Assign Modbus slave ID by hardware

[GoogleCodeExporter]

Dear all,

Here i am attaching working code & modified code for simple modbus.The 
difference between working code & alter code is assign method of slave ID. If i 
wanted to config the slave ID i need to do individually .i checked the code 
work with change in ID no in working code. but it difficult to keep track if 
there are 255 devices .

For that i used 8:1 multiplexer & 8pin dip . Depend on status output 
multiplexer i calculated the device ID. The function ID_Check() determine 
device ID>.when i debug initially via serial monitor the code seems device ID 
updating as expected. but when i enable slave , i get error msg didnt receive 
any response from slave. if i assign device id directly code start working. 

Let me know how to assign device ID here

Working code:


#include <ModbusRtu.h>
#define Device_ID 1
uint16_t au16data[16] = {
  3, 1415, 9265, 4, 2, 7182, 28182, 8, 0, 0, 0, 0, 0, 0, 1, -1 };

Modbus slave(Device_ID,10,0); // 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 );
}

Now alter code as below


#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];
  }
}











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Original issue reported on code.google.com by [email protected] on 10 Feb 2015 at 8:35

[GoogleCodeExporter]

If you altered the library I cant help you with out the source code ;-)

Original comment by [email protected] on 12 Feb 2015 at 4:52

• Removed labels: Type-Defect

[GoogleCodeExporter]

I didn't change any thing.I have all defined in Modbus RTU function.

Original comment by [email protected] on 12 Feb 2015 at 5:35