使用freemodbus主机协议栈，调用eMBMasterReqReadHoldingRegister()，寄存器地址设置为0000H时可以正常读取，但设置为0606H后，产生“MB_MRE_EXE_FUN”功能码错误的异常。
/* * Copyright (c) 2006-2021, RT-Thread Development Team * * SPDX-License-Identifier: Apache-2.0 * * Change Logs: * Date Author Notes * 2022-01-10 zf_19 the first version */#include <rtthread.h>#include "mb.h"#include "mb_m.h"#include "user_mb_app.h"#ifdef PKG_MODBUS_MASTER_SAMPLE#define SLAVE_ADDR MB_SAMPLE_TEST_SLAVE_ADDR#define PORT_NUM MB_MASTER_USING_PORT_NUM#define PORT_BAUDRATE MB_MASTER_USING_PORT_BAUDRATE#else#define SLAVE_ADDR 0x01#define PORT_NUM 5#define PORT_BAUDRATE 9600#endif#define PORT_PARITY MB_PAR_NONE //无校验位#define MB_POLL_THREAD_PRIORITY 10#define MB_SEND_THREAD_PRIORITY RT_THREAD_PRIORITY_MAX - 1#define MB_SEND_REG_START 3#define MB_SEND_REG_NUM 3#define MB_POLL_CYCLE_MS 500 //轮询间隔时间 5个传感器一轮走完需要500ms/*RS485_RE PI4 对应PI4引脚应填写：132 (I-A=8)*16+4=132 串口使用U5*//*各传感器地址配置*/#define Displacement_sensor01_SLAVE_ADDR 0x01#define Displacement_sensor02_SLAVE_ADDR 0x02#define Displacement_sensor03_SLAVE_ADDR 0x03#define Displacement_sensor04_SLAVE_ADDR 0x04#define Angle_sensor01_SLAVE_ADDR 0X05/*寄存器地址配置*/#define MB_READ_REG_00 0x00 //读当前测量值#define MB_READ_REG_01 0x01 //仪表类比及当前信息#define MB_READ_REG_02 0x02 //仪表编号低四位#define MB_READ_REG_LL_0606 0X0606//L600拉力传感器信息保存寄存器#define MB_READ_REG_LL_9C04 0X9C04//L600拉力传感器信息保存寄存器/*寄存器数量---modbus 读数据的长度*/#define MB_READ_REG_NUM_01 1#define MB_READ_REG_NUM_02 2#define MB_READ_REG_NUM_03 3#define MB_READ_REG_NUM_04 4static int is_got = 0;extern USHORT usMRegHoldBuf[MB_MASTER_TOTAL_SLAVE_NUM][M_REG_HOLDING_NREGS];// modbus master 用全局二维数组来记录多个从机的数据/*进行touchgfx数据更新、电压测量板显示数据格式为signed short -32768~32767*/int16_t value_FY_DCD_10;int16_t value_HX_DCD_10;int16_t value_ZHG_DCD_10;int16_t value_YHG_DCD_10;int16_t value_PULL_DLM_20;/*上传到model俯仰DCD-10传感器信息*/static int gfxget_FY_DCD_10(void){ return value_FY_DCD_10;}/*上传到model航向DCD-10传感器信息*/static int gfxget_HX_DCD_10(void){ return value_HX_DCD_10;}/*上传到model左横滚DCD-10传感器信息*/static int gfxget_ZHG_DCD_10(void){ return value_ZHG_DCD_10;}/*上传到model右横滚DCD-10传感器信息*/static int gfxget_YHG_DCD_10(void){ return value_YHG_DCD_10;}static int gfxget_PULL_DLM_20(void){ return value_PULL_DLM_20;}/*读取各传感器信息线程*/static void send_thread_entry(void *parameter){ eMBMasterReqErrCode error_code = MB_MRE_NO_ERR; rt_uint16_t error_count = 0; while (1) { /* Test Modbus Master *//* data[0] = (USHORT)(rt_tick_get() / 10); data[1] = (USHORT)(rt_tick_get() % 10);*/ /*接收标志位置零*/ is_got = 0;/* //往从机多个保持寄存器写入数据 error_code = eMBMasterReqWriteMultipleHoldingRegister(SLAVE_ADDR, //salve address MB_SEND_REG_START, //register start address MB_SEND_REG_NUM, //register total number data, //data to be written RT_WAITING_FOREVER); //timeout*//* //读位移传感器1多个保持寄存器数据 error_code = eMBMasterReqReadHoldingRegister(Displacement_sensor01_SLAVE_ADDR, MB_READ_REG_00, MB_READ_REG_NUM_01, 500); //读位移传感器2,000H多个保持寄存器数据 error_code = eMBMasterReqReadHoldingRegister(Displacement_sensor02_SLAVE_ADDR, MB_READ_REG_00, //0000H寄存器 MB_READ_REG_NUM_01, //读取数据数量 500); //读位移传感器3,0000H多个保持寄存器数据 error_code = eMBMasterReqReadHoldingRegister(Displacement_sensor03_SLAVE_ADDR, MB_READ_REG_00, //0000H寄存器 MB_READ_REG_NUM_01, //读取数据数量 500); //读位移传感器4,0000H开始5个保持寄存器数据 error_code = eMBMasterReqReadHoldingRegister(Displacement_sensor04_SLAVE_ADDR, MB_READ_REG_00, //0000H寄存器 MB_READ_REG_NUM_01, //读取数据数量 500);*/ //读角度传感器5,0000H开始2个保持寄存器数据 error_code = eMBMasterReqReadHoldingRegister(Angle_sensor01_SLAVE_ADDR, //角度传感器地址 MB_READ_REG_LL_0606, //0606H寄存器 MB_READ_REG_NUM_02, //读取数据数量 500);/* //打印节点1俯仰传感器 保持寄存器的数据 value_FY_DCD_10 = (int16_t)usMRegHoldBuf[0][0]; rt_kprintf("sensor1_detect: %d \t\r\n", (int16_t)usMRegHoldBuf[0][0]); //打印节点2航向传感器 保持寄存器的数据 value_HX_DCD_10 = (int16_t)usMRegHoldBuf[1][0]; rt_kprintf("sensor2_detect: %d \t\r\n", (int16_t)usMRegHoldBuf[1][0]); //打印节点3左横滚传感器 保持寄存器的数据 value_ZHG_DCD_10 = (int16_t)usMRegHoldBuf[2][0]; rt_kprintf("sensor3_detect: %d \t\r\n", (int16_t)usMRegHoldBuf[2][0]); //打印节点4右横滚传感器 保持寄存器的数据 value_YHG_DCD_10 = usMRegHoldBuf[3][0]; rt_kprintf("sensor4_detect: %d \t\r\n", (int16_t)usMRegHoldBuf[3][0]);*/ //打印节点5 拉力传感器 保持寄存器的数据 value_PULL_DLM_20 = usMRegHoldBuf[5][0]; rt_kprintf("sensor5_detect: %d \t\r\n", usMRegHoldBuf[5][0]); //打印时钟节点 rt_kprintf("tick is %d\r\n",rt_tick_get()); /* Record the number of errors */ if (error_code != MB_MRE_NO_ERR) { error_count++; rt_kprintf("error_count : %d \n",error_count); rt_kprintf("error_code %d\r\n",error_code); } is_got = 1; rt_thread_delay(100); }}static void mb_msg_get(void *parameter){ char mb_get_buf[05][64]; while(1) { if (is_got) { //置零 //memset(mb_get_buf, 0, 320);/* //提取数据 sprintf(mb_get_buf[Displacement_sensor01_SLAVE_ADDR - 1], usMRegHoldBuf[Displacement_sensor01_SLAVE_ADDR - 1][MB_READ_REG_NUM_01]);*/ } rt_thread_mdelay(5 * RT_TICK_PER_SECOND); } }static void mb_master_poll(void *parameter){ //MB初始化 内部已定义停止位，当前为停止位2； eMBMasterInit(MB_RTU, PORT_NUM, PORT_BAUDRATE, PORT_PARITY); eMBMasterEnable(); while (1) { eMBMasterPoll(); rt_thread_mdelay(MB_POLL_CYCLE_MS); }}static int TDM_TMD_modbus(int argc, char **argv){ static rt_uint8_t is_init = 0; rt_thread_t tid1 = RT_NULL, tid2 = RT_NULL,tid3 = RT_NULL; if (is_init > 0) { rt_kprintf("sample is running\n"); return -RT_ERROR; } tid1 = rt_thread_create("md_m_poll", mb_master_poll, RT_NULL, 512, MB_POLL_THREAD_PRIORITY, 10); if (tid1 != RT_NULL) { rt_thread_startup(tid1); } else { goto __exit; } tid2 = rt_thread_create("md_m_send", send_thread_entry, RT_NULL, 512, MB_SEND_THREAD_PRIORITY, 10); if (tid2 != RT_NULL) { rt_thread_startup(tid2); } else { goto __exit; } tid3 = rt_thread_create("mb_msg_get", mb_msg_get, RT_NULL, 2048, 13, 10); if (tid3 != RT_NULL) { rt_thread_startup(tid3); } else { goto __exit; } is_init = 1; return RT_EOK;//退出__exit: if (tid1) rt_thread_delete(tid1); if (tid2) rt_thread_delete(tid2); if (tid3) rt_thread_delete(tid3); return -RT_ERROR;}//导出命令行MSH_CMD_EXPORT(TDM_TMD_modbus, run a TDM_DTECT sample);//开机启动//INIT_APP_EXPORT(TDM_TMD_modbus);
读的是0606H（1542）的数据,设置此处 master holding regs numbers 为2000,仍然报同样错误；设置为4000后可在0606H处正常获取slave数据。
问此处的计算方式是如何？
这个具体看下代码实现吧。如果想随意的读取，可以使用 libmodbus，直接调用API，不必要设置那么大的数组存数据。
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