Using Ethernet Cable between devices whilst using WIFI network.

Hello,

Without too much information, I'm learning how to use Beckhoff hardware. I have a motor rigged up to a PLC that is programmable via Ethernet using a software called Twincat.

I'm a hardware person so hooking it up was no problem. But I'm venturing out into the world of PLC programming which I'm finding quite new and difficult. I use Google/ YouTube/ internet services to aid me in learning this.

The problem is, to connect with the PLC, my Ethernet port needs to be active. Whilst connected, (whilst programming) I'd like to connect to the internet via WIFI.

I've found a multitude of forums with instructions to change the priority of the network connections using metrics and all that, but none of the solutions allow me to connect to both.

Is it really impossible to connect with a device via Ethernet, whilst connected to the internet using WIFI?

I don't know the exact specs for all the different hardware cards on my laptop, but its a HP ZBook running windows 7.

Much obliged.

Thanks for your reply.

My laptop is connected to a Wi-Fi router. The PLC is connected directly with an Ethernet cable, from Ethernet port to Ethernet port so to speak.

When I plug in the Ethernet cable the Wi-Fi is disconnected. I know I can stop that happening by changing the interface metric to a lower number than the Ethernet connection, but doing that stops my connection to the PLC whenever Wi-Fi is active. So I effectively have the same problem in reverse.

Is your PLC on a different subnet from the WiFi because if its not you more than likely will have problems.

For example if your Wifi's IP is 192.168.0.X you could set your PLC to 192.168.10.X and after a few min's the computer should remember where it is.

Your best bet would be to grab a cheap router and have that take care of your internet and PLC. Did your ISP supply you with router with more than one lan jack because that would work to, instead of buying another cheap router

Sorry I should have specified;

The network is at work. I'm calling it the LAN because my company uses a LAN, in that I can login into any computer connected. When logged in I have access to my network drives and so on.

However we do have personal laptops so that I can store files on the laptop, whereby I can only access the files from that laptop. (this is probably all obvious I'm just trying to give you an accurate picture).

The 'LAN' is accessible via either WIFI (routers located throughout the building), or by Ethernet (again, ports located throughout the building).

Most of the time in my job I use large modelling files and transfer massive amounts of data around the network so my preference is to plug in with Ethernet. We have docking stations and everything it's all very good and easy.

But to program the PLC, it has to be connected using an Ethernet cable, and connected with Twincat (the programming software) as if in a network. But I'm totally useless at programming PLC's at the moment and I'm searching for videos and other literature online to help me learn, whilst doing it.

Isn't there a simple setting in windows, in order to listen to both the Ethernet port, and the Wi-Fi 'port'?

Technically I'm networking with the PLC, but it only needs to transfer data. It doesn't need access to the rest of the network, or the internet, or anything. It might as well be a USB connection. (accept it doesn't support a USB connection).

How can I tell what subnet its on? My apologies, I'm at the stage where the saying "A little knowledge is dangerous" definitely applies to me.

strollin said:

In case you missed what sml156 said because it was at the tail end of his reply, connect your PLC programmer to an ethernet port on your router instead of your PC. That will allow the PC to connect to the router via wifi but be connected to the PLC programmer via the router.

Since you say you prefer hardwire, you could connect both the PC and the PLC programmer to the router via ethernet. If your router has only one ethernet port or you don't have any free ethernet ports, you can use a switch to add more ethernet ports.

Thanks.

Your all giving me great advice I appreciate it. I think If I was at home this would be the perfect solution. I've tried connecting the PLC to the LAN, similarly to your advice, but I'm assuming the firewalls at work stop unknown devices from gaining access because It can't be found.

the PLC doesn't have its own UI, so I'm not even sure how I could go about logging it onto the network.

Thanks again. sorry for the essay posts by the way.

See image attached, hopefully that portrays what I'm trying to achieve more elegantly than I can type it.

Do you think its possible to connect with a router like you suggest, but then connect that router to the overall network of the building?

I remember at home a few years back I had a router connected to another router to boost the signal upstairs. (I had a spare router, and a not quite long enough wire to reach upstairs, so I put the other router at the top of the stairs to reach the bedrooms)
Might it be possible to connect one to the main network, effectively creating a sub network with just my laptop and the PLC on it?

Thanks again