controlling VFD with arduino...

i made a simple code to control VFD (change the speed and direction of ac drive) with arduino.

/*
Author : Kunchala Anil [anilkunchalaece@gmail.com]

Interfacing VFD with Arduino Via RS485 using MODBUS Protocol
MODBUS protocol
-------------------------------------------------------------------------
| Start Bit | Address | Function_Command | DATA | LRC or CRC | Stop bit |
| : | 2bytes | 2 bytes | | 2 bytes | \r\n |
-------------------------------------------------------------------------

Function Code : The format of data characters depend on function codes
The available function codes are described as follows:
0x03 : Read data from register
0x06 : Write single data to register
0x10 : Write multiple data to registers

MODBUS Protocol can be implemented in two ways ASCII or RTU(Remote Terminal Unit)
iam gonna use ASCII mode for this example

____________________________________________________________________________
| Content Address Functions
|-------------------------------------------------------------------------
| B1 B0
| 0 0 --> NO function
| Bit 0 - 1 0 1 --> Stop
| 1 0 --> Run
| 0x2000 1 1 --> Jog + Run
|
| Bit 2 - 3 Reserved
|
| B5 B4
| 0 0 --> No function
| Command Bit 4 - 5 0 1 --> FWD
| Read / Write 1 0 --> REV
| 1 1 --> Change Direction
|
| Bit 6 - 15 Reserved
|
| 0x2001 Frequency Command
|
|__________________________________________________________________________________


Command Address B15 B14 B13 B12 B11 B10 B9 B8 B7 B6 B5 B4 B3 B2 B1 B0 Hex Equalent
RUN 0x2000 0 0 0 0 0 0 0 0 0 0 0 1 0 0 1 0 0x0012
STOP 0x2000 0 0 0 0 0 0 0 0 0 0 0 1 0 0 0 1 0x0011
Format if data send to the VFD
':' --> Start bit in Ascii mode
\r\n --> Stop bit


*/

//commands values
#define VFD_START 1
#define VFD_STOP 2
#define VFD_SPEED 3

#define MAX_SIZE 20 // max size of data buffer

char speed_vfd[] = ":01062001";
const char start_vfd[] = ":010620000012C7\r\n";
const char stop_vfd[] = ":010620000011C8\r\n";
char data_buffer[MAX_SIZE];

void setup(){
Serial.begin(9600);
}//end of setup


void loop(){

serial_ask(); /* ask question the user to enter
1 to start the VFD
2 to stop the VFD
3 to set the speed of VFD */
int val = serial_check(); /* wait for user to enter the data and convert
it to Int and return value into function */
perform_action(val); /* perform the action based on the user entered value
which is passed to the function */

}//end of loop


/*
SERIAL_ASK() FUNCTION : this function is used to ask the user to enter the user choice via Serial monitor
*/
void serial_ask(){
Serial.println("Please Enter all values followed by \n");
Serial.println("Please enter the valid code to perform");
Serial.println("-------------------");
Serial.println("CODE\t ACTION");
Serial.print(VFD_START);Serial.println("\t START VFD");
Serial.print(VFD_STOP);Serial.println("\t STOP VFD");
Serial.print(VFD_SPEED);Serial.println("\t SET SPEED");
Serial.println("-------------------");
}//end of serial_ask() fucntion


/*
SERIAL_CHECK() FUNCTION : this function is used to receive the data into data_buffer
*/
int serial_check(){
while(!data_received())
{
//wait until full data is received
}//end of while
return atoi(data_buffer);
}//end of serial_check() function


boolean data_received(){
static byte index = 0;
while(!Serial.available())
{
//wait until user enter the data
}

if(Serial.available())
{
char input = Serial.read();
if(input !='\r')
{
data_buffer[index] = input;
index = index + 1;
}else
{
data_buffer[index] = 0;//null terminate the character array to make it string
index = 0;
return true;// we received the full code return true
}//end of ifelse condition
}
return false;
}//end of data_received()) function

void perform_action(int val){
switch(val)
{
case VFD_START:
Serial.println("VFD START");
VFD_control(start_vfd);
break;

case VFD_STOP:
Serial.println("VFD STOP");
VFD_control(stop_vfd);
break;

case VFD_SPEED:
Serial.println("SET SPEED");
set_speed();
break;

default:
error_message();

}//end of switch
}//end of perform action

void VFD_control(const char* command){
Serial.print(command);
Serial.println();
}

void set_speed(){
char freq_hex[4];//temporary string for sprintf
Serial.println("Set Speed");
Serial.println("enter the frequency");
int freq = serial_check();
Serial.print("the frequency you entered is");
Serial.println(freq);
sprintf(freq_hex,"%04X",freq);//convert it to hex using sprintf
strcat(speed_vfd,freq_hex);
cal_LRC();

}//end of set_speed() fucntion

void cal_LRC(){
int val = calculate(); //function to calculate the decimal value
convert_to_hex(val);// function to convert the decimal value to HEX
}//end of cal_LRC() fucntion


//CALCULATE() FUNCTION
int calculate(){
int val[strlen(speed_vfd)/2]; // val[] array is used to store the decimal value for two HEX digits
for (int i = 1, j = 0 ; i < strlen(speed_vfd); i = i+2, j++ ) //i = i+2 because we are finding the decimal equalent for two HEX values
{
val[j] = conv(speed_vfd[i],speed_vfd[i+1]); // function to convert Two Hex numbers into Decimal Value

}//end of for loop

int sum = find_sum(val); // function to calculate total sum of decimal equalents
return sum;
}//end of calculate() function

//FUNCTION_SUM() FUNCTION
int find_sum(const int * val) // we are passing an array to the function
{
int sum = 0;
for(int i=0;i<= (strlen(speed_vfd)/2) - 1;i++)
{
sum = sum + val[i];
}//end of for loop
return sum;
}//end of find_sum() function

//FUNCTION TO CONVERT HEX TO THE DECIMAL VALUE
int conv(char val1,char val2){
int val_a = toDec(val1); // convert to the decimal value
int val_b = toDec(val2);
return (val_a*16) + val_b; // converting decimal value into HEX decimal Equalent B1*16 + B0
}//end of conv() function

int toDec(char val){
if(val<='9')
{
return val - '0'; // please see the ASCII table for clarification
}
else
{
return val - '0'-7; // 7 is offset for capital letters please see the ASCII table
}

}//end of toDec() function

void convert_to_hex(int val){
char hex[5];
utoa((unsigned)val,hex,16); // utoa() function is used to convert unsigned int to HEX array (whatever the base we specified as third argument)

int hex_val = (int)strtol(hex,NULL,16);// strtol() is used to covert string into long int according to the given base

hex_val = ((~hex_val) + B01) & 0xff; /* finding the 2's complement of the number hex_val
'~' operator is the logical not and adding B01 to it and logical anding with 0xff
to omit any excess bites otherthan 8 bits or 1 byte
*/
Serial.print("the LRC value is : ");
Serial.println(hex_val,HEX);
char hex_val_str[4];
sprintf(hex_val_str,"%0.2X",hex_val);// putting hex value in the string back
Serial.print("the concated string is : ");
strcat(speed_vfd,hex_val_str);
char ter[] = "\r\n";
strcat(speed_vfd,ter);//adding terminators at the end STOP bits
Serial.println(speed_vfd);
}//end of convert_to_hex() fucntion


void error_message(){
Serial.println("You Entered Wrong Command");

}//end of error_message()

it actually doesn't do anything.. we can modify the code to send the modbus control to the VFD.
I don't have the hardware to test it But i made the code using VFD-m Manual
delta VFD-m