PID Control Simple P and I use DC Motor and Volume

#include <ModbusRtu.h>

// data array for modbus network sharing
uint16_t au16data[16];

#define E2 3
#define I3 12
#define I4 13
int Target_VR = A4;
int Position_VR = A5;
int Target = 0;
int feedback = 0;
double Error = 0;
double Output=0;

double Out_p = 0;
double Out_i = 0;
double Temp_i = 0;
double Kp = 1.0;
double Ki = 0.025;


Modbus slave(1,1,0); // this is slave @1 and RS-232 or USB-FTDI

void setup() {

slave.begin( 19200 ); // baud-rate at 19200

pinMode(E2,OUTPUT);
pinMode(I3,OUTPUT);
pinMode(I4,OUTPUT);
Serial.begin(9600);



}

void loop() {

  Target = analogRead(Target_VR);
  feedback = analogRead(Position_VR);

               Error = Target - feedback;
               Out_p = Error * Kp;
               Temp_i = Temp_i +Error;
               Out_i = Temp_i *Ki;
               if(Out_i>255)Out_i = 255;
               if(Out_i<-255)Out_i = -255;
               Output = Out_p + Out_i;


 if(Output>0)
 {
  if(Output > 255) Output=255;
  digitalWrite(I3,HIGH);
  digitalWrite(I4,LOW);
 }
 if(Output<0)
 {
  if(Output < -255) Output = -255;
 }
  analogWrite(E2,Output);




Serial.print("\nTarget  Feedback  Output2 OUT       P     I");
 Serial.print("\n");
 Serial.print(Target);
 Serial.print("\t");
 Serial.print(feedback);
 Serial.print("\t");
 Serial.print( 700);
 Serial.print("\t");
 Serial.print(300);
 //Serial.print("\t");
 //Serial.print(Out_p);
 //Serial.print("\t");
 //Serial.print(Out_i);

 au16data[1]= feedback;
 au16data[2]= Error;
 Target = au16data[3];

 delay(30);
 slave.poll( au16data, 16 );
}