480 volt hinder ethernet communication?

[tactical14]

I am trying to remotely connect into a device at my work. All the ethernet settings on the device are correct and this is verified by successfully pinging the device. Unfortunately I am unable to receive data back from the device. I have contacted the company's IT department and they basically told me they have no idea why it's not working and everything is set up correctly. My question is:

I am running the ethernet cable near some 480 volt (by near I mean 1 foot away) connections. Could the magnetic field of the 480 be causing the communication issues with the device? Any insight is greatly appreciated.

 

[Skogsgurra]

Ethernet cables are used in many industrial installations. The Profibus is essentially Ethernet and it is run in very noisy environments in large installations with frequency inverters in steel works and paper mills.

The magnetic field from a 480 V cable does not affect the signal quality.

What you may have a problem with is the termination. Be sure that you understand the need for it and that it is correctly made. There is also a restriction as to distance between drops. They shall not be too close. I have forgotten the actual limit, but if you are closer than a few feet, you may be getting problems.

If pinging works, then I think that your connection is OK. What about the remote device's ability to recognize the signal and respond to it?

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[FreddyNurk]

Pinging generally indicates that the device is powered up, has an appropriate IP address, and is capable of responding to ping requests. It does not, however, have any guarantee that anything else is not in the way.

As an example, ModbusTCP uses TCP port 502, thus depending on the company's IT architecture, it might be open to everything or all but ping is locked down. NMAP (google it, though be aware that some IT people consider it a hacking tool) can be a useful tool to check what ports are open on the device to confirm that its all operating correctly, but can also raise the ire of some IT people.

If you know the ports used by the protocol / communications method that you're using then you can ask the company's IT department to check if they're not blocking certain ports.

Best approach to start with is either get hold of a test device, or get yourself onto the same subnet as the device in question, and test for operation there. If the device in question has its own web server (port 80, secure port 443), this is a good start. If this works locally (i.e same subnet, or in its own isolated test network), but not across the network, generally its either a firewall or a routing issue.

Skogs is also pretty much right, if its responding to ping then chances are theres no cable interference.

 

[danw2]

>Could the magnetic field of the 480 be causing the communication issues with the device?

Yes, but not likely if the ping completes OK.

Assuming that you are using whatever software is designed to communicate with the appropriate ports enabled on your PC, what is much more likely is that a managed switch or router is blocking you.

When I run into 'can't connect' I do exactly what FreddyNurk advises - I take my laptop, a consumer grade unmanaged switch, a couple CAT 5 cables, and park myself next to the device, plug everything together and confirm that full comm works when I'm directly connected. When it does, then it's a network issue.

There's lots of corporate chatter about network security and isolation of production and process networks from office networks. Your plant might take this seriously. Are there two IT departments? One office, one production? Is your link crossing forbidden territory?

Network security can involve permission for specific MAC addresses to communicate with one another, is that the case? But no one's configured the releveant MAC addresses?

Sometimes a 2nd IT guy knows what the first one doesn't.