Many questions come from serial communications using the Click PLC. Most of these questions deal with communication timing when using multiple send and receive instructions. We will show you how to deal with serial communication timing in the Click PLC.
Receive and Send instructions will allow you to send and receive serial data to an external device. The communication method that you set up can be ASCII or Modbus. ASCII (American Standard Communication for Information Interchange) can be used to send to devices such as a printer. Receiving ASCII can be used for connecting barcode scanners to the PLC. The barcode will be read as an ASCII string in the PLC. Modbus serial communication (Modbus RTU) is a standard protocol used in many automation devices.
We will demonstrate the Send and Receive instruction by communicating Modbus RTU to a Solo Temperature Controller. Parameters from the Solo process temperature controller will be read using multiple receive instructions. The send instruction will be used multiple times as well to set the Set Value (SV) and Limits of the SV value entered in the temperature controller. The set values will only be changed when required. 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!
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!
We will now look at the Click PLC Modbus TCP remote io. The Click PLC can use remote inputs and outputs from Stride. The Stride Field I/O Modules are simple and compact. They provide an economical means to connect inputs and outputs to an Ethernet Modbus TCP communication network. Every module operates as a standalone Modbus TCP server and can be configured via a built-in web server.
Previously we looked at the Stride Field Remote IO Modules Modbus TCP Ethernet wiring and configuration.
Stride Field Remote IO Modules Modbus TCP Ethernet|
– Unboxing SIO MB12CDR and SIO MB04ADS Video
– Powering and Configuring Video
We will be connecting two Stride remote inputs and outputs to the Click PLC. Modbus TCP will be the protocol over Ethernet to communicate to the SIO-MB12CDR and SIO-MB04ADS units.
– STRIDE discrete combo module, Input: 8-point, 12-24 VDC, sinking, Output: 4-point, relay, (4) Form C (SPDT) relays, 2A/point, (1) Ethernet (RJ45) port(s), Modbus TCP server.
– STRIDE analog input module, 4-channel, current/voltage, 16-bit, isolated, input current signal range(s) of +/- 20 mA, input voltage signal range(s) of +/- 10 VDC, (1) Ethernet (RJ45) port(s), Modbus TCP server.
We will be reading an analog voltage into the Click PLC from the remote IO unit. We will then set an output to pulse on and off at a time range indicated by this analog signal. The output will be on the other remote IO unit and will trigger the input to signal. We will look at the Frequency, Count, and Status of this input. Our Click PLC program will also take into consideration watchdog (communication time out) and power-up events for the Stride remote input and output units.
Let’s get started. Keep on Reading!
A PID (Proportional, Integral, and Derivative) control is possible with the Click PLC. The Click Programming Software version 2.50 now includes PID. This features 8 full-featured control loops with an easy graphical user interface (GUI). PID will run on all of the Ethernet-enabled Click PLCs.
We will be using this PID along with a Factory IO scene to demonstrate PID control and Autotuning using our Click PLC.
Here are some references on PID control:
PID without a Ph.D. By Tim Wescott
Understanding PID in 4 minutes
PID Control – A brief introduction
PID Controllers Explained
Who Else Wants to Learn about On-Off and PID Control?
Our Factory IO scene will be controlling the level of water in a tank. PID will be used to maintain the level based on a dial pot knob on the control panel. Let’s get started! Keep on Reading!