View source for Template:Modbus RTU Master MQTT Serial Gateway

<p style="color:red">The information on this page is updated in accordance with the [https://wiki.teltonika-networks.com/view/FW_%26_SDK_Downloads'''00.07.14.2'''] firmware version .</p>
__TOC__
==Summary==
In this guide, the MQTT Serial Gateway function will be configured using third-party MQTT Broker services (in this example, ''Flespi.io'').

==Configuration overview & prerequisites==
*Two devices with serials ports - one acts as Modbus RTU Master, another as Modbus RTU Slave;
*Flespi.io account to act as an MQTT Broker/Publisher/Subscriber (for first configuration example);

[[File:MQTT Serial gateway topology v2.png|border|center|class=tlt-border|847x279px]]

RUT2 will act as a Modbus RTU slave and RUT1 as a Modbus RTU Master. On RUT1, MQTT Serial Gateway will be configured to transfer Modbus data over MQTT. Flespi.io platform will serve as an MQTT Broker

==RUT2 configuration==
===Configuring Modbus RTU Slave===
----
Go to '''Services → Modbus → Modbus TCP over Serial Gateway''' and create a new instance.
* Enter the '''desired instance name''';
* Select the '''desired serial interface'''.

[[File:Modbus_RTU_SlaveV2.png|border|center|class=tlt-border|855 × 308px]]

==RUT1 configuration==
===Configuring MQTT Gateway===
----
Go to '''Services → Modbus → MQTT Gateway''' and there:

# '''Enable''' the '''instance''';
# '''Enter Host''' (copied from flespi connection settings without 'wss://' and port);
# '''Enter Username''' (Copied from flespi Connection settings generated '''token''');
# '''Enter Password'''.

[[File:Modbus_Mqtt_gateway.png|border|center|class=tlt-border|862 × 412px]]

'''Note''': ''Everything else can be left as default or changed according to your needs.''

===Configuring Serial Gateway===
----
Under the MQTT Gateway configuration, create the Serial Gateway:
# Enter the '''desired device ID''';
# Select the '''desired serial interface'''.

[[File:Serial_gateway_configV2.png|border|center|class=tlt-border|868×308px]]

===Configuring Flespi.io MQTT Broker===
----
'''Log in''' or '''create an account''' on '''https://flespi.io''';

#Navigate to '''MQTT Board''' on the '''left side''' menu;                                         
#On the right-hand panel, top right corner, next to the name of the MQTT board, '''press the cogwheel-looking icon''' to open ''Connection Settings'';
#In the opened window, press '''"Get flespi token"''' to generate a username;
#Enter the '''Client name''';
#Copy the Host address;
#Copy '''Username''';
#Create a '''password'''.

Once done, save all the changes.
[[File:Flespi board.png|border|center|class=tlt-border|1102x729px]]

===Message format for MQTT publisher===
----
Modbus request data sent in the MQTT payload should be generated in accordance with the following format:

<pre>1 <COOKIE> <SERIAL_DEVICE_ID> <TIMEOUT> <SLAVE_ID> <MODBUS_FUNCTION> <FIRST_REGISTER> <REGISTER_COUNT> </pre>

The table below explains what each option means:

{| class="wikitable"
|1.  Format version
|'''1'''
|-
|2. Cookie
|from '''0''' to '''2<sup>64</sup> -1'''
|-
|3. Serial device ID
|a string used to identify a serial device. Must match with <u>Device ID</u> field in MQTT Gateway page Serial gateway configuration section
|-
|4. Timeout
|timeout for Modbus connection, in seconds. Range [1..999].
|-
|5. Slave ID
|Indicates to which slave request is sent
|-
|6. Modbus function
|Modbus task type that will be executed. Possible values are:
        <ul>
            <li><b>1</b> - read coils;</li>
            <li><b>2</b> - read input coils;</li>
            <li><b>3</b> - read holding registers;</li>
            <li><b>4</b> - read input registers;</li>
            <li><b>5</b> - set single coil;</li>
            <li><b>6</b> - write to a single holding register;</li>
            <li><b>15</b> - set multiple coils;</li>
            <li><b>16</b> - write to multiple holding registers.</li>
        </ul>
|-
|7. First register
|number (not address) of the first register/coil/input (in range [1..65536]) from which the registers/coils/inputs will be read/written to.
|-
|8. Registry count
| <li><b>1</b> - <u>coil count</u> (in range [1..2000]); must not exceed the boundary (first coil number + coil count <= 65537);</li>
            <li><b>2</b> - <u>input count</u> (in range [1..2000]); must not exceed the boundary (first input number + input count <= 65537);</li>
            <li><b>3</b> - <u>holding register count</u> (in range [0..125]); must not exceed the boundary (first register number + holding register count <= 65537);</li>
            <li><b>4</b> - <u>input register count</u> (in range [0..125]); must not exceed the boundary (first register number + input register count <= 65537);</li>
            <li><b>5</b> - <u>coil value</u> (in range [0..1]);</li>
            <li><b>6</b> - <u>holding register value</u> (in range [0..65535]);</li>
            <li><b>15</b> - <u>coil count</u> (in range [1..1968]); must not exceed the boundary (first coil number + coil count <= 65537); and <u>coil values</u> separated with commas, without spaces (e.g., <i>1,2,3,654,21,789</i>); there must be exactly as many values as specified (with coil count); each value must be in the range of [0..1].
|}
====Examples====
----
{| class="wikitable"
|Setting relay (on) (Relay address is 202, which means 'Number of first register will be 203)
|'''1 1 1 1 1 6 203 1'''
|-
|Getting temperature
|'''1 1 1 1 1 3 6 2'''
|}
Modbus parameters are held within registers. The register numbers and corresponding system values can be found [[RUT955_Monitoring_via_Modbus#Get_Parameters|'''in this article''']].

==Testing MQTT Publisher and Subscriber on flespi.io==
====Adding Flespi Subscriber====
----
To test the Modbus Serial Gateway functionality, '''log into''' your '''Flespi account''' → '''MQTT Board''' and '''add a Subscriber''':

#Press '''''<nowiki/>'+'''''' button on the top right corner
#Select '''''<nowiki/>'Subscriber''''''
# In the topic field enter '''''<nowiki/>'response''''''
#Press '''''<nowiki/>'Subscribe'''''' button

[[File:Flespi subscriber.png|border|class=tlt-border|496x204px]]           [[File:Flespi subscriber setup.png|border|class=tlt-border|496x205px]]
====Adding Flespi Subscriber====
----

Also, you will need to '''add a Publisher''':

#Press '''''<nowiki/>'+'''''' button on the top right corner
#Select '''''<nowiki/>'Publisher''''''
#In the topic field enter '''''<nowiki/>'request''''''
#In the message field enter message, for this example '''''<nowiki/>'Getting temperature'''''' is used
#Press '''''<nowiki/>'Publish'''''' button

[[File:Flespi publisher.png|border|class=tlt-border|495x238px]]   [[File:Flespi publisher setup.png|border|class=tlt-border|494x239px]]
====Flespi Subscriber output====
----
Check the response in the '''''<nowiki/>'Subscriber'''''' tab, you should receive a message similar to the one below.


[[File:Flespi response.png|border|center|class=tlt-border|500x305px]]


In the output, we can see that router's '''temperature''' is '''44 degrees Celsius'''.

==See Also==
*[[RUT955 Monitoring via Modbus#Get Parameters]]
*[[RUT955_Modbus#MQTT_Gateway|MQTT Gateway and Modbus]]
==External links==
[https://flespi.io/#/ Flespi.io]