The Dilemma of Handling a Large Number
of Modbus Devices

The widespread adoption of the industrial Internet of Things (IIoT) has connected a massive number of serial devices to the Internet. However, configuring and handling multiple serial devices can be a herculean task. Take data centers, for example, where hundreds to thousands of serial-based Modbus meters communicate via the Modbus RTU protocol. These meters also need to be monitored and controlled in a control room, which uses Modbus TCP protocol. To transmit data from serial to Ethernet and convert Modbus RTU to Modbus TCP, a high-port-density Modbus gateway is usually the best option for connecting a large number of serial devices to a control room. However, more time and effort are required to plan and manage a lot of Modbus devices with regard to topology and connectivity. Moreover, engineers have to deal with possible connectivity errors when dispatching a large number of Modbus requests to serial devices that are connected to a Modbus gateway.

The Key Challenges of Modbus Routing

Configuring a large number of Modbus devices can be arduous. Unlike Ethernet switches, where routing is accomplished automatically through an ARP table, the routing mechanism for Modbus gateways with multi-serial ports is much more complicated. The main purpose of a routing table is to indicate which Modbus device (slave ID) is connected to which serial port on a gateway. Once a gateway receives a Modbus request for a specific Modbus device, it can dispatch this request via the referring routing table to the serial port that connects to the target Modbus device. The routing table needs to be maintained for troubleshooting and maintenance; however, creating and managing a routing table is laborious.




Auto-Device Routing

Dispatching Your Modbus Requests with One Click

Moxa is continuously developing technologies that are designed to address the problems and inconveniences experienced during the configuration of a large number of Modbus devices. With only one click, Moxa’s Auto Device Routing function (patent pending) helps Modbus gateways automatically detect Modbus requests from a supervisory control and data acquisition (SCADA) system and set up a slave ID routing table by themselves. Therefore, significant time and costs are saved because engineers don’t need to manually create the client ID routing table anymore. Furthermore, it eliminates the effort needed to double-check the actual connections at field sites. This leading-edge technology also does not require extra time or effort to refer to a historical mapping table when adding or removing Modbus devices.



Simplicity

Automatically detects multiple Modbus requests and creates the ID routing table with a simple click

Saves Time

Significant time and effort are saved without having to manually type in the IDs or double-check connections at field sites

Scalability

No extra effort is required to add, remove, or change Modbus devices in the future


White Paper


Engineers are constantly on the lookout for solutions that address the pain points of setting up multiple Modbus devices. This white paper takes a closer look at different routing technologies and their pros and cons, as well as a new technology that helps save time and costs when configuring and managing a large number of Modbus devices.

MGate MB3660 Series


  • 8 and 16-port redundant Modbus gateways
  • Agent mode gives a higher performance through active and parallel polling of serial devices
  • Auto-Device Routing function
  • Innovative Command Learning eliminates the need to key in SCADA Modbus commands (acts as an agent gateway)
  • Supports serial-to-serial (Master-to-Slave) communications
  • 2 Ethernet ports with the same IP or dual IP addresses
  • Dual VDC or VAC power inputs
  • 3-pin fault relay circuit for event alarms
  • 2 kV isolation protection (for -I models)