Component: MQTT Client (Comms: IoT/Cloud)
| Author | Matrix TSL |
| Version | 1.1 |
| Category | Comms: IoT/Cloud |
MQTT Client component
A component providing access to MQTT IoT client. The client can connect to a MQTT server such as ThingSpeak. Allowing IoT type data to be published and read back.
Detailed description
No detailed description exists yet for this component
Examples
The MQTT component requires connection to a Network Comms component via the "Network Component" property, to provide the bridge for simulated TCP/IP communication.
The Network Comms component can then be linked to an embedded TCP/IP component to provide embedded TCP/IP support.
Here is a typical setup for using MQTT on a Raspberry Pi.
Local Weather
A simple example demonstrating how to use MQTT with Flowcode SCADA to get the local weather conditions.
The example shows temperatures from Halifax in the UK and from Sydney in Australia.
Publish
Raspberry Pi
Here we have an embedded Raspberry Pi project connected to an I2C Sensor, the sensor is sampled and the data is published to a MQTT server.
ESP8266 Module
Here we have an embedded project using an ESP8266 wifi module, an analogue input is sampled and the data is published to a MQTT server.
Subscribe
ESP8266 Module
Here we subscribe to a topic and receive it back into Flowcode embedded using an ESP8266 module.
Flowcode App Developer
Here we subscribe to a topic and receive it back into Flowcode App Developer.
Making your own Raspberry Pi based MQTT Broker
Click here for instructions on creating your own Raspberry Pi MQTT Broker.
Downloadable macro reference
|
GetTopic |
| Get the Topic of the last received (Read) packet. Returns the number of bytes for the Topic | |
 - STRING
|
Topic |
 - BYTE
|
Size |
| Byte count the Topic buffer | |
| - BYTE
|
Return |
|
|
ErrorAsString |
| - BYTE
|
Error |
| - STRING
|
Return |
|
|
Connect |
| Connect to the MQTT Server. Returns the connected state. 0 if not connected, 1 if successful connection, or already connected. | |
| - BYTE
|
Return |
|
|
Publish |
| Publish data to the server (broker) Returns non-zero if successful | |
| - STRING
|
Topic |
| - STRING
|
Payload |
| - BYTE
|
Return |
|
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LastError |
| Returns the last error | |
| - BYTE
|
Return |
|
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Read |
| Read incoming data. Returns non-zero if packet received. Use GetTopic and GetPayload to read the contents. | |
 - UINT
|
Return |
|
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Disconnect |
| Disconnects from the MQTT server and the network | |
| - BYTE
|
Return |
|
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Ping |
| Ping packet is sent to the Server and checks for a reply. Returns non-zero value if successful | |
| - BYTE
|
Return |
|
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GetPayload |
| Get the Payload of the last received (Read) packet. Returns the number of bytes for the Payload | |
| - STRING
|
Payload |
| - BYTE
|
Size |
| Byte count the Payload buffer | |
| - BYTE
|
Return |
|
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Subscribe |
| Subscribe to a Topic. Must be Connected first Returns non-zero if successful | |
| - STRING
|
Topic |
| - BYTE
|
Return |
|
|
Unsubscribe |
| Unsubscribe from a Topic. Must be Connected first Returns non-zero if successful | |
| - STRING
|
Topic |
| - BYTE
|
Return |
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Initialise |
 - VOID
|
Return |
|
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GetPayloadString |
| Get the Payload of the last received (Read) packet as a string value | |
| - STRING
|
Payload |
| - BYTE
|
Size |
| - BYTE
|
Return |
|
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Initialise |
| Starts up the MQTT component - call this after initialising the NetworkComms component. | |
| - VOID
|
Return |
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Initialise |
| Sets up the GSM module. Returns 0 for OK, 255 for no reply and 254 for command fail. | |
| - BYTE
|
Return |
|
|
Left |
| Rotates the robot left - waits for the angle to be traversed before returning | |
| - UINT
|
Angle |
| Angle to turn in degrees | |
| - VOID
|
Return |
|
|
ReadIR |
| Reads an IR sensor 0=Left, 1=FrontLeft, 2=Front, 3=FrontRight, 4=Right, 5=RearRight, 6=Rear, 7=RearLeft | |
| - BYTE
|
index |
| 0=Left, 1=FrontLeft, 2=Front, 3=FrontRight, 4=Right, 5=RearRight, 6=Rear, 7=RearLeft | |
| - UINT
|
Return |
|
|
LCDDrawPixel |
| Allows a single pixel on the LCD to be set or cleared | |
| - BYTE
|
X |
| X Pixel 0-127 | |
| - BYTE
|
Y |
| Y Pixel 0-31 | |
| - BYTE
|
State |
| 0=White (Off), 1=Black (On) | |
| - VOID
|
Return |
|
|
ServoSetPosition |
| Allows one of the servo positions to be assigned | |
| - BYTE
|
Channel |
| Range 0-3 | |
| - BYTE
|
Position |
| Range 0-255 | |
| - VOID
|
Return |
|
|
CardBitmap |
| Displays a monochrome bitmap read from the card on the LCD | |
| - BYTE
|
X |
| Range 0-127 | |
| - BYTE
|
Y |
| Range 0-31 | |
| - STRING
|
Filename |
| - BYTE
|
Return |
|
|
CardRecordMic |
| Records an audio stream on the card from the microphone | |
| - BYTE
|
BitDepth |
| 0=8-bit, 1=16-bit | |
| - BYTE
|
SampleRate |
| Sample Rate 0=8KHz, 1=16KHz | |
| - UINT
|
RecordTime |
| Time to record for in seconds, Range 0-65535 | |
| - STRING
|
Filename |
| - BYTE
|
Return |
|
|
CardOpen |
| Attempts to open an existing file on the SD card 255=Error, 1=File not found, 0=Open OK | |
| - STRING
|
Filename |
| - BYTE
|
Return |
|
|
Forwards |
| Drives the robot forwards - waits for the distance to be traversed before returning | |
| - UINT
|
Distance |
| Distance in mm | |
| - VOID
|
Return |
|
|
ReadBearing |
| Reads the compass bearing based on the degrees clockwise from magnetic north. | |
| [[File:]] - | Return |
|
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GetConsoleHandle |
| Gets the handle to the console allowing data displaying on the panel etc. | |
| [[File:]] - | Return |
|
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LCDDrawLine |
| Allows a single pixel width line to be drawn on the LCD | |
| - BYTE
|
X1 |
| X Pixel 0-127 | |
| - BYTE
|
Y1 |
| Y Pixel 0-31 | |
| - BYTE
|
X2 |
| X Pixel 0-127 | |
| - BYTE
|
Y2 |
| Y Pixel 0-31 | |
| - VOID
|
Return |
|
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ServoAutoMoveToPosition |
| Allows one of the servo positions to move gradually to a new position | |
| - BYTE
|
Channel |
| Range 0-3 | |
| - BYTE
|
Position |
| Range 0-255 | |
| - VOID
|
Return |
|
|
ReadAllValue |
| Reads a single value stored from the read all command Index dictates which sensor value to read | |
| - BYTE
|
Index |
| 0=SW, 1-8=IR, 9-10=Line, 11=Light, 12=Mic, 13-15=Accel | |
| - UINT
|
Return |
|
|
LCDBacklight |
| Allows the LCD backlight brighntess to be adjusted | |
| - BYTE
|
Intensity |
| Range 0-100, 0=Off, 1=Min Brightness, 100=Max Brightness | |
| - VOID
|
Return |
|
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LCDDrawRect |
| Allows a rectangle to be drawn on the LCD | |
| - BYTE
|
X1 |
| X Pixel 0-127 | |
| - BYTE
|
Y1 |
| Y Pixel 0-31 | |
| - BYTE
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X2 |
| X Pixel 0-127 | |
| - BYTE
|
Y2 |
| Y Pixel 0-31 | |
| - VOID
|
Return |
|
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ReadLine |
| Reads one of the IR line sensors 0-1 0=Left, 1=Right | |
| - BYTE
|
index |
| 0=Left, 1=Right | |
| - UINT
|
Return |
|
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ServoDisable |
| Allows one of the servo outputs 0-3 to be disabled | |
| - BYTE
|
Channel |
| Range 0-3 | |
| - VOID
|
Return |
|
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ServoEnable |
| Allows one of the servo outputs 0-3 to be enabled | |
| - BYTE
|
Channel |
| Range 0-3 | |
| - VOID
|
Return |
|
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CardReadByte |
| Reads a byte from the currently open file. Starts at the beginning of the file and auto increments to the end | |
| - BYTE
|
Return |
|
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CardErase |
| Attempts to delete an existing file on the SD card 255=Error, 1=File not found, 0=Delete OK | |
| - STRING
|
Filename |
| - BYTE
|
Return |
|
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CardWriteByte |
| Appends a byte to the end of the currently open file | |
| - BYTE
|
Data |
| - VOID
|
Return |
|
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EncoderRead |
| Reads one of the motor encoder counters. Approx 0.328296mm of travel per encoder unit. | |
| - BYTE
|
index |
| 0=Left, 1=Right | |
| - UINT
|
Return |
|
|
SetMotors |
| Sets the motor speeds without feedback Range -100 to 100 | |
| [[File:]] - | Left |
| Range -100 to 100 | |
| [[File:]] - | Right |
| Range -100 to 100 | |
| - VOID
|
Return |
|
|
Backwards |
| Drives the robot backwards - waits for the distance to be traversed before returning | |
| - UINT
|
Distance |
| Distance in mm | |
| - VOID
|
Return |
|
|
EncoderReset |
| Resets the motor encoder counters | |
| - VOID
|
Return |
|
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LCDVerbose |
| Allows the LCD to automatically report the API commands as they get processed. Default - verbose on | |
| - BYTE
|
State |
| 0=Off 1=On | |
| - VOID
|
Return |
|
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SetProp |
| Allows the COM port property to be set from a parent component. | |
| - STRING
|
PropName |
 - ULONG
|
PropVal |
| - VOID
|
Return |
|
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CardInit |
| Attempts to startup the SD card 255=No Card, 254=Init Fail, 0=Init OK | |
| - BYTE
|
Return |
|
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GetProp |
| Allows the property filter for the COM port list to be copied to a parent component. | |
| - STRING
|
PropName |
| - STRING
|
Return |
|
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LCDClear |
| Clears the LCD | |
| - VOID
|
Return |
Property reference
|
Properties |
|
Host |
| Address of MQTT Broker Can be an IP Address or URL (URL only supported by some hardware platforms) | |
|
Port |
| Port used by MQTT Broker Default 1883 for unencrypted access and 8883 for encrypted access. | |
|
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Client identifier |
| Client identifier (Maximum length 20 characters) Must be unique to the broker. | |
|
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Network Timeout |
| Maximum time in mS to wait for network responses | |
|
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Read Timeout |
| Amount of time in ms to wait for incoming messages. | |
|
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Keep Alive |
| The Keep Alive is the maximum time interval that is permitted to elapse between the point at which the Client finishes transmitting one Control Packet and the point it starts sending the next, measured in seconds. | |
|
Network Component |
| Pointer to the network communications component providing TCP simulation and abstraction for embedded TCP modules. | |
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Authentication |
| Selects if the broker is open or if the broker requires a username and password. | |
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Connections |
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Simulations |