1. Introduction

Hardwire is an Internet of Things platform that allows you to create smart connected objects. Data can be collected from many different sources, using different software libraries or APIs:

• Any Arduino or compatible device
• Raspberry PI or similars
• Industrial PLC through IEC libraries
• Any device running Android
• Linux operative system
• In general any embedded device

Data collected by Hardwire IoT platform can be accessed at any time through two different communication channels:

• Standard Rest APIs
• A push channel based on a secured WebSocket

The goal of this documentation is to provide a full description of how to integrate third party applications with Hardwire platform, how to send sensor data and how to access collected data through APIs and WebSocket. This document contains technical information, and it’s therefore intended for software developers.

Getting started

In order to start using Hardwire you must be a registered user. You can sign up at any time for a free plan following this URL: .

https://www.hardwire.io/en/iot/signup

If you are interested to use Rest API you can apply for an authorization token writing something about your application at this address:

hardwire@imotion.it

General concepts

CloudMonitor APIs and WebSocket make use of generic concepts and entities:

• Sensor: a sensor is the abstract entity that represents the target of each datum sent to the platform. A sensor can be anything, like a room, an electronic device or a generic object.
• Plant : a plant is typically an entity that contains or or more sensors. Within a plant, sensors are arranged in a tree structure, where plant is usually considered the father of any other element.
• Data logger : it’s the electronic device that collects and sends data to the platform. Every data logger is associated to a single plant but can send data for many different sensors.
• Variable : it’s what we usually call “measure”. It’s always associated to a sensor, and in general it represents the value of a measure at a specific time. Variables and alarms are collected by data logger and sent to the platform. A variable usually has an attribute that identifies its type. See appendix for list of variable types.
• Alarm : alarm is a generic and abnormal situation detected by a data logger. It’s usually sent to the platform by a data logger. Alarms don’t have a status but they just represent something happened in a specific moment.
• Event : events are objects generated only by the platform when a specific situation occurs. Any user can configure one or more situation to be monitored. Once an event occurs, the platform may generate a notification. An example of event configuration is “create an event when temperature goes below 12 degrees”.
• Notification : a notification has the goal to warn a user when an event occurs. Email is a typical example of notification althought there're other different methods.


2. API Reference

The most important method to integrate Hardwire with third party applications is using standard Rest APIs. Below a list of all the public APIs available.

Data format

Data contained in both APIs and WebSocket are represented using the standard JSON format. Also request parameters and any kind of output are formatted in JSON.

Authentication

Hardwire offers applications the ability to issue authenticated requests on behalf of the application itself (as opposed to on behalf of a specific user). The authentication process has been implemented following the OAuth 2 specification.

Each application that wants to use Hardwire APIs must be recognized and identified by the platform and needs an authentication token. Authentication tokens are strictly connected with a specific user of the platform, therefore a token grants access only to data and information related to that specific user.

Authentication token must be specified in any HTTP request, following the OAauth 2 standard:

"Authorization: Bearer <TOKEN>"

If you want to apply for an API token, just write us an email to: hardwire@imotion.it

Rate limit

Rate limiting of the API is primarily considered on a IP basis. Rate limits are calculated into 15 minute intervals. There’s a standard bucket of 60 calls every 15 minutes.

In case you need real-time data, a WebSocket is available.

Response codes

Hardwire platform can use different HTTP response codes, depending on the result of the operation.

HTTP response	Description
200 Ok	Request completed successfully
400 Malformed Request	Malformed request: check parameters or endpoint
401 Unauthorized	The authentication token is not allowed to access the resource specified on the request
403 Validation Error	Returned mainly during the creation of a resource, it specifies that some fields contains invalid data (like an invalid email)
404 Not Found	Record not found
500 Internal Server Error	Internal server error is a temporary response code due to an extraordinary condition. Retry later or contact the technical support if this error persists

API: Plant list

Useful to retrieve the list of plants. The request has no parameter.

URL	https://app.hardwire.io/api/v1/plant_list
TYPE	HTTP GET

Response format

{
  "plants": [
    {
      “id”: 32,
      “name”: “MyPlant1”,
  }, {
  “id”: 44,
      “name”: “MyPlant2”
    },
] }


The response is a JSON object that contains an array with a list of “plant” objects.

Field	Type	Always present	Description
id	Integer	yes	Unique ID of the object
name	String	yes	Plant name

API: Sensor map

This API returns the structure and relation of each sensor that composes a plant. The request has no parameter.

URL	https://app.hardwire.io/api/v1/sensor_map/<PLANT_ID>
TYPE	HTTP GET

Request parameters

The only parameter accepted by the request is specified as part of the endpoint URL.

Field	Type	Required	Description
PLANT_ID	Integer	yes	Plant ID. You can get it from Plant List API.

Response format

{
  "sensors": [{
      "id": "330",
      "name": "MySensor1",
      "sensor_id": 0,
      "icon": "remote_control",
      "children": [{
          "id": "331",
          "name": "MySensor2",
          "sensor_id": 1,
          "icon": "sun",
          "children": [
            {
              "id": "332",
              "name": "MySensor3",
              "sensor_id": 2,
              "icon": "air_conditioning_indoor",
              "children": []
			}]
      }] 
   }] 
}


The response is a JSON object that represents a tree of sensors and children. Each sensor object has these attributes.

Field	Type	Always present	Description
id	Integer	yes	Unique sensor id. Assigned automatically by the platform.
name	String	yes	Sensor name
sensor_id	Integer	yes	Unique within a plant. Assigned by the user.
icon	String	yes	A string that represents the icons assigned to this sensor.
children	Array	yes	An array of sensor objects, children of the current one.

There’s an important difference between “id” and “sensor_id”. The first one is auto-assigned by the platform every time you create a new sensor, while the second one is manually assigned from the user. The only exception is the first sensor of the tree that has always a fixed “sensor_id” set to 0.


API: Data history

This API returns historical data of a specific variable.

URL	https://app.hardwire.io/api/v1/history
TYPE	HTTP POST

Request parameters

{
  “sensor_id”: 32,
  “date”: “2014-12-17”,
  “var_type”: 34
}

The parameters must be sent into the body of the POST request as a JSON object:

Field	Type	Required	Description
sensor_id	Integer	yes	Unique ID of sensor. It can be obtained from the “id” field of the Sensor Map API. NOTE: Sensor Map API returns also a user defined sensor_id attribute. That value is only used by data loggers and it’s nothing in common with this parameter.
date	Date	yes	Date, in formato YYYY-MM-DD
var_type	Integer	yes	Identifier of the variable we’re requesting data. See appendix for all supported values.

Response format

{
  "sensor_id": "32",
  "date": "2014-12-17",
  "var_type": "34",
  "summary": {
    "sum": 12.60076878295,
    "count": 17,
    "min": 0.00033618172165006,
    "max": 1.7930368185043,
    "min_key": "1451431005",
    "max_key": “1451484793”,
  }, 
  "data": {
    "1451430105": 0.00084083323599771,
    "1451430165": 0.0021014518570155,
    "1451430225": 0.00092494185082614,
    "1451430285": 0.00075672467937693,
    "1451430345": 0.0010087979026139,
    "1451430405": 0.00092468928778544,
    "1451430465": 0.0014292144915089,
    "1451430526": 0.00058812863426283,
    "1451430585": 0.0009092777618207,
    "1451430645": 0.00084070692537352,
    "1451430705": 0.0014299730537459,
    "1451430765": 0.0013693266082555,
    "1451430825": 0.0016812877729535,
    "1451430885": 0.00067261612275615,
    "1451430945": 0.00058863376034424,
    "1451431005": 0.00033618172165006,
    "1451484793": 1.7930368185043
  } 
}

The response is a JSON object that contains the values of the variable on that specific interval.

Field	Type	Always present	Description
sensor_id	Integer	yes	Same value of request
date	Date	yes	Same value of request
var_type	Integer	yes	Same value of request
summary	Array	yes	A summary of the measures, count, min, max ...
data	Array	yes	An array of values in the format “timestamp” => “value”

API: Plant status

This API returns historical data of a specific variable.

URL	https://app.hardwire.io/api/v1/plant_status/<PLANT_ID>
TYPE	HTTP GET

Request parameters

The only parameter accepted by the request is specified as part of the endpoint URL.

Field	Type	Required	Description
PLANT_ID	Integer	yes	Plant ID. You can get it from Plant List API.

Response format

{
  "status": [{
    “var_type”: 32,
    “value”: 1.23,
    "sensor_id": 84,
    "timestamp": 1451486902
  }]
}

The response is a JSON object that contains an array of variables with these fields:

Field	Type	Always present	Description
var_type	Integer	yes	Id of the variable. It represents the type of variable. See appendix for all possibile values.
value	String	yes	Value of the variable
sensor_id	Integer	yes	Unique ID of sensor. Same value obtained from the “id” field of the Sensor Map API. NOTE: Sensor Map API returns also a user defined sensor_id attribute. That value is only used by data loggers and it’s nothing in common with this parameter.
timestamp	Integer	yes	Timestamp of the variable

API: Event list

This API returns a list of events generated from the platform for a specified plant. For real-time event acquisition use WebSocket instead of standard APIs.

URL	https://app.hardwire.io/api/v1/event_list
TYPE	HTTP POST

Request parameters

{
  “plant_id”: 32,
  “offset”: 200,
  “num_records”: 100
}

The parameters must be sent into the body of the POST request as a JSON object:

Field	Type	Required	Description
plant_id	Integer	yes	Plant ID. You can get it from Plant List API.
offset	Integer	no	Used for pagination, it skips the first “offset” elements. Default value is 0.
num_records	Integer	no	Number of records returned. Default value is 20. Maximum value 500.

Response format

{
  "events": [{
      “id”: 67933,
      “sensor_id”: 32,
      “event_type”: 3,
      "active": false,
      "description": “Temperature is below threshold of 23.5”,
      "timestamp": 1451486901
  }, {
      “id”: 67953,
      “sensor_id”: 18,
      “event_type”: 3,
      "active": true,
      "description": “Panic button pressed”,
      "timestamp": 1451484503
  }]
}

The response is a JSON object that contains an array of events with these attributes:

Field	Type	Always present	Description
id	Integer	yes	Unique id of the event.
sensor_id	Integer	yes	Id of the sensor that generated the event.
event_type	Integer	yes	Type of the event. See appendix for all possibile values.
active	Bool	yes	Whether event is still active or not.
description	String	yes	A description of the event.
timestamp	Integer	yes	The timestamp of the event.

Events are returned from the newest one.

API: Alarm list

This API returns a list of alarm collected by the platform for a specified plant. For real-time alarm acquisition use WebSocket instead of standard APIs.

URL	https://app.hardwire.io/api/v1/alarm_list
TYPE	HTTP POST

Request parameters

{
  “plant_id”: 32,
  “offset”: 200,
  “num_records”: 100
}

The parameters must be sent into the body of the POST request as a JSON object:

Field	Type	Required	Description
plant_id	Integer	yes	Plant ID. You can get it from Plant List API.
offset	Integer	no	Used for pagination, it skips the first “offset” elements. Default value is 0.
num_records	Integer	no	Number of records returned. Default value is 20. Maximum value 500.

Response format

{
  "alarms": [{
      “id”: 3288534,
      “sensor_id”: 32,
      “alarm_type”: 3,
      "description": “Internal data logger memory is full”,
      "timestamp": 1451486901
   }, {
      “id”: 3288554,
      “sensor_id”: 18,
      “alarm_type”: 3,
      "active": true,
      "description": “Panic button pressed”,
      "timestamp": 1451484503
   }]
}


The response is a JSON object that contains an array of alarms with these attributes:

Field	Type	Always present	Description
id	Integer	yes	Unique id of the alarm.
sensor_id	Integer	yes	Id of the sensor that generated the alarm.
alarm_type	Integer	yes	Type of the alarm. See appendix for all possibile values.
description	String	yes	A description of the alarm.
timestamp	Integer	yes	The timestamp of the alarm.

Alarm are returned from the newest one.

API: Send Command

This request sends a command to a specified device and returns the status of the command.

URL	https://app.hardwire.io/api/v1/send_command
TYPE	HTTP POST

Request parameters

{
  “plant_id”: 32,
  “command”: "SET_PWM_OUT_1",
  "parameter": "100"
}

The parameters must be sent into the body of the POST request as a JSON object:

Field	Type	Required	Description
plant_id	Integer	yes	Plant ID. You can get it from Plant List API.
command	String	yes	String of a specific command. See appendix for all possibile values.
parameters	String	no	Extra parameters to send together with the command.

Response format

{
  "command": {
    "id": 35,
    "status": "PEND"
  }
}

The response is a JSON object that contains the values of the command.

Field	Type	Always present	Description
id	Integer	yes	ID of the command.
status	String	yes	String for the result of the sending. Possible values: PEND   →   The command is pending SENT    →   The command was sent correctly CONF   →   The command is confirmed from the plant ERR     →   Error in sending the command from the server

If the command is not supported the response will be HTTP 400 code.

API: Command Status

This request returns the status of the specified command.

URL	https://app.hardwire.io/api/v1/command_status/<COMMAND_ID>
TYPE	HTTP GET

Request parameters

The only parameter accepted by the request is specified as part of the endpoint URL.

Field	Type	Required	Description
COMMAND_ID	Integer	yes	Command ID. You can get it from Send Command API.

Response format

{
  "command": {
    "id": 35,
    "status": "PEND"
  }
}

The response is a JSON object that contains the values of the command.

Field	Type	Always present	Description
id	Integer	yes	ID of the command.
status	String	yes	String for the result of the sending. Possible values: PEND   →   The command is pending SENT    →   The command was sent correctly CONF   →   The command is confirmed from the plant ERR     →   Error in sending the command from the server

If the command is not supported the response will be HTTP 400 code.

3. Arduino Library

Hardwire is fully compatible with any Arduino-compatible board. Integrating Hardwire Arduino Library into your project, you can add very powerful features like:

• Real time logging of variables
• Alerting and notification in case of any alarm or abnormal situation
• Remote commands

Please read general concepts about Hardwire platform before proceeding.

Requirements

Hardwire Arduino Library is compatible with any Arduino board. Due to the fact the board must be able to communicate with the platform, an Internet connection is required. You can connect your Arduino board to the Internet in any way:

• with an official or unofficial Ethernet shield
• with any WiFi shield or in general any WiFi module
• with any board that supports Ethernet or WiFi natively (like Arduino Yun, Arduino Ethernet or similars)

Getting started

In order to use Hardwire Arduino library you should install a valid Arduino IDE on your computer. Both Arduino.cc IDE and Arduino.org IDE are fully supported.
Once IDE is working and can communicate with your Arduino board, follow these instructions to install Hardwire Arduino Library:

1. Clone or download CloudMonitor Arduino Library from Github.
2. Install library into your IDE. For detailed information about adding an external library just follow this link.
3. Restart your IDE and check if library is successfully detected.
4. Go to File -> Example and load one of the samples contained into the the library for quick information about how to use it.

Standard usage

For a standard usage, Hardwire Arduino Library requires an instance of a generic Client object in order to connect to the Internet. Any class that extends Client can work properly (like EthernetClinet or WiFiClient).

Init function

// This will init the library
cm24_init("MY_PLANT_IDENTIFIER", "MY_PLANT_TOKEN", "MY_COMMAND_TOKEN", clientObjectInstance);

// This is for setting a specific callback function called once Arduino board receives a remote command
cm24_register_command_callback( my_callback_function );



Init of the library should be done within setup function of your sketch. This is the place where you have to specify your plant identifier and tokens. During the setup execution you can also specifiy a custom remote command callback, which is a function called every time Hardwire platform sends a command to the board.

Loop function

void loop()
{
	// Don't block loop in any way
	cm24_arduino_loop();
}




Hardwire loop function must be called within standard sketch loop function. This is a mandatory requirements, because loop function is responsible to transfer local data to the cloud platform. This function has an internal timing, so it should be called at the maximum speed possibile.

NOTE: try to avoid as much as possible any blocking operation within the main sketch loop function. If loop function is blocked by any other function, Hardwire Arduino Library cannot transfer local data to the platform nor receive any command.

Logging variables or alarms

cm24_log_variable( uint32_t VARIABLE_ID, float value, uint16_t sensor_id );
cm24_log_alarm( uint32_t ALARM_ID, float value, uint16_t sensor_id );




Logging variables and alarms have not been so easy! Just call cm24_log_variable and cm24_log_alarm function. The library will localy save the value of the variable or the code of the alarm and transfer it to the cloud platform as soon as possibile.

NOTE: you should always place a delay between two log function calls. Logging at the maximum speed without any delay will lead to fill local buffer and lose data.

Receiving remote commands

void setup()
{
	....
	cm24_register_command_callback( callback_function );
}

void callback_function( char *command )
{
	// This function will be called every time you get a new command.
}




Remote commands are a very interesting feature of the library, because they grant you control of your Arduino board from any place of the world. Remote commands are represented by standard text strings. It's in charge to your application to understand the command and execute it.

In order to receive remote commands, you firstly have to register a callback function during the setup process. This function will be called every time your board receives a remote command.

If you want to disable remote commands you can both avoid to specifiy the command callback or pass an empty command token to the cm24_init function.

Advanced configuration

// Change this values to have a larger or smaller buffer
#define CM24_BUFFER_ALARM_SIZE  5
#define CM24_BUFFER_VAR_SIZE  50



Hardwire Arduino Library has few optional configuration parameters, useful for fine tuning memory usage and performance. Usually default values are ok, but you can change any configuration parameter just editing the hardwire_config.h file, which is part of the library.

Parameter	Default	Description
CM24_BUFFER_ALARM_SIZE	5	Number of elements of the local buffer used to save alarms when connections to the platform is temporary not working. Higher the value higher the memory used by the library.
CM24_BUFFER_VAR_SIZE	50	Number of elements of the local buffer used to save variables when connections to the platform is temporary not working. Higher the value higher the memory used by the library.

Appendix: Variable types

Every variable has a type, that represents the physical measure it represents. The type of the variable helps the platform to understand what is the measure unit and how to format the value.

Below a list of supported variable IDs.

ID	Type	Description
1	String	IP Address (usually of the data logger that sent the record)
4	Float	Latitude
5	Float	Longitude
6	Float	Speed (Km/h)
7	Float	GPS Heading (degrees)
20	Float	Temperature (°C)
21	Float	Solar radiation (W/m2)
22	Float	Electrical current (A)
25	Float	Electrical power (kW)
26	String	Firmware version
38	Float	Data logger internal battery voltage (V)
52	Boolean	Generic Digital Input 1
53	Boolean	Generic Digital Input 2
54	Boolean	Generic Digital Input 3
55	Boolean	Generic Digital Input 4
56	Float	Generic Analog Input 1
57	Float	Generic Analog Input 2
58	Float	Generic Analog Input 3
59	Float	Generic Analog Input 4
63	Integer	Altitude (m)
64	Float	Generic Analog Input 5
65	Float	Generic Analog Input 6
66	Float	Generic Analog Input 7
67	Float	Generic Analog Input 8
69	Float	Humidity (%)
70	Float	Pressure (Bar)
75	Boolean	Generic Digital Output 1
76	Boolean	Generic Digital Output 1
77	Boolean	Generic Digital Output 1
78	Boolean	Generic Digital Output 1
79	Integer	Generic Counter
80	Integer	PWM Output 1
81	Integer	PWM Output 2
82	Integer	PWM Output 3
83	Integer	PWM Output 4
84	Float	Acceleration X-axis
85	Float	Acceleration Y-axis
86	Float	Acceleration Z-axis
87	Float	Ambient light (lux)
88	Integer	Battery level (%)

Appendix: Alarm types

Every alarm sent by the data logger must have a type, which helps to identify the meaning of the alarm.

Below a list of supported alarm IDs.

ID	Type	Description
9	Custom user alarm	Available for custom user alarms.
10	Internal battery low	Sent by the data logger when the internal battery (if available) is discharged.
11	Storage full	Sent by data logger once the internal storage is almost full.
12	Data logger tamper	Sent by data logger in case of tamper detection.

Appendix: Event types

Every event has a type, that represents the logic that stands behind it.

Below a list of supported event IDs.

ID	Type	Description
3	Variable Value	Created every time a variable has a value out or within a certain interval.
4	Sensor Offline	Created every time the platform doesn’t receive an update of some variables for a specified amount of time.
7	Input Activation	Created once we have a digital input activtion/ deactivation (see Generic Digital Input variable types).

Appendix: Command types

Every command has a type, that represents the command itself.

Below a list of supported command IDs.

Command	Description	Parameters
SET_DIG_OUT_1	Set digital output 1	None
RESET_DIG_OUT_1	Reset digital output 1	None
SET_DIG_OUT_2	Set digital output 2	None
RESET_DIG_OUT_2	Reset digital output 2	None
SET_DIG_OUT_3	Set digital output 3	None
RESET_DIG_OUT_3	Reset digital output 3	None
SET_DIG_OUT_4	Set digital output 4	None
RESET_DIG_OUT_4	Reset digital output 4	None
SET_DIG_OUT_5	Set digital output 5	None
RESET_DIG_OUT_5	Reset digital output 5	None
SET_DIG_OUT_6	Set digital output 6	None
RESET_DIG_OUT_6	Reset digital output 6	None
SET_DIG_OUT_7	Set digital output 7	None
RESET_DIG_OUT_7	Reset digital output 7	None
SET_DIG_OUT_8	Set digital output 8	None
RESET_DIG_OUT_8	Reset digital output 8	None
SET_DIG_OUT_9	Set digital output 9	None
RESET_DIG_OUT_9	Reset digital output 9	None
SET_DIG_OUT_10	Set digital output 10	None
RESET_DIG_OUT_10	Reset digital output 10	None
SET_PWM_OUT_1	Set the PWM output 1 to a specified value	Requires an INT value (0..100)
SET_PWM_OUT_2	Set the PWM output 2 to a specified value	Requires an INT value (0..100)
SET_PWM_OUT_3	Set the PWM output 3 to a specified value	Requires an INT value (0..100)
SET_PWM_OUT_4	Set the PWM output 4 to a specified value	Requires an INT value (0..100)