Reading writing CAN combined with lcd and rotary


#include <SPI.h>              //Library for using SPI Communication 
#include <mcp2515.h>          //Library for using CAN Communication
#include <LiquidCrystal.h>    //Library for using LCD display

const int rs = 3, en = 4, d4 = 5, d5 = 6, d6 = 7, d7 = 8;  

struct can_frame canMsg1;
struct can_frame canMsg2;

 #define outputA a0  //rotARY
 #define outputB a1  //ROTARY
#define rotbutton 9 /rotary switch

LiquidCrystal lcd(rs, en, d4, d5, d6, d7);  //Define LCD display pins RS,E,D4,D5,D6,D7

byte customChar[8] = {
  0b00000,
  0b01010,
  0b11111,
  0b11111,
  0b01110,
  0b00100,
  0b00000,
  0b00000
};

struct can_frame canMsg; 
MCP2515 mcp2515(10);                 // SPI CS Pin 10 
 
void setup() {
    pinMode (outputA,INPUT);
  pinMode (outputB,INPUT);
  pinMode (rotbutton,INPUT);
  
  lcd.begin(16,2);                   //Sets LCD as 16x2 type
  lcd.setCursor(0,0);                //Display Welcome Message
  lcd.print("adjust");
  lcd.setCursor(0,1);
  lcd.print(" CAN");
  delay(3000);
  lcd.clear();
  
  SPI.begin();                       //Begins SPI communication
  
  Serial.begin(9600);                //Begins Serial Communication at 9600 baudrate 
  
  mcp2515.reset();                          
  mcp2515.setBitrate(CAN_250KBPS,MCP_16MHZ); //Sets CAN at speed 500KBPS and Clock 8MHz 
  mcp2515.setNormalMode();                  //Sets CAN at normal mode
  
  canMsg1.can_id  = 0x601;  //reads status timer
  canMsg1.can_dlc = 8;
  canMsg1.data[0] = 0x40;
  canMsg1.data[1] = 0x00;
  canMsg1.data[2] = 0x21;
  canMsg1.data[3] = 0x00;
  canMsg1.data[4] = 0x00; //read this xx = 00=0 01=01 0A =10 etc max 20
  canMsg1.data[5] = 0x00;
  canMsg1.data[6] = 0x00;
  canMsg1.data[7] = 0x00;

  canMsg2.can_id  = 0x601;   //writes status timer
  canMsg2.can_dlc = 8;
  canMsg2.data[0] = 0x20;
  canMsg2.data[1] = 0x00;
  canMsg2.data[2] = 0x21;
  canMsg2.data[3] = 0x00;
  canMsg2.data[4] = 0x01;  //write this xx = 00=0 01=01 0A =10 etc
  canMsg2.data[5] = 0x00;
  canMsg2.data[6] = 0x00;
  canMsg2.data[7] = 0x00;
}

void loop() 
{
  mcp2515.sendMessage(&canMsg1);
  if (mcp2515.readMessage(&canMsg) == MCP2515::ERROR_OK) // To receive data (Poll Read)
  {
    
  lcd.print(canMsg.can_id, HEX); // print ID
    lcd.print(" "); 
    lcd.print(canMsg.can_dlc, HEX); // print DLC
    lcd.print(" ");
    
    for (int i = 0; i<canMsg.can_dlc; i++)  {  // print the data
      lcd.print(canMsg.data[i],HEX);
      lcd.print(" ");
    }

    lcd.println();  

        if ((canMsg.can_id == 0x701)&& (canMsg.data[0] == 0x5)){   
           lcd.createChar(0, customChar); // create a new custom character

  lcd.setCursor(15, 0); // move cursor to (2, 0)
  lcd.write((byte)0);  // print the custom char at (2, 0)  
  delay(1000);
  lcd.setCursor(15, 0);
       lcd.print(" ");
       delay(500);
      lcd.println();
{
      if ((canMsg.can_id == 0x581) and 
      (canMsg.data[0] == 0x43)and
      (canMsg.data[1] == 0x00)   
       {

  lcd.setCursor(2, 0); // move cursor to (2, 0)
   lcd.print("timer");

  }}
}

I am trying to read a value from a CAN-device by sending request

601 8 40 00 21 00 00 00 00 00

I will get an response like this:

581 8 43 00 21 00 xx 00 00 00  (xx = 00=0 01=01 0A =10 etc)

and than update value by rotaty swith (0 - 20 ) with command:

`601 8 20 00 21 00 xx 00 00 00   (xx = 00=0 01=01 0A =10 etc)`

hints welcome.

Sorry, but it's not clear what your problem is.