(Optional) Add a Modbus Interface (TCP/RTU)

Owned by Nina Cardillo
Last updated: 28-Mar-2024
2 min read

You can use the SmartServer to integrate and manage Modbus devices.  If you are using Modbus TCP devices, you can interface with them using the SmartServer's built-in Modbus driver and the built-in LAN and WAN Ethernet interfaces.  If you are using Modbus RTU devices, you can interface with the using the SmartServer's built-in Modbus driver and the built-in isolated RS-485 interface.  The RS-485 interface is only available on the SmartServer IoT EX model.  If you do not have an EX model, you can also add an IOX I/O Expansion Module for a Modbus RTU compatible isolated RS-485 interface. 

Modbus RTU support for SmartServer Pi requires a USB to RS-485 bidirectional converter (e.g., https://www.waveshare.com/usb-to-rs485.htm).

With SmartServer 4.2 and higher, the Modbus driver is enabled by default for SmartServer IoT and disabled by default for SmartServer Pi. When the Modbus option is set to enabled, Modbus TCP and RTU are enabled; however, Modbus RTU also requires that the RS-484 interface is configured. When the Modbus option is set to disabled, Modbus TCP and RTU are disabled.

To communicate with a Modbus TCP or Modbus RTU device, follow these steps:

  1. If you are using a Modbus RTU device and the SmartServer IoT EX RS-485 interface, configure the interface as described in (Optional) Add a Modbus RTU Interface.

  2. Create a Modbus device interface (XIF) definition as described in (Optional) Creating a Modbus Device Interface (XIF) Definition.

  3. Create a device type definition for your device as described in Defining Device Types.

  4. Define datapoint properties for any datapoints to be monitored or logged as described in Setting Datapoint Properties.  You must define at least one datapoint per Modbus TCP device to be polled at least once every 90 seconds.  Device communication failures will occur if there is no communication with a Modbus TCP device due to TCP socket failure.

  5. Provision the device as described in Site Provisioning.

  6. Optionally, provide a LON interface for your Modbus device; see (Optional) Create a LON Interface for a Modbus Device. SmartServer Pi does not support LON.

  7. Optionally, provide a BACnet interface for your Modbus device; see Setting up the BACnet Server.  This enables you to use a BACnet workstation with your Modbus device.