The DHT11 is a digital temperature and humidity sensor. It uses a capacitive humidity sensor and a thermistor to measure the surrounding air and sends out a digital signal on the data pin (no analog input pins needed). Its simple to use, and the update timing of the sensor is about 2 seconds. Thermistor temperature circuits can be much quicker and are very accurate in measuring temperature.
We will be using the DHT11 sensor to measure temperature and humidity. A separate thermistor circuit will also be used to measure temperature on an analog input. This will be all done on our Arduino UNO R3 controller on our super starter kit. Let’s get started. Continue Reading!
We will now look at the data logging capability using our Click plus PLC.
Data logging is the collection of data over time. This is usually used for data analysis at a later time. The amount of data (System Information) stored and the frequency of the storage will depend on your specific application.
The hardware used to store the data is usually called a data logger. Using the information from our last post, the MQTT information collected (Temperature in Atlanta and Click Analog) will now be logged in two different ways. A micro SD card on the Click Plus will be used to store the data every minute in a CSV (Comma Separated Value) file. Node-RED will also be used to store the same data in a SQL database. Let’s get started on how to use these data loggers. Keep on Reading!
We will now look at the connection to our SQL database using a spreadsheet application. Previously we used Node-RED to communicate Modbus TCP and RTU to our Click PLC and Solo Temperature Controller. The information collected from the controllers was then put into an SQLite SQL database.
Spreadsheets like Excel are great for analysis of the data. We will be connecting to our SQLite SQL database with WPS spreadsheets. This will be accomplished by using an ODBC driver as the translator between the database and spreadsheet. Let’s get started. Continue Reading!
The ultrasonic sensor (HC-SR04) is great for all kinds of projects that need distance measurements. The HC-SR04 is inexpensive and easy to use. We will be sending signals directly to the sensor and interpreting the results without the need for a library.
Ultrasonic sensor module HC-SR04 provides a 2cm-400cm non-contact measurement function, the accuracy can reach 3mm. The modules include ultrasonic transmitters, receivers, and control circuits. We will be wiring the ultrasonic sensor to our Arduino UNO R3 controller on our super starter kit. Let’s get started. Continue Reading!
We will now look at the MQTT communication capability using our Click plus PLC.
MQTT stands for Message Queuing Telemetry Transport. This simple ‘publish and subscribe’ communication protocol, does not take too many resources.
Constrained devices with low bandwidth are ideal for MQTT. This protocol provides machine-to-machine (M2M) connectivity which is ideal for the Internet of Things. (IoT) This protocol is not for remote IO or real-time (deterministic) applications. MQTT is a good solution for applications that move data from hundreds or thousands of machines (sensors) to clients in many networks.
We will be installing a windows based broker called Mosquitto. The Click Plus PLC will be one of the clients publishing and subscribing to the MQTT broker. Node-RED will be the other client publishing and subscribing to the MQTT broker. Each client will share information. Let’s get started. Keep on Reading!