PLC Wifi Access

Martindag

Member
Join Date
Sep 2009
Location
quebec
Posts
227
Hey guys,

I'm using some BasicLine unmanaged switches from Weidmuller to give my PLC and HMI access to the company network connected with a ethernet cable to their server.
(I think it would be better to have my own control network and not share the same one from my company but its the way that we do it ).

I got antenna that give us access to the company network prety much everywhere. All they need is to give them a Mac adress of the device, they add it and i can connect to the network via the antenna.

That been said,

If i wanted to connect all my PLC and HMI using WiFi and my actual antenna, what would be the best option to do it ?

Is there a way to simply provide my unmanaged switch that i use and link them like to my company antenna ? like by using my own little antenna locally to my control panel or something ?

Thanks for your suggestion!
 
The answer is a hard "maybe". Hypothetically, yes that can be done. Wireless is usually OK for typical HMI update rates.

Depending on the wireless manufacturer, there may be some limits in place, either for security, or because of the limitations of the 802.11 protocol. I'd discuss what you want to do with the IT guys, to make sure they get the info they need to set it up on their end.
 
I would used managed switches, faster speed.

I would also give the plc's and hmi's a separate network away from the corporate side.

Keep programming software away from corporate people.
most of them will not know the process and how things work,
they will change timers, setpoints, counters and ending up breaking things.

james
 
Unless your HMI's are displaying tons of variables and refreshing super fast (and even if they are in most cases), Wifi is fine. You can get any router that has a client mode and connect it to your switch to give the whole switch access. Client mode uses the router wifi to connect to an existing wifi signal and make it available on its LAN ports and I use it all the time to connect PLCs and service PCs to plant wifi. Specifically, I use the TP-Link N300 which is USB powered and has good signal strength through a panel door, and connect it to the PLC USB port for power (most panels I'm in don't have 120VAC, let alone an outlet available).

I do this all the time to either connect a machine to the plant wifi or to provide wireless access to the machine for programming or VNC connection to the HMI.
 
When you say "you got the antenna", what does that mean exactly?

I would personally drop in a industrial VPN and be done with it. You get access to your gear on their network, even remotely, but it's isolated in a far more secure way via VPN. **** Cosy is popular. Automation Direct just released their StrideLink which I'm pretty excited about. Mine should be here today so I can get on with testing to start rolling those out to replace ****. Setup on the industrial VPN's are designed so that folks not well versed in networking can set it up in a few minutes and move on to more important things, while still getting all of the benefits. You could drop a stand alone firewall in (assuming you need internet / remote management on your PLC's), but then you have to deal with firewall rules and you also have to deal with corporate IT to have them do port forwarding to your gear. It's a giant pain in the ***. You don't have to deal with that with an industrial VPN.

I would suggest NOT using a managed switch. They're no faster than unmanaged switches in 99% of situations. L2 or L3 switches allow you to have a little more control, do routing, split traffic off to a VLAN, setup 802.3ad LAG's or LACP trunks, etc etc. But none of those will apply to you. The only real tangible benefit to a managed switch for you is going to be to do port mirroring for troubleshooting via Wireshark, but even that's a stretch. I find more often than not that people setting up managed swtiches who don't know what they're doing tend to make it worse than a simple unmanaged switch.
 
I would suggest NOT using a managed switch. They're no faster than unmanaged switches in 99% of situations. L2 or L3 switches allow you to have a little more control, do routing, split traffic off to a VLAN, setup 802.3ad LAG's or LACP trunks, etc etc. But none of those will apply to you. The only real tangible benefit to a managed switch for you is going to be to do port mirroring for troubleshooting via Wireshark, but even that's a stretch. I find more often than not that people setting up managed swtiches who don't know what they're doing tend to make it worse than a simple unmanaged switch.

We have moved to managed switches for our machine networks mostly because of the port and cable monitoring options of these switches, not because of speed. It allows us to see remotely if a particular link is up or down. Most of these switches can even tell at what approximate distance from the switch an issue with a network cable exists. Limitation of broadcast traffic has also proven useful for us in a few occasions. I do agree that it requires some networking knowledge - don't go there if you don't know what you are doing.
 
We have moved to managed switches for our machine networks mostly because of the port and cable monitoring options of these switches, not because of speed. It allows us to see remotely if a particular link is up or down. Most of these switches can even tell at what approximate distance from the switch an issue with a network cable exists. Limitation of broadcast traffic has also proven useful for us in a few occasions. I do agree that it requires some networking knowledge - don't go there if you don't know what you are doing.

To clarify, I wasn't saying managed switches are bad. But if you improperly set one up because you don't understand 80% of what is in it, you'll be chasing random issues around constantly.

The diagnostics that you get with it can be super helpful in a complex network though, as you mentioned. Most high end switches have time-domain reflectometer testing built in them now, pretty crazy how close that can get you to finding a fault in a cable, isn't it?
 
Managed switches are a must with todays Ethernet communications networks for IO/Drive/etc. Just being able to provide multicast filtering and IGMP snooping will reduce network clutter significantly.

If you want ring networks, you need managed switches.

There is no reason to use an unmanaged switch for anything anymore. May as well just put in stupid hubs.
 

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