Cellular Modems

I have a project that is in a remote location. There will be a PLC and HMI in the panel and the customer wants to be able to monitor and even control the system over a Cell Modem.

I am planning on using a Red Lion HMI so it will have web access. My question is what do you recommend for a Cell Modem that will allow the customer to get into the HMI web page and do control?

The system is very simple so I dont anticipate a lot of pages in the HMI so not a lot of bandwidth will be required as they may look at the system once or twice a day.

I would appreciate your recommendations as I haven't messed with Cell Modems at all in my past.

Moxa have some options. I would personally pick a model that has VPN capability so you can secure it. Ideally your client would have a fixed IP at their head office and the cell modem vpn is set up to connect to that.

If they don't or thats too hard basket then you need a provider that can give you a fixed IP for your connection. That is often hard to find. Then your only option for providing a known address to connect to is a dynamic DNS service. The moxa units support this, but you need to set up and manage an account with the ddns provider.

If the moxa units are a bit dear then there are commercial grade 4G routers available now as well.

Four things to consider:

You need a consistently OK mobile signal with your chosen provider in the area of the machine.

A modem that will get you on to a mobile network.

A fixed address on the internet so that you know where to connect, or another method that I will mention later.

And you need security, just connecting a device to the internet is asking for a hacker to come and play.


The modem bit isn't a big issue, I go with Sierra modems because I know their firmware and they have proven reliable. There are plenty of other makes. For security you want one that has a NAT between the Internet and the machine, so the machine network is isolated from the internet. But not if you use the fixed IP address method. With the Sierra modem you can pay for a service that will keep you updated on the signal quality of the modem, it helps when you don't know why you suddenly can't connect to the remote site.


A fixed IP address also seems to be no big deal in the US, more of an issue in the UK. But I wouldn't bother with a fixed IP address I would use a system like the e.w.o.n (remove the dots), plenty of others that are similar. The machine creates a VPN tunnel to a server, you connect a VPN tunnel to the same server, the server connects the two ends together. You don't have to know or care about the machine IP address and you get a reasonable level of security at the same time.

this reminds me of a project I did a few years back. For a water authority. Kind of a backwoodsish town with very small plant. They didn't have internet at their plant, but they wanted to read the water level in their supply tank to then control the pumps at the plant. There was no way line-of-sight would work so we decided to go with 2 LTE cellular routers. We used the InHand brand, because we have good connections for them. They are a very industrial router that has a lot of configurations available. The one router has a static IP that we bought from Verizon for like $100. We created an IpSec VPN tunnel between the two. The nice thing about a static ip is that then you can log into the router to reboot, check logs or any other sort of troubleshooting unless you have lost 4G signal, then you are helpless.

Then the plcs are programmed for Modbus TCP/IP to share the data. So it is a little different than your application because we were not actually remotely viewing the HMI.
I have it programmed so that the Modbus connects every two minutes and pulls the water level. I have heartbeat signal as well so make sure the VPN didn't fail, and will send off comm alarms if so. The data usage is so low that i think our supplier even quit billing for the data usage because it wasn't worth their time to do the billing!

Multitech!!

Can support several different providers, VPN, they have their own server for automatic firmware updates, profile(configuration) changes, super reliable.

This modem is used in the medical industry to monitor remote heart patients, so it is very dependable.

Here's a good place to start I have used there products no problems and tech support is very good

https://multitech.com/

I've not used it (yet), but the wired version works well:

https://www.automationdirect.com/ad...PN/StrideLinx_VPN_Routers/4G_LTE/SE-SL3011-4G

plus1 for the E W O N, just used one to connect to my ClickPLC with Ease (Is this project related to the Click questions?)

There exist many 3g/4g routers with rj45 ethernet ports available at low cost, just a Google shopping search returns a lot results.

Due to the shortage of available public ip ranges some cellular providers assign private ip as the connected phones or modems were in a LAN.

Make sure the provider assign a public one, with a private one your remote equipment will be unreachable from outside.

The public Ip don't need strictly to be static. It can be dynamic if you contract a dynamic DNS service. Some routers have dynamic DNS configuration present on its configuration if not a daemon that periodically updates DNS can be run in a hmi windows computer or even in a cheap Raspberry pi running in the remote site.

Hope it will help

plus1 for the E W O N, just used one to connect to my ClickPLC with Ease (Is this project related to the Click questions?)

Click to expand...

Dan,
Yes and no. I am looking for a cell modem for a diffrent job that will use a ML1100 and a Red Lion HMI. The other job just has a moisture sensor (I posted about that too). I was thinking of using a Click for that but now thinking I just need a Cellular Modem/RTU combo. Any suggestions for that?

If you are thinking about a modem that can just transmit raw bytes for a RTU sensor then this is in nowdays an obsolete concept.

Cellular providers now offers an Internet connection, not a point to point byte transmission, then you need to solve how to transmit the RTU bytes over a TCP/IP connection, or directly change the sensor to other with TCP capabilities.

But also think about how to solve the security issue. The communication should be encrypted...

Bullzi said:

I have a project that is in a remote location. There will be a PLC and HMI in the panel and the customer wants to be able to monitor and even control the system over a Cell Modem.

I am planning on using a Red Lion HMI so it will have web access. My question is what do you recommend for a Cell Modem that will allow the customer to get into the HMI web page and do control?

The system is very simple so I dont anticipate a lot of pages in the HMI so not a lot of bandwidth will be required as they may look at the system once or twice a day.

I would appreciate your recommendations as I haven't messed with Cell Modems at all in my past.

Click to expand...

I have dealt with thousands of modems.



#1 Sierra Wireless RV50. Great modem, low power consumption, best modem in the business.


#2 Option Cloudgate. Lower cost, reliable modem. Simple interface but doesnt have onboard serial port, so if connecting to serial devices, have to add serial board which adds to cost and can be more confusing on setup.


If you are just doing a webpage, cloudgate would work great and you would save $100+ dollars. both are multi carrier, so either will do at&t or verizon.

Bullzi said:

Dan,
Yes and no. I am looking for a cell modem for a diffrent job that will use a ML1100 and a Red Lion HMI. The other job just has a moisture sensor (I posted about that too). I was thinking of using a Click for that but now thinking I just need a Cellular Modem/RTU combo. Any suggestions for that?

Click to expand...

Red Lion (sixnet) makes some cellular modems with IO, but you will probably spend more than buying a cloudgate and a click plc.

I have heard good things about Phoenix Contact "mGuard".
https://www.phoenixcontact.com/online/portal/us?1dmy&urile=wcmath:/usen/web/offcontext/insite_landing_pages/d3305227-6b9c-463b-88c6-d2d326ceb4b5/d3305227-6b9c-463b-88c6-d2d326ceb4b5