Use the Manage Topic to Stop a Device
Notes:
- When publishing structured data such as JSON, you must convert to a byte array (string) first. To do this in a flow, you can use the json node.
The Manage topic allows you to control the status of a DeviceHub device.
Video
User Scenario
You'd like to remotely disconnect a PLC from Litmus Edge.
Set Up and Use the Manage Topic
To set up and use the Manage topic:
- Follow the steps to Connect a Device. For this user scenario, a Simulator Generator device is used.
- Navigate to DeviceHub.
In the Generator device tile, click the Display Copy Options icon and select the Manage topic. This will copy the Manage status topic. You will refer to this topic later on.
Copy the manage topic- Navigate to Flows Manager.
For a Flows Manager, click the Go To Flow Definition icon. The Flow canvas opens in a new browser tab.
Go To Flow Definition iconOn the Flow canvas, copy the DataHub Publish node and inject node onto the canvas. Then, connect the two nodes.
The nodes needed for the manage topic- Double-click the DataHub Publish node.
- In the Topic field, paste the Manage topic you copied in step 3.
- If needed, configure the Datahub Publish connection. See the Step 3: Configure Connector Nodes section in Create a Flow to learn more.
- Click Done.
- Double-click the inject node. The Edit inject node dialog box displays.
For msg.payload, select string.
Select a string payloadFor msg.payload, enter {"command" : "stop"}.
Command to stop device- Click Done, and then click Deploy.
Click the inject button. This triggers the payload message you configured for the node.
The inject buttonReturn to the Litmus Edge browser window and navigate to DeviceHub. The device now shows a Stopped status.
Stopped status
To restart the device, you can use the following command: {"command" : "start"}.