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!
The Click Plus PLC has now been released. This can only be programmed with version 3.00 or higher of the Click Programming Software. Version 3.00 will program all of the Click PLC CPU units and add additional features to the Click Ethernet CPU units.
Features of the new Click PLUS PLC (C2-0xCPU) includes the following:
• Micro USB
• DHCP support
• DNS support
• Wi-Fi (programming and Modbus TCP)
• Bluetooth (Wi-Fi) provisioning
• SD Card (Data Logging)
• Data Logger
• Network Time Service
• MQTT (Publish/Subscribe)
• Required PLC Password
• Disable Ports
• Strong Password Support
• Disable Ping Response
• Encrypted Password Transfer
We will be installing version 3.00 of the Click programming software on our windows 10 computer. After starting the software we will review some of the new features. Let’s get started. Keep on Reading!
The click plc has a real-time clock that will allow us to control outputs based on a date or time of day. This real-time clock (RTC) can be set from the click programming software or through the program of the controller. Our programs in the click can use the following calendar and clock values:
SD19 – RTC Year – 4 digits (2021)
SD20 – RTC Year – 2 digits (21)
SD21 – RTC Month – (00 to 12)
SD22 – RTC Day – (00 to 31)
SD23 – RTC Day of the Week – 1 Sunday to 7 Saturday
SD24 – RTC Hour – (00 to 23)
SD25 – RTC Minute – (00 to 59)
SD26 – RTC Second – (00 to 59)
We will be using the RTC – Real Time Clock in a sample program. This program will turn on an output Monday to Friday from noon until 1 pm. It will also adjust for daylight savings time. Let’s get started. Keep on Reading!
The C-More EA9 Series of human-machine interfaces (HMI) provides a way for the operator to control and will perform a lot of additional items. The free programming software is very user friendly and fully featured. Here are some of the additional items that this robust and powerful HMI can do besides communicating to programmable logic controllers (PLCs).
Send Email – This includes authentication for the email client protocol
Log Data – This can log data files to the internal memory or an external thumb drive (32G)
FTP Server – Use file transfer protocol to retrieve information from the HMI to a network. This can be done automatically with a batch file.
Web Server – This HMI can be a web server on your network
Remote Internet Access – Windows, Android, and IOS operating systems have the ability to take advantage of this remote access to the HMI. The programs are free and fully functional.
Our sample CP1H PLC program will use buttons and indicators to control a start/stop jog circuit. An analog input into the PLC will be scaled and displayed on a gauge and numeric display on our HMI screen. We will also write information to our 7 segment display on the CPU from our HMI screen. Omron serial host link protocol will be used to communicate over an RS485 serial cable. We will demonstrate remote access using our windows and android device. Let’s get started. Continue Reading!
We will now look at the click plc modbus ascii protocol. This communication will happen in PLC ladder logic and communicate through the serial port (RS485) to a Solo process temperature controller. Modbus ASCII will be the communication protocol.
Modbus is a communication method used for transmitting information over serial lines between electronic devices. The device requesting the information is called the Modbus Master (Client) and the devices supplying information are Modbus Slaves (Servers). This protocol was originally developed by Modicon systems.
Modbus protocol comes in basically three different types. Ethernet (Modbus TCP) or Serial (Modbus RTU or Modbus ASCII). Modbus TCP and Modbus RTU come as standard protocols in the productivity series of PLCs.
We will connect the Click PLC to a Solo process temperature controller. This will be done using the Modbus ASCII protocol over serial RS485 communication wire. (Media) The present and set values (PV / SV) will be read from the Solo controller and the set value will be written when required. Let’s get started. Keep on Reading!