How to Read Data With Modbus RTU

Modbus RTU Master Device connection to Modbus RTU Slave Device:

  • Select “Modules” category from menu.
  • Select “Driver” to connect Modbus RTU Slave Device.

  • In “Drivers” page, click plus '+' button to add new driver.

  • Name: Write any name you like to describe connection, for example Modbus_RTU
  • Endpoint: Write port=0 or port=1 to connect Modbus Slave Device. (port=0 → Upper USB Port. port=1 → Bottom USB Port.)
  • Type: Choose MODBUS RTU for connection type.
  • Driver Specific Options: After choosing MODBUS RTU type for connection, default driver specific options will be appear. Set correct port, unitId and other components. If default values are correct, leave it like that.

  • Then click “Save” button to establish connection.

  • To see connection established, select “Status” category from menu then click “Driver” option.
  • Driver name, last message and status are shown in this page, if connection is completed, green connected bar will be shown.

  • After connection established, tag must be added to driver. To do that:
    • Select “Modules” from menu, then click “Tag” option.
    • In “Tags” page, click plus “+“ button to add new tag.

  • “Details” page will be shown after clicked ”+” button.
  • In this page:
    • Name: Choose any name you like to describe tag.
    • Type: Choose proper type for data.
    • Address: Write tag address, to use proper tag address scroll down page and look for “Modbus Tag Format”
    • Address Prefix: You can write address prefix.
    • Conversion Script: In this area, you can do mathematical operations with tag.
    • Driver Name: Choose correct Driver for Driver Name. In this example, Modbus_TCP.

  • Click “Save” button to add tag.

  • After adding tag, to see connection established and coming datas, select “Status” category from menu then click “Tag” option.
  • In this page: Name, Last Value, Last Message, Last Update Time and Status will be shown
  • If tag is added to driver successfuly, green OK message will be appear under Status.
  • Last Value: Last data will be shown coming from connection.

TROUBLESHOOTING:

  • If connection is not completed successfully, follow these steps to test connection:

  • There is connection button, click and then select connect.

  • After that connection screen pop up,
  • Choose Modbus Serial Port for connection type
  • Set correct Serial Settings
  • Click RTU Mode.
  • Then click “OK” button.

  • Modbus master simulator is now connected successfully to Modbus slave device.