AN30 Node-RED example of REST JSON communication with NETIO 4x

Supported devices: NETIO 4All, NETIO PowerPDU 4C, NETIO 4, PowerCable REST, PowerBOX 3Px, PowerPDU 4PS, PowerDIN 4Pz, PowerBOX 4Kx, PowerPDU 8QS

The AN30 Application Note shows two examples of working with NETIO smart outlets using http transfer of netio.json files.

• The first example demonstrates the measurement functions and options, as well as the control of one outlet (Output 1).
• The second example, AN30v2, is a simplified version that can serve as a template for your Node-RED projects.

The first AN30 Node-RED flow demonstrates the control of output no. 1 from the Dashboard that runs in the Node-RED environment. Five buttons displayed in the Dashboard call the five possible actions that can be performed with the output (off, on, short off (restart), short on, toggle). The netio.json file is uploaded to the http server of the smart socket device using http POST.

The dashboard periodically displays the states of all outputs as well as the measured values from the NETIO 4x device (current, voltage, total load), as long as the device is capable of measuring them. The reading of the output states and measured parameters takes place by downloading the netio.json file every second from the http server of the NETIO smart socket device using http GET.

Details about the M2M protocol: Description of the http(s) REST JSON protocol

Node-RED

The Node-RED environment can run on a PC, a Raspberry Pi, in a cloud (MS Azure, IBM) and so on.

Node-RED is very popular, so we have prepared more examples:

• AN29: Node-RED example of URL API communication with NETIO 4x 
• AN30: Node-RED example of REST JSON communication with NETIO 4x
• AN31: Node-RED example of XML communication with NETIO 4x
• AN32: Node-RED example of Modbus/TCP communication with NETIO 4x / PowerCable

Flow (Node-RED script) for AN30:

NETIO REST JSON http(s) protocol

The current outlet state when reading (0 / 1) is in the State variable. This variable is read/write, as long as the Action variable is omitted or set to 6.

If the Action variable in the uploaded netio.json file is set to a value different than 6, it takes priority and the value in the State variable is ignored.

Actions applicable to each output (electrical socket)

In all M2M protocols, NETIO power sockets use the same actions that can be applied to individual outputs. For example, a Toggle or Short Off action can be written to any output.
 

However, the Action variable can only be used for writing values, it cannot be used to read the current outlet state.

•  0 = Output switched off (Off)
•  1 = Output switched on (On)
•  2 = Output switched off for a short time (short Off)
•  3 = Output switched on for a short time (short On)
•  4 = Output switched from one state to the other (toggle)
•  5 = Output state unchanged (no change)
•  6 = Ignored

The value of 6 in the action tag means that the action is ignored and the outlet state is set according to the “State” variable (allowed values are 0 and 1 only). See the M2M JSON documentation.

Example – JSON file to toggle the output no. 1:

{

 "Outputs": [{

  "ID": 1,

  "Action": 4

 }]

}

Configuring NETIO 4x

In the M2M API Protocols - JSON API section of the web interface, enable URL JSON API.

Set the Username and Password for READ-WRITE access.

READ-WRITE credentials allow both reading and writing. The same READ-WRITE credentials can be used in both HTTP Request nodes (POST and GET).

Click Save Changes. After saving the changes, the device restarts (about 1 minute).

Importing the AN30 flow to node-RED

In the menu, select Import -> Clipboard.

Then, copy the text to the indicated field and click Import.

AN30 primarily consists of two parts: POST and GET.

POST: Writing to O1

• Five buttons created in the Dashboard in the Flow are displayed in the Dashboard.
• After clicking the Output 1 = ON button in the Dashboard, the payload is set to the netio.json file that specifies the output and the action (defined for each of the buttons).
• The HTTP Request (POST) node sends the netio.json file as a request to an IP address.
• The server response (status) is returned as the output.
• The Msg.payload node displays the result from HTTP Request (POST).

GET: Reading from O1 – O4

• The 1 Second Repeat node activates, with a period of one second, the HTTP Request (GET) node, which in turn sends netio.json as a GET request and returns a complete JSON file with the socket status as received from the server.
• The JSON Parse node transforms the JSON file from the HTTP Request (GET) node to a JSON Object so that it is possible to manipulate the properties in the JSON file.
• The Function node takes individual parts of the JSON object and transforms them into properties of a msg object for later use.
• The Current Chart node sets msg.payload to the msg.TotalCurrent property of the msg object, because the subsequent Current Chart (Device) node can only display the msg.payload value.
• Various output nodes then follow in order to display selected properties of the msg object, as taken from the JSON object, in the Dashboard. 

The msg object and msg.payload

For a simple and concise explanation, see here:

Example of a netio.json file:

HTTP Request (GET)

This node sends a HTTP Request (GET) and returns the status response.

Debug node

Displays the msg.payload.

By default, it is set to msg.payload, and therefore it displays the server response in Node-RED.

Inject node

Every second, this node activates the HTTP Request node that sends a GET request. As a result, the values in the Dashboard are updated with a period of one second.

Gauge node

This node adds a gauge widget to the Dashboard.

In AN30, each gauge visualizes one property of the msg object: voltage [V], curent [A], frequency [Hz] and the overall True Power Factor (TPF).

The code is divided into four sections:

• Assigning values from the JSON object to the individual properties of the msg object

If the NETIO 4x device does not support the measurement of global values, Node-RED would display errors because this function would not find the respective property, e.g. msg.payload.GlobalMeasure.Voltage, since it would not be present in the JSON object. In this case, the property of the msg object, e.g. msg.Voltage, is set to 0 and the error is caught.

• Assigning output state values

Link node

Link in and link out nodes work like a tunnel. The msg.payload arrives into the link in node and goes out of the link out node.

In AN30, this is used to make the flow a bit clearer.

The menu in the Dashboard includes a link to NETIO products website:

The Node-RED configuration is specified in a JSON structure and can be pasted via the clipboard.

 AN30 v2: Node-RED flow ke stažení

Supported devices

• NETIO 4
• NETIO 4All
• PowerPDU 4C
• PowerPDU 4PS
• PowerBOX 3Px
• PowerDIN 4Pz
• PowerCable REST 101x