Communication

A critical step during commissioning is to verify that the controller has successfully established communication with all devices in the microgrid. This is essential for running the application.

There are several methods to check the connection between the controller and the devices. One method is to use a tool called MQTT Explorer to monitor the devices in the microgrid. The state of each device will indicate whether it is operational or has a communication fault.

Another method is to run a custom NATS application. This application retrieves measurements from the controller and can display the device ID and state of each device, providing insight into their operational state.

Both approaches are effective. For more details on using MQTT Explorer or running the custom application, refer to the information below.

Get Device State

To determine whether the controller has successfully connected to the devices in the microgrid, it is necessary to check the state of each device. This can be accomplished through either MQTT Explorer or by running a custom NATS application. Detailed instructions for retrieving the device states using both methods are provided below.

Show MQTT Explorer

1. Download and Install MQTT Explorer

   • Go to the Website: Open your browser and visit mqtt-explorer.com.
   • Download the App: Select the version for your OS and download it.
   • Install: Run the downloaded file and follow the installation prompts.
2. Launch MQTT Explorer

   • Open the App: Find MQTT Explorer in your applications and launch it.
3. Create a New MQTT Connection

   • Add a Connection: Click the + button to create a new connection.
   • Enter Details:
     • Name: Give your connection a descriptive name.
     • Protocol: Choose mqtt://.
     • Host: Enter your controller’s IP address.
     • Port: Set to 1883.
     • Leave Username/Password Blank.
     • Save: Click Save to store the connection.
4. Connect to the Broker

   • Connect: Select your connection from the sidebar and click Connect.
   • Verify: Confirm the connection status and check for active topics.

   If the MQTT Explorer application cannot establish a connection to the host (i.e., the controller), please verify the configuration settings in the controller’s config.json file. You can find this file in the /etc folder of the ppl-base repository. Ensure that the MQTT broker is assigned the correct IP address of the controller.

   For more details, please refer to the Configure Config File section on the Configure PPL Files page.

   If the connection is successful, MQTT Explorer will start listening for incoming messages. The controller will update the MQTT messages, including device measurements, every 5 seconds.

5. Check the Device’s State

   • Select a topic from the device list on the left.
   • Choose the first (and only) entry from the dropdown menu.
   • The device measurements will appear on the right.
   • Look for the state parameter within the measurements.

Show Custom NATS Application

To run a custom NATS application, please refer to the Write Custom Applications page. It explains how to install the necessary libraries, update the IP address and NATS credentials, and execute the application.

To retrieve the state of each device, run the following application found in the examples folder: device-states.py. Execute the application in the Terminal of your code editor (VS Code) using the following command:

python device-states.py

This command will display the devices in the microgrid application along with their states.

When checking the device’s state, it is important to verify the devices that communicate over Modbus TCP/IP. If the connection between the controller and the Modbus device is not established, the state will display communicationFault. This indicates that the controller was unable to establish a connection, and further troubleshooting is needed.

Resolve Communication Failure

Below are the steps to help resolve the communication failure:

1. Ensure the Modbus device is powered on
2. Verify the Modbus device is connected to the network switch

   Verify that the Modbus device is connected to the network switch of the PPL controller using Ethernet cables. Check the Ethernet cable connections at both ends to ensure they are plugged in correctly.

3. Check the network settings on the Modbus device

   Check the network settings on the Modbus device to ensure the IP address, subnet mask, and gateway are correctly configured.

4. Review the device settings in the devices.json file

   Review the device settings in the devices.json file, located in the /etc folder in the ppl-base repository:

   • Ensure ipAddress is set correctly
   • Ensure slaveId is set correctly
   • Ensure port is set correctly

   Compare the IP address, slave ID, and port settings on the Modbus device with those in the devices.json file, and update them as needed.

   For more information on modifying device settings and uploading them to the controller, see the Configure PPL Files page.

5. Confirm only one controller is connected to the Modbus device

   Confirm that there is no other controller currently connected to the device (some devices only support a single Modbus client connection).

6. Check if the device’s address map includes a communicationCheck register

   Check if the device’s address map includes a communicationCheck register. For instructions on adding Modbus registers to the address map, refer to the Configure PPL Files page.

What’s next?

If none of the above steps resolve the connection issue, retrieve the log files from the controller. Refer to the next section on how to retrieve the log files. If you need assistance, contact PPL Support by emailing [e-mail].