无法配置并连接Azure IoT Edge Modbus模块求助排查

我正尝试搭建一个模拟场景，让IoT Edge设备接收来自设备的Modbus over IP数据并发送至IoT Hub。

已完成以下操作：

• 通过X509自签名认证完成IoT Edge设备部署
• 添加Azure Marketplace提供的Modbus模块
• 修改模块孪生标识，添加SlaveConfig配置：

"SlaveConfigs": {
    "Slave01": {
        "SlaveConnection": "localhost",
        "HwId": "SimulatedDevice-01",
        "Operations": {
            "Op01": {
                "PollingInterval": "1000",
                "UnitId": "1",
                "StartAddress": "0",
                "Count": "2",
                "DisplayName": "SensorData"
            }
        }
    }
},
"PublishInterval": "2000"

但查看Modbus模块日志时出现错误：

Desired property change:
{"properties":{"desired":{"PublishInterval":"2000","SlaveConfigs":{"Slave01":{"SlaveConnection":"localhost","HwId":"SimulatedDevice-01","Operations":{"Op01":{"PollingInterval":"1000","UnitId":"1","StartAddress":"0","Count":"2","DisplayName":"SensorData"}}}}}},"$version":5}
No configuration found in desired properties, look in local...
No configuration found in local file.
Saving reported properties: {"PublishInterval":null,"SlaveConfigs":null}
IoT Hub module client initialized.
Desired property change:
{"properties":{"desired":{"SlaveConfigs":{"Slave01":{"SlaveConnection":"localhost","HwId":"SimulatedDevice-01","Operations":{"Op01":{"PollingInterval":"1000","UnitId":"1","StartAddress":"0","Count":"2","DisplayName":"SensorData"}}}},"PublishInterval":"2000"}},"$version":5}
No configuration found in desired properties, look in local...
No configuration found in local file.
Saving reported properties: {"PublishInterval":null,"SlaveConfigs":null}

模拟Modbus服务器代码：

from pymodbus.server import StartTcpServer
from pymodbus.device import ModbusDeviceIdentification
from pymodbus.datastore import ModbusSequentialDataBlock
from pymodbus.datastore import ModbusSlaveContext, ModbusServerContext
 
import random
 
# Create a data block initialized with two values
block = ModbusSequentialDataBlock(0, [random.randint(20, 25), random.randint(30, 40)])
 
# Create a slave context with the data block
slaves = {
    0x01: ModbusSlaveContext(di=block, co=block, hr=block, ir=block)
}
context = ModbusServerContext(slaves=slaves, single=True)
 
# Create a Modbus device identification
identity = ModbusDeviceIdentification()
identity.VendorName = 'Mdb'
identity.ProductCode = 'Modbus Server'
identity.VendorUrl = 'http://github.com/username/repo'
identity.ProductName = 'Pymodbus Server'
identity.ModelName = 'Pymodbus Server'
identity.MajorMinorRevision = '1.0'
 
# Start the Modbus TCP server
StartTcpServer(context=context, identity=identity, address=('localhost', 502))

已尝试按「启动模拟服务器→启动IoT Edge设备」的顺序操作，但问题依旧，求排查方向。

1. 修正模块孪生配置的层级结构 #

Azure IoT Edge Modbus模块的配置必须嵌套在ModbusMaster节点下，你的当前配置直接将SlaveConfigs和PublishInterval放在desired根节点，模块无法识别。正确配置结构如下：

"properties": {
    "desired": {
        "ModbusMaster": {
            "SlaveConfigs": {
                "Slave01": {
                    "SlaveConnection": "localhost",
                    "HwId": "SimulatedDevice-01",
                    "Operations": {
                        "Op01": {
                            "PollingInterval": "1000",
                            "UnitId": "1",
                            "StartAddress": "0",
                            "Count": "2",
                            "DisplayName": "SensorData",
                            "FunctionCode": "3"
                        }
                    }
                }
            },
            "PublishInterval": "2000"
        }
    }
}

• 必须添加ModbusMaster父节点，这是模块识别配置的核心要求
• 每个操作需明确指定FunctionCode（比如读保持寄存器用3，读离散输入用2），你的模拟服务器给所有寄存器块复用了同一数据块，建议指定FunctionCode": "3"

2. 修正SlaveConnection地址 #

如果模拟Modbus服务器运行在IoT Edge设备的宿主机上，而Modbus模块运行在容器内，localhost在容器内指向容器自身，无法访问宿主机服务，需替换为：

• Linux/Windows系统：host.docker.internal（Docker Desktop环境）或宿主机的实际IP地址

3. 确保模拟服务器可被访问 #

修改模拟服务器代码，将绑定地址从localhost改为0.0.0.0，允许所有网卡访问：

StartTcpServer(context=context, identity=identity, address=('0.0.0.0', 502))

同时可在IoT Edge设备上执行以下命令测试连通性：

# 进入Modbus模块容器
docker exec -it <modbus-module-container-name> bash
# 测试Modbus服务器连接
telnet <host-ip> 502

4. 检查模块部署的端口配置 #

确保Modbus模块部署时，容器网络可访问宿主机的502端口。无需额外映射端口到外部，但需确认容器和宿主机处于同一网络环境（默认bridge网络即可）。

内容的提问来源于stack exchange，提问作者Whey