Connecting Ignition Modbus TCP to Modbus Serial Devices

Abstract

This tutorial details how to connect existing Modbus RTU devices over a serial network into the Ignition Modbus TCP driver using a third party serial to ethernet gateway.

For this tutorial we are using the MGate MB3170/MB3270 Series Gateway from Moxa which is readily available for purchase from Amazon.

MGate Topology and serial connections

The image below shows an example of how Modbus RTU Devices would be connected through the Moxa gateway.

The gateway uses male DB9 serial ports to connect to the Modbus RTU or ASCII devices.

Each port supports three serial interfaces: RS-232, RS-422 and RS-485 (both 2 and 4 wire) with the pinout shown below:

MGate Configuration

Initial Configuration Access

Moxa provide a Windows based utility that can be used to connect to the MGate and aid in configuring the unit. But the MGate also provides a native web UI that provides the same functionality from any operating system. Out of the box the MGate will have the following default TCP/IP address and default Account and Passwords:

Temporarily set your computer’s Ethernet domain to the 192.168.127.xxx domain. Once you have done that you should be able to open a web browser and then browse to http://192.168.127.254. That should result in the following web page to appear:

After you enter the default admin/moxa credentials you will be prompted to enter a new password. 

Setting a Static IP Address

Configuring the Serial Port