相關內容：

　　linux嵌入式軟體中libmudbus庫的移植與使用(一)

　　linux嵌入式軟體中libmudbus庫的移植與使用(二)

測試環境：

　　在上一篇文件中，建立的install資料夾下，看到include、lib，以備主程式呼叫。將install資料夾下include裡modbus中.h檔案、lib裡的直接複製到

含有下面測試程式碼modbus.c資料夾中。

測試程式碼modbus.c：

#include<errno.h>
#include<string.h>
#include <stdio.h>
#include <unistd.h>
#include 
 
<modbus.h>


typedef struct
{
    unsigned short null_0;                    // 0x00
    unsigned short key1_state;            // 0x01: 按鍵1狀態
    unsigned short key2_state;                // 0x02: 按鍵2狀態
    unsigned short key3_state;                // 0x03: 按鍵3狀態
    unsigned short key4_state;                // 0x04: 按鍵4狀態
 

    unsigned short wifi_comm_state;            // 0x05: wifi通訊狀態
    unsigned short batt_comm_state;            // 0x06:電池通訊狀態
    unsigned short null_1[9];                // 0x07~0xF

    unsigned short percentage;            // 0x10: 電量
    unsigned short voltage;               // 0x11: 電壓
    unsigned short in_current;            //
 
 0x12: 充電電流
    unsigned short out_current;        // 0x13: 放電電流
    unsigned short ch_state;            // 0x14: 充電狀態
    unsigned short ch_key;                // 0x15: 充電按鍵
    
       
}display_t;


display_t disp_date;


static void 
display_fresh(void)
{
    //
    disp_date.key1_state = 1;
    disp_date.key2_state =1;
    disp_date.key3_state = 1;
    disp_date.key4_state =1;

}

int main(void)
{
    modbus_t *ctx = NULL;
    
#if 0    
    ctx = modbus_new_rtu("/dev/ttyUSB0", 115200, 'N', 8, 1);        
    //設定從機號碼
    modbus_set_slave(ctx, 1);  
    //modbus_set_response_timeout(ctx, 3, 0); //sec，usec，超時設定 設定為3s
    if(modbus_connect(ctx) == -1)
    {        
        printf("Connection failed: %s\n",modbus_strerror(errno));        
        modbus_free(ctx);           
    }
    
    memset(&disp_date, 0, sizeof(display_t));    
    while(1)
    {
        display_fresh();
        printf("111:%d,%d,%d,%d,",disp_date.key1_state,disp_date.key2_state,disp_date.key3_state,disp_date.key4_state);
        modbus_write_registers(ctx, 0, sizeof(display_t)/sizeof(unsigned short), (const uint16_t*)&disp_date);        
        modbus_read_input_registers(ctx, 0, sizeof(display_t)/sizeof(unsigned short), ( uint16_t*)&disp_date);
        printf("222:%d,%d,%d,%d,",disp_date.key1_state,disp_date.key2_state,disp_date.key3_state,disp_date.key4_state);
        usleep(50*1000);
    }
    
#else 

　　ctx = modbus_new_tcp("192.168.43.123", 8080);    
    modbus_set_debug(ctx, TRUE); 
    modbus_set_slave(ctx, 1);//設定從機號碼
    if (modbus_connect(ctx) == -1) {        
        printf("modbus connection failed: %s\n",modbus_strerror(errno));       
        modbus_free(ctx);           
    }
    memset(&disp_date, 0, sizeof(display_t));
    while(1)
    {
        display_fresh();
        printf("1111:%d,%d,%d,%d\n",disp_date.key1_state,disp_date.key2_state,disp_date.key3_state,disp_date.key4_state);
        modbus_write_registers(ctx, 0, sizeof(display_t)/sizeof(unsigned short), (const uint16_t*)&disp_date);        
        modbus_read_input_registers(ctx, 0, sizeof(display_t)/sizeof(unsigned short), ( uint16_t*)&disp_date);
        printf("2222:%d,%d,%d,%d\n",disp_date.key1_state,disp_date.key2_state,disp_date.key3_state,disp_date.key4_state);
        usleep(1000*1000);
    }
#endif    

    modbus_close(ctx);    //關閉modbus連線
    modbus_free(ctx);    //釋放modbus資源，使用完libmodbus需要釋放掉     
    return 0;
}

makefile：

CROSS    =    
LIB_PWD = $(shell pwd)
TARGET_BIN = test



CPP    = $(CROSS)g++ -std=c++11
CC    = $(CROSS)gcc
LD    = $(CROSS)ld


CFLAGS  += -I$(shell pwd)

CFLAGS  += -Wall -g  
LDFLAGS += -lmodbus -ldl -lm -lrt  -L$(LIB_PWD)
STATIC_LIB += $(LIB_PWD)/libmodbus.a
        
        
SRCS = $(wildcard *.c)
OBJS = $(patsubst %.c,%.o,$(SRCS))
%.o: %.c
    $(CPP) $(CFLAGS) -o $@ -c $< 
    
all:$(OBJS)
    $(CPP) -o $(TARGET_BIN)  $(OBJS)  $(STATIC_LIB) $(LDFLAGS) 
    
clean:
    rm -f *.o