modbusc编程实例

⑴ 求ModBus TCP在PIC上的C语言实现

test1.cpp
-
Win32
console
app
to
read
registers
//
test1.cpp
5/23/97
//
example
Win32
C++
program
to
read
registers
from

PLC
via
gateway
//
compile
with
BC45
or
BC50
//
default
settings
for
Win32
console
app
//
empty
DEF
file
#include
<winsock.h>
#include
<stdio.h>
#include
<conio.h>
int
main(int
argc,
char
**argv)
{
if
(argc<5)
{
printf("usage:
test1
ip_adrs
unit
reg_no
num_regs\n"
"eg
test1
198.202.138.72
5
0
10\n");
return
1;
}
char
*ip_adrs
=
argv[1];
unsigned
short
unit
=
atoi(argv[2]);
unsigned
short
reg_no
=
atoi(argv[3]);
unsigned
short
num_regs
=
atoi(argv[4]);
printf("ip_adrs
=
%s
unit
=
%d
reg_no
=
%d
num_regs
=
%d\n",
ip_adrs,
unit,
reg_no,
num_regs);
//
initialize
WinSock
static
WSADATA
wd;
if
(WSAStartup(0x0101,
&wd))
{
printf("cannot
initialize
WinSock\n");

return
1;
}
//
set
up
socket
SOCKET
s;
s
=
socket(PF_INET,
SOCK_STREAM,
IPPROTO_TCP);
struct
sockaddr_in
server;
server.sin_family
=
AF_INET;
server.sin_port
=
htons(502);
//
ASA
standard
port
server.sin_addr.s_addr
=
inet_addr(ip_adrs);
int
i;
i
=
connect(s,
(sockaddr
*)&server,
sizeof(sockaddr_in));
if
(i<0)
{
printf("connect
-
error
%d\n",WSAGetLastError());
closesocket(s);
WSACleanup();
return
1;
}
fd_set
fds;
FD_ZERO(&fds);
timeval
tv;
tv.tv_sec
=
5;
tv.tv_usec
=
0;
//
wait
for
permission
to
send
FD_SET(s,
&fds);
i
=
select(32,
NULL,
&fds,
NULL,
&tv);
//
write
if
(i<=0)
{
printf("select
-
error
%d\n",WSAGetLastError());
closesocket(s);
WSACleanup();
return
1;
}
//
build
request
of
form
0
0
0
0
0
6
ui
3
rr
rr
nn
nn
unsigned
char
obuf[261];
unsigned
char
ibuf[261];

for
(i=0;i<5;i++)
obuf[i]
=
0;
obuf[5]
=
6;
obuf[6]
=
unit;
obuf[7]
=
3;
obuf[8]
=
reg_no
>>
8;
obuf[9]
=
reg_no
&
0xff;
obuf[10]
=
num_regs
>>
8;
obuf[11]
=
num_regs
&
0xff;
//
send
request
i
=
send(s,
obuf,
12,
0);
if
(i<12)
{
printf("failed
to
send
all
12
chars\n");
}
//
wait
for
response
FD_SET(s,
&fds);
i
=
select(32,
&fds,
NULL,
NULL,
&tv);
//read
if
(i<=0)
{
printf("no
TCP
response
received\n");
closesocket(s);
WSACleanup();
return
1;
}
//
read
response
i
=
recv(s,
ibuf,
261,
0);
if
(i<9)
{
if
(i==0)
{
printf("unexpected
close
of
connection
at
remote
end\n");
}
else
{
printf("response
was
too
short
-
%d
chars\n",
i);
}

}
else
if
(ibuf[7]
&
0x80)
{

printf("
Modbus
exception
response
-
type
%d\n",
ibuf[8]);
}
else
if
(i
!=
(9+2*num_regs))
{
printf("incorrect
response
size
is
%d
expected
%d\n",i,(9+2*num_regs));
}
else
{
for
(i=0;i<num_regs;i++)
{
unsigned
short
w
=
(ibuf[9+i+i]<<8)
+
ibuf[10+i+i];
printf("word
%d
=
%d\n",
i,
w);
}
}
//
close
down
closesocket(s);
WSACleanup();
return
0;
}

⑵ modbus tcp 协议的c语言怎么写

如果用C语言编程实现MODBUS通讯，难度还是很大的。首先需要实现TCP通讯，这里面涉及到TCP侦听模块、TCP数据收发模块、断线重连模块、如果是多信道连接，还需要处理多信道并行通讯等。在实现了TCP通讯核心程序的基础上，通过数据发送程序模块，按照MODBUS指令格式，向前端设备发出正确的MODBUS指令（RTU或ASCII）即可，然后就是通过数据接收模块等待接收前端返回的MODBUS数据包，这就还要编写MODBUS指令生成模块，MODBUS数据解析模块。
上述只是一个大致的思路，里面涉及的编程技术很多，有的技术环节还是很有挑战性的，比如大规模多信道并行通讯。

⑶ 用c语言编写modbus程序

#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_ration = 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_ration = 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;
}
}
}
}

⑷ C语言如何编写modbus RTU协议

如果你想了解MODBUS-RTU，看看下面这个链接。
http://www.360doc.com/content/14/0120/10/7991404_346584755.shtml
网上MODBUS-RTU的实例很多，你可以借鉴。

但是，协议这个东西不是变成达到的，它是在程序设计之前就要拟定好，协议定好以后才有C程序按照协议制定的来编写。针对modbus-rtu来说，你需要把链接里第二部分的协议基本约定看懂之后，再来着手。

加油吧。这个会花些时间。

⑸ 求助：谁能给我一份用C编写的Modbus程序

modbus程序应包含通讯模块，modbus读写指令生成模块，人机交互等主要组成部分。通过人机交互，设定前端设备id,以及通讯参数，寄存器地址等，通过modbus指令生成模块生成指令，并将指令通过通讯模块送出，并接收返回数据 ，数据解析后通过人机交...

⑹ 单片机 用c语言编写 modbus rtu 通讯怎么写啊 主要是crc 校验部分不知道怎么写 怎么把一窜字符进行CRC计算

我刚刚写好.跟PLC连接测试过,可以的.

/***************************************************************
CRC计算方法
1．预置1个16位的寄存器为十六进制FFFF（即全为1）；称此寄存器为CRC寄存器；
2．把第一个8位二进制数据（既通讯信息帧的第一个字节）与16位的CRC寄存器的低
8位相异或，把结果放于CRC寄存器；
3．把CRC寄存器的内容右移一位（朝低位）用0填补最高位，并检查右移后的移出位；
4．如果移出位为0：重复第3步（再次右移一位）；
如果移出位为1：CRC寄存器与多项式A001（1010 0000 0000 0001）进行异或；
5．重复步骤3和4，直到右移8次，这样整个8位数据全部进行了处理；
6．重复步骤2到步骤5，进行通讯信息帧下一个字节的处理；
7．将该通讯信息帧所有字节按上述步骤计算完成后，得到的16位CRC；

*****************************************************************/

/****************************************************************************
名称: UART_CRC16_Work()
说明: CRC16校验程序
参数: *CRC_Buf:数据地址
CRC_Leni:数据长度
返回: CRC_Sumx:校验值
*****************************************************************************/
unsigned int UART_CRC16_Work(unsigned char *CRC_Buf,unsigned char CRC_Leni)
{
unsigned char i,j;
unsigned int CRC_Sumx;

CRC_Sumx=0xFFFF;
for(i=0;i<CRC_Leni;i++)
{
CRC_Sumx^=*(CRC_Buf+i);//异或
for(j=0;j<8;j++)
{
if(CRC_Sumx & 0x01)
{
CRC_Sumx>>=1;
CRC_Sumx^=0xA001;
}
else
{
CRC_Sumx>>=1;
}
}
}
return (CRC_Sumx);
}

⑺ 单片机MODBUS RTU 作主机C程序

modbus的基本部分有现成的,自己写也不难,一般03和06指令用的最多,基本就够了.比较难的是数据分包检测,这块得根据你的mcu具体来做.
关于指令中的处理这部分只能自己写了.

⑻ 01 03 02 00 00 B8 44modbus用C语言怎么编写

你说的MODBUS指令是错误的，MODBUS指令至少八字节，一字节设备ID，一字节指令码，两字节偏移量，两字节寄存器个数，两字节CRC16，写指令还需要加上若干字节的写入数据。C语言描述MODBUS指令，只需要声明一个字节数组即可，数组长度等于指令字节数量，然后将指令的各个字节数值依次写入到数组，然后再将这个数组发送出去即可。

⑼ modbus通讯协议在PLC上怎么使用，举个例子，详细点最好！

通常PLC的使用说明书上有通信协议的格式，大多采用Modbus协议，要例子可以用类似格西烽火之类的软件，自带了Modbus协议测试例子。