Sending command to rs232 device

Projects General Guidance
4

@kemjasonwang, your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advise on) your project :wink: See About the Installation & Troubleshooting category.

Please post your sketch in a post, not as an attachment; please properly ident it in the IDE. Done it this time for you.

#include <SoftwareSerial.h>

SoftwareSerial mySerial(6, 7);  // RX, TX
byte STX = 0x02;                //STX=02h
byte ETX = 0x03;                //ETX=03h
byte CR = 0x0D;                 //CR=0Dh
byte LF = 0x0A;                 //LF=0A
byte EOT = 0x04;

byte NUL = 0x0;
byte SOH = 0x1;
byte ENQ = 0x5;
byte ACK = 0x6;
byte BEL = 0x7;
byte BS = 0x8;
byte HT = 0x9;
byte VT = 0xB;
byte FF = 0xC;
byte SO = 0xE;
byte SI = 0xF;

byte DLE = 0x10;
byte DC1 = 0x11;
byte DC2 = 0x12;
byte DC3 = 0x13;
byte DC4 = 0x14;

byte NAK = 0x15;
byte SYN = 0x16;
byte ETB = 0x17;
byte CAN = 0x18;
byte EM = 0x19;

byte SUB = 0x1A;
byte ESC = 0x1B;
byte FS = 0x1C;
byte GS = 0x1D;
byte RS = 0x1E;
byte US = 0x1F;
byte y = 0x30;

byte A = 0x41;
byte R = 0x52;
byte H = 0x48;
byte U = 0x55;
byte start = 0;



void setup() {

  Serial.begin(9600);
  Serial.println("USB Serial is up and running");
  mySerial.begin(4800);
  mySerial.write(0x30);
  mySerial.write(0x02);
  mySerial.write(0x55);
  mySerial.write(0x32);
  mySerial.write(0x0D);
  mySerial.write(0x0A);
  mySerial.write(0x0D);
  mySerial.write(0x0A);
  mySerial.write(0x04);
}
void loop() {
  mySerial.println("STX");
  mySerial.println("A");
  mySerial.println("ETX");
  if (mySerial.available()) {
    Serial.println(mySerial.read());
  }
}

mySerial.println("STX") will send the word STX (so 3 characters), not the character STX (hex 0x02) that's at the beginning of your code. It also sends a <CR><LF>.

Use mySerial.write(STX); and so on for a start (like you did in setup()).

What happens with this code?

#include <SoftwareSerial.h>

void setup()
{
  Serial.begin(9600);
  Serial.println("USB Serial is up and running");
  mySerial.begin(4800);
  mySerial.write(0x30);
  mySerial.write(0x02);
  mySerial.write(0x55);
  mySerial.write(0x32);
  mySerial.write(0x0D);
  mySerial.write(0x0A);
  mySerial.write(0x0D);
  mySerial.write(0x0A);
  mySerial.write(0x04);
}
void loop()
{

  if (mySerial.available()) {
    Serial.write(mySerial.read());
  }
}

Do you get a reply from the device?

Note:
I did not dig too deep into the manual.