Configuring a Modbus Device

In a Modbus configuration, a device represents a hardware device that communicates with the Modbus point manager over TCP/IP or a serial port (RS-232). The device is represented by its symbolic name and its channel and device type in combination with the unit identifier and other settings.

Setting up a device requires configuring its channel, device type, unit identifier, and scan rate.

To set up a device:

1. In Workbench, open your project and expand Data Connectivity > Modbus.

2. Right-click Address Space  and then select Add Device.

   You can also select Address Space and then click Add Device in the Edit section of the Home ribbon.

   

3. Name your new device. Make sure that the Enable checkbox is selected.
4. Select the communication Channel from the drop-down list. There is a predefined default channel. The channel specifies all the communication related parameters, such as TCP/IP or serial line settings, communication timeouts, and suspended mode settings.
5. From the Device Type drop-down list, specify the type of Modbus device. Various device types are predefined in the configuration. The device type specifies Modbus framing options and possible swapping options.

6. In Base Scan Rate, you set the rate (in milliseconds) at which the data will be polled from the device. Set a value of zero (0) to scan with the rate based on client-side requests.

   Fast scan rates may have an impact on a device's responsiveness.

7. In the Other Settings section, you can set the addressing of the registers and Modbus communication functions.
8. There are two ways of specifying the address space of your device:
   • By pre-configuring folders and data items under your device. Data items represent the values from the register map of your Modbus device.
   • By using a template. The folders and data items that are defined in the template are added to the device. For details, seeUsing Templates.
9. When you're done, click Apply & Close to close the window and create the device.