请问一下各位关于modbus/tcp的问题

[m0_37580103]

1.我写了一个tcp服务器的程序，程序应该是没有问题的，但是老提示网口打开失败。。是不是因为我用的是校园网，没有固定的物理IP，不知道测程序的时候怎么配置自己的电脑，，最好有附图说明。。
2.另外问一下各位有没有CRC-CCITT的c语言代码，最好是计算法不是查表法的，谢谢

[zgl7903]

在同一台电脑上同时运行服务器端和客户端程序， 就可以测试 (IP地址127.0.0.1 )
查表法速度是最快的
http://djb69.blog.163.com/blog/static/6776323420100158391490/

[赵4老师]

/***** crc16.c *****/
#include <stdio.h>

#define CRC16_DNP   0x3D65u     // DNP, IEC 870, M-BUS, wM-BUS, ...
#define CRC16_CCITT 0x1021u     // X.25, V.41, HDLC FCS, Bluetooth, ...

//Other polynoms not tested
#define CRC16_IBM   0x8005u     // ModBus, USB, Bisync, CRC-16, CRC-16-ANSI, ...
#define CRC16_T10_DIF   0x8BB7u     // SCSI DIF
#define CRC16_DECT  0x0589u     // Cordeless Telephones
#define CRC16_ARINC 0xA02Bu     // ACARS Aplications

#define POLYNOM     CRC16_DNP   // Define the used polynom from one of the aboves

// Calculates the new crc16 with the newByte. Variable crcValue is the actual or initial value (0).
unsigned short crc16(unsigned short crcValue, unsigned char newByte) {
    int i;

    for (i = 0; i < 8; i++) {
        if (((crcValue & 0x8000u) >> 8) ^ (newByte & 0x80u)){
            crcValue = (crcValue << 1)  ^ POLYNOM;
        } else {
            crcValue = (crcValue << 1);
        }
        newByte <<= 1;
    }
    return crcValue;
}

unsigned short exampleOfUseCRC16(unsigned char *Data, int len){

    unsigned short crc;
    int aux = 0;

    crc = 0x0000u; //Initialization of crc to 0x0000 for DNP
    //crc = 0xFFFFu; //Initialization of crc to 0xFFFF for CCITT

    while (aux < len){
        crc = crc16(crc,Data[aux]);
        aux++;
    }

    return (~crc); //The crc value for DNP it is obtained by NOT operation

    //return crc; //The crc value for CCITT
}

int main() {
    unsigned char d[10]={0,1,2,3,4,5,6,7,8,9};

    printf("0x%04hX\n",exampleOfUseCRC16(d,10));//0x1078
    return 0;
}