Abstract
This document describes setting up an OpenVPN connection that allows two FlexEdge devices to communicate through it via Modbus TCP.
Products
FlexEdge (DA50A and DA70A)
Use Case
Establishing a secure communications connection between multiple FlexEdge devices.
Required Software
Crimson 3.2 BUILD 3.2.0025.0 or later
Introduction
Using a VPN is a way to establish a secure connection between remote networks. Modbus is a common protocol used to communicate between Red Lion devices. Using them in combination allows secure communicate between multiple Red Lion devices located on remote networks.
OpenVPN Setup
Go to OpenVPN.net and create an OpenVPN account.
Go to users and create an OpenVPN connection for your computer.
Click on Networks and set up an OpenVPN profile for the DA50A device which is going to be the Modbus Master. 10.11.12.x is the subnet Ethernet 2 of DA50A device is on.
Similarly, set up an OpenVPN profile for the DA70A device which is going to be the Modbus Slave. 172.16.0.x is the subnet Ethernet 2 of DA70A device is on.
Click on the download icon and download the OpenVPN profile for both Master and Slave
And select “Download profile in .ovpn format'
Crimson 3.2 Configuration
Upload the .ovpn file in the Crimson database by navigating to Tunnels -> VPN1. Do this for both Master and Slave database.
Ethernet 1 port of both the Master and Slave databases are on 192.168.0.12 and 192.168.0.14 respectively with gateway address of 192.168.0.6 which is the LAN IP of the cell modem that they are connected to.
Ethernet 2 of Master is 10.11.12.31 and Ethernet 2 of Slave is 172.16.0.34. They are connected through an unmanaged switch.
Go to the system GUI of DA50A (Master) and ping the Slave to verify that VPN connection is established and similarly go to the system GUI of DA70A (Slave) and ping the Master. Below are screenshots showing the ping being successful.
With the VPN connection now established between the two devices, Modbus communication can now be set up to get a Master on 10.11.12.X subnet to talk to a Slave on 172.16.0.X subnet through OpenVPN connection.
Master Configuration
Slave Configuration
A tag could be configured to increment On Tick as shown below, this will provide a changing value to be monitored by the master device.
Proving Communications
Network Capture and web Interface of Master showing that Modbus comms is working correctly through OpenVPN. Tag 1 and Tag 2 are set up for Isdeviceonline () and Getdevicestatus ()
Wireshark Capture taken from the DA50A (Master) device with VPN1 set up as capture source and port number of 502.
Disclaimer
It is the customer's responsibility to review the advice provided herein and its applicability to the system. Red Lion makes no representation about specific knowledge of the customer's system or the specific performance of the system. Red Lion is not responsible for any damage to equipment or connected systems. The use of this document is at your own risk. Red Lion standard product warranty applies.
Red Lion Technical Support
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