This Driver's [P] configuration parameters are not used. All settings are performed on the configuration window, shown on the next figure.
General tab
The available options on the General tab are described on the next table.
Available options on the General tab
Option |
Description |
|---|---|
Version |
Protocol version. Available options are 3.1 or 3.1.1 |
KeepAlive (s) |
Time, in seconds, that a client sends a ping message in MQTT protocol (PingReq) to check whether a connection with a Broker is still active. Default value of this option is 5 (five) seconds |
Client ID |
Name used by this client as an identifier to all other clients. There must not be another client connected to the same Broker with that name |
User |
Name of a user used in connection messages (ConnAck) if needed and allowed by a Broker |
Password |
Password used along with the user name |
Read QoS |
Tells which QoS is used to request Tag subscriptions (QoS 0, 1, or 2). The Broker matches the requested QoS with the published QoS and then sends a minimum compatible data |
Resend Unanswered Subscriptions After (s) |
Informs the number of seconds to resend a subscription of an item if it did not receive the first value during the informed period |
Use Session Control |
Informs whether this Driver must keep the status of the active session, that is, if a disconnection occurs and then a connection occurs, the QoS 1 and 2 messages sent by other clients can be recovered |
Use Last Will Msg for Hierarchical Quality |
When selecting this option, if this Driver receives the message configured in the Message option of the Last Will and Testament group on the Publish tab, then this message's topic is used to hierarchically define other Tags configured with a bad quality |
Assuming that a Last Will message of a device is configured with an "Error" expression for the Device527 item, when receiving that message all addressed Tags containing the expression "Device527" starting at the beginning of their address have their quality set as bad, that is, the value of the Quality property is set to 20, 24, or 28 (invalid). Examples of device addresses:
Device527/Temperature
Device527/AnalogInput01
Device527
For these Tags to return to a good quality (192), a topic must receive any value different from the message configured in the Last Will and Testament option.
Publish tab
The available options on the Publish tab are described on the next table.
Available options on the Publish tab
Option |
Description |
|---|---|
QoS |
Indicates the service level of messages published by this Driver. The available options are QoS 0: There is almost always a deliver (there may have zero or more delivers), QoS 1: At least one or more delivers, or QoS 2: Exactly one deliver |
Deadband % |
Value for the relative dead band, applied when writing a numeric value to any Tag with no Template specified |
Retain messages on Server |
Selecting this option instructs a Broker to keep this client's messages with their QoS, so that clients subscribing in the future can receive accumulated messages. When a new client subscribes, the last message of each topic, if available, must be sent to that client by the Broker |
Enable Last Will |
When enabling this option, the server must keep in memory a topic and a message for the client, which are sent to all other clients when there is an unordered disconnection, that is, without sending a Disconnect message |
Topic |
Topic or address sent during disconnection (Last Will), such as "ELIPSE\goodbye" |
Message linked to a topic, such as "Goodbye" |
On the Templates tab, users can define different patterns for data on MQTT messages, whose elements can be automatically extracted or filled by this Driver using Tags or Block Tags.
Templates tab
The available options on the Templates tab are described on the next table.
Available options on the Templates tab
Option |
Description |
|---|---|
Apply local timezone to timestamps |
When this option is selected, the received timestamps are converted to the time zone used by the operating system. Otherwise, the received timestamps are displayed in UTC time zone |
Template Name |
Informs the name of a Template. Templates with the same name are not allowed |
Data Format |
Declares the format of a Template's message. The available options are JSON, CSV, or XML. The JSON format is preferred for use with MQTT, because it allows defining any type of data structure with less bytes |
Add |
Adds a Template to the list of Templates |
Edit |
Opens a window for editing the selected Template |
Delete |
Deletes the selected Template from the list of Templates |
Click Edit to open a window for editing the selected Template. The name and format of the Template are displayed at the top. The Template itself must be inserted in the edit box.
Window for editing a template
The available options on the window for editing a template are described on the next table.
Available options on the window for editing a template
Option |
Description |
|---|---|
Save |
Confirms all changes and closes this window |
Cancel |
Discards all changes and closes this window |
Syntax |
Informs the syntax of a message, in the selected format (JSON, CSV, or XML) along with the keywords used during the process of replacing them by timestamps, qualities, or values. For more information, please check topic Template Syntax |
On the Ethernet tab, users must configure an IP address and a TCP/IP port of an MQTT Broker. MQTT standard establishes TCP/IP port 1883 as a default port for direct unencrypted connections. TCP/IP port 8883 is defined as a default port for encrypted TLS/SSL connections without a certificate, and TCP/IP port 8884 is defined as a default port for TLS/SSL connections with a certificate.