Using Cellular to Go Remote

Now that the concept of remotely accessing manufacturing operations and assets has caught on — for reasons ranging from maintenance to production insights — more manufacturers are seriously rolling out remote access points. For the most part, manufacturers have quickly moved beyond the testing phase of remote access and are starting to use it as a regular part of their business and engineering operations.

As a result, the use of cellular technology for these connections has been attracting a lot of attention. In response to this, Siemens offered a special tips and tricks session at its 2013 Automation Summit to help users begin the process of incorporating cellular access points into their networks.

According to Siemens’ Ming Ng, some of the key points of advice users should follow include:
• First, check the cellular coverage in the area in which you’re looking to deploy the cellular routers. You can check this with various providers, such as at att.com/coverage. “This is really important,” says Ng, “because there’s a big difference between having a signal and having service. We’ve all experienced seeing signal bars on our phones but not being able to do anything. Just because you have a signal does not necessarily mean you have service.”
• Conduct an onsite survey of connections and upload/download speeds with iOS and Android apps such as opensignal.com. Most of these are free apps. “This is a good, empirical method for determining quality of the cellular service at the site.”
• Connection options. There are multiple ways to connect to most cellular modems. Using Siemens’ M875 3G/UMTS router as a reference point, Ng says, “the simplest option is to not use a VPN. To do this you’ll need a SIM card; but be aware that not all SIM cards are created equally. Don’t buy the SIM card for your industrial cellular router at the phone store down the street.” To do this kind of deployment, you’ll need a SIM card with the ability to connect to an APN (access point name).  To scale this for an industrial operation, you’ll get a special APN from your provider. The next step is to set up firewall rules and port forwarding on the modem so that it can act as a firewall.

“You can do actually control system programming over this non-VPN option, you just have to understand your security needs,” Ng adds.

Another connection option is via VPN from the cellular service provider. “These use private network SIM cards,” Ng says. “With this option, the use of different providers is limited but roaming is possible to some extent.”

A third option is with a private VPN where high levels of security are needed. “This is the most robust way to connect and do engineering remotely as if you were physically connected to the network at the site,” he says.

Ng says that Siemens offers an M875 demo with SIM card to customers looking to try out the APN method. He adds that further help is available at www.usa.siemens.com/scalancem to help M875 users get up and running with online guides and how to use the device.