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;
}

call: [float] = modbus_2regs_2_float([first register])

float modbus_2regs_2_float(uint16_t addr) {
    uint16_t a = node.getResponseBuffer(addr);
    uint16_t b = node.getResponseBuffer(addr+1);
    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);
 }

uint32_t make_32bit_word(uint16_t hi_word, uint16_t lo_word)
{
    uint16_t words_16bit[2] = {hi_word, lo_word};
    uint32_t word_32bit = 0;
 
    memcpy(&word_32bit, words_16bit, 4);
 
    return word_32bit;
}

int32 convert direct to float by division by a thousand:

float make_float_32bit_word(uint16_t hi_word, uint16_t lo_word)
{
    uint16_t words_16bit[2] = {hi_word, lo_word};
    uint32_t word_32bit = 0;
    float back;
 
    memcpy(&word_32bit, words_16bit, 4);
    back = word_32bit / 1000.0;
    return back;
}

call: [float] = make_float_32bit_word([first reg])

float make_float_32bit_word(uint16_t addr)
{
    uint16_t words_16bit[2]; 
    words_16bit[1] = node.getResponseBuffer(addr);
    words_16bit[0] = node.getResponseBuffer(addr+1);
    uint32_t word_32bit = 0;
    float back;
 
    memcpy(&word_32bit, words_16bit, 4);
    back = word_32bit / 1000.0;
    return back;
}

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;

#define MODBUS_GET_HIGH_BYTE(data) (((data) >> 8) & 0xFF)
#define MODBUS_GET_LOW_BYTE(data)  ((data) & 0xFF)
#define MODBUS_GET_INT64_FROM_INT16(tab_int16, index)                                  \
    (((int64_t) tab_int16[(index)] << 48) | ((int64_t) tab_int16[(index) + 1] << 32) | \
     ((int64_t) tab_int16[(index) + 2] << 16) | (int64_t) tab_int16[(index) + 3])
#define MODBUS_GET_INT32_FROM_INT16(tab_int16, index) \
    (((int32_t) tab_int16[(index)] << 16) | (int32_t) tab_int16[(index) + 1])
#define MODBUS_GET_INT16_FROM_INT8(tab_int8, index) \
    (((int16_t) tab_int8[(index)] << 8) | (int16_t) tab_int8[(index) + 1])
#define MODBUS_SET_INT16_TO_INT8(tab_int8, index, value)            \
    do {                                                            \
        ((int8_t *) (tab_int8))[(index)] = (int8_t) ((value) >> 8); \
        ((int8_t *) (tab_int8))[(index) + 1] = (int8_t) (value);    \
    } while (0)
#define MODBUS_SET_INT32_TO_INT16(tab_int16, index, value)              \
    do {                                                                \
        ((int16_t *) (tab_int16))[(index)] = (int16_t) ((value) >> 16); \
        ((int16_t *) (tab_int16))[(index) + 1] = (int16_t) (value);     \
    } while (0)
#define MODBUS_SET_INT64_TO_INT16(tab_int16, index, value)                  \
    do {                                                                    \
        ((int16_t *) (tab_int16))[(index)] = (int16_t) ((value) >> 48);     \
        ((int16_t *) (tab_int16))[(index) + 1] = (int16_t) ((value) >> 32); \
        ((int16_t *) (tab_int16))[(index) + 2] = (int16_t) ((value) >> 16); \
        ((int16_t *) (tab_int16))[(index) + 3] = (int16_t) (value);         \
    } while (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;
}

Generate random MAC using pseudo random generator, bytes 0, 1 and 2 are static (MAC_START), bytes 3, 4 and 5 are generated randomly

void generateMac() {
  // Marsaglia algorithm from https://github.com/RobTillaart/randomHelpers
  seed1 = 36969L * (seed1 & 65535L) + (seed1 >> 16);
  seed2 = 18000L * (seed2 & 65535L) + (seed2 >> 16);
  uint32_t randomBuffer = (seed1 << 16) + seed2; /* 32-bit random */
  memcpy(data.mac, MAC_START, 3);                // set first 3 bytes
  for (byte i = 0; i < 3; i++) {
    data.mac[i + 3] = randomBuffer & 0xFF;  // random last 3 bytes
    randomBuffer >>= 8;
  }
}