How does HMI communicate with PLC?

Human machine interface refers to the field where people and machines contact or interact with each other in information exchange and function. This joint surface includes not only the direct contact between point, line and surface, but also the action space of long-distance information transmission and control. So how does HMI communicate with PLC?

This is a delta human machine interface (HMI).

For communication between HMI and PLC, we need HMI, OMRON PLC, 24VDC power supply, data download line for HMI and PLC, communication line between HMI and PLC.

Wiring

1. Connect the 24VDC power supply to this HMI. And Omron PLC also requires 24VDC power supply. Yellow is 24V+, white is 0V.
2. There is a switch in the middle of the power cord to control on and off. RS232 interface is required for communication between HMI and PLC. Connect the communication line to COM2 of HMI, and on the RS232C interface of PLC.
3. Both the USB download of HMI and PLC use the printer data cable. Just plug the other end into the USB port of the PC.

Setting

1. Open DOPsoft and create a new project.
2. Select the corresponding HMI model and PLC model.
3. Set the communication parameters RS232, 8, 1, 38400, Even (note that it is the same as the PLC side, which will be described later).
4. After entering the page, we can also find the communication parameters just set from “communication” on the left.
5. After building the project, download to HMI.
6. The HMI screen has been updated from the bottom right corner.

PLC new project program

• Select the corresponding PLC model.
• Set the communication parameters in “Settings/ Built-in RS232C” To be consistent with HMI. (38400, 8, 1, E). (Note that we are using the Host Link protocol here.)
• Connect to the PLC and download the program and settings to the PLC.
• Restart the PLC.
• When the PLC communication light is always on or blinking continuously, it means that the HMI and PLC have successfully communicated.

View the video below to learn more details about HMI communicate with PLC.