Example 46: Modbus stepper motor control

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Example 46: Modbus stepper motor control

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Hardware purpose, wiring requirements, and firmware edition notes.
Peripheral configuration fields and JSON examples.
Validation steps, PeriphExec linkage, and field-operation notes.

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示例46:Modbus 步进电机控制

实验概述

通过 Modbus RTU 协议控制 RS485 步进电机驱动器，实现远程精确定位、速度调节和方向控制。适用于工业自动化、智能农业（卷帘/灌溉阀门）、精密定位等场景。

硬件接线

RS485 通信接线

ESP32 引脚	TTL转RS485模块	说明
GPIO 16	TXD	串口发送
GPIO 17	RXD	串口接收
GPIO 4（可选）	DE/RE	方向控制
3.3V	VCC	电源
GND	GND	地

RS485 到步进电机驱动器

RS485 模块	步进电机驱动器	说明
A+	RS485-A	差分信号正
B-	RS485-B	差分信号负

步进电机驱动器到电机

驱动器	步进电机	说明
A+	A 相正	电机线圈 A
A-	A 相负	电机线圈 A
B+	B 相正	电机线圈 B
B-	B 相负	电机线圈 B
VCC	外部电源	12-48V DC

步进电机驱动器（如 DM542、TB6600 RS485 版）需独立供电，电压根据电机型号选择。

JSON 配置示例

状态读取配置

{
  "id": "modbus_stepper",
  "name": "Modbus步进电机",
  "type": 1,
  "enabled": false,
  "pins": [16, 17],
  "params": {
    "baudRate": 9600,
    "dataBits": 8,
    "parity": "none",
    "stopBits": 1,
    "dePin": 4,
    "protocol": "modbus_rtu",
    "slaveId": 1,
    "function": 3,
    "startRegister": 0,
    "registerCount": 4,
    "interval": 2000,
    "dataMap": [
      { "register": 0, "name": "position", "scale": 1, "unit": "steps" },
      { "register": 1, "name": "speed", "scale": 1, "unit": "RPM" },
      { "register": 2, "name": "status", "scale": 1, "unit": "" },
      { "register": 3, "name": "error", "scale": 1, "unit": "" }
    ]
  }
}

控制写入配置

{
  "id": "modbus_stepper_ctrl",
  "name": "步进电机控制",
  "type": 1,
  "enabled": false,
  "pins": [16, 17],
  "params": {
    "protocol": "modbus_rtu",
    "slaveId": 1,
    "function": 6,
    "startRegister": 100,
    "registerCount": 3,
    "interval": 0,
    "controlMap": [
      { "register": 100, "name": "target_position", "min": -32768, "max": 32767 },
      { "register": 101, "name": "target_speed", "min": 0, "max": 3000 },
      { "register": 102, "name": "command", "values": { "start": 1, "stop": 2, "home": 3, "reset": 4 } }
    ]
  }
}

参数说明

参数	说明
slaveId	驱动器从站地址（拨码设置）
function	3=读寄存器，6=写单寄存器，16=写多寄存器
controlMap	控制寄存器映射，定义可写字段
target_position	目标位置（步数，带符号）
target_speed	目标转速（RPM）
command	运动命令：启动/停止/回零/复位

控制命令

通过 MQTT 发送控制：

[{"id": "modbus_stepper_ctrl", "value": "target_position:2048,target_speed:100,command:1"}]

target_position: 目标步数（正=正转，负=反转）
target_speed: 运行速度 RPM
command: 1=启动, 2=停止, 3=回零, 4=复位报警

滑台左右边界保护

若将 Modbus 步进电机用于直线滑台，建议在 Modbus 子设备配置中启用软限位：

{
  "name": "滑台步进电机",
  "sensorId": "slide_motor",
  "deviceType": "motor",
  "slaveAddress": 8,
  "motorRegs": [0, 1, 2, 5, 7],
  "motorMinPosition": 0,
  "motorMaxPosition": 10000,
  "motorCurrentPosition": 0,
  "motorMoveStep": 1600,
  "motorLastPulse": 1600,
  "enabled": true
}

motorMinPosition: 左边界，单位为步数。
motorMaxPosition: 右边界，单位为步数。
motorCurrentPosition: 当前估算位置，回零后通常设为 0。
motorMoveStep: 每次 forward/reverse 默认移动步数。
motorLastPulse: 最近一次 setPulse 脉冲数；规则未指定脉冲时会作为备用步长。

启用软限位后，系统会在发送正转/反转命令前计算下一位置。若会越过左右边界，会自动缩小本次脉冲数到边界内；若当前位置已经在边界，则拒绝动作。硬件限位开关和急停仍然必须保留，软件限位不能替代物理安全保护。

外设执行联动

定时往返运动

{
  "name": "步进电机往返",
  "enabled": true,
  "triggers": [
    { "type": "timer", "params": { "interval": 10000 } }
  ],
  "actions": [
    {
      "type": "modbus_write",
      "params": {
        "periphId": "modbus_stepper_ctrl",
        "register": 100,
        "value": 2048
      }
    },
    {
      "type": "modbus_write",
      "params": {
        "periphId": "modbus_stepper_ctrl",
        "register": 102,
        "value": 1
      }
    }
  ]
}

按键触发回零

{
  "name": "按键回零",
  "enabled": true,
  "triggers": [
    {
      "type": "event",
      "params": { "periphId": "btn1", "event": "pressed" }
    }
  ],
  "actions": [
    {
      "type": "modbus_write",
      "params": {
        "periphId": "modbus_stepper_ctrl",
        "register": 102,
        "value": 3
      }
    }
  ]
}

温度联动（配合温控卷帘）

{
  "name": "高温开卷帘",
  "enabled": true,
  "triggers": [
    {
      "type": "poll",
      "params": {
        "periphId": "modbus_th",
        "field": "temperature",
        "operator": ">",
        "threshold": 32
      }
    }
  ],
  "actions": [
    {
      "type": "modbus_write",
      "params": { "periphId": "modbus_stepper_ctrl", "register": 100, "value": 5000 }
    },
    {
      "type": "modbus_write",
      "params": { "periphId": "modbus_stepper_ctrl", "register": 102, "value": 1 }
    }
  ]
}

注意事项

驱动器选型：确保驱动器支持 RS485 Modbus RTU 协议（非脉冲/方向型）
寄存器地址：不同品牌驱动器寄存器定义不同，务必查阅对应手册
运动安全：建议添加限位开关，防止过行程损坏机械结构
急停功能：硬件急停按钮必不可少，不能仅依赖软件停止
通信超时：步进电机执行耗时较长，轮询 interval 建议 ≥ 2000ms
电源独立：电机驱动电源与 ESP32 电源完全隔离，共地即可