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Designer or ViSi: Modbus RTU How to Read Input Contacts


This codebase example demonstrates how a DIABLO-16 display module can be used as a Modbus RTU client or master device. The display module communicates with a Modbus RTU server or slave simulator software application running on the PC. The DIABLO-16 display module used in this codebase example is the uLCD-35DT. The Modbus RTU server/slave simulator software used is the pyModSlave.


This codebase example assumes the reader can program the 4D Systems display module using Workshop4 IDE designer environment. Beginners are advised to read the following aplication notes.

It is also assumed that the reader has a working knowledge of the Modbus RTU protocol.


Follow the procedure below to run this example. The reader is also advised to watch the accompanying video.

  1. Extract the content/s of the Workshop4 Project zip file to a folder.
  2. Open the project in Workshop.
  3. Compile the project source code and download or upload the program to the target display module (a uLCD-35DT in this codebase example).
  4. Download the Modbus RTU server/slave software application from here.
  5. Open and configure the Modbus RTU server/slave software application. See the video for details.
  6. Touch the display module to start the demo.


Project File