RS485和RS232 通信配置

232引脚

对应串口

RS232-1

UART4_M2

RS232-2

UART7_M2

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#修改配置文件
sudo vi /boot/uEnv/uEnv.txt

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#重启
sudo reboot

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#需要在root用户下运行#在板卡的终端执行如下命令
stty -F /dev/ttyS4

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#需要在root用户下运行#设置通讯速率，其中ispeed为输入速率，ospeed为输出速率
stty -F /dev/ttyS4 ispeed 115200 ospeed 115200

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#需要在root用户下运行stty -F /dev/ttyS4 -echo

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#需要在root用户下运行#发送消息
echo "I'm lubancat" > /dev/ttyS4#接收消息
cat /dev/ttyS4

TX1

连接

RX2

RX1

连接

TX2

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#需要在root用户下运行#RS232-2后台接收
cat /dev/ttyS7 &#RS232-1发送消息
echo "1234567890" > /dev/ttyS4
echo "abcdefghijklmn" > /dev/ttyS4

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pkill cat

485引脚

对应串口

RS485-1

UART4_M2

RS485-2

UART7-M2

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#修改配置文件
sudo vi /boot/uEnv/uEnv.txt

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#重启
sudo reboot

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#修改配置文件
sudo vi /boot/uEnv/uEnv.txt

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#重启
sudo reboot

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#需要在root用户下运行#在板卡的终端执行如下命令
stty -F /dev/ttyS4#信息输出如下
speed 9600 baud; line = 0;
-brkint -imaxbel

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#需要在root用户下运行#设置通讯速率，其中ispeed为输入速率，ospeed为输出速率
stty -F /dev/ttyS4 ispeed 115200 ospeed 115200

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#需要在root用户下运行stty -F /dev/ttyS4 -echo

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#需要在root用户下运行#操作和普通串口一样，直接收发即可
#发送消息
echo "I'm lubancat" > /dev/ttyS4#接收消息
cat /dev/ttyS4

板卡

RS485-1流控引脚

RS485-2流控引脚

LubanCat-5IO底板

GPIO3_PC7

GPIO3_PD0

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#需要在root用户下运行#使能引脚
echo 119 > /sys/class/gpio/export#设置引脚为输出模式
echo out > /sys/class/gpio/gpio119/direction#设置引脚为低电平
echo 0 > /sys/class/gpio/gpio119/value
#流控引脚为低时，数据接收
cat /dev/ttyS4#设置引脚为高电平
echo 1 > /sys/class/gpio/gpio119/value
#流控引脚为高时，数据发送
echo "I'm lubancat" > /dev/ttyS4

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#需要在root用户下运行#设置RS485-1的引脚为高电平
gpioset 3 23=1
#流控引脚为高时，数据发送
echo "I'm lubancat" > /dev/ttyS4#设置RS485-1的引脚为低电平
gpioset 3 23=0
#流控引脚为低时，数据接收
cat /dev/ttyS4

RS485-1A

连接

RS485-2A

RS485-1B

连接

RS485-2B

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#需要在root用户下运行#RS485-2后台接收数据
cat /dev/ttyS7 &#RS485-1发送消息
echo "12345678119" > /dev/ttyS4
echo "abcdefghijklmn" > /dev/ttyS4

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pkill cat

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#需要在root用户下运行#RS485-2流控脚拉低，数据接收
gpioset 3 24=0
#RS485-2后台接收
cat /dev/ttyS7 &#RS485-1流控脚拉高，数据发送
gpioset 3 23=1
#RS485-1发送消息
echo "12345678119" > /dev/ttyS4

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pkill cat

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#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>#include <unistd.h>
#include <termios.h>#define SERVER_GPIO_INDEX   "119"  //流控引脚对应编号
const char default_path[] = "/dev/ttyS4";  //rs485-1对应的串口/*
*串口配置成功返回0，失败返回-1；
*/
int set_uart(int fd,int nSpeed, int nBits, char nEvent, int nStop);static int _server_ioctl_init(void)
{int fd;//index configfd = open("/sys/class/gpio/export", O_WRONLY);if(fd < 0)return 1;write(fd, SERVER_GPIO_INDEX, strlen(SERVER_GPIO_INDEX));close(fd);//direction configfd = open("/sys/class/gpio/gpio" SERVER_GPIO_INDEX "/direction", O_WRONLY);if(fd < 0)return 2;write(fd, "out", strlen("out"));close(fd);return 0;
}static int _server_ioctl_on(void)
{int fd;fd = open("/sys/class/gpio/gpio" SERVER_GPIO_INDEX "/value", O_WRONLY);if(fd < 0){printf("_server_ioctl_open error\n");return 1;}write(fd, "1", 1);close(fd);return 0;
}static int _server_ioctl_off(void)
{int fd;fd = open("/sys/class/gpio/gpio" SERVER_GPIO_INDEX "/value", O_WRONLY);if(fd < 0)return 1;write(fd, "0", 1);close(fd);return 0;
}static void _modbus_rtu_server_ioctl(int on)
{if (on) {_server_ioctl_on();} else {_server_ioctl_off();}
}static int _server_ioctl_exit(void)
{int fd;fd = open("/sys/class/gpio/uexport", O_WRONLY);if(fd < 0)return 1;write(fd, SERVER_GPIO_INDEX, strlen(SERVER_GPIO_INDEX));close(fd);}int main(int argc,char *argv[])
{int fd;int res;char *path;//char buf[1024] = "Embedfire 485 send test.\n";char buf[1024] = "1111111\n";char buf1[1024];int i;if(argc > 1){path = argv[1];}else{path = (char *)default_path;}fd = open(path,O_RDWR);if(fd < 0){perror(path);exit(-1);}if( set_uart(fd,115200,8,'n',1) ){printf("set uart error\n");}_server_ioctl_init();for(i=0;i<100;i++){//485-1发送_modbus_rtu_server_ioctl(1);write(fd, buf, strlen(buf));printf("485-1 Send data, res = %d bytes data: %s\r\n",strlen(buf), buf);usleep(10000); // 10毫秒//sleep(1);//485-1读取_modbus_rtu_server_ioctl(0);memset(buf1,0,1024);res = read(fd, buf1, 1024);if(res > 0){printf("485-1 Read data, res = %d bytes data: %s\r\n",res, buf1);}printf("cycle index is %d\r\n",i);usleep(10000); // 10毫秒//sleep(1);}_server_ioctl_exit();close(fd);return 0;
}int set_uart(int fd,int nSpeed, int nBits, char nEvent, int nStop)
{struct termios opt;//清空串口接收缓冲区tcflush(fd, TCIOFLUSH);//获取串口配置参数tcgetattr(fd, &opt);opt.c_cflag &= (~CBAUD);    //清除数据位设置opt.c_cflag &= (~PARENB);   //清除校验位设置//opt.c_iflag |= IGNCR;       //忽略接收数据中的'\r'字符，在windows中换行为'\r\n'opt.c_iflag &= (~ICRNL);    //不将'\r'转换为'\n'opt.c_lflag &= (~ECHO);     //不使用回显//设置波特率switch(nSpeed){case 2400:cfsetspeed(&opt,B2400);break;case 4800:cfsetspeed(&opt,B4800);break;case 9600:cfsetspeed(&opt,B9600);break;case 38400:cfsetspeed(&opt,B38400);break;case 115200:cfsetspeed(&opt,B115200);break;default:return -1;}//设置数据位switch(nBits){case 7:opt.c_cflag |= CS7;break;case 8:opt.c_cflag |= CS8;break;default:return -1;}//设置校验位switch(nEvent){//无奇偶校验case 'n':case 'N':opt.c_cflag &= (~PARENB);break;//奇校验case 'o':case 'O':opt.c_cflag |= PARODD;break;//偶校验case 'e':case 'E':opt.c_cflag |= PARENB;opt.c_cflag &= (~PARODD);break;default:return -1;}//设置停止位switch(nStop){case 1:opt.c_cflag &= ~CSTOPB;break;case 2:opt.c_cflag |= CSTOPB;break;default:return -1;}//设置串口tcsetattr(fd,TCSANOW,&opt);return 0;
}

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#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>#include <unistd.h>
#include <termios.h>#define SERVER_GPIO_INDEX   "120" //流控引脚的对应编号
const char default_path[] = "/dev/ttyS7"; //rs485-2对应的串口/*
*串口配置成功返回0，失败返回-1；
*/
int set_uart(int fd,int nSpeed, int nBits, char nEvent, int nStop);static int _server_ioctl_init(void)
{int fd;//index configfd = open("/sys/class/gpio/export", O_WRONLY);if(fd < 0)return 1;write(fd, SERVER_GPIO_INDEX, strlen(SERVER_GPIO_INDEX));close(fd);//direction configfd = open("/sys/class/gpio/gpio" SERVER_GPIO_INDEX "/direction", O_WRONLY);if(fd < 0)return 2;write(fd, "out", strlen("out"));close(fd);return 0;
}static int _server_ioctl_on(void)
{int fd;fd = open("/sys/class/gpio/gpio" SERVER_GPIO_INDEX "/value", O_WRONLY);if(fd < 0)return 1;write(fd, "1", 1);close(fd);return 0;
}static int _server_ioctl_off(void)
{int fd;fd = open("/sys/class/gpio/gpio" SERVER_GPIO_INDEX "/value", O_WRONLY);if(fd < 0)return 1;write(fd, "0", 1);close(fd);return 0;
}static void _modbus_rtu_server_ioctl(int on)
{if (on) {_server_ioctl_on();} else {_server_ioctl_off();}
}static int _server_ioctl_exit(void)
{int fd;fd = open("/sys/class/gpio/uexport", O_WRONLY);if(fd < 0)return 1;write(fd, SERVER_GPIO_INDEX, strlen(SERVER_GPIO_INDEX));close(fd);}int main(int argc,char *argv[])
{int fd;int res;char *path;char buf[1024] = "0000000\n";;char buf1[1024];int i;if(argc > 1){path = argv[1];}else{path = (char *)default_path;}fd = open(path,O_RDWR);if(fd < 0){perror(path);exit(-1);}if( set_uart(fd,115200,8,'n',1) ){printf("set uart error\n");}_server_ioctl_init();for(i=0;i<100;i++){//485-2读取_modbus_rtu_server_ioctl(0);memset(buf1,0,1024);res = read(fd, buf1, 1024);if(res > 0){printf("485-2 Read data, res = %d bytes data: %s\r\n",res, buf1);}usleep(10000); // 10毫秒//sleep(1);//485-2发送_modbus_rtu_server_ioctl(1);write(fd, buf, strlen(buf));printf("485-2 Send data, res = %d bytes data: %s\r\n",strlen(buf), buf);printf("cycle index is %d\r\n",i);usleep(10000); // 10毫秒//sleep(1);}_server_ioctl_exit();close(fd);return 0;
}int set_uart(int fd,int nSpeed, int nBits, char nEvent, int nStop)
{struct termios opt;//清空串口接收缓冲区tcflush(fd, TCIOFLUSH);//获取串口配置参数tcgetattr(fd, &opt);opt.c_cflag &= (~CBAUD);    //清除数据位设置opt.c_cflag &= (~PARENB);   //清除校验位设置//opt.c_iflag |= IGNCR;       //忽略接收数据中的'\r'字符，在windows中换行为'\r\n'opt.c_iflag &= (~ICRNL);    //不将'\r'转换为'\n'opt.c_lflag &= (~ECHO);     //不使用回显//设置波特率switch(nSpeed){case 2400:cfsetspeed(&opt,B2400);break;case 4800:cfsetspeed(&opt,B4800);break;case 9600:cfsetspeed(&opt,B9600);break;case 38400:cfsetspeed(&opt,B38400);break;case 115200:cfsetspeed(&opt,B115200);break;default:return -1;}//设置数据位switch(nBits){case 7:opt.c_cflag |= CS7;break;case 8:opt.c_cflag |= CS8;break;default:return -1;}//设置校验位switch(nEvent){//无奇偶校验case 'n':case 'N':opt.c_cflag &= (~PARENB);break;//奇校验case 'o':case 'O':opt.c_cflag |= PARODD;break;//偶校验case 'e':case 'E':opt.c_cflag |= PARENB;opt.c_cflag &= (~PARODD);break;default:return -1;}//设置停止位switch(nStop){case 1:opt.c_cflag &= ~CSTOPB;break;case 2:opt.c_cflag |= CSTOPB;break;default:return -1;}//设置串口tcsetattr(fd,TCSANOW,&opt);return 0;
}

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gcc rs485_1_test_client.c -o rs485_1_test_client
gcc rs485_2_test_server.c -o rs485_2_test_server

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sudo ./rs485_2_test_server

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sudo ./rs485_1_test_client

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sudo apt update
sudo apt install gcc make git autoconf libtool automake

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git clone https://github.com/stephane/libmodbus.git

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#将libmodbus/tests/unit-test-server.c的第57行和第76行定义的接口修改为实际的接口
...
printf("Eg. tcp 127.0.0.1 or rtu /dev/ttyS4\n\n");
......
ip_or_device = "/dev/ttyS4";
...

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#将libmodbus/tests/unit-test-client.c的第93行和第112行定义的接口修改为实际的接口
...
printf("Eg. tcp 127.0.0.1 or rtu /dev/ttyS7\n\n");
......
ip_or_device = "/dev/ttyS7";
...

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./autogen.sh

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configure.ac:33: installing 'build-aux/compile'
configure.ac:56: installing 'build-aux/config.guess'
configure.ac:56: installing 'build-aux/config.sub'
configure.ac:32: installing 'build-aux/install-sh'
configure.ac:32: installing 'build-aux/missing'
src/Makefile.am: installing 'build-aux/depcomp'
parallel-tests: installing 'build-aux/test-driver'------------------------------------------------------
Initialized build system. You can now run ./configure
------------------------------------------------------

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./configure

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config.status: executing depfiles commands
config.status: executing libtool commandslibmodbus 3.1.10===============prefix:                 /usr/localsysconfdir:             ${prefix}/etclibdir:                 ${exec_prefix}/libincludedir:             ${prefix}/includecompiler:               gcccflags:                 -g -O2ldflags:tests:                  yes

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make

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root@lubancat:~/libmodbus/tests# ls
LICENSE                     bandwidth-server-one    unit-test-client.c
Makefile                    bandwidth-server-one.c  unit-test-client.o
Makefile.am                 bandwidth-server-one.o  unit-test-server
Makefile.in                 random-test-client      unit-test-server.c
README.md                   random-test-client.c    unit-test-server.o
bandwidth-client            random-test-client.o    unit-test.h
bandwidth-client.c          random-test-server      unit-test.h.in
bandwidth-client.o          random-test-server.c    unit-tests.sh
bandwidth-server-many-up    random-test-server.o    version
bandwidth-server-many-up.c  stamp-h2                version.c
bandwidth-server-many-up.o  unit-test-client        version.o

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./unit-test-server rtu

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./unit-test-client rtu

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[11][0F][01][60][00][00][00][02][2B][00][01][00][64][59][63]
* try function 0xF: write 0 values: Waiting for a confirmation...
<11><8F><03><05><F4>
OK
[11][0F][01][60][07][B0][06][02][2B][00][01][00][64][12][27]
* try function 0xF: write 1968 values: Waiting for a confirmation...
<11><8F><03><05><F4>
OK
[11][42][00][00][00][00][7B][55]
Waiting for a confirmation...
<11><C2><01><B1><65>
Return an exception on unknown function code: OKTEST INVALID INITIALIZATION:
The device string is empty
OK
The baud rate value must not be zero
OKALL TESTS PASS WITH SUCCESS.

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sudo apt update
sudo apt install gcc git libmodbus-dev pkg-config

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#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <modbus.h>
#include <sys/stat.h>
#include <fcntl.h>#define SERVER_GPIO_INDEX   "119"  //485-1的换流引脚
#define SERVER_ID         17
const uint16_t UT_REGISTERS_TAB[] = { 0x0A, 0x0E, 0x0A, 0x1B,0x0A};static int _server_ioctl_init(void)
{int fd;//index configfd = open("/sys/class/gpio/export", O_WRONLY);if(fd < 0)return 1;write(fd, SERVER_GPIO_INDEX, strlen(SERVER_GPIO_INDEX));close(fd);//direction configfd = open("/sys/class/gpio/gpio" SERVER_GPIO_INDEX "/direction", O_WRONLY);if(fd < 0)return 2;write(fd, "out", strlen("out"));close(fd);return 0;
}static int _server_ioctl_on(void)
{int fd;fd = open("/sys/class/gpio/gpio" SERVER_GPIO_INDEX "/value", O_WRONLY);if(fd < 0)return 1;write(fd, "1", 1);close(fd);return 0;
}static int _server_ioctl_off(void)
{int fd;fd = open("/sys/class/gpio/gpio" SERVER_GPIO_INDEX "/value", O_WRONLY);if(fd < 0)return 1;write(fd, "0", 1);close(fd);return 0;
}static void _modbus_rtu_server_ioctl(modbus_t *ctx, int on)
{if (on) {_server_ioctl_on();} else {_server_ioctl_off();}
}int main(int argc, char*argv[])
{modbus_t *ctx;modbus_mapping_t *mb_mapping;int rc;int i;uint8_t *query;/*设置串口信息*/ctx = modbus_new_rtu("/dev/ttyS4", 9600, 'N', 8, 1);_server_ioctl_init();/*设置从机地址，设置485模式*/modbus_set_slave(ctx, SERVER_ID);modbus_rtu_set_custom_rts(ctx, _modbus_rtu_server_ioctl);modbus_rtu_set_rts(ctx, MODBUS_RTU_RTS_UP);modbus_rtu_set_serial_mode(ctx, MODBUS_RTU_RS485);query = malloc(MODBUS_RTU_MAX_ADU_LENGTH);/*开启调试*/modbus_set_debug(ctx, TRUE);mb_mapping = modbus_mapping_new_start_address(0,0,0,0,0,5,0,0);if (mb_mapping == NULL) {fprintf(stderr, "Failed to allocate the mapping: %s\n",modbus_strerror(errno));modbus_free(ctx);return -1;}/* 初始化值 */for (i=0; i < 5; i++) {mb_mapping->tab_registers[i] = UT_REGISTERS_TAB[i];}rc = modbus_connect(ctx);if (rc == -1) {fprintf(stderr, "Unable to connect %s\n", modbus_strerror(errno));modbus_free(ctx);return -1;}modbus_flush(ctx);for (;;) {do {rc = modbus_receive(ctx, query);} while (rc == 0);rc = modbus_reply(ctx, query, rc, mb_mapping);if (rc == -1) {break;}}modbus_mapping_free(mb_mapping);free(query);modbus_close(ctx);modbus_free(ctx);return 0;
}

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#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#include <modbus.h>
#include <sys/stat.h>
#include <fcntl.h>#define CLIENT_GPIO_INDEX   "91"  //485-2的换流引脚
#define SERVER_ID         17static int _client_ioctl_init(void)
{int fd;//index configfd = open("/sys/class/gpio/export", O_WRONLY);if(fd < 0)return 1 ;write(fd, CLIENT_GPIO_INDEX, strlen(CLIENT_GPIO_INDEX));close(fd);//direction configfd = open("/sys/class/gpio/gpio" CLIENT_GPIO_INDEX "/direction", O_WRONLY);if(fd < 0)return 2;write(fd, "out", strlen("out"));close(fd);return 0;
}static int _client_ioctl_on(void)
{int fd;fd = open("/sys/class/gpio/gpio" CLIENT_GPIO_INDEX "/value", O_WRONLY);if(fd < 0)return 1;write(fd, "0", 1);close(fd);return 0;
}static int _client_ioctl_off(void)
{int fd;fd = open("/sys/class/gpio/gpio" CLIENT_GPIO_INDEX "/value", O_WRONLY);if(fd < 0)return 1;write(fd, "1", 1);close(fd);return 0;
}static void _modbus_rtu_client_ioctl(modbus_t *ctx, int on)
{if (on) {_client_ioctl_on();} else {_client_ioctl_off();}
}int main(int argc, char *argv[])
{modbus_t *ctx = NULL;int i,rc;uint16_t tab_rp_registers[5] = {0}; //定义存放数据的数组/*创建一个RTU类型的变量*//*设置要打开的串口设备  波特率 奇偶校验 数据位 停止位*/ctx = modbus_new_rtu("/dev/ttyS7", 9600, 'N', 8, 1);if (ctx == NULL) {fprintf(stderr, "Unable to allocate libmodbus context\n");return -1;}/*设置485模式*/_client_ioctl_init();modbus_rtu_set_custom_rts(ctx, _modbus_rtu_client_ioctl);modbus_rtu_set_rts(ctx, MODBUS_RTU_RTS_DOWN);modbus_rtu_set_serial_mode(ctx, MODBUS_RTU_RS485);/*设置debug模式*/modbus_set_debug(ctx, TRUE);/*设置从机地址*/modbus_set_slave(ctx, SERVER_ID);/*RTU模式 打开串口*/if (modbus_connect(ctx) == -1) {fprintf(stderr, "Connection failed: %s\n", modbus_strerror(errno));modbus_free(ctx);return -1;}//读取多个连续寄存器rc = modbus_read_registers(ctx, 0, 5, tab_rp_registers);if (rc == -1){fprintf(stderr,"%s\n", modbus_strerror(errno));return -1;}for (i=0; i<5; i++){//打印读取的数据printf("reg[%d] = %d(0x%x)\n", i, tab_rp_registers[i], tab_rp_registers[i]);}modbus_close(ctx);modbus_free(ctx);return 0;
}

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gcc test-server.c -o test-server `pkg-config --cflags --libs libmodbus`
gcc test-client.c -o test-client `pkg-config --cflags --libs libmodbus`

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root@lubancat:~$./test-server

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 root@lubancat:~$./test-client

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Opening /dev/ttyS7 at 9600 bauds (N, 8, 1)
[0A][03][00][00][00][05][84][B2]
Sending request using RTS signal
Waiting for a confirmation...
<0A><03><0A><00><0A><00><0E><00><0A><00><1B><00><0A><C7><5C>
reg[0] = 10(0xa)
reg[1] = 14(0xe)
reg[2] = 10(0xa)
reg[3] = 27(0x1b)
reg[4] = 10(0xa)

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 Opening /dev/ttyS4 at 9600 bauds (N, 8, 1)Bytes flushed (0)Waiting for a indication...<0A><03><00><00><00><05><84><B2>[0A][03][0A][00][0A][00][0E][00][0A][00][1B][00][0A][C7][5C]Sending request using RTS signalWaiting for a indication...