Modbus floating point conversion - arduino

Question

I am using Arduino modbus library for measuring string current using hall sensor.Here library downloaded.Modbus library .I have sensor data in floating value & the library store the value in integer format.
question :
how can save the sensor value into integer format
How can assign user defined address. start address like 4000h instead of 0000H
code
#include <avr/wdt.h>
#include"glob.h"
//#define ID 1
void Device_ID_Reading()
{
for(row=0;row<9;row++)
{
digitalWrite(SO_enable,array1[row][0]);
digitalWrite(S1_enable,array1[row][1]);
digitalWrite(S2_enable,array1[row][2]);
Status_Out[row]=digitalRead(Read_IDstatus);
Device_ID =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];
Serial.print("Device_ID");
Serial.print(row);
Serial.print(":\t");
Serial.println(Device_ID);
}
}
int8_t state = 0;
Modbus slave(Device_ID, 0, 0);
unsigned long tempus;
// data array for modbus network sharing
uint16_t au16data[30];
void Take_Reading()
{
for(row=0;row<9;row++)
{
// int k=(8*array[row][0]+4*array[row][1]+2*array[row][2]+1*array[row][3]);
// digitalWrite(Enablepin,array[row][0]);
digitalWrite(SO_enable,array1[row][1]);
digitalWrite(S1_enable,array1[row][2]);
digitalWrite(S2_enable,array1[row][3]);
//delay(100);
Sensor_Value0=analogRead(A0);
Sensor_Value1=analogRead(A5);
Mux1_array[row]=(Sensor_Value0 * ARDUINO_ANALOG_SCALING);
Mux2_array[row]=(Sensor_Value1 * ARDUINO_ANALOG_SCALING);
Current_Value1[row]= (Mux1_array[row]*35.1428571429)-87.6571428571;
Current_Value2[row]= (Mux2_array[row]*35.1428571429)-87.6571428571;
Current_Value3[row]=(Mux3_array[row]*35.1428571429)-87.6571428571;
}
}
void setup()
{
wdt_enable(WDTO_8S);
slave.begin( 9600 );
tempus = millis() + 100;
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(A1, INPUT) ;
pinMode(A2,INPUT);
// Serial.begin(9600);
}
void loop()
{
digitalWrite(3,HIGH);
// wdt_reset();
Take_Reading();
Device_ID_Reading();
state = slave.poll( au16data,30 );
if (state > 4) {
tempus = millis() + 50;
digitalWrite(13, HIGH);
}
if (millis() > tempus) digitalWrite(13, LOW );
Modbus_call();
}
void Modbus_call()
{
/*reading of coil where i can succefully read value*/
au16data[1]=(int)(100*Current_Value1[0]);
au16data[2]=(int)(100*Current_Value1[1]);
au16data[3]=(int)(100*Current_Value1[3]);
au16data[4]=(int)(100*Current_Value1[4]);
au16data[5]=(int)(100*Current_Value1[5]);
au16data[6]=(int)(100*Current_Value1[6]);
au16data[7]=(int)(100*Current_Value1[7]);
au16data[8]=(int)(100*Current_Value1[8]);
au16data[9]=(int)(100*Current_Value2[0]);
au16data[10]=(int)(100*Current_Value2[1]);
au16data[11]=(int)(100*Current_Value2[2]);
au16data[12]=(int)(100*Current_Value2[3]);
au16data[16]=(int)(100*Current_Value2[4]);
au16data[17]=(int)(100*Current_Value2[5]);
au16data[18]=(int)(100*Current_Value2[6]);
au16data[19]=(int)(100*Current_Value2[7]);
uint16_t calcCRC( au16data[15]);
au16data[13] = slave.getInCnt();
au16data[14] = slave.getOutCnt();
au16data[15] = slave.getErrCnt();
}
Is there any other library where i can use the floating point directly.

Answer 1

Modbus as a protocol does not directly support floats. However you can put float data into adjacent registers. Use type punning to put the float data into your registers and pull it out on the other side.
union Pun {float f; uint32_t u;};
void encodeFloat(uint16_t *regs, float x)
{
union Pun pun;
pun.f = x;
regs[0] = (pun.u >> 16) & 0xFFFFU;
regs[1] = pun.u & 0xFFFFU;
}
float decodeFloat(const uint16_t *regs)
{
union Pun pun;
pun.u = ((uint32_t)regs[0] << 16) | regs[1];
return pun.f;
}
You would use it like so:
void Modbus_call()
{
/*reading of coil where i can succefully read value*/
encodeFloat(&au16data[ 0], Current_Value1[0]);
encodeFloat(&au16data[ 2], Current_Value1[1]);
encodeFloat(&au16data[ 4], Current_Value1[2]);
/* And so on... */
}