AN14 Reading the digital inputs of a STE2 device

The script runs in the NETIO smart sockets device and every second reads the xml file with the status of the STE2 device. According to digital input states (0/1), electrical sockets of the NETIO device are switched on/off. In case of network or power failure, the output is set to a pre-defined state (0/1). When the connection is re-established, the script continues to run.

Digital inputs (DI) of the STE2 can be activated with any mechanical switch (dry contact) or a relay contact. 

STE2 Web Thermometer

• Recommended third-party device
• Manufacturer: HW group s.r.o. (Czech Republic)
• Product: STE2: WiFi and Ethernet Thermometer with Digital Inputs
• WiFi temperature and humidity sensor with two digital inputs for dry contacts. Connects to the network via WiFi or Ethernet with PoE (802.3af) support. STE2 is supplied with a power adapter and a temperature probe. STE2 wifi and ethernet thermometer supports SNMP. STE2 online thermometer can be connected to the SensDesk online portal or to a SMS gateway.

Supported devices: 

NETIO 4All, NETIO PowerPDU 4C, NETIO 4

Communication between NETIO 4x and STE2

1) NETIO 4x sends a CGI request to STE2

2) STE2 sends a xml response

3) NETIO 4x parses the required value from the xml response, compares it with the variable and switches the output if needed

Example of the STE2 xml response:

• After connecting STE2 to your network, find its IP address using the HWg-Config utility.

Creating the rule

To create and run the Lua script, do the following:

1) In the Actions section of NETIO 4 web administration, click Create Rule to add a rule.

------------Section 1------------
local output = 2 -- select output number (1 - 4)
local validValue = 1 -- select state for closed DI input
local invalidState = 0 -- select state for invalid values
local interval = 1 -- choose the period between controls (seconds)
local sensorID = 2 -- sensor ID
local ipSTE2 = "192.168.101.165" -- IP of your device
---------End of Section 1---------

local value = 0 -- internal variable, do not change

function call() -- send request on STE2
  cgiGet{url="https://" .. ipSTE2 .. "/values.xml", callback=getTemperature}
end

function control() -- check value
  --devices.system.SetOut{output=4, value=false}
  if value == 0 then
    devices.system.SetOut{output=output, value=1-validValue}
  else
    devices.system.SetOut{output=output, value=validValue}
  end
  delay(interval,function() call() end)
end


function getTemperature(o)
   if o.result == 0 then
     local myxml = o.buffer
     if xml.check(myxml) then
       local parsed = xml.parse(myxml,xml.STRIP_PREFIXES)
       local nmbOfSensors = # (parsed.get("BinaryInSet").children())
       local sensor = parsed.get("BinaryInSet","Entry")
       for i=1,nmbOfSensors do 
         idVal = tonumber(sensor.get("ID").text)
         if sensorID == idVal then 
           sensor = sensor.get("Value").text
           value = tonumber(sensor)
           control()
           return
         else 
           sensor = sensor.next
         end
       end
       logf("Can´t find sensor with ID: %d, shutting down protocol", sensorID)
     else
       log("Invalid XML, next attempt in 10s.")
  	   devices.system.SetOut{output=output, value=invalidState}
  	   --devices.system.SetOut{output=4, value=true}
  	   delay(10, function() call() end)
     end
   else
     log(string.format("CGI get failed with error %d: %s. Next attempt in 10s.", o.result, o.errorInfo))
     devices.system.SetOut{output=output, value=invalidState}
     --devices.system.SetOut{output=4, value=true}
     delay(10, function() call() end)
   end
end

call()

Method of operation 

• The temperature and humidity values measured by the STE2 and its digital input states are available in its web interface. There they can be checked. 
• NETIO sends an http request and STE2 sends back a values.xml file with sensor values and digital input states. 
• The Lua script looks for the configured input ID and processes its value. 
• The Lua script parses the state of the digital input and sets the output accordingly.
• The cycle periodically repeats.

Setting the variables

• output
• Specifies the socket to control.
• Example – to control socket 1: output = 1

• validValue
• Specifies the output state to set when the digital input is closed.
• To switch off the output when the input is closed, set validValue = 0; to switch it on, set ValidValue = 1

• invalidState
• Specifies the socket state to set if there is an error (e.g. STE2 power failure, network failure etc.).
• To switch off the output in such cases, set invalidState = 0; to switch it on, set invalidState = 1.

• sensorID
• Specifies the ID of the input to monitor (see above).
• Possible values are 1 and 2.
• Example – to monitor the input with ID 1: sensorID = 1

• ipSTE2
• Specifies the IP address of the STE2 device. The IP address can be found with HWg-Config (see above).
• It is a string, so it has to be in double quotes.
• If the STE2 device uses a HTTP Port different from the default 80, the port needs to be specified after a colon.
• Example (port 80): ipSTE2 = "192.168.101.165"
• Example (port 8080): ipSTE2 = "192.168.101.165:8080"

STE2 web thermometer with LAN or WiFi connectivity is produced by HW group s.r.o. (Czech Republic).

• For more information, see www.HW-group.com / STE2.
• NETIO products company does not sell these devices; this example only shows our customers a potential use of NETIO products

The green digital inputs are used to connect a button or a switch. These inputs can be connected to “dry contacts” (voltage-free contacts) such as mechanical buttons or switches; HW group calls such devices  “detectors”. NETIO 4x can react to a digital input being closed/opened, as shown in this Application Note. 

The manufacturer includes a temperature probe in the STE2 package. A humidity sensor can be also connected to the sensor port. NETIO can work with data from these sensors as well, as shown in NETIO AN13. 

For reacting to STE2 failures, see NETIO AN09 – the network presence of the device can be checked by sending PING requests to its IP address and a NETIO socket can be switched on if there is no response. 

This Application Note is compatible with:

	NETIO 4 NETIO 4 is smart power socket (smart power strip) with four 230V/8A sockets, connected to LAN and WiFi. Each of the four power sockets can be individually switched on/off using various M2M API protocols. NETIO 4 is a unique product designed for IT, industry, smart homes, multimedia installations and other applications. Use the product whenever you need 230V sockets controlled by a mobile app, by a computer program (via M2M API) or by a custom script (Lua), and featuring a timer (Scheduler) or auto reboot functionality (IP WatchDog).  More about NETIO 4
	NETIO 4All NETIO 4All is a PDU module featuring four 230V/8A power sockets with consumption metering for each socket as well as LAN and WiFi connectivity. Each of the four sockets can be individually switched on/off over the Web or using various M2M API protocols. Electricity consumption (A, W, kWh) can be measured at each power socket. NETIO 4All smart sockets are designed for remote measurement and control of electrical sockets. Use the product whenever you need 230V sockets controlled by a mobile app, by a computer program (via M2M API) or by a custom script (Lua) that runs directly in the NETIO 4All smart socket device. More about NETIO 4All
	NETIO PowerPDU 4C NETIO PowerPDU 4C is a small 110/230V PDU (Power Distribution Unit). Each of the four IEC-320 C13 outlets can be independently controlled (On / Off / Reset / Toggle). Electrical parameters (A, W, kWh, TPF, V, Hz) are measured with high accuracy at each outlet. The device features two LAN ports (and a built-in Ethernet switch) for connecting to a LAN. Each power output supports ZCS (Zero Current Switching) to protect the connected equipment. More about NETIO PowerPDU 4C