Modbus RTU¶

The Modbus RTU driver in VC Hub communicates data with devices (typically PLCs, sensors or other industrial devices) via the COM port. The driver handles the underlying details of the Modbus RTU communication protocol and ensures that reliable serial data interaction between devices is possible.

Connecting to a Modbus RTU Device¶

1. On the "Devices" -> "Modbus RTU" page, click the "Add" button.
2. On the Add page, keep the default values and enter the following information in the following fields (Note: The following data is only an example, please fill in the fields according to the actual situation).
   • Name: test1
   • COM: 2
   • Baud Rate: 9600
   • Data Bits: 8
   • Stop Bits: 1 bit
   • Parity: None
   • Connection Timeout (ms): 10000
   • Read Data Timeout (ms): 5000
   • Write Data Timeout (ms): 2000
3. Click the "OK" button. The data will be displayed in the device list page of Modbus RTU.
4. Click the Enable button in the Enable Status column to enable the device. Configuration Fields

5.Click on the "Add Frame" button on the created device to add a frame to the current device.

• Frame: The frame is the same as a data frame in the Modbus protocol, it is the basic unit of data transmission, it is used to record the slave address, storage area, start and end address, data encoding format and frequency of data acquisition for data communication, and the I/O tags can be bound to the frame in the VC Hub program.

6.In the Add Frame screen, leave the default values and enter the following information in the following fields.

Note: The following data is only an example, please fill in the fields according to the actual situation

• Name: HoldingRegister1
• Slave Address: 1
• Function: Holding Register
• Start Address: 1
• Endind Address: 11
• Data Encoding: Big Endian
• Frequency (ms): 1000

7.Click the "OK" button. The data will be displayed under the previously created device.

Configuration Fields

Note:

1. In the device list, The Enabled Status indicates whether the device has been enabled or not, unenabled devices will not connect and enabled devices will try to connect; the Connection Status indicates whether the device has successfully established a communication connection with the system.
2. Enable All and Disable All are to enable or disable all data in the list.
3. The data code is not required when the function is a coil status and input status.
4. Connections are not shared between all devices.

Tag Binding¶

Bind a tag to the data of a Modbus RTU device.

1. Create an I/O tag.
   
2. On the add window, click the binding button of data source.
3. In the pop-up data source window, select the frame under the created Modbus RTU device and enter the following information in the following fields (Note: The following data is only an example, please fill in according to the actual situation).
   • Function: Holding Register
   • Address Range: 1 ~ 11
   • Data Type: UINT16
   • Address: 1
   • Bit: 1

Configuration Fields