Integration with Smart Water Meter

This topic describes how to integrate smart water meters with the Tuya Developer Platform.

Overview

We provide the following solution to help connect smart water meters to the Tuya Developer Platform by using Tuya IoT Edge Gateway. The architecture is shown as follows:

Integration protocol

During communications over the MQTT protocol, the smart water meter gateway works as a client, and Tuya’s IoT Edge Gateway works as a broker.

Development guide

The following table lists the specified properties of a smart water meter for your reference.

Standard property values of a smart water meter

DP ID	DP name	Identifier	Data transfer type	Data type	DP property
1	Water flow	water_flow	Report only (read-only)	value	Value range: 0 to 999999999. Unit: ㎥.
2	Total monthly water consumption	monthly_water_total	Report only (read-only)	value	Value range: 0 to 999999999. Unit: ㎥.
3	Total daily water consumption	daily_water_total	Report only (read-only)	value	Value range: 0 to 999999999. Unit: ㎥.
4	Switch status	switch_state	Send and report (read-write)	bool	/
5	First reading of a day	d_begin_water_total	Report only (read-only)	value	Value range: 0 to 999999999. Unit: ㎥.
6	Last reading of a day	d_end_water_total	Report only (read-only)	value	Value range: 0 to 999999999. Unit: ㎥.
7	First reading time of a day	d_begin_time	Report only (read-only)	string	The Unix timestamp.
8	Last reading time of a day	d_end_time	Report only (read-only)	string	The Unix timestamp.
9	Valve status	valve_state	Send and report (read-write)	enum	Enumeration values: opened, closed, opening, and closing.
10	First reading of a month	m_begin_water_total	Report only (read-only)	value	Value range: 0 to 999999999. Unit: ㎥.
11	Last reading of a month	m_end_water_total	Report only (read-only)	value	Value range: 0 to 999999999. Unit: ㎥.
12	First reading time of a month	m_begin_time	Report only (read-only)	string	The Unix timestamp.
13	Last reading time of a month	m_end_time	Report only (read-only)	string	The Unix timestamp.
14	Shared usage of cold water	cold_stall_userdata	Report only (read-only)	value	Value range: 0 to 999999999. Unit: ㎥.
15	Sharing type of cold water	cold_stall_type	Send and report (read-write)	enum	Enumeration values: square_area, ignore, consumption, proportion, lease, and power.
16	Shared usage of hot water	hot_stall_userdata	Report only (read-only)	value	Value range: 0 to 999999999. Unit: ㎥.
17	Sharing type of hot water	hot_stall_type	Send and report (read-write)	enum	Enumeration values: square_area, ignore, consumption, proportion, lease, and power.
18	Valve openness	valve_open_degree	Send and report (read-write)	value	Value range: 0 to 999999999. Unit: %.

API reference

MQTT API reference for the device

Overview

An MQTT message consists of a fixed header, variable header, and payload.

For more information about the format of fixed headers and variable headers, see MQTT Specification. The format of the payload is defined by Tuya as follows.

Common MQTT message types include CONNECT, SUBSCRIBE, and PUBLISH.

• CONNECT: A client requests a connection to a server. It is the main parameter of a payload. For more information, see Device Connection Authentication.
• SUBSCRIBE: A client requests to subscribe to a specified topic. For more information about the topic name in a payload, see the specified topic whose subscriber is a device in the Topic definition.
• PUBLISH: The platform publishes messages.
  • The Topic name in a variable header refers to a specified topic whose publisher is a device during reporting to the platform. For more information, see Topic definition.
  • The main parameter in a payload is the complete message content between the device and the platform. It is currently a JSON object.

Limitations

• Uplink topic indicates that the device sends a request to the platform, reports data, or replies with a response.
• Downlink topic means that the platform sends commands to the device or replies with a response.
• After the device establishes a connection with the platform, the device must subscribe to the downlink topic. Otherwise, the device will not be able to receive the command or response sent by the platform.

Communication between the device and platform

The device connects to and communicates with Tuya’s IoT edge gateway. The following figure shows how the communications between the device, Tuya’s IoT edge gateway, and Tuya Developer Platform work.

The device reports data to Tuya IoT Edge Gateway

The device connects to and communicates with Tuya IoT Edge Gateway. The device can report data to the platform in the following ways.

Device property reporting: The device reports property data to the platform in the format defined in the product model.

The application server sends commands to the device.

After the connection is established, Tuya IoT Edge Gateway can send commands to the device as follows.

Platform command sending: The application server sends control commands to the device in a format defined in the product model.

Topic definition

After the device connects to Tuya IoT Edge Gateway over the MQTT protocol, the platform communicates with the device through topics. The following table lists the preset topics:

Type	Topic	Publisher	Subscriber	Purpose
Device sync topic	gateway_id/{gateway_id}/devices/sync	Device	Platform	Activate devices.
Device sync topic	gateway_id/{gateway_id}/devices/sync/response	Platform	Device	The platform returns an activation response.
Device command topic	gateway_id/{gateway_id}/commands	Platform	Device	The platform sends commands to the device.
Device command topic	gateway_id/{gateway_id}/commands/response	Device	Platform	The device returns a command response.
Device property topic	gateway_id/{gateway_id}/properties/report	Device	Platform	Report device properties.
Device property topic	gateway_id/{gateway_id}/properties/report/response	Platform	Device	The platform returns a response to property reporting.
Device online/offline topic	gateway_id/{gateway_id}/devices/status	Device	Platform	Report device online and offline events.

QoS level setting

The MQTT protocol specifies the quality of service (QoS) to ensure the reliability of message delivery in different network environments. The MQTT protocol has designed three QoS levels.

• QoS 0: The message is delivered at most once. If the client is unavailable at that time, the message will be lost.
• QoS 1: The message is delivered at least once.
• QoS 2: The message is delivered exactly once.

The higher the QoS level, the more complex the process, and the greater the consumption of system resources. Applications can choose the appropriate QoS level based on the network scenarios and business requirements.

We recommend that you set the QoS level to 1 for message publishing and subscription during third-party device integration.

Connection authentication

Interface description

On the Tuya Developer Platform, devices support the connect message interface of the MQTT protocol. After the authentication is passed, the MQTT connection between the device and the platform is established.

Parameters

Parameter	Required	Type	Description
broker	Yes	String	The IP address of Tuya IoT Edge Gateway, to be provided by Tuya.
port	Yes	String	The TCP port number is 21883.
clientId	Yes	String	The unique ID of a specified third-party gateway.
username	Yes	String	The username to identify a third-party manufacturer, to be provided by Tuya.
password	Yes	String	The value of a password is generated using the MD5 encryption algorithm. For more information, see Password generation rules.

Password generation rules

Concatenate the clientId and username variables, and then encrypt the concatenated variables with the MD5 encryption algorithm.

The following sample shows how to generate a connection password for Go.

func generatePassword() string {
	var (
		clientId string
		username string
		password string
	)
	// Assign values to clientId and username first
	password = md5V(clientId + username)
	return password
}

// MD5 encryption algorithm function
func md5V(str string) string {
	h := md5.New()
	h.Write([]byte(str))
	return hex.EncodeToString(h.Sum(nil))
}

Return code of native MQTT protocol

The following table lists the return codes when a device establishes a connection to the platform over the native MQTT protocol.

Return code	Identifier	Description	Reason
0x00	connection accepted	The connection is successful.	The connection is successful.
0x01	unacceptable protocol version	The request is rejected because the protocol version is incorrect.	The server does not support the MQTT protocol version, based on which the client sends the request.
0x02	identifier rejected	The request is rejected because the client identifier is invalid.	The clientId is not in the required format or the heartbeat interval does not meet the platform requirements.
0x03	server unavailable	The request is rejected because the server is unavailable.	The platform service is unavailable.
0x04	bad user name or password	The request is rejected because the username or password is incorrect.	The username or password is incorrect.
0x05	not authorized	The request is rejected because the client is not authorized.	The client is not authorized to establish a connection.

Synchronize devices

It is used for device synchronization. After the device gateway is connected to the MQTT server of Tuya IoT Edge Gateway, send the device synchronization command. Then, Tuya IoT Edge Gateway will add or update the reported devices.

Topic

• Uplink: gateway_id/{gateway_id}/devices/sync

• Downlink: gateway_id/{gateway_id}/devices/sync/response

Uplink parameters

Field	Required	Type	Description
t	Yes	Integer	The Unix timestamp.
request_id	Yes	String	The identifier of a specified request. We recommend the request identifier be generated by using the UUID algorithm.
param	Yes	Object	The object.
param.cid	Yes	String	The ID of a specified third-party device, to be defined by the device. It can be a unique readable identifier of the device, such as device SN or IMEI.
param.product_id	Yes	String	The ID of a specified product.
param.vendor_code	Optional	String	The code of a specified manufacturer.
param.comm_type	Optional	String	The communication mode between a device and a gateway. Enter mqtt.
param.device_ip	Optional	String	The IP address of a specified device.
param.mac_address	Optional	String	The MAC address of a specified device.
param.device_desc	Optional	String	The description of a specified device.
param.install_location	Optional	String	The installation location of a specified device.
param.device_server_id	Optional	String	The ID of a specified device server.
param.product_sub_type	Optional	String	The sub-type of a specified product.

Downlink parameters

Field	Required	Type	Description
t	Yes	Integer	The Unix timestamp.
request_id	Yes	String	The unique identifier of a request.
param	Yes	Object	The object.
param.cid	Yes	String	The CID of a specified device.
param.msg	Yes	String	The message. See Global error codes.
param.code	Yes	Integer	The execution result of a specified command. If the result is 0, it indicates success. All other values indicate failure.

Sample of uplink parameters

Topic: gateway_id/{gateway_id}/devices/sync
Data format:
{
    "t":162728***,
    "request_id":"cd0fd3c3-bd15-42f6-8bf9-d230a***",
    "param":{
        "cid":"92dda538fc2e636fd***",
        "product_id":"",// Enter the pid of a specified product
        "vendor_code":"",// The code of a specified device manufacturer
        "comm_type":"",
        "device_ip":"",
        "mac_address":"",
        "device_name":"",
        "device_desc":"",
        "install_location":"",
        "device_server_id":"",
        "product_sub_type":""
    }
}

Sample of downlink parameters

Topic: gateway_id/{gateway_id}/devices/sync/response
Data format:
{
    "t":162728***,
    "request_id":"cd0fd3c3-bd15-42f6-8bf9-d230a08***",
    "param":{
        "cid":"92dda538fc2e636fd4b0c37f***",
        "msg":"success",
        "code":0
    }
}

Device commands

Send a command from the platform

Send a device control command from the platform to a specified smart device. After the command is sent, the device needs to return the execution result to the platform in time. If the device does not respond, the platform will consider the command execution timed out.

Topic

• Downlink: gateway_id/{gateway_id}/commands

• Uplink: gateway_id/{gateway_id}/commands/response

Downlink request parameters

Field	Required	Type	Description
t	Yes	Integer	The Unix timestamp.
cid	Yes	String	The ID of a specified third-party device, to be defined by the device. It can be a unique readable identifier of the device, such as device SN or IMEI.
request_id	Yes	String	The identifier of a specified request. We recommend the request identifier be generated by using the UUID algorithm.
param	Yes	Object	The object.
param.id	Yes	String	The ID of a specified data point.
param.value	Yes	Not fixed	The execution parameters of device commands.

Uplink response parameters

Respond the command in JSON format.

Field	Required	Type	Description
t	Yes	Integer	The Unix timestamp.
cid	Yes	String	The ID of a specified third-party device, to be defined by the device. It can be a unique readable identifier of the device, such as device SN or IMEI.
request_id	Yes	String	The unique identifier of a specified request. We recommend the request identifier be generated with the UUID algorithm.
param	Yes	Object	The object.
param.msg	Yes	String	The execution result. Enter success to indicate a successful execution.
param.code	Yes	Integer	The execution result of a specified command. If the result is 0, it indicates success. All other values indicate failure.

Sample downlink request

Topic: gateway_id/{gateway_id}/commands
Data format:
{
  "t":162728***,
  "cid": "92dda538fc2e636fd4b0c37f980***",
  "request_id":"cd0fd3c3-bd15-42f6-8bf9-d230a08***",
  "param": {
    "id":"1",
    "value": "1"
  }
}

Sample uplink response

Topic: gateway_id/{gateway_id}/commands/response
Data format:
{
  "t":162728***,
  "cid": "92dda538fc2e636fd4b0c37f980***",
  "request_id":"cd0fd3c3-bd15-42f6-8bf9-d230a***",
  "param": {
    "msg": "success",
    "code":0
  }
}

Device properties

Report device properties

The device reports property data to the platform in the format defined in the product model. After receiving the reported message, the platform will return the execution result to the device.

Topic

• Uplink: gateway_id/{gateway_id}/properties/report

• Downlink: gateway_id/{gateway_id}/properties/report/response

Uplink parameters

Field	Required	Type	Description
t	Yes	Integer	The UTC timestamp when a device connects to the platform.
request_id	Yes	String	The unique identifier of a specified request. We recommend the request identifier be generated with the UUID algorithm.
param	Yes	Object	The object.
param.cid	Yes	String	The ID of a specified third-party device, to be defined by the device. It can be a unique readable identifier of the device, such as device SN or IMEI.
param.id	Yes	String	The ID of a specified data point (DP) among properties of a smart water meter.
param.value	Yes	Refer to the DP type	The property value of a specified device.

Downlink parameters

Field	Required	Type	Description
t	Yes	Integer	The Unix timestamp.
request_id	Yes	String	The unique identifier of a request.
param	Yes	Object	The object.
param.cid	Yes	String	The ID of a specified third-party device, to be defined by the device. It can be a unique readable identifier of the device, such as device SN or IMEI.
param.msg	Yes	String	The message. See Global error codes.
param.code	Yes	Integer	The execution result of a specified command. If the result is 0, it indicates success. All other values indicate failure.

Sample of uplink parameters

gateway_id/{gateway_id}/properties/report
{
    "t":162728***,
    "request_id":"cd0fd3c3-bd15-42f6-8bf9-d230a0***",
    "param":{
        "cid":"ee1880aca6b***",
        "id":"1",
        "value":"run"
    }
}

Sample of downlink parameters

Topic: gateway_id/{gateway_id}/properties/report/response
Data format:
{
    "t":162728***,
    "request_id":"cd0fd3c3-bd15-42f6-8bf9-d230a085***",
    "param":{
        "cid":"92dda538fc2e636fd4b0c37f98***",
        "msg":"success",
        "code":0
    }
}

Report device online and offline event

Report device online and offline events

The device gateway needs to regularly synchronize the device online and offline status to the Tuya IoT Edge Gateway. We recommend the status of the sub-devices be reported at least once every minute.

Topic

Uplink: gateway_id/{gateway_id}/devices/status

Uplink parameters

Field	Required	Type	Description
t	Yes	Integer	The UTC timestamp when a device connects to the platform.
request_id	Yes	String	The unique identifier of a specified request. We recommend the request identifier be generated with the UUID algorithm.
param	Yes	Object	The array of objects.
param.cid	Yes	String	The ID of a specified third-party device, to be defined by the device. It can be a unique readable identifier of the device, such as device SN or IMEI.
param.status	Yes	Bool	The device status. true means online and false means offline.

Sample of uplink parameters

Topic: gateway_id/{gateway_id}/devices/status
Data format:
{
  "t":162728***,
  "request_id":"cd0fd3c3-bd15-42f6-8bf9-d230a08***",
  "param": [{
    "cid": "92dda538fc2e636fd4b0c37f98***",
    "status":true
  },
  {
    "cid": "da538fc2ebffdb463692dfdb0c3***",
    "status":false
  }
 ]
}

Sample application

To help you make API requests, we provide development samples for Java, PHP, and Go, and demonstrate basic features such as **service connection, verification, encryption and decryption of sensitive information, and message subscription. Development libraries for more languages will be available in the near future.

Java

Add the dependency definitions shown below to the Maven POM file.

<dependencies>
    <dependency>
        <groupId>org.eclipse.paho</groupId>
        <artifactId>org.eclipse.paho.client.mqttv3</artifactId>
        <version>1.2.0</version>
    </dependency>
</dependencies>

// Message publishing
public class Publish {
    public static void main(String[] args) {
        String clientId = "";                     // The gatewayID that identifies the third-party manufacturer
        String topic = ""; 											 // The topic
        String content = ""; // The content
        int qos = 1;                              //  The QoS
        String broker = "";                       // The IP address of the server
        String userName = "";                     // The username, to be provided by Tuya
        String password = "";                     // The password. See password generation rules.
        // The memory
        MemoryPersistence persistence = new MemoryPersistence();

        try {
            // Create a client
            MqttClient sampleClient = new MqttClient(broker, clientId, persistence);
            // Create link parameters
            MqttConnectOptions connOpts = new MqttConnectOptions();
            // Remember state on reboot and reconnection
            connOpts.setCleanSession(false);
            // Set a username used for connection
            connOpts.setUserName(userName);
            connOpts.setPassword(password.toCharArray());
            // Establish a connection
            sampleClient.connect(connOpts);
            // Create a message
            MqttMessage message = new MqttMessage(content.getBytes());
            // Set the message QoS
            message.setQos(qos);
            // Publish the message
            sampleClient.publish(topic, message);
            // Close a connection
            sampleClient.disconnect();
            // Close the client
            sampleClient.close();
        } catch (MqttException me) {
            System.out.println("reason " + me.getReasonCode());
            System.out.println("msg " + me.getMessage());
            System.out.println("loc " + me.getLocalizedMessage());
            System.out.println("cause " + me.getCause());
            System.out.println("excep " + me);
            me.printStackTrace();
        }
    }
}

// Message subscription
public class Subscribe {

    public static void main(String[] args) throws MqttException {  
        String clientId = "";                     // The gatewayID that identifies the third-party manufacturer
        String host = "";                      // The IP address of the server
        String topic = "gateway/in/" + clientId;  // The topic
        int qos = 1;                              //  The QoS
        String userName = "";                     // The username, to be provided by Tuya
        String password = "";                     // The password. See password generation rules.
        try {

            MqttClient client = new MqttClient(host, clientid, new MemoryPersistence());
            // Set the MQTT connection
            MqttConnectOptions options = new MqttConnectOptions();
            // Set whether to clear the session. `false` means the server will keep the connection record of the client, and `true` means every time the client connects to the server with a new identity.
            options.setCleanSession(true);
            // Set a username used for connection
            options.setUserName(userName);
            // Set a password used for connection
            options.setPassword(passWord.toCharArray());
            // Set a timeout value in seconds
            options.setConnectionTimeout(10);
            // Set a session heartbeat interval in seconds
            options.setKeepAliveInterval(20);
            // Set a callback function
            client.setCallback(new MqttCallback() {

                public void connectionLost(Throwable cause) {

                }
                public void messageArrived(String topic, MqttMessage message) throws Exception {
                  	// Message processing
                    System.out.println("message content:"+new String(message.getPayload()));

                }
                public void deliveryComplete(IMqttDeliveryToken token) {

                }

            });
            client.connect(options);
            // Subscribe to the message
            client.subscribe(topic, qos);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

Go

package main

import (
	"fmt"
	mqtt "github.com/eclipse/paho.mqtt.golang"
	"log"
	"os"
	"time"
)

const broker = ""                // The IP address of the server. Contact Tuya's administrator.
const username = ""              // The username, to be provided by Tuya.
const password = ""              // The password. See password generation rules.
const clientID = ""              // The gatewayID, the gateway ID of the third-party manufacturer.
const topic = ""                // The topic
const port = "21883"            // The port number of the server

// Message subscription topic = "gateway/in/" + clientID
// Message publishing topic = "gateway/out/" + clientID

var f mqtt.MessageHandler = func(client mqtt.Client, msg mqtt.Message) {
	fmt.Printf("TOPIC: %s\n", msg.Topic())
	fmt.Printf("MSG: %s\n", msg.Payload())
}

func main() {
	mqtt.DEBUG = log.New(os.Stdout, "", 0)
	mqtt.ERROR = log.New(os.Stdout, "", 0)
	opts := mqtt.NewClientOptions().AddBroker(fmt.Sprintf("tcp://%s:%s", broker, port)).SetClientID(clientID).
		SetUsername(username).SetPassword(password)
	
	
	opts.SetKeepAlive(60 * time.Second)
	// Set a message callback function
	opts.SetDefaultPublishHandler(f)
	opts.SetPingTimeout(1 * time.Second)
	
	
	c := mqtt.NewClient(opts)
    if token := c.Connect(); token.Wait() && token.Error() != nil {
		panic(token.Error())
	}
	
	
   // Subscribe to the topic
	if token := c.Subscribe(topic, 1, nil); token.Wait() && token.Error() != nil {
		fmt.Println(token.Error())
		os.Exit(1)
	}
	
	
 // Publish the message
	token := c.Publish(topic, 1, false, "Hello World")
	token.Wait()
	
	time.Sleep(6 * time.Second)
	
	
 // Unsubscribe from the topic
	if token := c.Unsubscribe(topic); token.Wait() && token.Error() != nil {
		fmt.Println(token.Error())
		os.Exit(1)
	}
	
	
 // Close a connection
	c.Disconnect(250)
	time.Sleep(1 * time.Second)
}

PHP

Publish a message

<?php
require("");                                // Import mqtt class file
$server    = '';                            // The IP address of the server. Contact Tuya's administrator.
$port      = 21883;                         // The port number of the server
$username  = '';                             // The username, to be provided by Tuya
$password  = '';                             // The password. See password generation rules.
$client_id = ''                             // The gatewayID that identifies the third-party manufacturer.

$mqtt = new Bluerhinos\phpMQTT($server, $port, $client_id); // Instantiate the MQTT class

if ($mqtt->connect(true, NULL, $username, $password))   // Establish a connection
{
    $topic = 'gateway/out/'.$client_id;	 	   // The topic
    $key =  ''    // The encryption key, which is the password used for connection authentication
    $msg = '';   // The message in the above-mentioned format
    // qos = 0: Send only once, regardless of whether it is received or not
    // qos ＝ 1: Keep sending a message if no result is returned, and a duplicate message might be received
    // qos = 2: Make sure the message must be received and not repeated
    $mqtt->publish($topic, $msg, 0);// Send the data
    $mqtt->close();        // Close a connection
}
else
{
    echo "Time out!\n";
}

Subscribe to a message

<?php
require("");                                // Import mqtt class file
$server    = '';                            // The IP address of the server. Contact Tuya's administrator.
$port      = 21883;                         // The port number of the server
$username  = '';                             // The username, to be provided by Tuya
$password  = '';                             // The password. See password generation rules.
$client_id = ''                             // The gatewayID that identifies the third-party manufacturer.

$mqtt = new Bluerhinos\phpMQTT($server, $port, $client_id);

$mqtt->debug = true;
if(!$mqtt->connect(true, NULL, $username, $password))
{
    echo "Connection failed!\n";
    exit(1);
}
$topic = 'gateway/in/'.$client_id;          //  The topic
// Subscription list
$topics = [
    $topic => ['qos' => 0, 'function' => 'procmsg'],
];

$mqtt->subscribe($topics, 0);

while ($mqtt->proc()){}

$mqtt->close();



function procmsg($topic, $msg)  // Message processing function
{
    $key =  ''                              
  	echo $msg;	
}

Global error codes

If errors occur when you make API requests, custom error messages will be returned. This section describes the global error codes.

Error code	Error message	Description
400	tedge error: uplink specific error message	The uplink error to be defined by the uplink service.
500	system error, please contact the admin	A system error occurs while processing your request. Contact your administrator.
1001	request time is invalid	The request time is invalid.
1100	params is empty	The parameter is empty.
1101	params range invalid	The parameter range is invalid.
1102	params is null	The parameter is null.
1103	params type is incorrect	The parameter type is incorrect.
2001	device is offline	The device is offline.
2002	command or value not support	The command or value is not supported.
2003	device not exist	The device does not exist.