TinyModbus

// 简化示例

static struct modbus_s slave;
static uint8_t mb_buffer[256];

static struct object_item_s basic_object_maps[] =
{
    {OBJID_BASIC_VENDOR_NAME,         "Vendor name"},
    {OBJID_BASIC_PRODUCT_CODE,        "A0000000001"},
    {OBJID_BASIC_SOFTWARE_VERSION,    "0.1"},
    {OBJID_REGULAR_VENDOR_URL,        "www.example.com"},
    {OBJID_REGULAR_PRODUCT_NAME,      "Product name"},
    {OBJID_REGULAR_MODEL_NAME,        "Model name"},
    {OBJID_REGULAR_USER_APP_NAME,     "User application nam"},
    {OBJID_REGULAR_DATE,              __DATE__},
    {OBJID_REGULAR_HARDWARE_VERSION,  "0.1"}
};

static uint8_t  coil[10]           = {0, 1, 0, 1, 0, 0, 0, 0, 0, 0};
static uint8_t  discrete_input[10] = {0, 1, 0, 1, 0, 0, 0, 0, 0, 0};
static uint16_t input_regs[10]     = {0, 10, 20, 30, 40, 50, 60, 70, 80, 90};
static uint16_t hold_regs[10]      = {0, 100, 200, 300, 400, 500, 600, 700, 800, 900};

static int read_hold_regs(uint8_t *buffer, uint16_t index, uint16_t length)
{
    LOG_D("Read holding register: %d ~ %d", 40001 + index, 40000 + index + length);

    rt_mutex_take(&mb_lock, RT_WAITING_FOREVER);

    for (int i = 0; i < length; i++)
    {
        *buffer++ = (uint8_t)(hold_regs[index + i] >> 8);
        *buffer++ = (uint8_t)(hold_regs[index + i] & 0xFF);
    }

    rt_mutex_release(&mb_lock);

    return MB_EX_NONE;
}

static int write_hold_regs(const uint8_t *buffer, uint16_t index, uint16_t length)
{
    LOG_D("Write holding register: %d ~ %d", 40001 + index, 40000 + index + length);

    // 1. 拷贝数据至缓存
    // 2. 校验数据

    rt_mutex_take(&mb_lock, RT_WAITING_FOREVER);

    for (int i = 0; i < length; i++)
    {
        hold_regs[index + i]  = *buffer++ << 8;
        hold_regs[index + i] |= *buffer++;
    }

    rt_mutex_release(&mb_lock);

    return MB_EX_NONE;
}

static struct modbus_slave_util_s hold_util = {0, sizeof(hold_regs),  &read_hold_regs,      &write_hold_regs};

int main(void)
{
    /* 初始化 Modbus slave */

    mb_slave_init(&slave, MB_BACKEND_TYPE_RTU);
    mb_slave_set_addr(&slave, 1);
    mb_slave_set_dev_info(&slave, &basic_object_maps[0], sizeof(basic_object_maps) / sizeof(struct object_item_s));

    /* 注册寄存器回调函数 */

    mb_slave_set_util(&slave, MB_REG_TYPE_COIL,            &coil_util);
    mb_slave_set_util(&slave, MB_REG_TYPE_DISCRETE_INPUTS, &discrete_input_util);
    mb_slave_set_util(&slave, MB_REG_TYPE_INPUT_REGS,      &input_util);
    mb_slave_set_util(&slave, MB_REG_TYPE_HOLD_REGS,       &hold_util);

    for (;;)
    {
        uint16_t len = serial_receive(serial, mb_buffer, sizeof(mb_buffer), 20);

        len = mb_slave_handle(&slave, mb_buffer, len);

        if (len > 0)
        {
            serial_transfer(serial, mb_buffer, len);
        }
    }
}

Code (inc. data)   RO Data    RW Data    ZI Data      Debug   Object Name
1356        308        120        184        360      12486   modbus_rtu_slave.o
  56          8        512          0          0       1207   mb_crc.o
 108          0          0         20          0       5185   mb_rtu.o
2022        292         72          0          0      13359   tinymodbus.o