Tag communication
Tag communication is mainly used for data exchange between controller layers. Controllers (including PLCs, touch screens, robot controllers, motion controllers, etc.) do not communicate with each other using actual memory addresses, but directly use tag variable names.
In particular, the use of tag communication between the touch screen and the PLC makes data exchange more intuitive and convenient.
The following example, using the communication between MC508 and LT2100T, illustrates the method of tag communication.
PLC configuration
1. Create a new project example_MC508_Tag Communication. In the device tree on the left, select "Application", right-click, and then click "Add Object". Select "Symbol Configuration", as shown in the following figure:
2. After the following window pops up, check the "Support OPC UA" feature, as shown in the image below:
3. Create a new variable and program in PLC_PRG as shown in Figure 1; then double-click "Symbol Configuration" in the device tree on the left to open the symbol configuration page, and then compile the project as shown in Figure 2 (communication with Chinese labels on the touch screen is currently only supported with Leadshine touch screens).
Figure 1: PLC_PRG Program Example
Figure 2: Opening the "Symbol Configuration" page
4. Then select the variables that need to be used for tag communication (all variables are selected in the example below, but only the variables that are needed should be selected in actual use), and then click "Generate Code", as shown in the figure below, to compile and generate the XML file for tag communication.
5. Open the directory where the "Example_MC508_Tag Communication" project is located. You will see the generated XML file, as shown in the figure below. This XML file is used to import the tag communication variables of the touch screen.
The PLC configuration is now complete. Compile the program and download it to the PLC, then press F5 to run it.
Touchscreen configuration
The following section uses the LT2100T touchscreen as an example to introduce the touchscreen configuration.
1. Open LT Studio V1.5 3 software, create a new HMI project "LT2100T_Tag Communication", select LT2100T, as shown in the figure below:
2. Click Next, select Static IP Address Assignment, and set the touchscreen IP address to be on the same network segment as the PLC, as shown in the following figure:
3. Click Next, select "Network PLC", click "Add", select the manufacturer "Leadshine", and the device type "Leadshine_EthernetTab"; set the PLC's IP address (the network port IP used by the PLC), the port number is 11740 by default and does not need to be modified, as shown in the figure below:
4. Click "Confirm" and wait for the new project to be generated; then click "Settings" in the menu bar - "Communication Settings" - "Local Connection", select "Network PLC", and double-click the device MC508; select the "Import Variables" label as shown in the following figure:
5. Select the XML document generated during the PLC compilation process, as shown in the image below:
6. Add a digital element to the touchscreen interface, select the corresponding label, and then confirm, as shown in the image below:
7. Add components one by one and select the corresponding labels. The touch interface is shown in the following figure:
8. Compile and download the touchscreen program to the touchscreen. Connect the PLC and touchscreen using a network cable. Click the switch on the touchscreen; the PLC's OUT0 and OUT1 lights will illuminate. This indicates that the touchscreen and PLC tags are communicating normally.
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