INPUT);
  pinMode(DC_STATUS_PIN,INPUT);
  //Serial.begin(9600);
  slave->begin(9600);
}
void modbus_call() {


  for(int i = 0; i<8; i++)
  {
    au16data[i] = Mod_current1[i];
    au16data[i+8] = Mod_current2[i+8];
    au16data[i+16] = Mod_current3[i+16];
  }


  au16data[25]=(int)(temp*1000);
  au16data[26]=ID_Check();
  au16data[27]=SPD_Check();
  au16data[28]= DC_Status();
  au16data[29]=slave->getInCnt(); 
  au16data[30]=slave->getOutCnt(); 
  //  au16data[31]=slave.getErrCnt();
}




void loop() {
  // wdt_reset();
  Take_Reading();
  Take_Temp_Reading();
  modbus_call();
  // slave->poll( au16data, 30 );
}

Please let me know how to resolve this