The industrial automation world is increasingly connected. One of the projects this week involved a remote desktop session with a customer in the Midwest , from my NC location. The two of us were trying to log in to a PLC located in Alabama through a cloud based service. This is when I realized the utility of the multi IP setting on gateway devices.
An increasing number of PLC, drives and HMI’s include Ethernet based protocols as standard. Many also allow program updates via the ethernet connection. This makes it easier to implement remote access solutions for troubleshooting and maintenance purposes. Set up the IP addresses for the control devices, use a gateway device from eWon, InHand Networks or Netbiter and you’re ready to go.
The Reason for Multiple IP Subnets on the Remote Network
Our PLC on this project was a Modicon M251. On this setup, for various reasons, the PLC program download for the M251 had to be through the Ethernet 1 port( M251 has two separate Ethernet networks embedded). The field devices connected to it ( drives, HMI) were on Ethernet 2. The customer wanted to retain access to the webservers of the field devices when they connected remotely. Occasionally they also needed to log in to the PLC and update the program.
So, in short, we had to connect to Ethernet 1 of the PLC but the gateway device had its IP settings set to the Ethernet 2 port.
To illustrate the setup:
Drives, HMI and PLC Ethernet network 2 located on the 192.168.3.xx subnet
PLC program download port on Ethernet network 1 located on 192.168.4.xx subnet
Multi IP setting on IG601
This is where the InHand IG601 multiple IP LAN could be useful. Typically, the gateway device would need to set to the same IP subnet as the PLC, HMI or remote network. When there are multiple subnets in the remote network then the gateway device would have to be changed to access each of the subnets. The IG601 solves this as it can be set up with multiple IP addresses. Both M251 ethernet networks were set up with the corresponding gateway IP address on the IG601 as the gateway address:
Ethernet 1 at 192.168.4.3 was set up to look at 192.168.4.1 which was set up as one of the IP’s on the IG601.
Ethernet 2 at 192.168.3.3 was set up to look at 192.168.3.1 which was set up as the other IP on the IG601.
In the IG601 configuration, the multi-IP setting is easily setup in the Network>LAN settings.
The multi-IP feature was tested on my test setup and worked well.
Items to look out for during the M251/SoMachine and InHand IG601 setup
1. If the M251 IP address is altered, it may take a power cycle for it to take effect. If possible, set this up and test it before shipping the PLC or while onsite with it.
2. The gateway IP address needs to be set up on the M251 for both ports- Ethernet 2 and Ethernet 2. On this note, try to set and follow rules of setting the gateway IP address on your remote systems. Example : use xxx.xxx.xxx.1 for the gateway IP …etc.
3. The setup of the IG601 was covered in a previous post about connecting to a Modicon M241. Having done this twice before, I still slipped up with one setting on the IG601. That is to set the cellular Access Number to *99***1# instead of leaving it blank. Not sure what this means but the system registered on the AT&T network after that setting was made.
Hope this helps save a controls engineer some energy and potentially hours/days of travel time just to perform a PLC program update or some troubleshooting. Thank you to the folks at InHand Network for their guidance on this back when I first set it up.
Amazingly, I went through this post without saying IoT or IIoT once. 🙂
Drop a line in the comments section below with questions or comments on this setup.
