modbus.c

#ifdef MODBUS
//
//******************************************************************************
//  CRC 16 Data Table
//  *****************
const unsigned int crc_tbl[256]={
  0x0000, 0xC0C1, 0xC181, 0x0140, 0xC301, 0x03C0, 0x0280, 0xC241,
  0xC601, 0x06C0, 0x0780, 0xC741, 0x0500, 0xC5C1, 0xC481, 0x0440,
  0xCC01, 0x0CC0, 0x0D80, 0xCD41, 0x0F00, 0xCFC1, 0xCE81, 0x0E40,
  0x0A00, 0xCAC1, 0xCB81, 0x0B40, 0xC901, 0x09C0, 0x0880, 0xC841,
  0xD801, 0x18C0, 0x1980, 0xD941, 0x1B00, 0xDBC1, 0xDA81, 0x1A40,
  0x1E00, 0xDEC1, 0xDF81, 0x1F40, 0xDD01, 0x1DC0, 0x1C80, 0xDC41,
  0x1400, 0xD4C1, 0xD581, 0x1540, 0xD701, 0x17C0, 0x1680, 0xD641,
  0xD201, 0x12C0, 0x1380, 0xD341, 0x1100, 0xD1C1, 0xD081, 0x1040,
  0xF001, 0x30C0, 0x3180, 0xF141, 0x3300, 0xF3C1, 0xF281, 0x3240,
  0x3600, 0xF6C1, 0xF781, 0x3740, 0xF501, 0x35C0, 0x3480, 0xF441,
  0x3C00, 0xFCC1, 0xFD81, 0x3D40, 0xFF01, 0x3FC0, 0x3E80, 0xFE41,
  0xFA01, 0x3AC0, 0x3B80, 0xFB41, 0x3900, 0xF9C1, 0xF881, 0x3840,
  0x2800, 0xE8C1, 0xE981, 0x2940, 0xEB01, 0x2BC0, 0x2A80, 0xEA41,
  0xEE01, 0x2EC0, 0x2F80, 0xEF41, 0x2D00, 0xEDC1, 0xEC81, 0x2C40,
  0xE401, 0x24C0, 0x2580, 0xE541, 0x2700, 0xE7C1, 0xE681, 0x2640,
  0x2200, 0xE2C1, 0xE381, 0x2340, 0xE101, 0x21C0, 0x2080, 0xE041,
  0xA001, 0x60C0, 0x6180, 0xA141, 0x6300, 0xA3C1, 0xA281, 0x6240,
  0x6600, 0xA6C1, 0xA781, 0x6740, 0xA501, 0x65C0, 0x6480, 0xA441,
  0x6C00, 0xACC1, 0xAD81, 0x6D40, 0xAF01, 0x6FC0, 0x6E80, 0xAE41,
  0xAA01, 0x6AC0, 0x6B80, 0xAB41, 0x6900, 0xA9C1, 0xA881, 0x6840,
  0x7800, 0xB8C1, 0xb981, 0x7940, 0xBB01, 0x7BC0, 0x7A80, 0xBA41,
  0xBE01, 0x7EC0, 0x7F80, 0xBF41, 0x7D00, 0xBDC1, 0xBC81, 0x7C40,
  0xB401, 0x74C0, 0x7580, 0xB541, 0x7700, 0xB7C1, 0xB681, 0x7640,
  0x7200, 0xB2C1, 0xB381, 0x7340, 0xB101, 0x71C0, 0x7080, 0xB041,
  0x5000, 0x90C1, 0x9181, 0x5140, 0x9301, 0x53C0, 0x5280, 0x9241,
  0x9601, 0x56C0, 0x5780, 0x9741, 0x5500, 0x95C1, 0x9481, 0x5440,
  0x9C01, 0x5CC0, 0x5D80, 0x9D41, 0x5F00, 0x9FC1, 0x9E81, 0x5E40,
  0x5A00, 0x9AC1, 0x9B81, 0x5B40, 0x9901, 0x59C0, 0x5880, 0x9841,
  0x8801, 0x48C0, 0x4980, 0x8941, 0x4B00, 0x8BC1, 0x8A81, 0x4A40,
  0x4E00, 0x8EC1, 0x8F81, 0x4F40, 0x8D01, 0x4DC0, 0x4C80, 0x8C41,
  0x4400, 0x84C1, 0x8581, 0x4540, 0x8701, 0x47C0, 0x4680, 0x8641,
  0x8201, 0x42C0, 0x4380, 0x8341, 0x4100, 0x81C1, 0x8081, 0x4040};
//#pragma end_abs_address
//******************************************************************************
//

#define DEFAULT_ADDRESS 1        // all slaves start with this Modbus
address

// communication commands:
//#define CHOOSE_SLOT    0x80
//#define POLL_SLOT    0x81
//#define POLL_ACK    0x82

// positions in a Modbus packet
#define ADDR        0
#define FCN         1
#define REGHI         2
#define REGLO        3
#define NUMREGSHI     4
#define NUMREGSLO     5
#define OUTBYTES     2

// Modbus exception codes
#define FCN_NOT_SUPPORTED    1    // a Modbus function code we can't
handle
#define BAD_ADDR_OR_CMD        2    // a Modbus "register"
(command or address to us) we don't know
#define BAD_COUNT            3    // num regs != num bytes
* 2
#define CMD_NOT_COMPLETE    4    // command didn't complete
successfully

// other defines
#define IN    0
#define OUT    1
//
// SLOT_NUMBER is the 2 byte device configuration
// the first byte is the ID
// the second byte is the transmission mode coded as follows:
//    bit 0x01: 0=19200, 1=9600 baud
//    bit 0x02: 0=even parity, 1=odd parity
//    bit 0x04: 0=parity, 1=no parity
//    bit 0x08: 0=1 stop bit, 1=2 stop bits
//        if bit 0x04 is set and bit 0x08 is not set then it's 8
bit mode (vs 9 bit mode)
//
//unsigned char receiveBuffer[32] = {0};  // Reserve 32 bytes for packet.
unsigned char device_addr = DEFAULT_ADDRESS; // assigned device address - start
with disconnected
//unsigned char timeout_counter = 10;
//unsigned char timeout_duration = 10;    // seconds, default
//unsigned char pkt_index = 0;

// return number of bytes in packet, not including crc
unsigned char MDB_get_length(unsigned char in_out, unsigned char* ptr)
{
    if(comControlByte & 0x20)
        return 6;
    switch(*(ptr+FCN))
    {
        case 0x06:     // write single reg
            return 6;
        case 0x03:    // read multiple regs
            if (in_out == IN) // incoming packet
                return 6;
            else
                return *(ptr+OUTBYTES) + 3;
        case 0x10:    // write multiple regs
            return (*(ptr+NUMREGSLO) << 1) + 7;
        default:    // assume error packet
            return 3;
    }
}

// calculate CRC16 on a packet
unsigned int MDB_crc_calc(unsigned char in_out, unsigned char* ptr)
{
    unsigned char c1, c2;
    unsigned int crc = 0xffff;                    
    // initial value
    unsigned char* ptr_pkt_hdr = ptr;
    c2 = MDB_get_length(in_out,ptr);
    for(c1=0; c1<c2; c1++)
        crc = ((crc >> 8) & 0xFF) ^ crc_tbl[(crc ^ *ptr_pkt_hdr++) & 0xFF];
    return crc;
}

// check crc on an incoming packet
unsigned char MDB_crc_check(unsigned char* ptr)
{
    unsigned int i1;
      unsigned char c1, c2, c3;
    i1 = MDB_crc_calc(IN, ptr);
      c1 = *(ptr+MDB_get_length(IN,ptr)+1);    // msb of incoming crc
      c2 = *(ptr+MDB_get_length(IN,ptr));        // lsb of
incoming crc
      c3 = (i1 >> 8);                   
            // msb of calculated crc
      if((c2 == (i1 & 0x00FF)) && (c1 == c3))        // compare msb
& lsb
        return 1;
    else
        return 0;
}

// send Modbus packets
void MDB_pkt_sender(unsigned char* ptr)
{
    unsigned char idx, pkt_len;
    unsigned int i1;
// append crc, lsb 1st
    i1 = MDB_crc_calc(OUT,ptr);
    pkt_len = MDB_get_length(OUT,ptr);
    *(ptr+pkt_len++) = (unsigned char)i1;    // lsb
    *(ptr+pkt_len++) = (i1 >> 8);        // msb
    //SCI1C2 = 0x08;    // transmit enable
    //comLedOn();
    PTGD |= 0x80;
    for (idx = 0; idx < pkt_len; idx++)
    {
        while(!(SCI1S1 & 0x80));    // wait for tdre=1
        i1 = SCI1S1;
        SCI1D = *(ptr+idx);
    }
    while(!(SCI1S1 & 0x80));
    while(!(SCI1S1 & 0x40));
    //comLedOff();
    PTGD &= 0x7f;
    //SCI1C2 = 0x2c;    // back to receive mode
}

// return a Modbus error packet
void MDB_error(unsigned char exp_code, unsigned char* ptr)
{
    *(ptr+FCN) |= 0x80;            // set error code
    *(ptr+FCN+1) = exp_code;    // set exception code
    MDB_pkt_sender(ptr);
}

//
void MDB_read_data(unsigned char* ptr)
{
    if(get_data((ptr+2), *(ptr+3)))
    {
        // get_data() sticks the length of the data in
receiveBuffer[2]
        // receiveBuffer[3] & on will have actual data
        // receiveBuffer[0] & receiveBuffer[1] unchanged
          MDB_pkt_sender(ptr);    // appends CRC before sending
    }
       else
        MDB_error(BAD_ADDR_OR_CMD, ptr);
}
// handle data writes
void MDB_write_data(unsigned char* ptr)
{
    if((*(ptr+5)<<1) == *(ptr+6))
    {
        switch(*(ptr+3))//receiveBuffer[3])
        {
            //case 0x18:    // new timeout value
            //    timeout_duration = receiveBuffer[7];
            //    MDB_pkt_sender();    // echo
received command
            //    break;
            //case 0x63:    // lamp test
            //    clampTest = 40;
            //    MDB_pkt_sender();    // echo
received command
            //    break;
            case ADDRESS:
                //if(receiveBuffer[8] &&
(receiveBuffer[8] < 248))    // valid addresses
                if(*(ptr+8) && (*(ptr+8) < 248))
                {
                    //device_addr = *
(ptr+8); // not until reset
                    nonvolatile[0] = *(ptr+8);
    // device ID
                    nonvolatile[1] = *(ptr+7);
    // transmission mode
                    nonvolatile[2] =
~nonvolatile[0];
                    nonvolatile[3] =
~nonvolatile[1];
                    writeToNonvolatile
(SLOT_NUMBER, &nonvolatile[0]);
                    comControlByte |= 0x20;
                    MDB_pkt_sender(ptr);
                    comControlByte &= 0xdf;
                }
                else
                    MDB_error
(BAD_ADDR_OR_CMD, ptr);
                break;
            case INSTALLATION_DATE:    // installation
date
                readFromNonvolatile(DATE_DATA,
&nonvolatile[0]);
                nonvolatile[4] = *
(ptr+7);//receiveBuffer[7];
                nonvolatile[5] = *
(ptr+8);//receiveBuffer[8];
                nonvolatile[6] = *
(ptr+9);//receiveBuffer[9];
                nonvolatile[7] = *
(ptr+10);//receiveBuffer[10];
                nonvolatile[12] = ~nonvolatile[4];
                nonvolatile[13] = ~nonvolatile[5];
                nonvolatile[14] = ~nonvolatile[6];
                nonvolatile[15] = ~nonvolatile[7];
                writeToNonvolatile(DATE_DATA,
&nonvolatile[0]);
                comControlByte |= 0x20;
                MDB_pkt_sender(ptr);    // echo
received command
                comControlByte &= 0xdf;
                break;
            default:
                   MDB_error(BAD_ADDR_OR_CMD, ptr);
                break;
        }
    }
    else
        MDB_error(BAD_COUNT, ptr);
}
//
void MDB_parse(char *bufPtr)
{
    unsigned char i = 0;
   
    if(MDB_crc_check(bufPtr))
    {
          if(*(bufPtr+ADDR) == device_addr)
          {
            switch(*(bufPtr+FCN))
            {
                case 0x03: // modbus read multiple
regs
                    MDB_read_data(bufPtr);
                    break;
                case 0x10:    // modbus write multiple
regs
                    MDB_write_data(bufPtr);
                    break;
                default:    // modbus function not
supported
                    MDB_error
(FCN_NOT_SUPPORTED, bufPtr);
                    break;
            }
        }
    }
}