Pass array of bytes into function header file

Question

I would like to pass an array of bytes to a function but I got an error when compiling.

I need the array in order to use CRC16.h because it wants uint8_t type data.

I already tried to put byte; array byte; byte* in void calcCRC() but I always got this error:

variable or field 'calcCRC' declared void

comm_modbus.cpp:

#include <Crc16.h>
Crc16 crc; 

#include "Arduino_MachineControl.h"
using namespace machinecontrol;

#include "comm_modbus.h"

byte SlaveID = 0x01;
byte FunctionID;
byte addressHI;
byte addressLO;
byte quantityHI = 0x00;
byte quantityLO = 0x02;
byte totalByteWrite = 0x04;
byte Value24;
byte Value16;
byte Value8;
byte Value0;
byte crcHI;
byte crcLO;

int trameRecus[9];
int trameTraiter [9];
byte check[2];


void initModbus() {
    Serial.begin(9600);
    // Wait for Serial or start after 2.5s
    for (auto const timeout = millis() + 2500; !Serial && timeout < millis(); delay(500))
        ;

    delay(2500);
    Serial.println("Start RS485 initialization");

    // Set the PMC Communication Protocols to default config
    comm_protocols.init();

    // RS485/RS232 default config is:
    // - RS485 mode
    // - Half Duplex
    // - No A/B and Y/Z 120 Ohm termination enabled

    // Enable the RS485/RS232 system
    comm_protocols.rs485Enable(true);

    // Specify baudrate, and preamble and postamble times for RS485 communication
    comm_protocols.rs485.begin(19200,SERIAL_8E1 ,0, 500);
    // Start in receive mode
    comm_protocols.rs485.receive();

    Serial.println("Initialization done!");
}

long ModbusRead(unsigned int addrMB) {
      FunctionID = 0x03;
      addrModbus(addrMB);
      
      byte trame [] = {SlaveID,FunctionID,addressHI,addressLO,quantityHI,quantityLO};
      
      calcCRC(trame);
      
      byte trameComplet []={SlaveID,FunctionID,addressHI,addressLO,quantityHI,quantityLO,crcHI,crcLO};
      
        // Disable receive mode before transmission
        comm_protocols.rs485.noReceive();

        comm_protocols.rs485.beginTransmission();

        comm_protocols.rs485.write(trameComplet[0]);
        comm_protocols.rs485.write(trameComplet[1]);
        comm_protocols.rs485.write(trameComplet[2]);
        comm_protocols.rs485.write(trameComplet[3]);
        comm_protocols.rs485.write(trameComplet[4]);
        comm_protocols.rs485.write(trameComplet[5]);
        comm_protocols.rs485.write(trameComplet[6]);
        comm_protocols.rs485.write(trameComplet[7]);

        comm_protocols.rs485.endTransmission();

        // Re-enable receive mode after transmission
        comm_protocols.rs485.receive();
        
    auto const timeout = millis() + 500;
    while (comm_protocols.rs485.available() < 9) {
        if (millis()> timeout) {
          Serial.println("communication timeout!");
          Serial.println("erreur : ");
          while(comm_protocols.rs485.available()) {
            Serial.println(comm_protocols.rs485.read());
          }
          break;
        }
      }
    if (comm_protocols.rs485.available()==9) {
    
      long value;
      reception();
      value = VARvalue();
      return value;
    }
}

void ModbusWrite(unsigned int addrMB, long ValueMB) {
  
  FunctionID = 0x10;
  addrModbus(addrMB);
  ValueModbus(ValueMB);
  
  byte trame [] = {SlaveID,FunctionID,addressHI,addressLO,quantityHI,quantityLO,totalByteWrite,Value24,Value16,Value8,Value0};
  
  calcCRC(trame);

   byte trameComplet []={SlaveID,FunctionID,addressHI,addressLO,quantityHI,quantityLO,totalByteWrite,Value24,Value16,Value8,Value0,crcHI,crcLO};

   comm_protocols.rs485.noReceive();

        comm_protocols.rs485.beginTransmission();

        comm_protocols.rs485.write(trameComplet[0]);
        comm_protocols.rs485.write(trameComplet[1]);
        comm_protocols.rs485.write(trameComplet[2]);
        comm_protocols.rs485.write(trameComplet[3]);
        comm_protocols.rs485.write(trameComplet[4]);
        comm_protocols.rs485.write(trameComplet[5]);
        comm_protocols.rs485.write(trameComplet[6]);
        comm_protocols.rs485.write(trameComplet[7]);
        comm_protocols.rs485.write(trameComplet[8]);
        comm_protocols.rs485.write(trameComplet[9]);
        comm_protocols.rs485.write(trameComplet[10]);

        comm_protocols.rs485.endTransmission();

        // Re-enable receive mode after transmission
        comm_protocols.rs485.receive();
}

void addrModbus(unsigned int addresseMB) {
 
  addressHI = (addresseMB >> 8) & 0xFF; //highbyte
  addressLO = (addresseMB & 0xFF);      //lowbyte
}

void ValueModbus(long valMB) {
 
    Value24 = (valMB & 0xFF000000) >> 24; 
    Value16 = (valMB & 0x00FF0000) >> 16; 
    Value8  = (valMB & 0x0000FF00) >> 8; 
    Value0  = valMB & 0xFF; 
    
}

void calcCRC(byte *trame) {
  
   unsigned short crcTrame;
   int sizeTrame= sizeof(trame);
    
    crc.clearCrc();
    for(int i=0;i< sizeTrame;i++)
    {
      Serial.print("byte ");
      Serial.print(i);
      Serial.print(" = ");
      Serial.println(trame[i],HEX);
     crc.updateCrc(trame[i]);
    }
    
    crcTrame = crc.Modbus(trame,0,sizeTrame);

    check[1] = (crcTrame >> 8) & 0xFF; //highbyte
    check[0] = (crcTrame & 0xFF);      //lowbyte

    crcHI = check[0],HEX;
    crcLO = check[1],HEX;

    Serial.print("Modbus crcHI = 0x");    
    Serial.println(crcHI,HEX);
    Serial.print("Modbus crcLO = 0x");    
    Serial.println(crcLO,HEX);
}

long VARvalue() {
  long Value = 0;
  int expo = 0;
  int multi = 0;
  for( int i = 3 ;i <= trameRecus[2]+2;i++) {
    expo = 6-i;
    multi = pow(256,expo);
    trameRecus[i]= trameRecus[i] * multi;
    Value = Value + trameRecus[i];
  }
  Serial.print("valeur reel = ");
  Serial.println(Value);
  return Value;
}

void reception() {
 
  int compteur = 0;
  byte ValueModbus;
  
  while (comm_protocols.rs485.available()> 0) {
      ValueModbus = comm_protocols.rs485.read();
      Serial.println("Reception :");
      Serial.println(ValueModbus);
      trameRecus[compteur] = ValueModbus;
      
      compteur++;
  }
}

comm_modbus.h:

void initModbus();
long ModbusRead(unsigned int);
void ModbusWrite(unsigned int, long);
void addrModbus(unsigned int);
void ValueModbus(long);
void calcCRC(byte*);
long VARvalue();
void reception();

The error happend at this line: void calcCRC(byte*);

UPDATE:

I commented out the function //void calcCRC(byte*); and did the same for the call function //calcCRC(trame);.

After that, the error was no longer there, so I concluded this error is in the function calcCRC(trame) and I think the problem comes from data type void calcCRC(byte*); in comm_modbus.h brcause when I replace it with int the error disappears.

So why header file can't get byte into argument function?

Try to removing all code in the ModbusWrite. Everything. Delete its code. Try compiling it now, do you get the same compilation error? If yes: take the next function you've shown, delete all of its code, repeat. Still get the same compilation error? Remove more code. Keep removing code until you end up with something that can't be removed without affecting the error. Now, take what you have left, edit your question, and replace this massive code dump with your minimal reproducible example. Unfortunately, Stackoverflow is not a debugging service. If you're asking a specifc error, everything else is irrelevant. — Sam Varshavchik
– Sam Varshavchik, Commented Aug 26, 2022 at 13:18

Mark Adler · Accepted Answer · 2022-08-26 19:26:42Z

1

I don't know why you're getting that error, but this:

void calcCRC(byte *trame){
  
   unsigned short crcTrame;
   int sizeTrame= sizeof(trame);

makes no sense. trame is just a pointer, and carries no information about the length of what it is pointing to. sizeof(trame) gives you the size of the pointer, which will always be the same (2, 4, or 8, depending on your architecure). You need to pass a length along with trame.

Also your code after that makes no sense. You are computing the default xmodem CRC on trane bytes, and then ignoring that, instead computing a modbus CRC.

answered Aug 26, 2022 at 19:26

Mark Adler

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2 Comments

nicolas h Over a year ago

ok I change it by void calcCRC(byte trame [],int sizeTrame ) but i always get error from my header file comm_modbus.h : void calcCRC(byte[],int);

Mark Adler Over a year ago

Try giving it a different name. Maybe it's used somewhere else.

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