Category Archives: Remote Access

Multiple IP Settings, Modicon M251 PLC remote connections and the InHand Networks IG601

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.

Cellular Remote Access devices- eWon Cosy 131, InHand Networks IG601 and Netbiter EC350.
Cellular Remote Access devices- eWon Cosy 131, InHand Networks IG601 and Netbiter EC350.


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

Remote PLC gateway
Two ethernet networks and a cellular gateway. PLC program was to be updated remotely via the cellular gateway device.


 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 was set up to look at which was set up as one of the IP’s on the IG601.

Ethernet 2 at was set up to look at 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.

Multi-IP LAN setting
Multi-IP setting page on the InHand IG601

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 for the gateway IP …etc.

SoMachine Ethernet gateway address
Gateway addresses are set for both networks.

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.

Remember to enter the access number as shown. It made a difference on my setup.
Remember to enter the access number as shown. It made a difference on my setup.


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.


Remote PLC Connection: Connecting to a SoMachine M241 PLC using InHand Networks IG601 Cellular Gateway and Device Touch


The ability to connect to a PLC remotely (or HMI) and to pull data, access webservers and download programs is increasingly a requirement on industrial automation projects. Remote data access and program maintenance saves travel time to sites and simplifies daily operations. Some of the PLC features that enable this are:

  • Webserver on PLC and HMI: Allows data monitoring and some updates to PLC configurations


  • WebVisualization: These are customizable user interface pages that are embedded in the PLC. WebVisu is the CODESYS term for these HTML5 pages. Some examples of their usage from YouTube are noted here.


  • PLC Programming software remote gateway support: This is the ability for a PLC programming software to connect to remote Ethernet based devices. This could be for program downloads or regular program viewing.

This article will cover the steps for remotely connecting from the SoMachine PLC programming software to a remote M241 PLC. The InHand Networks IG601 cellular gateway device is used as the intermediary. Other examples of intermediary gateway devices may include Netbiter by HMS and eWon ( also by HMS now I believe).

Over the last few years, the criteria I have laid out for these devices have included the means to use them without the manufacturer’s cloud- based connection service. Simultaneously, keeping the option to route more secure connections through the cloud service, only when required, is a plus.


The criteria for the gateway device:


  • Ability to setup port forwarding at the gateway device
  • Ability to use a VPN connection for secure PLC program downloads
  • Ability to support a static IP at the gateway device and allow for the above mentioned VPN connection at the same time.

The InHand Networks IG601 meets these criteria. Getting this set up can be accomplished with two sets of steps. The InHand steps and the SoMachine steps.

InHand Networks Steps:


  1. Connect to the InHand Device Cloud at For initial setup, follow instructions per the Device Manager configuration video.


  1. Install Device Touch on the connecting PC. The installer is available in the Device Cloud portal. The next steps will assume proper setup of the Device Cloud and connection using Device Touch on the local PC. Instructions on Device Touch are available at the following link.


NOTE: While in the Device Cloud, be sure to set up a site, a device and the PLC. I forgot to add the ‘Controller’ once. It took some time and a call to InHand’s support team to figure it out.

InHand Device Cloud


  1. Open Device Touch on your computer and connect with your Device Cloud account. Once connected to the cloud. Connect to the specific site/gateway but selecting it and clicking on the ON/OFF slider bar.
Device Touch connection

SoMachine Steps

  1. In SoMachine, configure connectivity in the SoMachine gateway. The gateway is accessible by double clicking on the root of the controller directory in the device tree.
SoMachine Gateway setup for Remote PLC Connection
SoMachine Gateway

5. The connection method is set to IP address. In the example, the remote controller IP address was set to with a subnet mask of

IP Address connection mode

    6.  Per step 3 above, if Device Touch is active and the Maintenance Channel is on/ready (screen cap below), go to the Online menu and select Login.


IP Address Remote PLC
IP Address Connection Mode

NOTE: The update key on the gateway will not result in the detection of the controller in the Gateway list. Entering the IP address and selecting ‘Login’ actually triggers the process if searching for the device and placing it in the available controllers list in the Gateway. The Update button in the Gateway may not find remote devices. As such, the remote PLC may not show up even if by clicking on the Update button.



  1. The gateway will scan the remote network via the Device Touch adapter. Once the controller has been found, it will show up on the controller list in the gateway with a REM icon next to it.
Remote PLC detected

Note: The standard warning message indicating the pending connection to a controller will pop up prior to an actual login. Entering Alt-F will proceed with the connection and potential remote download of a program. Clicking the Cancel button will abort the connection.


Troubleshooting tip:

Should the remote controller not be detected using the IP address connection method above, restart the SoMachine gateway as shown in the screen cap below. Subsequently repeat step 4 above.

Restart SoMachine Gateway

Should questions or comments arise, put it in the comments section below.