LamaPLC: Arduino code collection

call: [float] = modbus_2regs_2_float([1.register], [2.register])

float modbus_2regs_2_float(uint16_t a, uint16_t b) {
    uint32_t combined = ((uint32_t)a << 16) | b;
    float f;
    memcpy(&f, &combined, sizeof f);
    return f;
}

def: int16_t regs[2];
call: modbus_set_float([float], regs);
back: register1: regs[1], register2: [regs[2]

 void modbus_set_float(float f, uint16_t *dest)
 {
     uint32_t i = 0;
 
     memcpy(&i, &f, sizeof(uint32_t));
     dest[0] = (uint16_t)i;
     dest[1] = (uint16_t)(i >> 16);
 }

Note: The maximum value of the int16 type is 32767, so in this format only the value range 0 .. 327.67 can be stored with 2 decimal places!

// float 2 reg
holdingRegs[REG_HUM] = (int16_t)(Humidity * 100);
// back one reg to float
float Humidity = holdingRegs[REG_HUM] / 100.0;

bool getResultMsg(uint8_t result)
{
  String tmpstr2;
 
  switch (result) {
    case node.ku8MBSuccess:
      return true;
      break;
    case node.ku8MBIllegalFunction:
      tmpstr2 = "Illegal Function";
      break;
    case node.ku8MBIllegalDataAddress:
      tmpstr2 = "Illegal Data Address";
      break;
    case node.ku8MBIllegalDataValue:
      tmpstr2 = "Illegal Data Value";
      break;
    case node.ku8MBSlaveDeviceFailure:
      tmpstr2 = "Slave Device Failure";
      break;
    case node.ku8MBInvalidSlaveID:
      tmpstr2 = "Invalid Slave ID";
      break;
    case node.ku8MBInvalidFunction:
      tmpstr2 = "Invalid Function";
      break;
    case node.ku8MBResponseTimedOut:
      tmpstr2 = "Response Timed Out";
      break;
    case node.ku8MBInvalidCRC:
      tmpstr2 = "Invalid CRC";
      break;
    default:
      tmpstr2 = "Unknown error: " + String(result);
      break;
  }
  Serial.println(tmpstr2);
  return false;
}